JPH0730721A - Image reader - Google Patents

Abstract

(57) [Summary] [Purpose] You can set a large return distance during return scanning,
Without re-detecting the reference position mark for each return scan,
(EN) An image reading device capable of surely returning a reading optical system to a reading start position, enabling miniaturization, and improving efficiency of reading operation. [Structure] During self-diagnosis performed immediately after power is turned on, the line sensor 11 is reciprocally scanned to detect the front end position PF of the detection mark 4 on the positioning member 3 at the time of scanning for reading.
(Steps S5 to S7) and the front end position PR (steps S9 to S11) of the detection mark 4 at the time of return scanning are calculated, and the backlash amount ΔL of the apparatus is calculated based on the deviation between the front end positions PF and PR and stored. (Step S14).
After the reading scan is completed, the return scanning distance LR is calculated using the stored backlash amount ΔL.

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 used in an image processing apparatus. More specifically, the reading optical system is moved and scanned along an original so that an image on the original is read by a line sensor. The present invention relates to an image reading device.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus of an image processing apparatus moves a scanning optical system along a document and scans the document to read an image on the document, and a reading operation of a document positioned at a reading position. In general, the reading start position is detected by a detection unit such as a mechanical micro switch or an optical switch unit (hereinafter referred to as a home position sensor), and the detection unit detects it based on the detection signal. It is designed to start a read operation.

However, the above-described detection method using the home position sensor has a problem in the accuracy of the sensor, and there is a problem in that adjustment is time-consuming to accurately detect the reading start position.

Therefore, as shown in FIG. 9, instead of the home position sensor, a frame-shaped surface member 3 of the same color having a uniform density is provided in the peripheral portion of the reading area 20 of the original, which also serves as the original positioning. An apparatus has been proposed in which reference position marks 22 having different colors or densities are formed on the frame-shaped surface member 3 at the scanning start position of the scanning area of the optical system. According to this device, the scanning position 21 of the reading optical system is
After the reference position mark 22 is detected by using a line sensor (not shown) that performs reading according to the above, the position at which a predetermined amount of scanning is performed is determined as the reading start position.

Further, as shown in FIG. 10, the frame type surface member is not L-shaped as shown in FIG. 9 for the reasons of the structure and assembly of the apparatus, but rather the portion 16 in the arrangement direction of the line sensor and the optical system scanning direction. There is also a part that is configured separately from the part 17.
In this case, the groove 19 is formed between the members 16 and 17, and the shadow generated by the groove 19 may be erroneously recognized as the reference position mark 23.
It has been proposed to add a home position sensor (not shown) for distinguishing 3 from 3 and to determine the reading start position together with the output of the line sensor.

In the above conventional image reading apparatus, the reference position mark 2 detected by the line sensor is used.
The reading start position is determined based on the positions 2 and 23. However, since the reference position marks 22 and 23 are at the starting position of the optical system scanning, the line sensor is surely provided during the return scanning for the next reading operation. On the reference position marks 22, 2
It is necessary to return the optical system to a position where 3 can be read.

[0007]

However, in the above-mentioned image reading apparatus, when the back scanning is performed by the pulses corresponding to the number of pulses sent to the optical system driving circuit (not shown) during the reading scanning, the gear backlash occurs. Since the optical system cannot reliably return to the reference position mark due to play in the drive system, etc., the return scanning distance should be set larger than the reading scanning distance in consideration of variations in the backlash amount that differ from device to device. Was there. Therefore, it is necessary to make the reference position mark 4 large and to set the movable range of the optical system with a margin, which causes a problem that the downsizing of the image reading apparatus is hindered.

Further, when the position of the reference position mark is approached, the light source turned off at the end of image reading is turned on again for re-detection of the reference position mark, and after detecting the reference position mark, the return scanning is ended and turned off. Therefore, there is a problem that the life of the light source is shortened.

Further, conventionally, when the return scanning is performed at a high speed, it is not possible to stop at a desired position after the reference position is detected during the return scanning, so it is necessary to decelerate in the vicinity of the reference position in advance. However, there is a problem that the efficiency of the reading operation becomes poor.

The present invention has been made in order to solve the above problems, and a reading optical system is provided without setting a large return distance during return scanning or re-detecting a reference position mark for each return scanning. It is an object of the present invention to provide an image reading apparatus capable of surely returning to the reading start position, enabling miniaturization, and improving the efficiency of reading operation.

[0011]

In order to achieve the above object, an image reading apparatus according to the present invention is an image in which a reading optical system is moved and scanned along a document, and an image on the document is read by a line sensor. In the reading device, a positioning member that is provided outside the reading area in which the image is read and that can position the document,
The reading of the reading area is started based on the detection mark provided on the positioning member immediately before the start of reading the reading area and detectable by the line sensor, and the position of the detection mark detected by the line sensor. A position discriminating means for discriminating a position, a reciprocating operation of the reading optical system near the detection mark at the start of the reading operation, and a detection position of the detection mark at the time of reading scanning and a detection position of the detection mark at the time of returning scanning. Deviation calculating means for calculating the deviation, and return scanning distance determining means for determining the distance to perform the return scanning based on the deviation.

[0012]

According to the above construction, the return scanning distance of the reading optical system is determined by the return scanning distance determining means based on the deviation calculated by the deviation calculating means.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

First, the first embodiment of the present invention will be described with reference to FIG.
It will be described with reference to FIG. FIG. 1 is a block diagram showing a schematic configuration of an image reading apparatus according to the present invention. In the figure, 1 is a platen glass on which the original 2 is placed.
A frame-shaped positioning member 3 is arranged on the upper surface of the platen glass 1 immediately before the reading start position on the platen glass 1 to position the leading edge of the original 2 and one side edge thereof. A detection mark 4 is formed on the back surface of the positioning member 3, that is, the surface in contact with the platen glass 1.

On the lower surface side of the platen glass 1, a light source 5 which moves and scans along the platen glass 1, a reflection shade 6,
Mirrors 7, 8 and 9 that move and scan with the light source 5, a lens 10, and a line sensor 11 are arranged. The light emitted from the light source 5 is reflected by the original 2 and the mirrors 7, 8, 9 and guided to the line sensor 11 via the lens 10. The line sensor 11 is arranged so as to extend in a direction perpendicular to the scanning direction of the optical systems 5 to 9 and reads the image data on the original 2 and the detection mark 4 on the positioning member 3 and photoelectrically converts it into an electric signal. It is to convert. Further, the detection mark 4 has a sufficient width so that the line sensor 11 does not read beyond the front end portion (the right end portion in FIG. 1) of the detection mark 4.

A mark detection circuit 12 for detecting the detection mark 4 on the positioning member 3 based on an electric signal output from the line sensor 11 is connected to the line sensor 11, and the mark detection circuit 12 is provided with an apparatus. A control circuit 13 which controls the entire control is connected, and further, an optical system drive circuit 14 for driving the optical systems 5 to 9 is connected to the control circuit 13. Further, an image processing circuit 15 is connected to the line sensor 11, and the image processing circuit 15 is connected to the control circuit 13.

The mark detection circuit 12 detects the detection mark 4 by the electric signal from the line sensor 11 and sends the mark detection signal to the control circuit 13. The control circuit 13 controls the image processing circuit 15 as described later on the basis of the timing of the mark detection signal, and also controls the optical system driving section 14.
Is driven to move the optical system to an appropriate position, or an image reading operation described later is performed. The image data read by the line sensor 11 is appropriately processed by the image processing circuit 15, and the image information is output to a host device (not shown) such as a recording device.

Next, the backlash detection operation of the above-mentioned image reading apparatus will be described with reference to FIGS. This operation is performed at the time of self-diagnosis performed immediately after the power is turned on.

FIG. 2 is an explanatory diagram showing the relationship between the detection signal of the detection mark 4 and the reading area, and FIG. 3 is the mark detection circuit 1.
2 is an explanatory diagram showing the relationship between the output signal of 2 and the drive pulse input to the optical system drive section 14, and FIG. 4 is a flowchart showing the procedure for detecting backlash. 2 and 3, the positions PR and PF indicate the positions where the front end of the detection mark 4 is detected during the return scanning and the feed scanning, respectively, and the position PR is detected at the timings T ₁ , T ₃ and T ₅ , respectively. The PF is detected at timings T ₂ and T ₄ . Further, the position P ₀ is the reference position for reading scanning and coincides with PF. ΔL is the distance between PR and PF and corresponds to the amount of backlash. L ₀ is the distance from P ₀ to one end of the reading area 20, that is, the reading start position, L 0
S indicates the length of the reading area 20. Further, reference numeral 21 denotes a scanning position by the optical systems 5 to 9, and the scanning position 21 moves back and forth as the optical systems 5 to 9 move.

In FIG. 4, first, in step S1
Then, based on the mark detection signal sent from the mark detection circuit 12, it is determined whether or not the current scanning position 21 is on the detection mark 4. If it is determined that the scanning position 21 is not on the detection mark 4, the process branches to step S2, the scanning position 21 is returned to the rear by one line of reading (left in FIG. 2), and the scanning position is again determined in step S3. It is determined whether or not 21 is on the detection mark 4. When it is determined that the scanning position 21 is not on the detection mark 4, the step S
Returning to step 2, steps S2 and S3 are repeated until it is determined that the scanning position 21 is on the detection mark 4. When it is determined in step S3 that the scanning position 21 is on the detection mark 4, the process proceeds to step S4, the scanning position 21 is further moved backward by a predetermined line LH, and the process proceeds to step S5. The operation of step S4 is performed to prevent an error from occurring in the PF position determination described below. The scanning position 21 is set to the position shown in FIG.
It moves as shown in (d1) and the detection mark 4 shown in FIG.
It is confirmed that it is in the upper position P ₁ .

Next, the scanning position 21 is moved back and forth near the front end of the detection mark 4, and the backlash amount ΔL is measured.
This corresponds to the operations indicated by d2 and d3 in the operation of the optical system in FIG.

First, in step S5, the scanning position 21 is moved forward by one line for reading (to the right in FIG. 2). In step S6, it is determined whether or not the scanning position 21 is on the detection mark 4, and the detection is performed. When it is determined that the mark is on the mark 4, the process returns to step S5. By repeating steps S5 and S6, the scanning position 21 approaches the front end of the detection mark 4, and when it is determined in step S6 that the scanning position 21 is not on the detection mark 4, this position is the front end PF of the detection mark 4. Assuming that there is, the position PF is stored in step S7, and then the scanning position 21 is moved forward by a predetermined line LC in step S8. The operation of step S8 is performed in order to prevent an error from occurring in the position determination of the position PR which is performed next, and this operation causes the scanning position 21 to deviate from the detection mark 4 and the position in FIG. P
_Up to ₂ .

Next, in order to reverse the driving direction, step S
At 9 the scanning position 21 is moved back by one line for reading,
In step S10, it is determined whether or not the scanning position 21 is on the detection mark 4. If it is determined that it is not on the detection mark 4, the process returns to step S9, and steps S9 and S10 are repeated until it is determined that the scanning position 21 is on the detection mark 4. When it is determined in step S10 that the scanning position 21 is on the detection mark 4, this position is regarded as the front end of the detection mark 4, and the position PR is stored in step S11. Then, in step S12, an operation of returning the predetermined line LH backward is performed, and in step S13, the optical system driving unit 14 is stopped.

By the steps S5 to S11 described above, the front end position P of the detection mark 4 is detected during the feed scanning and the return scanning.
F and PR are obtained, and the backlash amount ΔL (= PF-PR) is calculated and stored in step S14.

Next, the control procedure of the image reading scan and the optical system return scan performed by using the backlash amount ΔL obtained as described above will be described with reference to FIG. FIG. 5 is a flowchart showing a control procedure of the image reading scan and the optical system return scan.

In the figure, the operations of steps S20 to S25 are the same as steps S1 to S6 in FIG. 4 described above, and therefore the description thereof is omitted.

When it is confirmed in step S25 that the scanning position 21 is not on the detection mark 4, this position is set as the reading reference position P _0, and the position P ₀ is stored in the next step S26. Subsequently, after pre-processing for reading is performed in step S27, the scanning position 21 is advanced to the start position P ₀ + L ₀ (position P ₃ in FIG. 2) of the reading area 20 in step S28. And step S
At 29, the tip of the reading area, that is, position P ₄ in FIG.
The original 2 is read over the length LS until
In step S30, the reading ending process is performed. By the operations of steps S20 to S30 described above, the scanning for reading the image data on the original 2 (operation d in FIGS. 2 and 3 is performed).
4) is executed.

At the end of the reading operation, the scanning position 21
Is a position which has moved forward (to the right in FIG. 2) from the reference position P ₀ by L ₀ + LS. Therefore, the backlash amount ΔL obtained in advance and the position for surely returning the scanning position 21 to the detection mark 4 are set. The distance LR at the time of return scanning considering the quantitative LH
(= L ₀ + LS + ΔL + LH) is calculated in step S31. In step S32, the return scanning of the distance LR calculated in step S31 is performed (operation d5), then in step S33, the optical system driving unit 14 is stopped and the optical system return scanning is completed.

In this way, by determining the distance to perform the return scanning using the backlash amount measured in advance, the optical detection can be performed without re-detection of the position detection mark 4 at every return scanning of the optical system. The system can be returned to the position above the detection mark 4, that is, the position at the start of reading. For this reason, it is not necessary to provide a large detection mark or an unnecessarily large movable range of the optical system, so that the device can be downsized. Further, when the return scanning is performed at high speed, the remaining distance of the return scanning can be determined with high accuracy based on the distance LR, so that the deceleration start timing can be delayed as compared with the conventional case, and the reading efficiency is improved.

Next, another embodiment of the present invention (second embodiment)
Will be described with reference to FIGS. 6 and 7.

In this embodiment, the line-shaped sensor 11 is replaced with the frame-shaped positioning member in the L-shape as in the above-described first embodiment due to, for example, the structure and assembly of the apparatus.
The first embodiment differs from the first embodiment in that it is configured by being divided into a member 16 extending in the arrangement direction and a member 17 extending in the scanning direction of the optical systems 5 to 9. Other configurations are the same as those in FIG. 1 in the first embodiment. Further, a home position sensor (not shown) is provided to distinguish the groove 19 formed between the member 16 and the member 17 and the detection mark 18 provided on the side surface of the platen glass 1 of the member 16. Further, in order to facilitate the assembly adjustment, the accuracy of the position where the output of the home position sensor changes is adjusted to a degree of accuracy that is within the range of the member 16. The detection mark 18 is shown in FIG.
And the relationship between the mark detection signal, the home position sensor output signal, and the reading area 20.

Next, the procedure for measuring the backlash amount according to this embodiment will be described with reference to FIGS. Figure 7,
FIG. 8 is a flowchart explaining the measurement procedure.

First, in step S40, it is determined whether or not the scanning position 21 is surely on the member 16 based on the signal from the home position sensor. That is, when the home position (HP) sensor is off, the scanning position 21 is not on the member 16, so the process proceeds to step S41 and the scanning position 21 is read back by one line (left in FIG. 6).
, And step S40 is repeated. When the home position sensor is on, it is determined that the scanning position 21 is on the member 16, so the process proceeds to step S42 and thereafter. In steps S42 to S48, the same operation as steps S1 to S7 in FIG. 4 of the first embodiment described above is performed to determine the front end position PF of the detection mark 18.

Next, in step S49, it is determined whether or not the home position sensor is off. If the home position sensor is on, the reading is advanced line by line in step S50 until the sensor is turned off. When it is determined that the home position sensor is off, the scan position 21 is set in step S51 in order to stabilize the output signal of the sensor.
Is further forwarded by the LC line, and then the driving direction is reversed.

Next, in step S52, the scanning position 21 is set to 1
Return line by line backward, and scan position 21 in step S53.
It is determined whether or not is on the detection mark 18. If it is not on the detection mark 18, it is determined in step S54 whether or not the home position sensor is on. If it is off, step S52 is repeated. When the home position sensor is on in step S54, that is, (e) in FIG.
When the home position sensor is turned on first as shown in FIG. 5, this position is regarded as the home position sensor output signal change position PR 'during the return scanning, and step S
The position PR 'is stored at 55. Then, step S56
~ S58, the above-mentioned steps S9 ~ S1 of FIG.
Similar to step 1, after the position PR of the front end of the detection mark 18 at the time of return scanning is determined and stored, the scanning position 21 is returned backward by LH lines in step S59, and the optical system driving unit 14 is stopped (step S66). ). On the other hand, the step S5
When it is determined in 3 that the scanning position 21 is above the detection mark 18, that is, when the front end of the detection mark 18 is detected before the home position sensor is turned on, as shown in (d) of FIG. , Return to this position and detect mark 18 at the time of scanning
The position PR at the front end of the
Memorize After that, step S61 and step S62
In, the scanning position 21 is returned to the position where the home position sensor signal is switched, the position where the output of the home position sensor is turned on is regarded as the position PR ′, and it is stored in step S63. Here, the position PR stored in step S60 and the position PR ′ stored in step S63.
Is longer than the LH line. If the answer is affirmative, the process proceeds to step S66 to stop the optical system drive unit 14, and if the answer is negative, the distance LH line from the position PR is determined by step S65. After returning the scanning position 21 to the position back by the minute, the process proceeds to step S66. After the optical system driving unit 14 is stopped in step S66, the backlash amount ΔL (= PF-PR) is calculated in step S67.

The image reading scan and the optical system return scan when the backlash amount ΔL obtained as described above is used are performed in the same manner as the control procedure of FIG. 5 in the first embodiment. Omit it.

Further, by using the distance between the changing position PR ′ of the home position sensor signal and the front end position PR of the detection mark 18, (PR′−PR) + LH + ΔL after the home position sensor signal changes during the return scanning. It is also possible to perform control to return the scanning position 21 to the position where it has just returned and stop it. When performing such control, the value of (PR'-PR) + LH + ΔL needs to be longer than the distance required to stop the optical system.

As described above, even when the positioning member is divided and provided as in the present embodiment, the position detection mark is detected for each return scan of the optical system as in the first embodiment. Is unnecessary, and the same effect as described above can be obtained.

[0039]

As described above, according to the image reading apparatus of the present invention, the reading optical system is moved and scanned along the original, and the image on the original is read by the line sensor. A positioning member provided outside the reading area where the image is read and capable of positioning the document, and provided on the positioning member immediately before the start of reading of the reading area and detectable by the line sensor. Detection mark,
Position determination means for determining the reading start position of the reading area based on the position of the detection mark detected by the line sensor, and reading by reciprocating the reading optical system near the detection mark at the start of the reading operation. Deviation calculation means for calculating a deviation between the detection position of the detection mark at the time of scanning and the detection position of the detection mark at the time of return scanning, and return scanning distance determination means for determining a distance at which return scanning should be performed based on the deviation. Since the return scanning distance is calculated by using the calculated backlash amount, the reading optical system can be surely returned to the reading start position without setting the return scanning distance too much. Miniaturization is possible.

Further, the backlash amount is calculated at the time of self-diagnosis immediately after the power is turned on, and the calculated amount is stored, so that it is not necessary to re-detect the reference position mark for each return scanning, and the reading operation can be performed. The efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a main part of an image reading apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship among a detection mark and its detection signal, a reading area, and an optical system driving operation in the embodiment.

FIG. 3 is an explanatory diagram showing a relationship between an optical system drive pulse and a detection mark detection signal in the embodiment.

FIG. 4 is a flowchart showing a backlash detection procedure in the embodiment.

FIG. 5 is a flowchart showing a procedure for performing image reading scanning and return scanning in the same embodiment.

FIG. 6 is a detection mark and its detection signal in the second embodiment of the present invention, a home position sensor output signal,
It is explanatory drawing which shows the relationship with a reading area.

FIG. 7 is a flowchart showing a backlash detection procedure in the embodiment.

FIG. 8 is a flowchart showing a backlash detection procedure in the embodiment.

FIG. 9 is a diagram showing a schematic configuration of a conventional image reading apparatus.

FIG. 10 is a diagram showing a schematic configuration of a conventional image reading apparatus.

[Explanation of symbols]

3 Positioning member 4 Detection mark 12 Mark detection circuit (position determination means) 13 Control circuit (position determination means, deviation calculation means, return scanning distance determination means)

Claims (1)

[Claims] 1. An image reading apparatus in which a reading optical system is moved and scanned along a document, and an image on the document is read by a line sensor, the document being provided outside a reading region where the image is read. A positioning member that can be positioned, a detection mark that is provided on the positioning member immediately before the start of reading of the reading area, and that can be detected by the line sensor, and a position of the detection mark that is detected by the line sensor. Position determining means for determining the reading start position of the reading area based on the above, and the reading optical system is reciprocated near the detection mark at the start of the reading operation to detect the detection position of the detection mark and the return scanning. Deviation calculating means for calculating a deviation from the detection position of the detection mark at the time, Image reading apparatus characterized by comprising a return scanning distance determining means for determining the distance to be performed Zui the return scan.