JPH09247375A - Picture reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely judge the size of an original without the effect of environment factors by judging the size of original based on the combination of a comparing result concerning a precisely obtained before shielding representative value and that concerning after shielding representative value. SOLUTION: A control part 54 controls the position of a carriage member so that the sensing area of a CCD line sensor 44 is at a prescribed position. Next, the control part 54 compares picture information at each small area obtained before a transparent member is shielded by a cover and a first threshold value with each other. Next, the control part 54 compares a representative value at each small area obtained after the transparent member is shielded by the cover and a threshold value set after the transparent member is shielded with each other. Then based on the combination of the comparing result by a comparing means at each small area, a size detection part 58 judges the size of the original on the transparent member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus for reading an image recorded on an original placed on a plate-shaped transparent member such as a platen glass.

[0002]

2. Description of the Related Art Conventionally, in a copying machine, the size of a document placed on a platen glass is detected, and the image recorded on the document is copied based on the detection result. There is known a technique for automatically determining a paper size, a copy magnification, and the like. The most general method for detecting the size of a document placed on the platen glass is to detect the size of the original below the platen glass as described in JP-A-61-20936. This is a method in which one or more sensors are arranged, the presence or absence of a document at the position where the photosensor is arranged is detected by the photosensor, and the size of the document is judged based on the detection result of the photosensor.

However, in the above-mentioned size detecting method, it is necessary to dispose the photosensors at different positions under the platen glass, corresponding to the originals of various sizes, and in reality, the photosensors can be placed on the platen glass. Since a large number of optical sensors are required corresponding to a large number of different document sizes, there is a problem that the configuration becomes complicated.

Further, in a copying machine (so-called digital copying machine), a facsimile machine or the like which converts an image recorded on a document into digital image data and then records (copies) the image on a sheet based on the image data. Generally, a configuration is provided in which a large number of photoelectric conversion elements such as CCDs arranged in a line are provided, and the image of the original is read by scanning the original with the photoelectric conversion elements. For this reason, in this type of device, it is also found that the original is scanned by the photoelectric conversion element before image reading (so-called pre-scan) and the size of the original is detected based on the signal output from the photoelectric conversion element. To be

In the above detection method, since the size of the original is also detected by the photoelectric conversion element provided for reading the image, a large number of originals are newly added in accordance with the number of types of originals placed on the platen glass. Although it is not necessary to provide a sensor, it is necessary to perform a prescan every time an original is placed, so that the prescan becomes a bottleneck in improving the processing capability of the apparatus (for example, the number of copies per unit time). was there.

By the way, the size of the original document on the platen glass is generally detected by assuming that the original document is placed on the platen glass when the platen cover is closed. Since the back side is usually white, the size of the document should be detected optically when the background of the placed document is white, that is, when the light reflectance of the document is close to the light reflectance of the back side of the platen cover. Becomes difficult.

Therefore, in order to improve the certainty of detecting the size of the document, it has been proposed to form a surface having a low light reflectance on the back surface of the platen cover or to make the back surface of the platen cover a color other than white. (See Japanese Examined Patent Publication No. 62-47026).

However, if it is assumed that the light reflectance of the back surface of the platen cover is obviously lower than the light transmittance of the original whose white background is white (for example, the back surface of the platen cover is gray, black, or a mirror surface), the original However, the so-called show-through occurs in which the density of the background portion of the copied image is increased as a whole. This show-through becomes remarkable especially when copying an image recorded on a paper such as tracing paper having a small thickness and a relatively high light transmittance.

Further, when the light reflectance of the back surface of the platen cover is made significantly lower than the light transmittance of the original whose white background is white, when the platen cover is closed and the original is read in the digital copying machine. , The part of the platen glass where the original is not placed is recognized as high density (for example, black), and the image is simply copied onto the paper based on the image data obtained by reading the original. In that case, a portion corresponding to a portion on which the original document is not placed in the copied image becomes, for example, solid black, which is not preferable.

In order to avoid this, for example, after prescanning is performed to detect the size of the original, the portion of the platen glass on which the original is not placed is determined based on the detected size of the original, and the original is detected. Of the signals output from the photoelectric converter at the time of reading, the signal output corresponding to the portion on which the original document is not placed is electrically masked, or the portion on which the original document is not placed So that the density becomes 0 (white) on the image data, it is necessary to automatically change the input / output characteristics when converting the signal output from the photoelectric converter into the image data, There was a problem that the configuration became complicated.

Further, in a conventional digital image reading apparatus, a document size detecting method for detecting a document size using a CCD image sensor has been proposed (Japanese Patent Laid-Open No. 62-76962 and Japanese Patent Laid-Open No. 5-207239). (See the official gazette).

However, in this method, when detecting when the platen cover is closed or when detecting by the reading operation with the platen cover open, the environmental factors in which the image reading apparatus is installed,
For example, there is a possibility that the document size may be erroneously detected due to the influence of outside light when the document size is set under a fluorescent lamp or near a window.

The present invention has been made in view of the above facts, and it is a first object of the present invention to provide an image reading apparatus having a simple structure and capable of detecting the size of an original in a short time. A second object is to provide an image reading apparatus that can accurately detect the size of a document without being affected by environmental factors.

[0014]

In order to achieve the first and second objects, the image reading apparatus according to claim 1 is a plate-shaped transparent member formed by a photoelectric converter having a large number of photoelectric conversion elements. An image reading device that optically scans a document placed on the document to read an image recorded on the document, and is movable to a shielding position that shields the transparent member and an exposure position where the transparent member is exposed. A cover and photoelectric conversion elements in a plurality of small areas corresponding to an area extending over a specific one side of each of a plurality of types of originals of different sizes placed at each substantially constant position on the transparent member. Representative value calculating means for calculating a representative value of image information in each small area based on a signal output from each, and a representative value of image information for each small area before the transparent member is shielded by the cover. And the first threshold value At the same time, a comparison means for comparing the representative value of the image information of each small area after the transparent member is shielded by the cover with a second threshold different from the first threshold, Size determining means for determining the size of the document placed on the transparent member based on the combination of the comparison results by the comparing means for each area.

In the image reading apparatus according to the first aspect of the present invention, when the image recorded on the original is read, the original is placed on the transparent member and the cover is moved from the exposed position to the shielded position. After that, the image reading is started by giving a predetermined start instruction (for example, a start button operation or the like).

According to the first aspect of the invention, a plurality of types of originals of different sizes placed at substantially constant positions on the transparent member are provided in a plurality of areas corresponding to an area extending over a specific side. The small area of is predetermined.

In the image reading apparatus according to the first aspect of the present invention, the representative value calculation unit calculates the representative value of the image information in each small area based on the signal output from each of the photoelectric conversion elements in the plurality of small areas. Can be calculated. That is, at the time of reading an image, the representative value calculation means calculates a representative value of image information in each small area (hereinafter referred to as a pre-shielding representative value) before the transparent member is shielded by the cover, and is transparent by the cover. After the member is shielded, a representative value of image information in each small area (hereinafter, referred to as a shielded representative value) is calculated.

The comparing means compares the calculated pre-shielding representative value with the first threshold value and compares the post-shielding representative value with the second threshold value.

Before the transparent member is shielded by the cover, the portion other than the original is generally black, but it may be slightly whitish due to the influence of external light. Therefore, in the comparison by the comparison means, if the first threshold value is set to a normal value, there is a possibility that a portion other than the original portion, which should be determined to be black, may be erroneously determined to be white. Therefore, it is desirable that the first threshold value is set to be slightly white to avoid the above situation.

Similarly, after the transparent member is shielded by the cover, the portion other than the original is generally white, but the outer edge and the central portion of the portion covered by the cover are affected by the external light. The whiteness may vary. Therefore, if the second threshold value is set to a normal value in the comparison by the comparison means, there is a possibility that a portion other than the original should be determined to be white, but it is erroneously determined to be black. Therefore, it is desirable that the second threshold value is set to be slightly blacker in order to avoid the above situation.

In the invention according to claim 1, the first threshold value and the second threshold value are set to be different from each other.
For example, since the first threshold value is set to the white side and the second threshold value is set to the black side, it is possible to prevent the erroneous comparison result from occurring. .

Then, the size judgment means compares the comparison result of the representative value before shielding and the comparison result of the representative value after shielding, which are accurately obtained in consideration of the influence of outside light as described above, for each small area. It is determined whether the small area is black or white based on the combination of, and the size of the document is determined from the determination result for each small area.

According to the first aspect of the present invention, the comparison result of the representative value before shielding and the representative value after shielding are accurately obtained in consideration of the factors of the environment in which the device is installed (external light etc.). Since the size of the original is determined based on the combination with the result of the comparison, the size of the original can be accurately determined without being affected by environmental factors.

Further, according to the first aspect of the invention, since the size of the document is determined as described above by using the photoelectric conversion element provided for reading the image recorded on the document, the size of the document is detected. It is not necessary to provide a large number of dedicated sensors, and the structure of the device can be simplified.

Further, since the prescan for detecting the document size is not required, the problem that the prescan becomes a bottleneck in improving the processing capability of the image reading apparatus (for example, the number of copies per unit time) is solved. You can

Next, the image reading apparatus according to a second aspect is the image reading apparatus according to the first aspect, wherein each small area before the transparent member is shielded while the document is not placed on the transparent member. The first threshold value is set based on the representative value of the image information for each of the image information of each small area after the transparent member is shielded while the document is not placed on the transparent member. It is characterized by further comprising threshold setting means for setting the second threshold based on the representative value.

In the image reading device according to the third aspect,
The image reading apparatus according to claim 2, wherein the threshold value setting means sets a first threshold value and a second threshold value for each small area.

According to the image reading apparatus of the fourth aspect,
3. The image reading apparatus according to claim 2, wherein the threshold value setting means is a representative value of image information for each small area before the transparent member is shielded in a state where the original is not placed on the transparent member, And a first value for each small area based on the difference between the maximum value and the minimum value in the representative value of the image information for each small area.
The threshold value of, and the representative value of the image information of each small area after the transparent member is shielded in the state that the original is not placed on the transparent member, and the image information of each small area The second threshold value is set for each small area based on the difference between the maximum value and the minimum value in the representative value of.

By the way, the before-shielding representative value and the after-shielding representative value of the image information calculated in the state where the document is not placed on the transparent member include the influence of external light as described above. Specifically, the pre-shielding representative value indicated by the curve K1 in FIG. 16 is close to “0” (black), but the smaller the region (# 1, # 8, etc.) closer to the outer edge is, the more pre-shielding is in the small region. The representative value becomes large (a little whiter).

Although the representative value after shielding shown by the curve L1 in FIG. 17 is close to "255" (white), the representative value before shielding in the smaller area is larger in the smaller area closer to the outer edge.

Therefore, in the image reading apparatus according to the second aspect, the representative value before shielding of the image information of each small area (that is, the outside light as described above) in the state where the document is not placed on the transparent member. The first threshold value is set on the basis of the pre-shielding representative value including the influence of 1. Specifically, it is possible to set an arithmetic mean value, a maximum value, a minimum value, an intermediate value, a mode value, etc. regarding the representative value before occlusion of the image information for each small area as the first threshold value.

Further, a table in which the pre-shielding representative value and the first threshold value which is obtained in advance and which is optimum for the pre-shielding representative value are associated with each other is stored in advance, and this table is referred to. , The first threshold may be set.

By thus setting the first threshold value based on the pre-shielding representative value including the influence of external light, the first threshold value can be set in consideration of the influence of external light. And the first representative value of the image information for each small area (in the state where the original is placed on the transparent member) before the shielding by the comparison means and the first
The comparison with the threshold value of can be performed accurately after reducing the influence of environmental factors.

Similarly to the above, with respect to the second threshold value, the masked representative value of the image information of each small area (that is, the outside By setting it based on the after-shielding representative value including the influence of light, it is possible to set the second threshold value that takes into account the influence of outside light. The shielded representative value of the image information for each small area (in the mounted state) and the second threshold value can be accurately compared with the influence of environmental factors being reduced.

Further, in the image reading apparatus according to the second aspect, as in the invention according to the third aspect, the threshold value setting means sets each small area in a state in which the original is not placed on the transparent member. If the first threshold value is set for each small region based on the before-shielding representative value of image information for each (that is, the before-shielding representative value including the influence of external light as described above), It is possible to set an appropriate first threshold value in consideration of the influence of outside light for each small area, and for each small area (when the original is placed on the transparent member) by the comparison means. The comparison between the representative value of the image information before occlusion and the first threshold value for each small area can be performed more accurately after further reducing the influence of environmental factors.

The setting of the second threshold is also
When each small area is set as described above, it is possible to set an appropriate second threshold value in consideration of the influence of external light in each small area for each small area. The comparison between the masked representative value of the image information for each small area (when placed on the transparent member) and the second threshold value for each small area was made to further reduce the influence of environmental factors. Can be done more accurately above.

Further, in the image reading apparatus according to the second aspect, as in the invention according to the fourth aspect, the threshold value setting means sets each small area in a state in which the original is not placed on the transparent member. The pre-shielding representative value of each image information (that is, the pre-shielding representative value including the influence of external light as described above) and the difference between the maximum value and the minimum value of the pre-shielding representative value (that is, the maximum influence amount by the external light). )
Based on the above, the first threshold value may be set for each small area. That is, after the value based on the representative value before shielding of the image information for each small area in the state where the document is not placed on the transparent member is obtained for each small area, the value obtained for each small area is set to the value obtained. , By adding the difference between the maximum value and the minimum value of the unshielded representative value (maximum influence by external light), a more appropriate first threshold value that takes into account the maximum influence by external light in each small area is obtained. It can be set for each small area. This allows
The comparison means compares the unshielded representative value of the image information for each small area (when the original is placed on the transparent member) with the first threshold value for each small area as an environmental factor. This can be performed more accurately after further reducing the influence of.

Regarding the setting of the second threshold value,
As described above, the image information for each small area (when the original is placed on the transparent member) by the comparison means is set by taking into account the maximum influence of external light for each small area. It is possible to more accurately compare the representative value after shielding with the second threshold value for each small area after further reducing the influence of environmental factors.

Next, an image reading apparatus according to a fifth aspect is the image reading apparatus according to any one of the first to fourth aspects, wherein the first threshold value and the second threshold value are set. It is characterized by further comprising threshold changing means for changing each of the values to a desired value.

According to a sixth aspect of the present invention, in the image reading apparatus according to the fifth aspect, the time zone in which the changed first threshold value is valid and the changed second threshold value are effective. It is characterized by further comprising an effective time zone setting means for setting each of the time zones for which is effective to a desired time zone.

According to the image reading apparatus of the seventh aspect,
The image reading apparatus according to any one of claims 1 to 6, wherein a surface of the cover facing the transparent member when the transparent member is shielded is white.

Since the image reading device according to the fifth aspect has the threshold value changing means, even when the image reading device is installed, for example, directly under a fluorescent lamp or at a window into which sunlight is inserted. , The user uses the threshold changing means
By changing the threshold value and the second threshold value to desired values, it is possible to prevent erroneous detection of the document size.

Further, since the image reading device according to the sixth aspect has the effective time zone setting means, the image reading device is installed at the window and is installed in a specific time zone (for example, in the morning when the sun rises or in the west). When there is a possibility that the external light may affect the effect of the external light such as the evening when the sun is shining, the user uses the effective time zone setting means to activate the first threshold value or the second threshold value. The band can be set to a desired time period. As a result, the changed first threshold value and second threshold value are validated in a desired time zone, and it is possible to appropriately respond to changes in the environment over time.

Furthermore, in the cover according to the present invention, the surface facing the transparent member when the transparent member is shielded is white as in the invention described in claim 7, so that the effect of show-through on the image quality is eliminated. Therefore, the size of the original can be accurately determined.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIG. 1 shows an external view of an image reading apparatus 10 according to the present embodiment. The image reading device 10 includes a box-shaped housing 12.
A lid-shaped document table 14 that closes the upper opening of the housing 12 is attached to the upper part of the. The document table 14 includes a platen glass 16 which is a plate-shaped and rectangular transparent member, and a rectangular frame-shaped registration guide plate 18 which is arranged on the outer periphery of the platen glass 16. In the present embodiment, the size of the portion of the platen glass 16 exposed from the registration guide plate 18 is made substantially equal to the A3 size.

As shown in FIG. 3, the height of the upper surface of the registration guide plate 18 is higher than that of the platen glass 16, and the position corresponding to the left rear corner of the platen glass 16 in FIG. A document alignment mark 20 is provided. The document has a platen glass 16 in which the surface on which the image is recorded faces the platen glass 16 side, and one of the four corners of the document is located at a position where the document alignment mark 20 is provided. Corresponding to the corners of the original and 2
It is placed on the platen glass 16 so that its side comes into contact with the inner side surface of the registration guide plate 18 (see the document 21 shown in FIG. 3). As a result, the document is placed at a substantially constant position on the platen glass 16 regardless of its size.

A platen cover 24 (corresponding to the cover of the present invention) is attached to the housing 12 via a pair of hinges 22 on one long side. The platen cover 24 can be rotated by a hinge 22 between an upright position (fully open position) shown in FIG. 2A and a position (not shown) at which the document table 14 is completely closed (fully closed position). It is said that. A rectangular platen cushion 26 is attached to the back side of the platen cover 24 (the side facing the platen glass 16). The platen cushion 26 is a platen glass 1
The surface of the surface facing 6 is white, and consideration is given to eliminate the influence of so-called show-through on image quality.

An angle sensor 28, which is an on / off switch and is provided so that the mover projects from the document table 14, is mounted near the position where the one hinge 22 is provided. The angle sensor 28 shown in FIGS.
Only the mover of is shown. The mover of the angle sensor 28 is movable in the longitudinal direction, and is provided with a biasing means (not shown) such as a spring, which is shown in FIGS.
It is held at the position shown in (A), and at this time, the angle sensor 28 is in the off state. When the platen cover 24 is rotated from the fully open position shown in FIG. 2 (A) to the fully closed position by a predetermined angle or more, as shown in FIG. 2 (B), the mover of the angle sensor 28 is placed on the back surface of the platen cover 24. By contacting and pressing, the angle sensor 28 changes to the ON state before the platen cover 24 is rotated to the fully closed position (in the state shown in FIG. 2B).

As shown in FIG. 2, the platen interlock sensor 3 is provided on the rear surface of the platen cover 24 at the end opposite to the end where the hinge 22 is attached.
0 is attached. Platen interlock sensor 3
0 is configured to be in an off state when the platen cover 24 is not in the fully closed state and to be in an on state when the platen cover 24 is in the fully closed state.

As shown in FIG. 3, a scanning device 32 is provided in the housing 12. The scanning device 32 includes a lamp 34 that emits light toward the platen glass 16, a first reflection mirror 36 that reflects the reflected light from the platen glass 16 side substantially horizontally, and a light emission of the first reflection mirror 36. A second reflection mirror 38 which is disposed on the side and which emits light incident from the first reflection mirror 36 downward along a substantially vertical direction;
The third reflection mirror 40 is provided on the light emission side of the second reflection mirror 38 and reflects the light incident from the second reflection mirror 38 substantially horizontally. An image forming lens 42 and a CCD line sensor 44 as a photoelectric converter of the present invention are provided on the light emitting side of the third reflecting mirror 40.

FIG. 3 is a sectional view taken along the long side direction of the platen glass 16, where the lamp 34 and the reflection mirror 3 are shown.
6, 38, 40 and the imaging lens 42 extend from one end of the platen glass 16 to the other end along the short side direction of the platen glass 16 (direction orthogonal to the plane of FIG. 3; hereinafter referred to as main scanning direction). The CCD line sensor is provided by extending the light from the lamp 34 toward the platen glass 16 and the light reflected from the platen glass 16 side through the reflection mirrors 36, 38, 40 and the imaging lens 42. The light imaged on the light receiving unit 44 is a slit-like light elongated in the main scanning direction.

The CCD line sensor 44 is provided with a large number of cells (photoelectric conversion elements of the present invention) arranged at a constant density along the main scanning direction, and along the main scanning direction on the light receiving portion of the CCD line sensor 44. The received light amount at each position is converted into an electric signal by each cell and output.

Further, the lamp 34 and the first reflecting mirror 3
6 is a sub scanning direction (arrow S in FIG. 3) orthogonal to the main scanning direction.
Direction), and is mounted on a carriage member 46 that is capable of reciprocating in the housing 12 in the same direction, and the second reflecting mirror 38 and the third reflecting mirror 40 are also mounted in the housing 12 along the sub-scanning direction. It is attached to a carriage member 48 capable of reciprocating inside. These carriage members 4
Reference numerals 6 and 48 are connected by a wire (not shown), and are structurally adjusted so that the optical path length until the light reflected by the original 21 reaches the light receiving portion of the CCD line sensor 44 is constant. In addition, these carriage members 46 and 48
Is moved in the sub-scanning direction by the carriage member driving unit 50 (see FIG. 4).

As shown in FIG. 4, the carriage member driving section 50 is connected to the control section 54, and the operation is controlled by the control section 54. The control unit 54 is configured to include a microcomputer and the like.

When the image of the original document placed on the platen glass 16 is read, the control unit 54 causes the carriage member drive unit 50 to move the carriage member 46 at a predetermined speed in the sub-scanning direction, and at the same time, to move the carriage. Member 4
8 is moved in the same direction as the moving direction of the carriage member 46 at a speed half the predetermined speed. Platen cover 2
When 4 is in the fully closed state, the light emitted from the lamp 34 is reflected by the document 21 placed on the platen glass 16 or the surface of the platen cushion 26 that is in close contact with the platen glass 16. Therefore, by moving the carriage members 46 and 48 as described above,
The optical path length from the lamp 34 to the CCD line sensor 44 is constant regardless of the position of the carriage member 46 along the sub-scanning direction.

As shown in FIG. 4, the angle sensor 28 and the platen interlock sensor 30 are connected to the control unit 54, and the detection results of each sensor are input to the control unit 54. Further, the lamp 34 is connected to the control unit 54, and the blinking of the lamp 34 is controlled by the control unit 54. The CCD line sensor 44 is connected to the control unit 54 via the CCD driver 56 and the size detection unit 58.

Further, the control unit 54 includes a keyboard 64 for the operator to input a desired threshold value and the like, and a display 62 for displaying a value input from the keyboard 64, a message from the control unit 54 and the like. A start button 66 for the operator to instruct execution start of the image reading process is connected. The keyboard 64 is provided with a Yes key 6 for the operator to affirmatively respond to the inquiry message displayed on the display 62.
4A and a No key 64B for making a negative response are provided.

The size detecting section 58 receives various signals and data including synchronizing signals such as video clock signals and line synchronizing signals from the controlling section 54 (the contents of the signals and data will be described later). The video clock signal input to the size detector 58 controls the CCD line sensor 44 via the CCD driver 56. The CCD line sensor 44 operates at a timing synchronized with the video clock signal, and sequentially outputs a signal indicating the amount of light received by each cell at a timing synchronized with the video clock signal. The signal output from the CCD line sensor 44 is amplified by the CCD driver 56, converted into digital image data, and output to the size detection unit 58.

Further, an optical sensor 60 for detecting the orientation of the document is connected to the size detecting section 58. The optical sensor 60 is arranged below the platen glass 16, and as shown in FIG. 5, the document is placed sideways on the platen glass 16 (the direction in which the long side direction coincides with the longitudinal direction of the platen glass 16: SEF). ), The original exists regardless of the size of the original (B5, A4, B4, A3, etc.), and the original is oriented vertically on the platen glass 16 (the long side direction is the short side of the platen glass). Direction that matches the direction: LE
When placed on F), it is arranged at a position where the presence or absence of a document can be detected at a predetermined position (a position shown as “# 0” in FIG. 5) where the document does not exist regardless of the size of the document. .

The image reading apparatus 10 described above constitutes a part of a digital copying machine (not shown), and the image of the original read by the image reading apparatus 10 is copied onto a sheet by the copying machine. The size and orientation of the original document determined by the image reading apparatus 10 (details of determination of the original document size and orientation will be described later) are used for selection of paper and determination of copy magnification.

Next, the operation of the first embodiment will be described. In the standby state where the document is not read (including the document size determination), the control unit 54 controls the CCD line sensor 4
The positions of the carriage members 46 and 48 are controlled so that the sensing area 4 is located inside the boundary between the registration guide plate 18 and the platen glass 16 by about 20 mm in the sub-scanning direction (the range shown by hatching in FIG. 5). (So-called home position). As is apparent from FIG. 5, the length of the sensing area of the CCD line sensor 44 along the main scanning direction is slightly longer than the length of the platen glass 16 along the main scanning direction.

Further, in the first embodiment, eight sensing areas shown by # 1 to # 8 in FIG. 5 are defined as the sensing areas of the CCD line sensor 44 used when determining the size of the original. . As shown in FIG. 5, each sensing area is C when a document of various sizes is placed vertically or horizontally on the platen glass 16.
The position is determined in consideration of the position on the platen glass 16 of a specific side of the document that crosses the sensing area of the CD line sensor 44.

That is, sensing areas # 2 and # 3
When a B5 size document is placed sideways on the platen glass 16, one side of the document that crosses the sensing area of the CCD line sensor 44 (side 6 shown in FIG.
4A) are located at predetermined intervals so as to be sandwiched therebetween. In addition, sensing areas # 4 and # 5 are A
A specific side of the document that crosses the sensing area of the CCD line sensor 44 when a 4 size document is placed horizontally and when an A5 size document is placed vertically (the side 64B shown in FIG. 5). The respective positions are determined so as to be sandwiched at predetermined intervals.

The sensing areas # 6 and # 7 are
A specific side of the document that crosses the sensing area of the CCD line sensor 44 when the B4 size document is placed horizontally and the B5 size document is placed vertically (the side 64C shown in FIG. 5). The respective positions are determined so as to be sandwiched at predetermined intervals. Further, the sensing areas # 1 and # 8 are slightly inside the two long sides of the original document that traverses the sensing area of the CCD line sensor 44 (when the A3 size original document is placed sideways). (Slightly inside the position where the ends of the registration guide plate 18 cross the vicinity of both ends of the sensing area)
Each position is defined so that

In the following, the CCD line sensor 44 will be described.
Of the two locations where the sensing area and the edge of the cash register guide plate 16 intersect, the location near the sensing area # 1 is the first cash register position, and the location near the sensing area # 8 is the second cash register position. (See also FIG. 6).

FIG. 6 conceptually shows the light receiving portion of the CCD line sensor 44. In the first embodiment, sensing areas # 1 to # 8 are provided on the light receiving portion of the CCD line sensor 44 corresponding to the sensing areas # 1 to # 8 shown in FIG.
(Corresponding to a plurality of small areas of the present invention) is predetermined. Each of the sensing areas # 1 to # 8 includes a plurality of pixels (= cells, which are 34 in FIG. 6) arranged in the main scanning direction.
Cells). In the present embodiment,
The number of pixels from the pixel corresponding to the first registration position is the position on the light receiving portion of the CCD line sensor 44 corresponding to the position on the platen glass 16 of the side crossing the sensing area of the CCD line sensor 44 of various sizes of originals. It is converted into (the number of cells) and obtained in advance (see FIG. 6).

The controller 54 controls the CCs corresponding to the size of each sensing area and the position on the platen glass 16 of the side that crosses the sensing area of the document of various sizes.
A value obtained by converting the distance from the first registration position to the position where each sensing region starts to the number of pixels, which is obtained based on the position on the light receiving portion of the D line sensor 44, is stored (see the table below as an example). 1), and outputs this data to the size detection unit 58 as a sensing start position (sensing start position S _n : n is the number of the sensing area).

[0069]

[Table 1]

As will be described later, the size detector 58 compares the image data output from the cells in each sensing area with a threshold value, sets the comparison result in the status register, and outputs it to the controller 54. . The control unit 54 outputs the above-mentioned threshold value determined for each sensing area to the size detection unit 58, and when the size detection unit 58 wants to hold the value of the status register, it sends a register hold signal to the status register. When it is desired to reset the register value, a register reset signal is output.

Next, the signal generation processing will be described with reference to the flowchart of FIG. In this signal generation process, in order to detect the size of the document placed on the platen glass 16, the control unit 54 releases the hold of the value of the status register by the register hold signal, and further outputs the register reset signal. When output, size detector 58
Run on.

In step 100, 1 is substituted for the sensing area number n, 0 is substituted for the counter s and the counter v, and the levels of the sensing area signal and the video sampling signal (both of the signals inside the size detecting section 58) are set to low. Initialization processing such as setting the level (“L”) is performed.
In the next step 102, it is determined whether or not the level of the line synchronization signal input from the control unit 54 has become a high level (“H”). If the determination is negative, the process waits until the determination is affirmed. .

The CCD line sensor 44 synchronizes the signal from each cell from the cell located at the end on the side corresponding to the first registration position side in the main scanning direction in synchronization with the video clock signal. The output is repeated in order. The above-mentioned line synchronization signal becomes high level at the timing synchronized with the signal output from the cell corresponding to the first registration position as being input as image data to the size detection unit 58 via the CCD driver 56. Until the signal output from the cell corresponding to the second registration position is input to the size detection unit 58 as image data via the CCD driver 56, it is held at a high level as shown in FIG.

When the level of the line synchronization signal becomes "H", the affirmative decision in step 102 results in step 104.
Then, the process waits until the video clock signal input from the control unit 54 rises (becomes a high level). In the next step 106, the value of the counter v is counted up, and in the next step 108, it is determined whether or not the value of the counter v is equal to the value of the sensing start position S _n . If the determination is negative, the process returns to step 104, and step 10 is performed until the determination of step 108 is positive.
Repeat 4 to 108.

In the above, the counter v holds the number of clocks of the video clock signal after the level of the line synchronization signal becomes “H”, that is, the number of pixels input as image data to the size detection unit 58. By comparing the value of the counter v with the sensing start position S _n , it is determined whether the input of the image data of the sensing area #n has started.

If the determination in step 108 is affirmative, the level of the sensing area signal (see FIG. 8) is set to "H" in step 110, and the value of the counter v is substituted into the variable v ₀ in the next step 111. At 112, the process waits until the video clock signal rises. Step 114
Then, it is determined whether or not the level of the video sampling signal is "H". In this case, the determination is negative, the value of the counter v is counted up in step 118, and the value obtained by subtracting the value of the variable v ₀ from the value of the counter v is “3” in step 120.
4 ”(“ 34 ”is the number of pixels (cells) forming a single sensing area).

If the determination is negative, step 12
The value of the counter s is counted up by shifting to 2, and it is determined in step 124 whether the value of the counter s is "3". If the determination is negative, the process returns to step 112 and steps 112 to 124 are repeated. Step 12
When the process of 2 is executed three times, the determination of step 124 is affirmed, the level of the video sampling signal (see FIG. 8) is set to “H” in step 126, the value of the counter s is reset to 0 in step 128, and Return to 112. In this case, the determination is affirmative in step 114 after passing through step 112, the process proceeds to step 116, and the level of the video sampling signal is set to "L", and then step 118 is performed.
Move to.

As described above, while the image data from each cell in the sensing area #n is being input, that is, while the determination at step 120 is denied (while the level of the sensing area signal is "H"). As shown in FIG. 8, every three cycles of the video clock signal, the level of the video sampling signal becomes "H" during the next one cycle.

When the determination in step 120 is affirmative, it is determined that the image data input from each cell in the sensing area #n is completed, and the level of the sensing area signal is set to "L" in step 130, and the next In step 132, it is determined whether or not the sensing area number n is “8”, that is, whether or not the image data of all areas of the sensing areas # 1 to # 8 have been input. When the determination is negative, the value of the sensing area number n is incremented in step 134, the process returns to step 102, and the processes of step 102 and subsequent steps are repeated. Then, when the determination in step 132 is affirmative, the processing ends.

Next, with reference to the flowchart of FIG. 9, the area sensing process executed in parallel with the above-described signal generating process in the size detecting section 58 will be described. In step 140, initialization processing such as substituting 1 for the sensing area number n is performed. In step 142, the process stands by until the video clock signal rises, and in the next step 144, it is determined whether or not the level of the line synchronization signal is "H". If this determination is negative, the procedure returns to step 142, and step 14 is continued until the determination of step 144 is positive.
Repeat steps 2 and 144. When the determination in step 144 is affirmed, it is determined in step 146 whether the level of the sensing area signal is “H”. If the determination is negative, the process returns to step 142, and steps 142 to 146 are repeated until the determination of step 146 is positive.

When the determination at step 146 is affirmative, the routine proceeds to step 148, where it is determined whether or not the level of the video sampling signal is "H". If the verdict is denied,
In step 150, the process stands by until the video clock signal rises, and in the next step 152, it is determined whether or not the level of the sensing area signal is "H". If the determination in step 152 is negative, step 148
Return to If the determination in step 148 is affirmative, in step 154, the image data for one pixel input from the CCD driver 56 is fetched and stored in a memory or the like, and in the next step 156, the process waits until the video clock signal rises, and then step Return to 148.

As described above, while the level of the sensing area signal is "H", the level of the video sampling signal is set to "H" for the next one cycle every three cycles of the video clock signal. Therefore, in the above description, of the 34 pixels forming the single sensing region, only the data of 8 pixels of ~ shown by hatching in FIG. 6 are fetched and stored.

When the acquisition of the image data from the single sensing area is completed, the determination in step 152 is denied, and thus the process proceeds to step 158, and the processing described above captures the image data from the sensing area n and stores it. The average value of the data of the individual pixels is calculated. Next step 160
Then, the average value calculated in step 158 is calculated by the control unit 54.
It is determined whether or not the value is larger than the determination threshold value of the sensing area #n input from.

If the determination in step 160 is negative, the average value of the amount of light received by each cell in the sensing area #n is less than or equal to the threshold value, so in step 162 the status register corresponding to the sensing area #n. A value (“1”) indicating that the amount of received light is low (that is, “black”) is set in the bit of (1), and the process proceeds to step 166. If the determination in step 160 is affirmative, the average value of the amount of light received by each cell in the sensing area #n is larger than the threshold value.
A value (“0”) indicating that the amount of received light is high (that is, “white”) is set in the bit of the status register corresponding to, and the process proceeds to step 166.

In step 166, the sensing area number n
Is "8", that is, whether or not the above processing has been performed for all the sensing areas # 1 to # 8.
If the determination is negative, the value of the sensing area number n is incremented in step 168 and then step 1
Returning to step 42, the above-mentioned processing after step 142 is repeated.

When the determination in step 166 is affirmative, the process proceeds to step 170 and the signal output from the optical sensor 60 is fetched. In the next step 172, it is determined whether or not the level of the signal taken in from the optical sensor 60 is higher than a predetermined threshold value.

If the above determination is negative, the amount of light received by the optical sensor 60 is less than or equal to the threshold value.
In 4, the value (“1”) indicating that the amount of received light is low (that is, “black”) is set in the bit of the status register corresponding to the optical sensor 60, and the process is ended. If the determination in step 172 is affirmative, the optical sensor 60
Since the amount of received light of is larger than the threshold value, step 176
Then, a value (“0”) indicating that the amount of received light is high (that is, “white”) is set in the bit of the status register corresponding to the optical sensor 60, and the process is ended.

As described above, a value is set in each bit of the status register depending on whether or not the amount of light received by each cell in the sensing areas # 1 to # 8 and the photosensor 60 is larger than the threshold value. become.

Next, the document size determination process executed by the controller 54 will be described with reference to the flowchart of FIG. The document size determination process is executed in a standby state where the document is not read, and the carriage members 46 and 48 are at the home position.
The sensing area of the D line sensor 44 is also located in the range shown by hatching in FIG.

In step 180, the angle sensor 28
Is in the off state (the platen cover 24 is open from the fully closed state by a predetermined angle or more). If the determination is negative, it is determined in step 182 whether the start button for instructing the start of copying the original has been pressed. If the determination in step 182 is also denied, the process returns to step 180, and until any of the above determinations is affirmed,
Repeat steps 180 and 182.

Here, if the determination in step 182 is affirmed by pressing the start button, it is determined whether or not the document is placed on the platen glass 16 and whether the document is placed. Since it is difficult to accurately detect the size of the document, it is determined that the size cannot be detected in step 184, and the process ends. In this case, the user selects the size of the recording paper and the like.

On the other hand, if the determination in step 180 is affirmative because the angle sensor 28 is in the off state, it is determined in step 186 whether the start button has been pressed, and if the determination is negative, the step is determined. At 188, it is determined whether the angle sensor 28 has been turned on (whether the platen cover 24 has been once moved to the open position and then turned toward the fully closed position to be in the nearly closed state). If this determination is also negative, the process returns to step 186, and step 18 is repeated until one of the above determinations is affirmed.
Repeat steps 6 and 188.

When the determination in step 188 is affirmed by turning on the angle sensor 28, the lamp 34 is turned on in step 190, and in step 192, the light amount of the lamp 34 is stabilized for a predetermined time (for example, 20 m).
Wait) In the next step 194, the hold register is set to "1". As a result, the size detector 58 is instructed to release the hold of the data set in the status register, and a register reset signal is output. In the next step 196, the data set in the status register by the area sensing process described above is read, and in step 198 the hold register is set to "0". As a result, a register hold signal is output and the data set in the status register is held.

At the next step 200, it is determined whether or not all the bits of the status register are "1"("black"). The processing of steps 190 to 198 described above is performed before the platen cover 24 is in the nearly closed state, that is, before the fully closed state, and the light emitted from the lamp 34 and reflected on the surface of the platen cushion 26 is in the CCD line. Sensor 4
Since almost no light is incident on the platen 4, if the original is not placed on the platen glass 16, the sensing areas # 1 to #
The amount of light received by each cell in 8 and the photosensor 60 is less than or equal to the threshold value, and "1" is set in all bits of the status register.

Therefore, if the determination in step 200 is negative, that is, if at least one of the bits of the status register is "0", the process proceeds to step 214 and the base is white or white on the platen glass 16. It is determined that an original of a similar color is placed (there is a white original), and in the next step 216, the orientation and size of the original on the platen glass 16 are determined based on the value of each bit of the status register, and the processing is performed. finish.

In this step 216, the detection results by the sensing areas # 1 to # 8 and the optical sensor 60 represented by the status register are "document present" if the value of the corresponding bit of the status register is "0". If "1", it is replaced with "no document", and the size and orientation of the document are determined according to the following Table 2.

[0097]

[Table 2]

However, in Table 2, "○" means "there is an original", "x" means "there is no original", and "-" means "there is original" but "no original". Indicates that the judgment result is not changed (that is, Don't Care). Although Table 2 does not use the detection result of the sensing area # 1 for determining the size and orientation of the document, the detection result of the sensing area # 1 indicates whether the document is correctly placed on the platen glass 16. That is, any one of the four corners of the original corresponds to the corner of the platen glass 16 located at the position where the original alignment mark 20 is provided,
In addition, it is used to confirm whether or not the two sides of the document are placed on the platen glass 16 so that the two sides of the document come into contact with the inner surface of the registration guide plate 18.

In the above, since the size and orientation of the document is determined without moving the sensing area of the CCD line sensor 44, the sensing area of the CCD line sensor 44 is moved along the sub-scanning direction to scan the document. The process is completed in a shorter time than in the case of determining the size and orientation.

On the other hand, if the determination in step 200 is affirmative, that is, if all the bits of the status register taken in when the platen cover 24 is almost closed are "1", the original is placed on the platen glass 16. Since the original is not placed on the platen glass 16 or the original with a black background is placed on the platen glass 16, step 218 is performed.
Then, it is determined whether or not the start button has been pressed after shifting to.
When the determination in step 218 is negative, it is determined in step 220 whether the platen interlock sensor 30 is turned on (the platen cover 24 is in the fully closed state). If this determination is also negative, the process returns to step 218, and step 21 is performed until one of the above determinations is affirmed.
Repeat steps 8 and 220.

If the start button is pressed before the platen cover 24 is fully closed and the platen interlock sensor 30 is turned on, the platen glass 1
6 No original is placed on the platen glass 1
Since it is not possible to determine whether or not a document whose black background is black is placed on the sheet 6, it is determined in step 234 that there is no document and the process ends. The platen glass 16
If there is no original placed on the platen glass 16
When it is not possible to determine whether a document with a black background is placed on it, instead of determining that there is no document, it may be determined to be undetectable.

On the other hand, when the platen cover 24 is fully closed and the platen interlock sensor 30 is turned on, the routine proceeds to step 222, and at steps 222 to 226, the status register is stored in the same manner as at steps 194 to 198. The set data is taken in, and it is determined in the next step 228 whether or not there is a bit whose value is "1" in the status register.

When the determination in step 228 is executed, when the platen cover 24 is almost closed,
Since all the bits of the status register are "1", it is possible to exclude the possibility that an original having a white background or a color close to white is placed on the platen glass 16.
Since the surface of the platen cushion 26 is white, when the platen cover 24 is fully closed, the platen glass 16
If no original with a black background or a color close to black is placed on top, all bits of the status register are "0".
(White).

Therefore, if the determination in step 228 is negative, it is determined in step 234 that there is no document, and the process ends, but if the determination in step 228 is negative, the process proceeds to step 230 and the platen is moved. It is determined that an original with a black or near black color is placed on the glass 16 (there is a black original), and in the next step 232, on the platen glass 16 based on the value of each bit of the status register. The orientation and size of the document are determined, and the process ends. In step 232, the detection results of the sensing areas # 1 to # 8 and the optical sensor 60 represented by the status register are “no document” and “1” if the corresponding bit value of the status register is “0”. If so, the document is replaced with "document present" and the size and orientation of the document are determined according to Table 2 above.

On the other hand, if the start button is pressed before the angle sensor 28 is turned on (while the platen cover 24 is still open), the determination at step 186 is affirmative and the process proceeds to step 202. 202-21
At 0, the same processing as the above steps 190 to 198 is performed,
In step 212, it is judged whether all the bits of the status register are "1". Even when the platen cover 24 is in the open state, as in the case of the above-described closing, if the document is not placed on the platen glass 16, each cell and light in the sensing areas # 1 to # 8 is detected. The amount of light received by the sensor 60 is less than or equal to the threshold value, and "1" is set in all bits of the status register.

Therefore, if the determination at step 212 is negative, the routine proceeds to step 214, where it is determined that "white original exists", and at step 216 the original size and orientation are determined. If the determination in step 212 is affirmative, it is not possible to determine whether the original is not placed on the platen glass 16 or the original whose black background is placed on the platen glass 16. In step 234, it is determined that there is no document, and the process ends.

Table 3 below summarizes the determination of the presence / absence of a document in the above processing.

[0108]

[Table 3]

As described above, in the first embodiment, since the CCD line sensor 44 determines the size and orientation of the original document, a large number of sensors are newly provided to detect the size and orientation of the original document. No need. Further, since the size and orientation of the document is determined without moving the sensing area of the CCD line sensor 44, the size and orientation of the document are determined by scanning the sensing area of the CCD line sensor 44 along the sub-scanning direction. The processing is completed in a shorter time than the case where the pre-scan is performed.

Further, when the sensing is performed with the platen cover 24 closed, and the detection results of the sensing areas # 1 to # 8 and the optical sensor 60 are all “black”, the platen cover 24 is completely removed. Since the presence / absence of the original is determined by performing the sensing even when the original is closed, even if the original having a black background or a color close to black is placed on the platen glass 16, the orientation and direction of the original are not detected. The size can be detected accurately.

Further, when the size of the original is judged using the signals output from all the cells of the CCD line sensor 44, a large-capacity memory is used to store the level of the signals output from each cell. Although it may be necessary to use the above, the above uses only the signals output from the cells in the sensing areas # 1 to # 8, and therefore it is not necessary to provide a large capacity memory or the like.

Further, in the above, for the size detection unit 58,
Since the sensing start position is input from the control unit 54 as the position of the sensing region, even when the position of the sensing region is changed with the change of the size of the document to be detected, the size detection unit is controlled by the control unit 54. The position of the sensing area can be easily changed by changing the sensing start position input to 58. Therefore, even when the size of the document to be detected is changed, it is not necessary to change the position of the sensor or perform prescan.

In the first embodiment, when the sensing is performed while the platen cover 24 is in the closed state and any one of the detection results of the sensing areas # 1 to # 8 and the optical sensor 60 is “white”. Has determined the size and orientation of the original by determining that "the original is white". However, even when the platen cover 24 is fully closed, sensing is performed to determine the size and orientation of the original. Good.
In this case, although not normally possible, any one of the sensing areas # 1 to # 8 and the detection result of the optical sensor 60 is “white” in the sensing in the closed state, and the sensing area # in the sensing in the fully closed state. It is logically possible that any one of the detection results of 1 to # 8 and the optical sensor 60 becomes “black”, but in the above case,
It is conceivable that "white" or "black" is detected from the image recorded on the original, and the placement position of the original is displaced while the platen cover 24 is in the closed state to the fully closed state. It is desirable to determine that there is a document.

Now, the operation of the invention according to claim 1 or 2 will be described. Before executing the document size determination process of FIG. 10 described above, the operator uses a common threshold value in the nearly closed state and the closed state as a threshold value used in the document size determination process. The keyboard 64 is used to instruct execution of a mode setting process for selecting and setting "mode" or "separation mode" using different threshold values. By this instruction, the control unit 54 starts executing the control routine of the mode setting process shown in FIG.

The common threshold data th0 used in the "common mode", the closing state threshold data th1 and the closed state threshold data th2 used in the "separation mode" are stored in the control unit. RO in 54 microcomputer
M is stored in advance. Among them, the common threshold value data th0 is set to “127”, and the closing state threshold value data th1 is closer to white than “127”.
The closed state threshold value data th2 is set to be closer to black than “127”.

First, in step 252 of FIG. 11, a message “Do you want to use common mode?” Is displayed on the display 62. The operator who saw this display
If you want to use the "common mode", the keyboard 64
Press the Yes key 64A provided on the
If you want to use, press No key 64B.

When the operator presses the Yes key 64A or the No key 64B, an affirmative decision is made in the next step 254 and the operation proceeds to step 256, where the pressed key is the Yes key 64
It is determined whether it is A or not. Yes by operator
If the key 64A has been pressed, the routine proceeds to step 266, where the threshold data is rewritten to the predetermined common threshold data th0 and the processing is terminated.

On the other hand, the operator presses the No key 64B.
If is pressed, a negative determination is made in step 256 and the process proceeds to step 258, and "Do you want to use separation mode?"
Is displayed on the display 62. When the operator sees this display and wants to use the "separation mode", the Yes key 6 provided on the keyboard 64
When 4A is pressed and it is considered that it is better to use the "common mode" as a result of reconsideration, the No key 64B is pressed.

When the operator presses the Yes key 64A or the No key 64B, an affirmative decision is made in the next step 260, the flow proceeds to step 262, and the pressed key is the Yes key 64
It is determined whether it is A or not. If the No key 64B has been pressed by the operator, the procedure returns to step 252,
On the other hand, if the Yes key 64A has been pressed, the routine proceeds to step 264, where the separation mode threshold value setting process shown in FIG. 12 is activated and the process ends.

The threshold value setting process for the separation mode of FIG. 12 started up as described above is continuously executed thereafter, and is executed in parallel with the original size determining process when the original size determining process of FIG. 10 is executed. It

In such a separation mode threshold value setting process, whether or not the state of the platen cover 24 has changed in step 272 of FIG. 12 is checked by the ON / OFF state of the angle sensor 28 and the platen interlock sensor 30. The platen cover 24 is monitored based on the on / off state.
Only when there is a change in the state of, go to step 274,
It is determined whether the platen cover 24 is in a state of being closed. When the platen cover 24 is in the nearly closed state,
Proceeding to step 280, the threshold value data is rewritten to the predetermined threshold value data for closing state th1.

On the other hand, if the platen cover 24 is not closed, the process proceeds to step 276 and the platen cover 2 is closed.
It is determined whether or not 4 is in the closed state. If the platen cover 24 is in the closed state, the process proceeds to step 278 and the threshold data is rewritten to the predetermined closed state threshold data th2. Meanwhile, the platen cover 24
Is not nearly closed or closed, the process returns to step 272.

By the processing of FIG. 11 explained above, the operator can set a desired mode, and when the separation mode is set, the processing of FIG. 12 causes a threshold value depending on the state of the platen cover 24. The data is automatically rewritten to the threshold value data for closing state th1 or the threshold value data for closing state th2. Then, the rewritten threshold value is used in step 160 of the area sensing process (FIG. 9) described above.

As described above, the threshold value data th1 for the closing state is whiter than the standard value "127", and the threshold value data th2 for the closed state is blacker than the standard value "127". Since it is set, it is possible to prevent erroneous black and white determination due to the influence of external light in the area sensing process, and it is possible to accurately determine the document size.

[Second Embodiment] Next, a second embodiment of the present invention will be described. The second embodiment corresponds to the invention described in claim 3, and here, from the image data of each sensing area in the state where the document is not placed on the platen glass 16, the threshold value thA for the closing state and An embodiment for calculating the threshold value thB for the closed state will be described.

Since the second embodiment has the same configuration as the first embodiment, the same reference numerals are given to the respective parts and the description of the configuration will be omitted. In the following, the operation of the second embodiment will be described. To do.

In the second embodiment, before executing the document size determination process of FIG. 10, the operator sets a threshold value setting process for setting a threshold value used in the document size determination process. Is instructed by the keyboard 64. By this instruction, the control unit 54 starts executing the control routine of the threshold value setting process shown in FIG. First, in step 302 of FIG. 13, the message “Please close the platen cover and press the start button” is displayed on the display 62, and in the next step 304, the start button 66 is pressed with the platen cover 24 closed. To monitor.

When the operator presses the start button 66 while the platen cover 24 is in the closed state, the process proceeds to step 306, and the subroutine of the process for calculating the closed state threshold value shown in FIG. 14 is executed.

In step 322 of FIG. 14, the image data of each sensing area is read, and in the next step 324, the average value D of the read image data of each sensing area.
Calculate _AVE . Then, in the next step 326, the threshold value thA for the closing state is calculated based on the following equation (1), the calculated value is stored, and the process returns. thA = (D _AVE +255) / 2 (1) As a result of the above-described closing threshold value calculation process, as shown in FIG. (Value shown by arrow A2) is calculated as the threshold value thA for closing state.

In the next step 308 in the main routine of FIG. 13, the message "Please close the platen cover and press the start button" is displayed on the display 6
2, and in the next step 310, it is monitored that the start button 66 is pressed with the platen cover 24 closed.

When the operator presses the start button 66 with the platen cover 24 closed, the routine proceeds to step 312, where the closed state threshold value calculation processing subroutine shown in FIG. 15 is executed.

In step 332 of FIG. 15, the image data of each sensing area is read, and in the next step 334, the average value D of the read image data of each sensing area.
Calculate _AVE . Then, in the next step 336, the closed state threshold value thB is calculated based on the following equation (2), the calculated value is stored, and the process returns. thB = (D _AVE +0) / 2 (2) By the above calculation processing of the threshold value for the closed state, FIG.
As shown in FIG. 7, the threshold value t for the state in which the value closer to the black (the value shown by the arrow B2) than the normal threshold value “127” is closed
Calculated as hB.

At the next step 314 in the main routine of FIG. 13, the separation mode threshold value setting process shown in FIG. 12 similar to that of the first embodiment is activated and the process is terminated.

By the threshold value setting process of FIGS. 13 to 15 described above, based on the image data of each sensing area when the original is not placed on the platen glass 16,
The threshold value thA for closing state and the threshold value thB for closing state can be automatically calculated. Further, in the threshold value setting process for the separation mode (FIG. 12) started in step 314, the threshold value data is automatically closed according to the state of the platen cover 24 or the threshold value thA for the state is closed or closed. The state threshold value thB is rewritten and used in step 160 of the area sensing process (FIG. 9) described above.

In the above embodiment, the average value D _AVE of the image data of each sensing area is calculated, and the average value D _AVE is calculated.
_{Although the} threshold value thA for closing state or the threshold value thB for closed state is calculated using _AVE , for example, the maximum value D _MAX of the image data of each sensing area is calculated as an average value D.
_The threshold value thA for the closed state or the threshold value thB for the closed state may be calculated by substituting the equations (1) and (2) instead of _AVE . In this case, the value indicated by arrow A1 in FIG. 16 is calculated as the threshold value thA for closing state, and the value indicated by arrow B1 in FIG. 17 is calculated as the threshold value thB for closed state.

Similarly, by substituting the minimum value D _MIN of the image data in each sensing area into the above equations (1) and (2) instead of the average value D _AVE , the threshold value thA for the closing state or the closing state The threshold value thB for the open state may be calculated. In this case, the value indicated by the arrow A3 in FIG. 16 is set as the threshold value thA for the closing state, and the arrow B3 in FIG.
The value indicated by is calculated as the closed state threshold value thB.

[Third Embodiment] Next, a third embodiment of the present invention will be described. This third embodiment corresponds to the invention described in claim 4, and here, from the image data of each sensing area in the state where the document is not placed on the platen glass 16, the closed state is set for each sensing area. Threshold thAn and closed state threshold thB
An embodiment for calculating n will be described.

Since the third embodiment has the same structure as the first embodiment, the same reference numerals are given to the respective parts and the description of the structure will be omitted. The operation of the third embodiment will be described below. To do.

In the third embodiment, only the respective subroutines of the process for calculating the threshold value for closing state and the process for calculating the threshold value for closed state are different from those in the second embodiment. explain.

In the process of calculating the threshold value for closed state shown in FIG. 18, the image data Dn of one sensing area is read in step 342, and in the next step 344, the read image data Dn is expressed by the following equation ( By applying this to 3), the threshold value thAn for the closed state of the one sensing region is calculated. thAn = (Dn + 255) / 2 (3) Then, the processes of steps 342 and 344 are executed for all sensing regions, and the process returns when completed.

As a result of the above-described closing state threshold value calculation processing, as shown by ⊚ in FIG. 20, values closer to the white than the normal threshold value "127" are used for the closing state state for each sensing area. It is calculated as the threshold value thAn.

In the closed state threshold value calculation process shown in FIG. 19, the image data Dn of one sensing area is read in step 352, and in the next step 354, the read image data Dn is expressed by the following equation ( By applying it to 4), the closed state threshold value thBn for the one sensing region is calculated. thBn = (Dn + 0) / 2 (4) Then, the processes of steps 352 and 354 are executed for all sensing regions, and the process returns when completed.

As a result of the calculation processing of the threshold value for the closed state described above, as shown by ⊚ in FIG.
The value closer to black than “27” is calculated as the threshold value thBn for the closing state for each sensing region.

As described above, since the closed state threshold value thAn and the closing state threshold value thBn are calculated for each sensing area based on the image data, the influence of environmental factors in each sensing area is calculated. It is possible to set a more appropriate threshold after more closely reflecting the above.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described. The fourth embodiment corresponds to the invention described in claim 5, and here, from the image data of each sensing area and the maximum value and the minimum value thereof in the state where the document is not placed on the platen glass 16, An embodiment will be described in which the threshold value thAn for closing state and the threshold value thBn for closing state are calculated for each sensing region.

Since the fourth embodiment has the same structure as the first embodiment, the same reference numerals are given to the respective parts and the description of the structure will be omitted. The operation of the fourth embodiment will be described below. explain.

In the fourth embodiment, only the respective subroutines of the process for calculating the threshold value for closing state and the process for calculating the threshold value for closed state are different from those in the second embodiment described above. explain.

In the closed state threshold value calculation process shown in FIG. 22, the image data of each sensing area is read in step 362, and in the next step 364, the maximum value of the read image data is set to D _max. And the minimum value is D _min . In the next step 366, the image data Dn of one sensing area, the maximum value D _max and the minimum value D _min are applied to the following equation (5) to determine the threshold value for the closing state of the one sensing area. Value thA
Calculate and store n. thAn = (Dn + 255) / 2 + ( _{Dmax- Dmin} ) (5) Then, the process of step 366 is executed for all the sensing regions, and when the process is completed, the process returns.

By the calculation processing of the threshold value for closing state, as shown by ⊚ in FIG. 24, a value based on the image data Dn of each sensing area (that is, (Dn + 255))
The value obtained by adding the difference between the maximum value D _max and the minimum value D _min to / 2) is calculated as the threshold value thAn for the closed state for each sensing region.

In the closed state threshold value calculation process shown in FIG. 23, the image data of each sensing area is read in step 372, and in the next step 374, the maximum value of the read image data is set to D _max. And the minimum value is D
_min . In the next step 376, the image data Dn of one sensing region, the maximum value D _max and the minimum value D
By applying _min to the following equation (6), the closed state threshold value thBn for the one sensing region is calculated and stored. thBn = (Dn + 0) / 2- ( _{Dmax- Dmin} ) (6) Then, the process of step 376 is executed for all sensing regions, and the process returns when completed.

By the calculation processing of the closed state threshold value, as shown by ⊚ in FIG. 25, a value based on the image data Dn of each sensing area (that is, (Dn + 0) / 2).
The value obtained by subtracting the difference between the maximum value D _max and the minimum value D _min from the
It is calculated as Bn.

Thus, the value based on the image data for each sensing area (for example, (Dn + 255) / 2, etc.)
Since the closed state threshold value thAn and the closing state threshold value thBn are calculated after adding the difference between the maximum value D _max and the minimum value D _min of the image data, An appropriate threshold value can be set for each sensing area in consideration of the maximum influence of light.

[Fifth Embodiment] Next, a fifth embodiment of the present invention will be described. The fifth embodiment corresponds to the invention described in claim 6 or claim 7, in which a user (operator) can input a desired threshold value and an effective time zone of the threshold value with the keyboard 64. The embodiment will be described.

Since the fifth embodiment has the same structure as the first embodiment, the same reference numerals are given to the respective parts and the description of the structure will be omitted. In the following, the operation of the fifth embodiment will be described. explain.

In the fifth embodiment, the operator first
The keyboard 64 is used to instruct execution of the user threshold setting process. By this instruction, the control unit 54 starts executing the control routine of the user threshold value setting process shown in FIG.

First, in step 402 of FIG. 26, a message "Please change the threshold value" is displayed on the display 62, and in the next step 404, the input of the changed threshold value is waited.

A threshold value (hereinafter,
When a user threshold value is input), step 40
6, the message "Please set the document and press the start button" is displayed on the display 62, and in the next step 408, the operation of the start button 66 is awaited.

Then, the operator operates the platen cover 24.
Open to set the original, close the platen cover 24, and press the start button 66. In parallel with this operation, the area sensing process of FIG. 9 and the area sensing process of FIG.
The document size determination process is executed to determine the document size.

Since the start button 66 has been pressed, an affirmative decision is made in step 408, and the operation proceeds to step 410, and a message "original size is xx. Are you sure you want to save the threshold value, yorn?" Is displayed on the display 62. Display it. It should be noted that xx in the above message indicates the document size obtained above (for example, A4 or B4).
Etc.) Then, in the next step 412, it is determined whether or not the n button has been pressed.

If the input threshold value is not an appropriate value and the document size is erroneously determined to be different from the original size, the operator presses the n button. In this case, an affirmative decision is made in step 412, the flow returns to step 402, and a message prompting the input of the threshold value is again displayed on the display 62. On the other hand, when the operator presses a button other than the n button, the process proceeds to step 414,
It is determined whether the y button has been pressed.

Since the input threshold value is an appropriate value, the operator presses the y button when the document size is correctly determined. In this case, an affirmative decision is made in step 414, and the processing ends.

As a result, an appropriate value is set as the user threshold value so that the original size can be correctly determined.

After setting an appropriate user threshold value as described above, the operator sets a user threshold value use time zone setting process for setting a time zone in which the user threshold value is used (valid). Is instructed by the keyboard 64. By this instruction, the control unit 54 starts executing the control routine of the user threshold value use time zone setting process shown in FIG.

In step 422 of FIG. 27, a message "Do you always use the user threshold?" Is displayed on the display 62, and the response (whether y or n) is judged. If the response is y, it can be determined that the user threshold value is always used, and therefore step 43 described later is performed.
Go to 6.

On the other hand, if the response is n in step 422, the process proceeds to step 424 to display the message "Do you want to use the timer?" On the display 62,
The response (y or n) is determined. If the response is n, the process proceeds to step 436 described later.

On the other hand, if the response is y in step 424, the process proceeds to step 426 to display a message "Set timer?" On the display 62,
The response (y or n) is determined. If the response is n, the process proceeds to step 436 described later.

On the other hand, if the answer is y in step 426, the process proceeds to step 428 to display the message “Please enter the use start time?” On the display 62, and in the next step 430, input the use start time. To wait.

When the operator inputs the use start time T1, the process proceeds to step 432, the message "Please enter the use end time?" Is displayed on the display 62, and the next step 434 waits for the input of the use end time. to go into.

When the operator inputs the end-of-use time T2, the operation proceeds to step 436 and the message "Do you want to end the use time zone setting process?" Is displayed on the display 6
2, and the response (whether y or n) is judged. If the response is n, the process returns to step 422, and if the response is y, the process ends.

As a result, the use start time T1 and the use end time T2 are stored, and the time zone (T1 to T2) between them is stored.
2) is set as the user threshold use time zone.

The user threshold setting process (FIG. 26) and the user threshold use time zone setting process (FIG. 27) described above.
After executing, the operator replaces the user threshold value with a default threshold value (hereinafter, referred to as a fixed value) so that the user threshold value becomes effective during the set use time period. Execution of the user threshold value replacement process (FIG. 28) is instructed by the keyboard 64. In response to this instruction, the control unit 54 starts executing the control routine of the user threshold value replacement process shown in FIG. It should be noted that this user threshold value replacement processing is continuously executed, and is executed in parallel with the original size determination processing even when the original size determination processing of FIG. 10 is executed.

In step 442 of FIG. 28, it is determined whether or not the timer is set to be used. If the timer is not set, the process proceeds to step 444 to set the user threshold to be always used. Is determined. If it is set to be always used, the process proceeds to step 446 to replace the fixed value with the user value.

On the other hand, when the timer is set to be used in step 442, the process proceeds to step 448, and it is determined using the timer whether or not the current time is the use start time T1. When the current time reaches the use start time T1, an affirmative decision is made in step 448 and the operation proceeds to step 454 where the fixed value is replaced with the user threshold value.

On the other hand, when the current time is not the use start time T1, the routine proceeds to step 450, where it is determined using a timer whether or not the current time has reached the use end time T2. When the current time reaches the use end time T2, step 4
An affirmative determination is made at 50, and the routine proceeds to step 452, where the threshold value is replaced (returned) with a fixed value from the user threshold value.

If the current time is neither the use start time T1 nor the use end time T2, the process returns to step 442 to repeat the process.

By the above user threshold value replacement processing, the user threshold value is immediately set as the threshold value when it is set to be always used. Further, when the timer is set to be used, the user threshold is set as the threshold only from the use start time T1 to the use end time T2.

As described above, according to the fifth embodiment, it is possible to set the threshold value to a desired value and to make it effective in a desired time zone.
Even when installed directly under a fluorescent lamp or near a window where sunlight is inserted, by appropriately setting the threshold value and the time zone in which it is effective, it is possible to respond appropriately to the installation environment and environmental changes due to time. Therefore, it is possible to prevent false detection of the document size.

In the first to fifth embodiments described above, the CCD line sensor 4 provided for reading the image of the original document.
Although the size of the document is also determined by using the document No. 4, it is not limited to this, and the light reflected from the document is directly radiated to the photoconductor drum without reading the image of the document. In the image recording apparatus for recording the image on the recording paper, the image reading apparatus according to the present invention may be provided only for determining the size of the original.

Although the CCD line sensor 44 is applied as the photoelectric converter in the first to fifth embodiments, the present invention is not limited to this, and various known photoelectric sensors such as a MOS type image sensor are used. A converter is applicable. Further, in the above, the platen glass 16 is used as the transparent member.
However, it is also possible to form the transparent member by using other materials such as synthetic resin other than glass.

[0180]

As described above, according to the first aspect of the present invention, the comparison of the representative values before shielding, which are accurately obtained in consideration of the factors of the environment in which the apparatus is installed (external light etc.) Since the size of the document is determined based on the combination of the result and the comparison result of the masked representative value, it is possible to accurately determine the size of the document without being affected by environmental factors. .

Further, since the size of the document is judged as described above by using the photoelectric conversion element provided for reading the image recorded on the document, it is necessary to provide a large number of sensors exclusively for detecting the size of the document. In addition, the effect that the structure of the device can be simplified can be obtained. Also,
Since the prescan for detecting the document size is not necessary, it is possible to solve the problem that the prescan becomes a bottleneck in improving the processing capability of the image reading apparatus (for example, the number of copies per unit time). Can also be obtained.

Further, according to the second aspect of the invention, it is possible to set the first threshold value in consideration of the influence of external light, and (when the original is placed on the transparent member, It is possible to obtain an effect that the representative value before shielding of the image information for each small region and the first threshold value can be accurately compared with each other while reducing the influence of environmental factors. Note that the second threshold value can also be set to a value that takes into consideration the influence of external light, and accurate comparison can be performed after reducing the influence of environmental factors.

According to the third aspect of the present invention, an appropriate first threshold value considering the influence of external light in each small area can be set for each small area. Comparison of the pre-shielding representative value of the image information for each small area (when placed on a transparent member) with the first threshold value for each small area has made the influence of environmental factors even smaller. The effect that the above can be performed more accurately is obtained. In addition,
Also for the second threshold value, an appropriate value in consideration of the influence of external light in each small area can be set for each small area, and the effect due to environmental factors can be further reduced and then more accurate. A comparison can be made.

According to the invention as set forth in claim 4, a more appropriate first threshold value in which the maximum influence of external light in each small region is added can be set for each small region,
The comparison between the pre-shielding representative value of the image information for each small area (in the state where the original is placed on the transparent member) and the first threshold value for each small area is compared to determine the influence of environmental factors. It is possible to obtain the effect that it can be performed more accurately after being made smaller. As for the second threshold value, a more appropriate value can be set for each small area in consideration of the maximum influence of external light in each small area, and the influence of environmental factors can be further reduced. For a more accurate comparison.

According to the invention described in claim 5, even when the image reading device is installed, for example, directly under a fluorescent lamp or at a window where sunlight is inserted, the user can use the threshold changing means to make the first change. By changing the threshold value of 1 or the second threshold value to a desired value, it is possible to prevent the erroneous detection of the document size.

According to the invention described in claim 6, when the image reading device is installed near a window and there is a possibility that external light may affect a specific time zone (for example, the evening when the sun sets), the user can Since the valid time zone setting means can set the time zone in which the first threshold value is valid and the time zone in which the second threshold value is valid, to the desired time zone, The effect that the changed first threshold value and the changed second threshold value are validated and the change of the environment due to time can be appropriately dealt with is obtained.

Further, according to the invention described in claim 7, since the surface facing the transparent member is white when the transparent member is shielded, it is possible to eliminate the influence of the show-through on the image quality, and to accurately The effect is that the size of the original can be determined.

[Brief description of drawings]

FIG. 1 is a perspective view showing the outer appearance of an image reading apparatus according to this embodiment.

FIG. 2A is a state in which the platen cover is upright,
FIG. 3B is a side view of the image reading apparatus showing a state in which the platen cover is rotated from the standing state by a predetermined angle or more and the angle sensor is turned on.

FIG. 3 is a cross-sectional view showing a schematic configuration of an optical system arranged in a housing of the image reading apparatus.

FIG. 4 is a schematic block diagram showing a configuration of a control unit of the image reading apparatus and its periphery.

FIG. 5 is a plan view showing a sensing area on a platen glass.

FIG. 6 is set on the light receiving part of the CCD line sensor,
FIG. 6 is a conceptual diagram showing a sensing area when detecting the size of a document.

FIG. 7 is a flowchart illustrating a signal generation process executed by a size detection unit.

FIG. 8 is a timing chart showing a relationship among a line synchronization signal, a video clock signal, a sensing area signal, image data, and a video sampling signal.

FIG. 9 is a flowchart illustrating an area sensing process executed by a size detection unit.

FIG. 10 is a flowchart illustrating a document size determination process executed by a control unit.

FIG. 11 is a flowchart illustrating a mode setting process according to the first embodiment.

FIG. 12 is a flowchart for explaining a separation mode threshold value setting process in the first embodiment.

FIG. 13 is a flowchart for explaining threshold value setting processing in the second, third, and fourth embodiments.

FIG. 14 is a flowchart illustrating a process of calculating a threshold value for a closing state according to the second embodiment.

FIG. 15 is a flowchart for explaining a closed state threshold value calculation process in the second embodiment.

FIG. 16 is a diagram illustrating a procedure for setting a threshold value for a closing state according to the second embodiment.

FIG. 17 is a diagram for explaining a procedure for setting a threshold value for a closed state in the second embodiment.

FIG. 18 is a flowchart illustrating a process of calculating a threshold value for a closing state according to the third embodiment.

FIG. 19 is a flowchart for explaining a closed state threshold value calculation process in the third embodiment.

FIG. 20 is a diagram for explaining a procedure for setting a threshold value for a closing state according to the third embodiment.

FIG. 21 is a diagram for explaining a procedure for setting a threshold value for a closed state in the third embodiment.

FIG. 22 is a flowchart illustrating a process of calculating a threshold value for a closing state according to the fourth embodiment.

FIG. 23 is a flowchart for explaining a closed state threshold value calculation process in the fourth embodiment.

FIG. 24 is a diagram for explaining a procedure for setting a threshold value for a closing state according to the fourth embodiment.

FIG. 25 is a diagram for explaining a procedure for setting a threshold value for a closed state in the fourth embodiment.

FIG. 26 is a flowchart illustrating a user threshold value setting process according to the fifth embodiment.

FIG. 27 is a flow chart for explaining a user threshold value use time zone setting process in the fifth embodiment.

FIG. 28 is a flow chart for explaining user threshold value replacement processing in the fifth embodiment.

[Explanation of symbols]

 10 image reading device 16 platen glass (transparent member) 24 platen cover (cover) 28 angle sensor 30 platen interlock sensor 44 CCD line sensor 54 control unit 58 size detection unit 60 optical sensor 62 display 64 keyboard

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomoyuki Yamada 3-7-1 Fuchu, Iwatsuki City, Saitama Prefecture Fuji Zerox Co., Ltd. Iwatsuki Plant (72) Kazuhiko Minowa 3-7-1, Fuchu, Iwatsuki City, Saitama Prefecture No. Fuji Xerox Co., Ltd. Iwatsuki Works (72) Inventor Daisuke Kono 3-7-1 Fuchu, Iwatsuki City, Saitama Fuji Xerox Co., Ltd. Iwatsuki Works

Claims (7)

[Claims] 1. An image reading apparatus that optically scans a document placed on a plate-shaped transparent member by a photoelectric converter having a large number of photoelectric conversion elements to read an image recorded on the document. And a cover that is movable to a shielding position that shields the transparent member and an exposure position where the transparent member is exposed, and each of a plurality of types of originals of different sizes that are placed at substantially constant positions on the transparent member. A representative value calculating means for calculating a representative value of the image information in each small area based on a signal output from each of the photoelectric conversion elements in the plurality of small areas corresponding to an area extending over one specific side of , Comparing a representative value of image information for each small area before the transparent member is shielded by the cover with a first threshold value, and for each small area after the transparent member is shielded by the cover Image information representative value And a comparison means for comparing the first threshold value with a second threshold value different from the first threshold value, and a comparison result by the comparison means for each small area. An image reading apparatus comprising: a size determination unit that determines the size of a document. 2. A first threshold value is set on the basis of a representative value of image information for each small area before the transparent member is shielded in a state where an original is not placed on the transparent member, and Further, there is further provided threshold setting means for setting the second threshold based on the representative value of the image information for each small area after the transparent member is shielded while the original is not placed on the transparent member. The image reading apparatus according to claim 1, further comprising. 3. The image reading apparatus according to claim 2, wherein the threshold value setting unit sets a first threshold value and a second threshold value for each small area. 4. The threshold value setting means is a representative value of image information for each small area before the transparent member is shielded in a state where an original is not placed on the transparent member,
And a first threshold value is set for each small area based on the difference between the maximum value and the minimum value of the representative values of the image information for each small area, and the document is placed on the transparent member. The representative value of the image information of each small area after the transparent member is shielded in the non-displayed state, and the difference between the maximum value and the minimum value of the representative values of the image information of each small area, The image reading apparatus according to claim 2, wherein the second threshold value is set for each area. 5. The method according to claim 1, further comprising threshold changing means for changing each of the first threshold value and the second threshold value to a desired value. The image reading device described in the paragraph. 6. An effective time period for setting each of a time zone in which the changed first threshold value is valid and a time zone in which the changed second threshold value is valid as a desired time zone. The image reading apparatus according to claim 5, further comprising a band setting unit. 7. The image reading device according to claim 1, wherein a surface of the cover facing the transparent member when the transparent member is shielded is white. .