JP2021083011A - Document reading device - Google Patents

Abstract

To provide a document reading device capable of detecting a defective state immediately before a document image is read.SOLUTION: A document reading device is designed to perform inspection using a test pattern before a document reading job is input and a document reading operation is performed so as not to output an abnormal image due to a defect in an image signal transmission path. In addition, the inspection is performed by utilizing a time during preparation for the start of the reading operation of a line sensor before a document is read, such that the inspection does not delay the start of reading.SELECTED DRAWING: Figure 4

Description

The present invention relates to a document reader that reads an image of a document.

In an image reading device used in a multifunction device or the like, a contact image sensor (hereinafter referred to as CIS) or a 1BOX optical system in which various parts of a reduction optical system are tailored into one unit is often used as a means for reading an image.

Both have a line sensor, receive and store diffused light when the original is irradiated with light, and output it as an analog image signal. The analog image signal is AD-converted into a digital image signal, and various image processing is performed by the image processing unit in the subsequent stage.

The AD converter is often mounted on a circuit board on which a line sensor is mounted. In such a configuration, if the digital image signal is to be transmitted to the subsequent stage in a single-ended format, it is disadvantageous in terms of waveform quality and radiation noise of the digital image signal. Therefore, a method may be adopted in which a plurality of digital image signals are serialized to have a high data rate, converted into a low voltage differential signal (LVDS), and transmitted to a subsequent stage. For such applications, the analog image signal output by the line sensor is sample-held, analog signal processing such as gain processing and offset correction, and AD conversion processing are performed, and the digital image signal is parallel-serially converted and output to LVDS. End ICs (hereinafter referred to as AFE) are often used.

For signal transmission from the CIS or 1BOX optical system to the image processing unit in the subsequent stage, the CIS or 1BOX optical system reciprocates in the reading device in the sub-scanning direction, so that it is a flexible flat cable with good slidability and light weight (hereinafter referred to as “flexible flat cable”). FFC) is often used.

However, if the CIS, 1BOX optical system is reciprocated in the sub-scanning direction many times in order to read the image, and if the FFC has scratches, creases, etc. for some reason in the place where the sliding is large, it is physically Stress occurs. As a result, mechanical deterioration gradually progresses, and eventually the conductor inside the FFC may break. When a disconnection occurs in the image signal transmission line, the image signal is not correctly transmitted in the subsequent stage, so that an image abnormality occurs in the read image data.

As a method for detecting such an image signal transmission defect, there is an image reading device described in Patent Document 1.

In the image reading device of Patent Document 1, it is proposed that a test pattern generation circuit, which is conventionally provided individually after the AFE, is built in the AFE. The test pattern is a signal for checking that the image signal is normally transmitted from the AFE to the image processing unit in the subsequent stage. Instead of the image signal read by the line sensor, the main scanning direction gradation pattern data, all fixed value data, the grid pattern, etc. can be selected and output. It is said that such a test pattern will be taken in by the image processing section in the latter stage and it will be checked whether it matches the test pattern.

This is used for failure detection when the image reading device fails and analysis when an abnormal image occurs, and it is expected that the accuracy of failure detection and analysis will be improved. It can also be used for inspection of AFE parts as a single unit, and it is expected that the inspection accuracy of AFE parts as a single unit will be improved.

Japanese Unexamined Patent Publication No. 2008-035295

It is said that inspection will be carried out using a test pattern when the image reading device breaks down or an abnormal image occurs, but it is desirable to be able to detect a defective state immediately before scanning the original image. Otherwise, the abnormal image will be exposed as copy output, and copy paper, toner, and ink will be wasted.

In order to solve the above problems, the document reader according to the present invention is
A photoelectric conversion means that receives the diffused light of the document obtained by illuminating the document, and
An analog processing means that samples-holds the output signal of the photoelectric conversion means and converts it into a digital image signal.
A test pattern generation means that generates a digital image signal for testing,
The image signal output by the analog processing means and the image signal output by the test pattern generation means are switched, and the switching means having a transmission unit for transmitting the image signal to the subsequent stage and the image signal from the switching means are added by a predetermined line. Or, a holding means for holding the result of line averaging as a correction coefficient used for shading correction processing,
In an image reading device having a control means for controlling each of the means.
From the time when the photoelectric conversion means is put into the reading operation state to the time when the shading correction coefficient is generated by the holding means.
The switching circuit is switched to a signal generated by the test pattern generation means,
The test pattern signal is added and held by a predetermined line by the holding means, and held.
An image reading device for inspecting whether or not the signal luminance value of the test pattern signal held in the holding means matches a predetermined luminance value.

A document reading job was submitted, and an inspection using a test pattern was performed before the document scanning operation was performed so that an abnormal image due to a defect in the image signal transmission path was not output. In addition, the inspection is performed by utilizing the time during preparation for the start of the scanning operation of the line sensor before scanning the original so that the inspection does not delay the start of scanning.

The figure explaining the document reading apparatus which concerns on embodiment of this invention. Block diagram of the document reading device of the present invention Flowchart of the present invention The flow diagram explaining the 1st Example of this invention The flow diagram explaining the 2nd Example of this invention

Preferred embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a document reading device according to an embodiment of the present invention. Reference numeral 100 denotes a document transporting device. Reference numeral 101 is a document tray on which a bundle of documents is placed, and 116 is a document placement sensor for detecting whether or not a document is placed on the document tray 101. When the document is set on the document tray 101, the document placement sensor 116 detects that the document is set on the document tray 101, and the user instructs the user to start scanning the document, the document is conveyed on the document tray 101. It will be started.

Reference numeral 102 denotes a pickup roller, which descends in the direction of the arrow in the drawing so as to come into contact with the document on the upper surface of the document bundle on the document tray 101. After that, by rotating the pickup roller 102, the document is picked up and conveyed toward the separation roller 103, which will be described later.

Reference numeral 103 is a separation roller. The rotation of the separation roller 103 is started, and the documents conveyed by the pickup roller 102 are drawn into the document transfer path one by one. 104 is a cash register roller. The conveyed original material is brought into contact with the cash register roller 104, and a loop is formed in the original material. By forming a loop, the tip of the document is aligned parallel to the register roller 104 to correct the inclination of the document. Reference numeral 105 denotes a cash register sensor, which is arranged in the vicinity of the cash register roller 104. When the document is detected by the registration sensor 105, the rotation of the registration roller is started after the time required for forming the loop in the document has elapsed, and the document passes through the registration roller 104.

Reference numeral 106 is a lead roller. The original is conveyed by the cash register roller 104 and reaches the lead roller 106. The lead roller 106 is rotated to convey the document at a predetermined reading speed, and the document is conveyed to the document reading position by the lead roller 106. Reference numeral 107 denotes a lead sensor, which is arranged in the vicinity of the lead roller 106.

The read sensor 107 is a sensor for generating a document reading start timing. It detects that the document has reached the read sensor 107, and is controlled so that the document reading is started after a predetermined time from the detected timing.

Reference numeral 111 denotes a document reading device for reading a document placed on the platen glass, which will be described later. Reference numeral 1122 is a document reading unit for reading a document. It is an integrated unit with a built-in line sensor, reflection mirror, imaging lens, and light source required for reading documents. Reference numeral 113 denotes a platen glass, which is used for placing a document when scanning the platen. The document reading unit 112a moves in the document reading device in the direction of the arrow in the drawing by driving a motor (not shown) to read the document on the platen glass 113. Reference numeral 114a is a reference white plate, which is attached to the platen glass 113 and is read to generate a shading correction coefficient.

Reference numeral 115a is a scanning glass. When the document conveyed by the document transfer device 100 passes over the scanning glass 115a, the document is read by the document reading unit 112a in the stopped state. So-called manuscript scanning is performed.

A document reading unit 112b is also provided in the document transport device 100. A reference white plate 114b and a scanning glass 115b are arranged around the document scanning unit 112b as in the configuration of the document scanning device 111, and the conveyed document is illuminated by a light source when passing over the scanning glass 115b. And read the original. The document scanning unit 112a has a double-sided simultaneous scanning configuration in which one surface (referred to as the front surface) of the document is read, and the document reading unit 112b reads the other surface (referred to as the back surface) of the document.

108 is a paper ejection roller, and 109 is a paper ejection tray. Document reading unit 112a. The original document read by 112b is conveyed by the paper ejection roller 108 and is ejected onto the paper ejection tray 108. The pickup roller 102, the separation roller 103, the cash register roller 104, and the paper ejection roller 108 are driven by a motor (not shown).

The document reading units 112a and 112b are electrically connected to the main control board described later, and the reading unit 112a on the document reading device 111 side reciprocates in the machine, so that the slidability is good as described above. , Connected using a lightweight FFC. The reading unit 112b of the document transporting device 100 does not move and is mounted so as to be fixed in the machine. However, since it is easy to rotate in the machine and easy to handle, there are cases where FFC is also used here.

When the start of reading the document is instructed, the document reading unit 112a of the document reading device 111 moves below the reference white plate 114 in order to read the reference white plate 114a. The light source for document illumination is turned on, the reference white plate 114a is irradiated, the reference white plate 114b is read, and a shading correction coefficient is generated. After that, the document reading unit 112a is moved under the scanning glass 115a. Similarly, the document reading unit 112b of the document transport device 100 reads the reference white plate 114b and generates a shading correction coefficient. After that, the conveyed originals are read by both the original reading units 112a and 112b, and the image data is subjected to shading correction processing using the shading correction coefficient generated earlier, and the subsequent printer device. Will be sent to.

FIG. 2 is a block diagram showing a configuration of a document reading unit 112a described with reference to FIG. 1 and a main control unit 213 for controlling the unit reading unit 112a. Since the block diagram of the document reading unit 112b on the document transfer device 100 side has the same configuration as 112a, only 112a is described, and 112b is omitted.

Reference numeral 201 denotes a line sensor (photoelectric conversion means), which receives and stores the document diffused light obtained by illuminating the document and outputs it as an analog image signal. 202a is an analog front-end IC (hereinafter referred to as AFE) as an analog processing means for the line sensor 201a, equipped with a sample hold circuit 203a (hereinafter referred to as S / H circuit), and sample-holds an analog image signal output by the line sensor 201a. To do. Reference numeral 204 denotes an AD converter, which converts an analog image signal output by the S / H circuit into a digital image signal.

Reference numeral 205 denotes a test pattern generation circuit that generates a test pattern signal as a test digital image signal, and is used when inspecting the soundness of an image signal transmission path. It is possible to generate a test image signal such as an increment pattern for increasing the signal luminance value (output code value) of the image signal or a fixed pattern with a constant luminance value.

206a is a switching circuit. This is a circuit that selects and outputs one of the output of the AD converter 204a and the output of the test pattern generation circuit 205a. The output of the AD converter 204a is selected when reading the original image, and the output of the test pattern generation circuit 205a is selected when inspecting the image signal transmission path.

FIG. 3 shows an example of a signal output by the switching circuit 206a. (A) is the digital signal output of the line sensor 201a when the AD converter 204a output is selected and the reference white plate 114a is illuminated. (B) is an example in which the test pattern generation circuit 205a is selected and the test pattern is output. The vertical axis is the brightness value (output code) of the image signal, and the horizontal axis is time.

(A) is an example in which the output of the AD converter 204a is set to 10 bit gradation and the brightness value is from 0d to 1023d, and the entire effective image range of the line sensor 201a is output. The test pattern of (b) is an example when an increment pattern is output, and is output with the same 10-bit gradation as the output of the AD converter 204a, and 0d to 1023d are incremented by 1d for each pixel, and (a) The increment pattern is output by repeating it multiple times with respect to the effective image range of the line sensor output. The switching circuit 206a can switch and output the image signal of the line sensor 201a of FIG. 3A and the test pattern of FIG. 3B.

Reference numeral 207a is an image signal transmission circuit, and the image signal output by the switching circuit 206a is subjected to the above-mentioned parallel-serial conversion processing, converted into an LVDS format signal, and output to be transmitted to the image processing unit in the subsequent stage of AFE202a. To do.

Reference numeral 209a is a timing signal generation circuit. A control signal for reading and operating the line sensor is generated and output to the line sensor 201a. A control signal for operating each of the circuit blocks in the AFE202a including the S / H circuit 203a is generated and output.

Reference numeral 211a is a power supply circuit that supplies a power supply voltage to the line sensor 201a. The 210a is a power supply control circuit that controls the operation of the power supply circuit 211a, and is a port that outputs an L level or H level signal. At the time of L output, the power supply circuit 211a stops the power supply output, and at the time of H output, the power supply output is started, and the power supply voltage is supplied to the line sensor 201a.

When the document reading job is input, the power supply circuit 211a starts supplying power to the line sensor 201a, the timing signal generation circuit 209a is started, and the control signals are sent to the circuits such as the line sensor 201a and the S / H circuit 203 of the AFE202a. To supply.

208a is a communication I / F circuit. The AFE202a is connected to the CPU 219 and communicates with the CPU 219, receives a command signal from the CPU 219, supplies power to the line sensor 201a, starts and stops the control signal, and starts the control signal for various circuits in the AFE202a. And stop are controlled. The signal switching circuit 206a is controlled to switch the output signal to be executed at the start of the document reading operation, and the test pattern generation circuit 205a is controlled to select the type of the test pattern.

Reference numeral 213 is a main control unit, which controls the document transport device 100 and the document reading device 111, and performs image processing. Reference numeral 214 denotes an image processing unit, which is arranged in the main control unit 213 and performs various image processing such as shading correction processing on the image signals transmitted from the document reading units 112a and 112b.

Reference numeral 215a in the image processing unit 214 is an image signal receiving circuit, and is a circuit for receiving an LVDS image signal output by the image signal transmitting circuit 207a in the AFE202a. Reference numeral 212a represents a cable such as an FFC that electrically connects the document reading unit 112a and the main control unit 209, and the image signal output by the image signal transmission circuit 207a and the communication between the communication I / F circuit 208a and the CPU 219. Signals, power supply voltages for operating line sensors 201a and AFE202a, etc. are exchanged.

Reference numeral 216a is a shading correction unit. This is an image processing circuit that performs black shading correction processing and white shading correction processing on the image signal output by the image signal receiving circuit 215a.

Reference numeral 217a is a shading memory for storing the shading correction coefficient used for the black and white shading correction processing. The white shading correction is a process of performing gain correction for each pixel of the image signal read by the line sensor 201a, and a correction coefficient is prepared for each pixel. The number is the number of effective pixels of the line sensor 201a or the number of pixels corresponding to the maximum main scanning reading size of the document, and the shading memory 217a is provided with a capacity sufficient to hold the correction coefficient. The same applies to the correction coefficient of the black shading correction process.

The shading correction unit 216a also has a function of generating a shading correction coefficient, and stores the image signal read by the line sensor 201a as a shading correction coefficient in the shading memory 217a. In calculating the correction coefficient, it is possible to perform line averaging processing to obtain a shading correction coefficient in order to reduce noise components included in the read image signal such as random noise and shot noise of the line sensor 201a. Specifically, the shading memory 217a can add and hold an image signal such as 64 lines, which is the number of lines set by a power of 2, by adding lines and performing a bit shift operation after the addition. Dividing by 64, averaging is performed.

When the test pattern is output from the test pattern generation circuit 205a and the transmission path of the image signal is inspected, the test pattern signals are added for a plurality of lines by using the addition function of the shading correction coefficient generation function of the shading correction unit 216a. , It is controlled to be held in the shading memory 217a.

The image processing unit 214 is connected to the CPU 219, and the shading correction unit 216a is controlled by the CPU 219 to perform shading correction processing and generate a shading correction coefficient. The shading memory 217a can be read-accessed by the CPU 219, and the data held in the shading memory 217a can be referred to.

When inspecting the image transmission path, the held test pattern signal is read-accessed by the CPU 219, and the signal value assumed when the test pattern signal is normally received (hereinafter, this is referred to as the correct signal value). To determine if it matches. For example, assuming that the test pattern output by the test pattern generation circuit 205a is the increment pattern shown in FIG. 3 (b), the value obtained by multiplying the signal value of the increment pattern by the number of addition lines is set as the correct signal value, and shading. The work of confirming that all the signal values held in the memory 217a match is performed.

The image signal subjected to the shading correction processing by the shading correction unit 216a is smoothed by the filter processing unit 218a in the subsequent stage, various image processing is performed, and is sent to the image processing unit in the subsequent stage.

In FIG. 3, image processing circuits such as an image signal receiving circuit 215a, a shading correction circuit 216a, and a shading memory 217a are also prepared for the document reading unit 112b of the document transport device 100. Since the configuration is the same as that for the document reading unit 112a, the description of the block diagram is omitted.

FIG. 4 is a flow chart of the present invention, and shows a control step when an inspection of an image signal transmission path using a test pattern is performed immediately after a document reading job is input.

S400 is a step of starting the operation of the AFE202a in the document reading unit 112a. When the original is set in the original tray 101 or the original is placed on the platen glass 113, the job is set via the operation unit, and the start button is pressed, the CPU 219 timings the AFE202a to operate. The operation of the signal generation circuit 209a is started. The AFE202a is in the operating state, but the line sensor 201a is not yet in the operating state, so that an invalid image signal is output from the AD converter 204a.

S401 is a step of starting power supply to the line sensor 201a. The output of the power supply control circuit 210a is switched from the L level to the H level, the power supply voltage output for the line sensor 201a is started from the power supply circuit 211a, and power is supplied to the line sensor 201a.

S402 is a step of starting the supply of the control signal so as to read the line sensor 201a and put it into the operating state. When the feeding voltage to the line sensor 201a in S401 is stable, the timing signal generation circuit 209a supplies a control signal to the line sensor 201a to bring it into a reading operation state.

S403 is a step of switching the switching circuit 206a to the test pattern generation circuit output, and from this step, it becomes a flow of inspection of the image signal transmission path using the test pattern signal. If several types of test patterns can be output, the desired pattern may be output in this step.

S404 is a step of performing line addition processing on the test pattern signal by the shading correction unit 216a. The test pattern signal received by the image signal receiving circuit 215a is sent to the shading correction unit 216a, is subjected to addition processing for a set number of lines, for example, 64 lines, and is held in the shading memory 217a. The purpose of this step is to store the test pattern signal in the shading memory 217a, and the number of addition lines is not limited to 64, and the number of addition lines may be set to 1 and no averaging processing may be performed.

S405 is a step of switching the access setting of the shading memory 217a to the mode accessed by the CPU 219. In S404 of the previous step, the shading correction unit 216a was accessible to the shading memory 217a, and processing such as storing the addition result was performed. However, in this step, the CPU 219 read-accessed the shading memory 217a and stored the test. The data value of the pattern signal can be read out.

S406 is a step of comparing the data value of the test pattern signal read from the shading memory 217a in S405 with the correct signal value pixel by pixel, and checking whether there is a discrepancy. If it is determined that there is a discrepancy (Yes), the process proceeds to S407. If it is determined that there is no discrepancy (No), it is determined that the image signal transmission path and components are in a sound state, and the process proceeds to S408.

S407 is a step of performing error processing. Judging that there is a problem with the image signal transmission path or parts of the FFC212a, etc., a message on the operation unit (not shown) telling the user that the job cannot be started, and an error for the serviceman. Display the code, etc., and end the document scanning job.

S408 is a step of switching the switching circuit 206a to the output of the AD converter 204a. In order to move to the work of reading the original, the AD converter 204a is switched to output the image signal. The step before S408 is the inspection of the image signal transmission path using the test pattern signal, and the subsequent steps are the steps of acquiring the original image, and the shading correction coefficient is generated.

S409 is a step of changing the access setting of the shading memory 217a from the CPU 219 to the shading correction unit 216a. Since the shading correction unit 216a accesses the shading memory 217a in the generation of the black / white shading correction coefficient and the execution of the shading correction processing performed in the next and subsequent steps, the shading correction unit 216a is switched here.

S410 is a step of generating a black shading correction coefficient. The output of the AD converter 204a with the light source that illuminates the document turned off is added and averaged by a predetermined line by the shading correction unit 216a, and the output is stored in the shading memory 217a as a black shading correction coefficient.

S411 is a step of turning on the light source. In order to generate the white shading correction coefficient in the next step, the light source is turned on to read the reference white plate 114a, and the reference white plate 114a is illuminated.

S412 is a step of generating a white shading correction coefficient. The output of the AD converter 204a when the reference white plate 114a is read is received, and the white shading correction coefficient is generated in the same manner as in S409.

S413 is a step of starting the shading correction process. Shading correction processing is performed on the image signal output of the image signal receiving circuit 215a that has received the output of the AD converter 204a by using the generated black / white shading correction coefficient. After the shading correction process is started, the document transfer device 100 starts the document transfer, or the document reading unit 112a is moved in the sub-scanning direction to perform shading correction on the image signal received by the line sensor 201a. Generate image data.

Although only the control of the reading unit 112a of the document reading device 111 has been described with reference to FIG. 4, the image signal transmission path can be inspected for the document reading unit 112b of the document transporting device 100 with the same control flow. When performing double-sided simultaneous scanning, the flow of FIG. 4 may be performed for the document scanning units 112a and 112b, respectively.

As described above, since it is determined that the image signal transmission path and other parts are sound, there is no problem with the image signal when generating the shading correction coefficient or when reading the original, and the image is read without image defects. Is expected, leading to improved reliability of the device.

Further, in this embodiment, the inspection of the image signal transmission path using the test pattern signal is performed after the power-on of the line sensor 201a of S402 is started and the control signal to the line sensor 201a of S403 is started. This is intended to start and carry out the inspection at the time when the power supply voltage rises and stabilizes, and the image signal output stabilizes after the line sensor 201a starts operating. As a result, it is possible to speed up the calculation of the shading correction coefficient and the reading of the original, and the time from job submission to job start is shortened, leading to improvement in usability.

Further, at the time of inspection, the test pattern signal is taken into the shading memory 217a by using the shading correction coefficient generation function of the shading correction unit 216a. As a result, the test pattern signal can be added over the entire area in the main scanning direction and in the sub-scanning direction, and a large number of pixels can be secured as the test pattern signal to be inspected, so that the inspection accuracy can be improved.

FIG. 5 is a flow showing a second embodiment according to the present invention. In the flow described with reference to FIG. 4, the inspection of the image signal transmission path using the test pattern signal was carried out by using the power supply voltage to the line sensor 201a at the start of the job and the time for waiting for the image signal output to stabilize. Is a control flow in which an inspection is performed at the end of a job.

The FFC212a will not slide unless there is an operation or operation that causes a problem in the image signal transmission path between the end of the job and the start of the next job, for example, the movement of the document reading unit 112a in the sub-scanning direction. .. If there is no concern about disconnection, the job is completed based on the idea that by conducting an inspection at the end of the job, it is possible to ensure that there will be no problems with the transmission of image signals at the start of the next job. It is intended to carry out inspections from time to time.

The flow of FIG. 5 has a starting point in the middle of transporting a document by the document transporting device 100 and performing a document scanning job. S500 is a step of reading a document, and reads a document passing over the scanning glass 115a or 115b.

S501 is a step of confirming whether or not there is a next document to be read. Whether or not there is a next document is determined from the detection signal output of the document placement detection sensor 116 or the paper passing sensor (not shown) in the transfer path of the document transfer device 100. If it is determined that there is a next document (Yes), the process proceeds to S500 in order to continue the document transfer and read the document. If it is determined that there is no next document (No), the process proceeds to S502.

S502 is a step of moving the document reading unit 112a to the standby position. The standby position is a position where the document reading unit 112a is waiting until the next document reading job is started, and is also a position at the start of the job. Since the shading correction coefficient is generated, the reference white plate 114a is often set at a readable position. Since it was determined in S501 that there is no document to be read, the document scanning unit 112a is moved from the position where the document is read on the scanning glass 115a to the standby position in order to end the scanning job. Since the document reading unit 112b on the document transporting device 100 side is dedicated to scanning, does not move, and is fixed, this step is not performed.

S503 is a step of switching the switching circuit 206a to the output of the test pattern generation circuit 205a. Prior to this step, the document was being read, and the AD converter 204a output was selected for the switching circuit 206a. In the next step, the output is switched to the test pattern generation circuit 205a in order to carry out the inspection by the test pattern.

S504 is a step of performing line addition processing of the test pattern signal by the shading correction unit 216a, and S505 is a step of switching the access setting of the shading memory 217a to a mode accessed by the CPU 219. S506 is a step of comparing the data value of the test pattern signal read from the shading memory 217a with the correct answer signal value and checking whether there is a discrepancy. If there is a discrepancy (Yes), the process proceeds to S507, error processing is performed, and then the process proceeds to S508. Even if it is determined that there is no discrepancy (No), the process proceeds to S508. Since the steps from S504 to S507 have the same control as S404 to S407 described with reference to FIG. 4, the description thereof will be omitted.

S508 is a step of stopping the operation control signal supplied to the line sensor 201a, and stops the control signal generated and output by the timing signal generation circuit 209a.

S509 is a step of stopping the power supply voltage supplied to the line sensor 201a. The output of the power supply control circuit 210a is switched from the H level to the L level, and the power supply voltage output for the line sensor 201a of the power supply circuit 211a is stopped.

S510 is a step of stopping AFE202a. The timing signal generation circuit 209a generates and stops the output control signal for AFE. The operations of the line sensors 201a and AFE202a are stopped, and the document reading job ends.

As described above, when the AFE202a immediately before the end of the document reading job is in operation, the image signal transmission path is inspected by the test pattern signal. As a result, it is not necessary to inspect at the start of the job, the time from job submission to job start is shortened, which leads to improvement in usability.

In the flow of FIG. 4, the document scanning using the document conveying device 100 has been described as an example, but it can also be applied to the scanning using the document base glass 113 by the document reading device 111.

100 Document carrier 101 Document tray 102 Pickup roller 103 Separation roller 104 Register roller 105 Register sensor 106 Lead roller 107 Lead sensor 108 Output roller 109 Output tray 111 Document reader 112a, 112b Document reading unit 113 Document base glass 114a, 114b Reference White plate 115a, 115b Scanning glass 116 Document placement detection sensor 201a Line sensor 202a Analog front-end IC
203a Sample hold circuit (S / H circuit)
204a AD converter 205a Test pattern generation circuit 206a Switching circuit 207a Image signal transmission circuit 208a Communication I / F circuit 209a Timing signal generation circuit 210a Power control output port 211a Power supply circuit for line sensor 212a Flexible flat cable (FFC)
213 Main control unit 214 Image processing unit 215a Image signal receiving circuit 216a Shading correction unit 217a Shading memory 218a Filter processing unit 219 CPU

Claims (2)

A photoelectric conversion means that receives the diffused light of the document obtained by illuminating the document, and
An analog processing means that samples-holds the output signal of the photoelectric conversion means and converts it into a digital image signal.
A test pattern generation means that generates a digital image signal for testing,
The image signal output by the analog processing means and the image signal output by the test pattern generation means are switched, and the switching means having a transmission unit for transmitting the image signal to the subsequent stage and the image signal from the switching means are added by a predetermined line. Or, a holding means for holding the result of line averaging as a correction coefficient used for shading correction processing,
In an image reading device having a control means for controlling each of the means.
From the time when the photoelectric conversion means is put into the reading operation state to the time when the shading correction coefficient is generated by the holding means.
The switching circuit is switched to a signal generated by the test pattern generation means,
The test pattern signal is added and held by a predetermined line by the holding means, and held.
An image reading device for inspecting whether or not the signal luminance value of the test pattern signal held in the holding means matches a predetermined luminance value. A photoelectric conversion means that receives the diffused light of the document obtained by illuminating the document, and
An analog processing means that samples-holds the output signal of the photoelectric conversion means and converts it into a digital image signal.
A test pattern generation means that generates a digital image signal for testing,
The image signal output by the analog processing means and the image signal output by the test pattern generation means are switched, and the switching means having a transmission unit for transmitting the image signal to the subsequent stage and the image signal from the switching means are added by a predetermined line. Or, a holding means for holding the result of line averaging as a correction coefficient used for shading correction processing,
In an image reading device having a control means for controlling each of the means.
After reading the original, before stopping the operation of the analog processing means, the switching circuit is switched to the signal generated by the test pattern generating means.
Using the holding means, the test pattern signal is added and held by a predetermined line, and held.
An image reading device for inspecting whether or not the signal luminance value of the test pattern signal held in the holding means matches a predetermined luminance value.

Images