JPH031127A - Original size detection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention automatically adjusts the size of a document placed on a transparent document table of an image forming device such as a copying machine, a facsimile machine, an image scanner, etc. The present invention relates to a document size detection device.

[Conventional technology]

It is equipped with a transparent document table and a document holding member that opens and closes in a closed position that covers the upper surface of the document table and an open position that opens the top surface of the document table. Conventionally, in devices that emit light, such as electrophotographic copying machines and digital copying machines, the original platen (
There is a device that detects the size of a document placed on a contact glass (contact glass) and automatically selects and feeds transfer paper of an appropriate size.

As a document size detection device for this purpose, for example,
As described in Japanese Patent No. 6-78849, a light emitting section and a plurality of light receiving sections are provided at the bottom of the document table, and when the document holding member is closed, a microswitch is activated to light up the light emitting sections. Some document sizes are determined based on a combination of light receiving states of a plurality of light receiving sections.

Furthermore, as described in Japanese Patent Application Laid-open No. 58-95367, when the original holding member is closed or when the start button is pressed even when the original holding member is open, the original platen J-, There is also a device that shines light onto a document placed on the paper and detects the size of the document by receiving the reflected light.

Both are designed to eliminate the influence of reflected light from the document holding member.

Furthermore, before copying a document placed on the document table, there are devices that detect the document size by scanning a light receiving section fixed to the light source together with the light source, and devices that detect the size of the document by scanning the light receiving section fixed to the light source and the document holding member and the bottom of the document table. There are also known devices in which a light emitting section and a light receiving section are installed separately, and the document size is detected using transmitted light.

[Problem to be solved by the invention]

However, among these conventional document size detection devices, those that detect the document size using reflected light from the document have a minimum number of light receiving sections necessary to detect the document size. Since the number of sensors is limited, it is good for receiving the reflected light from the white part of the original, but if the original has a black part such as a solid black part, the light receiving part that happens to be there will receive the reflected light from this black part. If you are in a position to
Since the amount of light received becomes extremely small, it becomes difficult to distinguish from the case where there is no document, and there is always a problem when it becomes impossible to accurately detect the size of the document.

In addition, the above problem can be alleviated by optically scanning the original to detect the original size before copying, but it is difficult to distinguish between the light reflected by the original and the original holding member, and optical scanning takes time. This has the disadvantage that the copying speed is significantly reduced, especially when copying one original.

Furthermore, if the document size is detected using transmitted light, the problem described above will not occur even if there is a black part because the document itself blocks the optical path. Since either the light-emitting part or the light-receiving part must be provided, there are problems in that the structure becomes complicated and the durability deteriorates.

This invention has been made in view of the above points, and has a simple structure without reducing processing speed.

It is an object of the present invention to provide a document size detection device that can reliably detect the document size.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a transparent document table and a document holding member that opens and closes in a closed position covering the upper surface of the document table and an open position in which it opens. In an apparatus for reading or exposing an image of a document held by a member, as shown in a functional block diagram in FIG.

A light-emitting section that illuminates at least a plurality of detection points on the document table necessary for determining the size of the document from the back side of the document table, and a plurality of light-receiving sections that each receive reflected light from the plurality of detection points. document detection means 1 for detecting the open/closed position of the document presser; document presser open/close detector 2 for detecting the open/closed position of the document presser; and document detection when the document presser open/close detector 2 detects the open position of the document presser. a first detection result storage means 3 for storing detection results at each detection point according to the amount of light received by each light receiving section by the means 1;

a second detection result storage means for storing the detection results of each detection point according to the amount of light received by each receiving section by the document detection means 1 when the document presser open/close detection means 2 detects the closed position of the document presser; 4, and the first of these. a document presence/absence determining means 5 that determines that a document is present at a detection point where the detection results stored in the second detection result storage means match, and that a document is not present at a detection point where the detection results do not match; The present invention provides a document size detecting device comprising a document size determining means 6 for determining the size of a document placed on a document table based on a combination of detection points at which a document is determined to be present.

[For production]

According to the document size detecting device configured in this way, the amount of light received by each light receiving section of the document detecting means 1 is such that the amount of light received by each light receiving section of the document detecting means 1 is as follows: There is no change in the open position or the closed position, that is, the amount of reflected light received from the white portion of the document is large, and the amount of reflected light received from the solid black portion of the document is small.

On the other hand, when the original holding member is in the open position, the light from the light emitting part is not reflected and does not enter the light receiving area at the light receiving part for the detection point on the part of the document table where no original is placed. When it is in the closed position, the light from the light emitting section is reflected by the inner surface of the document holding member and enters the light receiving section, so the amount of light received changes greatly.

Therefore, the detection results of each detection point according to the amount of light received by each light receiving section of the document detection means 1 when the document holding member is in the open position and in the closed position are stored in the first and second detection results, respectively. The first . By determining that a document exists at the detection points where the detection results stored in the second detection result storage means 3 and 4 match, and that there is no document at the detection points where the detection results do not match, the presence or absence of the document can be accurately determined. Can be judged.

Then, the 1M document size determination means 6 determines the size of the document placed on the document table based on the combination of detection points determined by the document presence/absence determination means 5 to indicate that there is a document, so that the image state of the yX document is determined. Regardless of the size of the document, the document size can always be detected accurately.

〔Example〕

Embodiments of the present invention will be described below with reference to FIG. 2 and subsequent drawings. do.

FIG. 2 shows a document detection means 1 in an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a specific configuration example.

At the bottom of a plurality of detection points P (only one of which is shown in FIG. 2) on a transparent document table (contact glass) 10 provided at the top of the copying machine (not shown), there are LEDs 2a each serving as a light emitting section. A reflective photosensor 12 is provided, which includes a phototransistor 12b and a phototransistor 12b serving as a light receiving section.

The LED 12a is a switch 1 made of a transistor.
1, the light from the LE012a flashes and emits light on the document 13 placed on the document table 10, or the document 13.
The light reflected by the document holding plate 14, which is a document holding member that presses the document onto the document table 10, is transferred to the phototransistor 12.
b receives light.

If the signal input to the switch 11 via the I10 port 32 (FIG. 5), which will be described later, is L°, the switch 11
is off, so LEDl 2a does not emit light, and if the signal is °H°, switch 11 is on, and the power supply Vce
A current flows through resistor R1 to LED 12a, causing it to emit light.

The phototransistor 12b is connected to the LED at the detection point P.
The reflected light from i'la is detected, and the photocurrent is converted into a voltage by a resistor Rz, which is output as a detection signal to an A/D converter (ADC) 31 in FIG. 5.

When the document 13 is present at the detection point P, the detection signal is at a high level if it is white, and is almost O if it is black, depending on its density.

In addition, if there is no document 13 at the detection point 'P, the document holding plate 1
If 4 is fully open or half open, there is no reflected light, so the detection signal is almost O1.If O1 is closed, strong reflected light from the holding surface (white or bright color) of document holding plate 14 enters, so there is no detection signal. The signal will be at a high level.

Although FIG. 2 shows an example of using a reflective photosensor in which the light emitting part and the light receiving part are integrated, the LED and the phototransistor may be arranged separately, or the phototransistor may be arranged separately. Only a light-receiving section such as a transistor or photodiode is arranged so as to receive the reflected light from each detection point P individually, and a light-emitting section is arranged so as to individually receive the reflected light from each detection point P, and one or the required number of light-emitting sections are arranged so as to illuminate all the detection points. A light source such as a lamp or an LED may be arranged.

FIG. 3 is a plan view showing an example of the arrangement of seven detection points ■ to ■ (corresponding to detection point P in FIG. 2) on the A3-sized document table 10, in which an operator directly facing the copying machine The direction of the transfer paper (vertical, horizontal) is shown as seen from the paper feeding side (right side) in the paper feeding direction indicated by the arrow.

For each of these detection points ■ to ■, a reflective photosensor 12 shown in FIG.
3. B4. A4 vertical, B5 vertical.

When divided into eight types of document placement positions: A4 horizontal, A5 vertical, B5 horizontal, and A5 horizontal, the document size is placed in a position that does not interfere with movable parts such as lenses and scanner mirrors so that the document size can be determined. has been done.

In this way, as shown in Table 1, the size of the original 13 can be determined based on the combination of the presence or absence of the original at each detection point. In addition, [1] in this Table 1 indicates that there is a manuscript,
“0” indicates that there is no original.

FIG. 4 is an explanatory diagram showing a specific configuration example of the document holding member opening/closing detection means 2. As shown in FIG.

One end of a document holding plate 14 is rotatably attached to one end of a top panel 16 of the copying machine on which a document table 10 is provided by a hinge 17 .

An opening/closing instruction plate 20 is provided protruding from the rotating end of the document holding plate 14, that is, the lower surface near the hinge 17;
A bracket 1 is installed on the bottom surface of the top panel 16 near the hinge 17.
1st through 8. Second switches 21.22 are mounted above and below.

The first switch 21 on the upper stage is formed, for example, by a photoelectric switch using a transmission type photosensor, and the second switch 22 at the lower stage is formed by, for example, a microswitch. When the document holding plate 14 is closed, the tip 20a of the opening/closing instruction plate 20 is turned on so that the switch 21 is turned on when the transmitted light is blocked.
respectively, so as to turn on the switch 22.

That is, when the original holding plate 14 is fully opened, both the first and second switches 21 and 22 are off, and the original holding plate 14 is turned off.
When it starts to close and reaches the half-open position W (light reflected by the original holding plate is not received yet), the first switch 21 is turned on, but the second switch 22 remains off.

When the document holding plate 14 is closed, the second switch 22 is turned on for the first time.
The first switch 21 and Kyo 1 are turned on.

FIG. 5 is a block diagram showing an example of the configuration of the control section of this embodiment.

The CPU30 consisting of a microcomputer has an A/D
Each phototransistor (PTR) 12 of the seven reflective photosensors 12 is connected via a converter (ADC) 31
b and each LED 12 a of the reflective photosensor 12 are connected via the I10 port 32 and the switch 11.

Further, the I10 port 32 is connected to a first switch 21 that detects whether the original holding plate 14 is open, and a second switch 22 that detects when the original holding plate 14 is open.

Furthermore, the CPU 3Q includes a ROM 33 that stores programs and constant data, and a ROM 33 that stores programs and constant data. Second detection result storage means 3
, 4 is also connected to the RAM 34.

In the process of closing the document presser plate 14 (Fig. 2) which is in the fully open state,
When the first switch 21 is turned on, the I10 port 32
The CPU 30 detects that the switch 21 is turned on via the
LEDl via I10 boat 32 and switch 11
2a is turned on, the original 13 on the original table 10 is irradiated, and the light reflected by the original 13 is incident on the phototransistor 12b located below.

The level of the detection signal output by the phototransistor 12b according to the amount of light received is converted into a digital value by the A/D converter 31 and input to the cpty 30, and is set to "1" when the level is equal to or higher than the value corresponding to the threshold of the amount of light received. , when less than rQ
It is binarized as J.

The CPU 30 converts the binarized data into detection points ■～・■
After editing into 7-bit data arranged in the order of
It is stored in the first detection result area provided in ES4.

Next, when the document holding plate 14 is closed, the second switch 22 is turned on, and the detection signals output from each transistor 15 are converted and edited in the same way as in the above case, and stored in the RAM 34.
The detection results are stored in the second detection result area provided in the.

Next, the CPU 30, which is the document presence/absence determining means 5, executes the stored first . Comparing the second detection results for each detection point ■ to ■, there is a document at the matching detection point (rlJ),
It is determined that there is no original ("OJ") at the detection points that do not match, and the detection points are treated as original presence/absence data.

Furthermore, the CPU 30, which is also the document size determining means 6,
By sequentially comparing the document presence/absence data with the list of data from ■ to ■ corresponding to each document size as shown in Table 1 stored in the ROM 33, the document size corresponding to the matching data is determined. It can be determined that there is.

The operation of this embodiment will be explained below with reference to the flowcharts shown in FIGS. 6 to 9.

FIG. 6 is a flowchart showing an example of a subroutine for detecting the document size, and FIGS.
FIG. 3 is a flow diagram showing each subroutine used by the subroutine r size detection j shown in the figure.

The subroutine "input judgment" shown in FIG.

The detection signal output from the phototransistor 12b at a certain detection point is converted into a digital value by the A/D converter 31 and inputted, and the value is determined by 2 depending on whether the value is above or below a predetermined threshold.
The converted detection results are stored in a buffer corresponding to the detection point.

The subroutine “presence/absence determination” shown in FIG.
The first .M stored in M34. From the second detection result,
Compare the first detection result and the second detection result for each detection point, and if they are equal, it is determined that there is a document and the determination result is set to "1".
If they are not equal, it is determined that there is no manuscript and the determination result is "
0". When the document presence/absence determination at all detection points is completed, the process returns.

Or already the first one. The second detection results are organized and 7
If it is bit data, the same determination result, that is, document presence/absence data, can be obtained even if the exclusive OR is performed for each bit and then inverted by 1.

The subroutine ``Size determination'' shown in FIG. If there is, it is determined that the document size corresponds to that data.

If there is no matching data, it is determined that it is a size error or special size and returns.

Returning to Fig. 6, when jumping from the main routine to the subroutine r size detection shown in the same figure, first
switch 21 (hereinafter, together with the second switch 22,
rsWIJ, rsW2J) is on.

If the original holding plate 14 is fully open (beyond half open), S
Since WI is off, proceed to routine O and flags 1 and 2
Clear and return.

When the first switch 21 is turned on during the process of placing the original 13 on the original platen 10 and closing the original holding plate 14, the LED lights up through the I10 port 32 and the switch 11.
12a is turned on, and reflected light, which differs depending on the presence or absence of the document 13, enters the phototransistor 12b of the plurality of reflective photosensors 12 provided at each detection point, as described above.

When SWI is turned on, it is next determined whether flag 1 is off.

If it is the first time, Flag 1 is off, so proceed to Routine 1 and turn on Flag 1, then jump to the subroutine "Input Judgment" (Figure 7) and check the first detection point for each detection point in turn. When all the detection points are completed, the first detection results stored in the buffer are organized, stored in the first detection result area of the RAM 34, and the process returns.

From the second time onward, since both SW1 and flag 1 are on, the routine proceeds to routine 2 to determine whether SW2 is on.

Since SW2 is off until the document holding plate 14 is closed, the process returns directly.

When the document holding plate 14 is closed on the document table 10, the second switch 22 is turned on.

When SW2 is turned on, it is next determined whether flag 2 is off, but since flag 2 is initially off, after flag 2 is turned on.

As in routine 1, the routine jumps to the subroutine "input determination" to execute the second detection, and when all detection points are completed, the second detection results are organized and stored in the second detection result area.

Next, the first. Based on the second detection result, a jump is made to the subroutine "Presence/Presence Determination" (FIG. 8) in order to determine the presence or absence of a document at each detection point.

At this time, the first detection result for each detection point is the one detected when the document holding plate 14 is in a half-open state (same as open when viewed from the light receiving section), so in the place where there is no document, it is [0], and the document (rl) in the regular character portion or white background portion of , and rQJ in the black solid portion of the M manuscript.

Similarly, the second detection result is the one detected when the document holding plate 14 is in the leap state, so it is "1" in the place where there is no document, rlJ in the normal character part or white background part of the document, and "1" in the black solid part of the JX manuscript. In the section, it is rQJ.

A state in which the first detection result is "1" with reflected light and the second detection result is "rO" with no reflected light cannot occur (unless it is caused intentionally).

The above relationships are summarized and shown in Table 2.

As is clear from Table 2, the subroutine [presence/absence determination]
In 1. It is determined that there is a document at detection points where the second detection results are equal, and that there is no document at detection points where the second detection results are not equal.

If there is a halftone part in the area above the detection point of m manuscripts, the same detection point will be converted into a detection signal by the same light receiving unit and compared with the same threshold value. In the subroutine "input judgment", the detection results are "rl", "rQ"
No matter which way it is judged, the first. The second detection results are equal, and it is determined that there is a document without any problem.

When the document existence determination is completed in FIG. 6, the subroutine ``Size determination J
Jump to (Figure 9).

When the original size determination is completed, the subroutine ``Size Detection'' returns to the main routine. Although not shown in the figure, the main routine selects, for example, paper of the same size or a size corrected for the specified copying magnification based on the original size data. If there is a size error, predetermined error processing is performed.

If there is no subroutine "presence/absence determination" and the document size is determined only from the first detection result, the document 13 contains many solid black areas (including questionable halftone areas), and this solid black area If the phototransistor 12b detects the original document, it will be determined that there is no document, and the correct size will not be determined.

Tables 3 and 4 show examples of detection when, for example, an A4 horizontal document is a blank document, and a case where a black solid portion is located at the position marked with ■ in FIG. 3, respectively.

Table 3: A4 horizontal blank manuscript Table 4: Original with a black solid area at the A4 horizontal ■ position As shown in Table 3, in the case of an A4 horizontal blank manuscript, the first detection result and the presence/absence determination result by the subroutine match, and it is determined from the document size list shown in Table 1 that it is A4 landscape.

However, if there is a solid black area at the position marked ■ in the A4 horizontal document shown in Table 4, it will be misjudged as A5 vertical based on the first detection result, but according to the presence/absence determination result by the subroutine. It is correctly identified as A4 landscape.

Similarly, for example, if the black solid area of an A4 horizontal document is at the position of ■ or ■, the first detection result indicates that
Although it is misjudged as a 5-width error or a size error, both are correctly determined by executing the presence/absence determination.

In the embodiment described above, the first. Although a case has been described in which a transmissive photosensor and a microswitch are used as the second switches 21 and 22, other configurations may be used as long as they can detect whether the document holding plate 14 is half-open or fully closed.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a document size detection device that has a simple configuration and reliably detects the document size even if there is a black solid area on the document without reducing the processing speed. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the functional configuration of an embodiment of the present invention, FIG. 2 is an explanatory diagram showing an example of the configuration of the document detecting means, and FIG. 3 is an example of the arrangement of detection points on the document table. FIG. 4 is an explanatory diagram showing an example of the structure of the document holding member opening/closing detection means. FIG. 5 is a block diagram showing an example of the configuration of the control section, and FIGS. 6 to 9 are flow diagrams showing the operation of this embodiment. 1... Document detection means 2... Document holding member opening/closing detection means 3... First detection result storage means 4... Second detection result storage means 5... Original presence/absence determination means 6...・Document size determination means 10...Document table (contact glass) 12...Reflective photosensor 12a-LED (light emitting section) 12b...Phototransistor (light receiving section) 13...
Original 14... Original holding plate (original holding member) 21... First
Switch 22...Second switch l1 Figure I2 Figure 4 Figure *5 Figure l ii7 Figure 9

Claims (1)

[Claims] 1. A document holding member that opens and closes in a closed position covering the upper surface of the transparent original table and an open position in which the upper surface thereof is opened; In an apparatus that reads or exposes an image of a pressed document, the light emitting unit illuminates at least a plurality of detection points necessary for determining the size of the document on the document table from the back side of the document table;
document detection means comprising a plurality of light receiving sections each receiving reflected light from the plurality of detection points; document presser opening/closing detection means detecting an open/closed position of the document presser; and document presser opening/closing detection. a first detection result storage means for storing the detection result of each detection point according to the amount of light received by each light receiving section by the document detection means when the means detects the open position of the document presser; and the document presser; a second detection result storage means for storing the detection results of each detection point according to the amount of light received by each light receiving section by the document detection means when the member opening/closing detection means detects the closed position of the document holding member; document presence/absence determining means for determining that there is a document at a detection point where the detection results stored in the first and second detection result storage means match and that there is no document at a detection point where the detection results do not match; A document size detecting device comprising a document size determining means for determining the size of the document placed on the document table based on a combination of detection points determined by the determining device to indicate that a document is present.