JPH0313063A - Picture reader - Google Patents

Abstract

PURPOSE:To make the relation of DIN/DOUT close to linearity by optimizing the form of a video signal and the combination of A/D converter systems. CONSTITUTION:A polarity of an output signal of a line sensor 1 is inverted by an inverse amplifier 2, inputted to a parallel A/D converter circuit 3 to form a digital signal having a prescribed bit number. In this case, a black level is set to the MSB(Most significant bit) and the white level is set to the LSB(Least significant bit). Thus, when the A/D conversion is implemented in 8-bit, the full white level is set to 0 gradation and the full black level is set to 255 gradation. An output of the parallel A/D converter circuit 3 is inputted to a buffer 4 and the polarity of the data to the said buffer 4 is inverted for the output. The S/N of the parallel A/D converter circuit 3 is deteriorated when a signal level is small, and it is possible to keep the S/N in the excellent state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device for a recording device such as a copying machine, facsimile machine, or printer, and particularly relates to an A/D conversion circuit in an image reading device. .

[Prior Art] In image reading devices of recording devices such as copying machines, facsimiles, and printers, a line sensor composed of a COD or the like reads an image of a document, converts it into an electrical signal, digitizes it, and performs predetermined processing. Things are being done. and,
Digitization makes it easier to perform various image processing, and therefore digital processing is being adopted to realize various editing functions, particularly in color digital copying machines, which have been actively developed in recent years.

[Problem to be solved by the invention] Now, A used when digitizing an analog signal
Various types of /D conversion circuits have been proposed, and various configurations of CCD line sensors for obtaining color video signals are known, but the format of the output signal of the CCD line sensor is Depending on the combination of and A/D conversion method, the relationship between the density of the original (DIN) and the density of the printed or copied image (DOUT) may not be linear, and the image of the original may not be reproduced well. It has become clear that there is.

The present invention solves the above-mentioned problems, and by optimizing the combination of video signal format and A/D conversion method, the present invention provides an image that can bring the DIN/DOUT relationship close to linear. The purpose of this invention is to provide a reading device.

[Means and Operations for Solving the Problems] In order to achieve the above object, an image reading apparatus according to the present invention has the configuration shown in FIG.

FIG. 1(a) is a diagram showing one configuration example of the present invention. In the figure, 1 is a line sensor, 2 is an inverting amplifier consisting of an operational amplifier, etc., 3 is a parallel type A/D conversion circuit, and 4 is an output. This is a buffer that performs polarity reversal when

In the configuration of FIG. 1(a), the line sensor 1 is composed of, for example, a CCD line sensor, and the GRBGR
A point-sequential color video signal of B... is output. The signal level is set to be high when the density of the original is high, and to be low when the density of the original is low. The output signal of the line sensor 1 has its polarity inverted by an inverting amplifier 2, and is input to a parallel A/D conversion circuit 3 to be converted into a digital signal having a predetermined number of bits. At that time, Dark is MSB (N
.

st 51gn1flcant 'Bit) side, white is L S B (Last Significant B
It is designed to correspond to the IT) side. Therefore, A/
Assuming that D conversion is performed in 8 bits, pure white is O
The gradation and total black are set to 255 gradations.

The output of the parallel A/D conversion circuit 3 is input to a buffer 4, and the buffer 4 inverts the polarity of the input digital data when outputting the data. The output of the buffer 4 is supplied to a subsequent processing circuit.

Due to its configuration, when the signal level is small, the parallel A/D conversion circuit 3 suffers from so-called kick pack (Kl
However, by using the circuit configuration shown in FIG. 1(a), it is possible to maintain the S/N in a good state.

FIG. 1(b) is a diagram showing another configuration example of the present invention, in which 1 is a line sensor, 4 is a non-inverting amplifier consisting of an operational amplifier, etc., 5 is a series-parallel type A/D conversion circuit, 6 is a buffer that outputs without inverting the polarity.

In the configuration of FIG. 1(b), the line sensor 1 is the same as that shown in FIG. 1(a), and the line sensor 1
The output signal is inputted to the serial/parallel type A/D conversion circuit 6 by the non-inverting amplifier 5 without inverting the polarity of the signal, and is converted into a digital signal that develops a predetermined number of bits. The output of the serial/parallel type A/D conversion circuit 6 is input to a buffer 7, outputted with the same polarity, and supplied to a subsequent processing circuit.

The series/parallel type A/D conversion circuit 6 is the parallel type A/D conversion circuit 3
Innote, which has an extremely small amount of kick pack compared to the DIFI
/DOU has good linearity.

[Example code] Hereinafter, the present invention will be described in detail with reference to Examples.

In this embodiment, a color copying machine will be explained as an example of a recording device, but the present invention is not limited to this and can of course be applied to printers, facsimile machines, and other image recording devices. .

First, prior to explaining the examples, a table of contents will be shown.

In the following description, (I) is a section that outlines the overall configuration of a copying machine to which the present invention is applied,
In the configuration, the section (n) provides a detailed explanation of the present invention.

1←LΣ1'' and λ and A (I-1) Equipment configuration (I-2) Equipment characteristics (I-3) Electrical control system configuration (I-4) Image processing system (IPS) (I-5)
Image output terminal (IOT) (I-6) User interface (U/I) (I-7) Film image reading device ■) Image terminal I (n-1) Imaging unit drive mechanism (II-2)
Stepping motor control method % formula % (n-4) I IT control method (II-5) Video signal processing circuit FIG. 2 is a diagram showing an example of the overall configuration of a color copying machine to which the present invention is applied. be.

A color copying machine to which the present invention is applied has a base machine 30 as a basic configuration, a platen glass 31 on which a document is placed, an image input terminal (IIT) 32, an electrical control storage section 33, an image output terminal ( IOT)
34, paper tray 35, user interface (U/I
) 3B, optionally an edit pad 61 and an auto document feeder (ADF) 82.
, sorter 63 and film projector 9 (F/P)
64.

Electrical hardware is required to control the above-mentioned IIT, IOT, U/1, etc., but these hardwares include IIT, IPS, U/L F/1, etc. that performs image processing on the output signals of IIT, etc. It is divided into a plurality of boards for each processing unit such as P, and the SYS board and IOT that control them.

Electrical control system storage part 3 together with MCB board (master control board) etc. for controlling ADFl sorter etc.
It is stored in 3.

Furthermore, the feature of this embodiment is that the platen glass 31
A mirror unit (M/U) 65 is placed on top, and the F
By projecting a film image from the /P 64 and reading it as an image signal by the imaging unit 37 of the IIT 32, it is possible to make a color copy directly from the color film. Target manuscripts include negative film,
It can use positive film and slides, and is equipped with an autofocus device and automatic correction filter exchange device.

I-24's (a) Achievement of high image quality in full color This device has the following features: black image quality reproduction, light color reproduction, generation copy quality, OH2 image quality, thin line reproduction, film copy image quality reproduction, and copy maintainability. The aim is to achieve high-quality, full-color images that can clearly reproduce color documents.

(b) Lower costs We have lowered the cost of consumables such as photoreceptors, developing machines, and toner, and reduced service costs such as UMRl parts costs.We have also made it possible to use it as a black-and-white copier, and furthermore By achieving a copying speed of 30 sheets/A4, which is about three times that of conventional models, we aim to reduce running costs and copy unit prices.

(c) Improving productivity By installing an ADFl sorter (optional) on the input/output device, it is possible to process multiple documents.The magnification can be selected from 50 to 400%.The maximum document size is A3, and the paper tray is upper B.
5-B4, middle B5-B4, lower B5-A3.5SIB
5 to A3, copy speed is 4 full color A4
4.8CPM1 in B4 4.8CPM1 in A3 2.4
CPM, black and white, 19.2 CPM1 for A4 1 for B4
9.20PM1A3 with 9.8CPM1 warm-up time within 8 minutes, FCOT achieved in 28 seconds or less for 4 full colors and 7 seconds or less for black and white, and continuous copy speed is 7.5 full color sheets/A4, 30 black and white sheets. Aiming for high productivity by achieving paper/A4 paper.

(d) Improved operability Hard buttons on the hard control panel, 02
By using soft buttons on a single-screen soft panel, it is easy for beginners to understand, does not bother experts, allows for direct selection of functions, and improves operability by concentrating operations in one place as much as possible. Colors are used effectively to accurately convey the necessary information to the operator. High-fidelity copying can be performed using only the hard control panel and basic screen operations.
Start, stop, all clear, interrupts, etc. that cannot be specified in the operation 1 flow are performed by operating the hard buttons, and paper selection, reduction/enlargement, copy density, image quality adjustment, color mode, color balance adjustment, etc. are performed by operating the basic screen soft panel. This makes it easy for users of conventional single-color copy machines to use it naturally. Furthermore, each sv
For i-collection functions, etc., you can open the busway and select various editing functions by simply touching the busway tab in the busway area of the soft panel. Furthermore, by storing the copy mode, its execution conditions, etc. in advance in the memory card, it is possible to automate certain operations.

(E) Enhancement of functions In the user interface of the present invention, selection of functions, selection of execution conditions, and other menus are displayed on a display such as a CRT as described above, so that anyone can easily operate the user interface. In addition to being equipped with a wide variety of functions that meet the needs of users, its major feature is that it fully automates the copying process from entry to exit.

Its main functions include start, stop, all clear, numeric key interactive, and
Information, language switching, etc. are performed, and various functions can be selected by touching soft buttons on the basic screen. In addition, in the function selection area, by touching the busway tab corresponding to a busway, you can open the busway and select various editing functions such as marker editing, business editing, creative editing, etc., and it can be used like a conventional copy. Full-color and black-and-white copies can be made with simple operations. Furthermore, the area specified in the editing function is displayed as a bitmap area, allowing you to confirm the specified area. In this way, you can greatly improve your writing expressiveness with the rich editing functions and color cleaner.

(f) Achievement of power saving Achieving a high-performance copying machine with 4 full colors and 1.5kVA. Therefore, 1.5kV in each operation mode
A control method to achieve A has been determined, and power distribution by function has been determined to set target values. In addition, an energy system table is created to determine energy transmission routes, and energy system management and verification are performed.

In this section of the system, the hardware architecture and software architecture of the electrical control system of this copying machine will be described.

Figure 3 shows the hardware architecture, Figure 4 shows the hardware architecture.
The figure is a diagram showing the software architecture.

When a color CRT is used as a UI like this copying machine, there is more data for color display than when using a monochrome CRT, and the display screen configuration and screen transitions have been devised to make it more user-friendly. If you try to construct a Ul, the amount of data will increase.

On the other hand, although it is possible to use a CPU with a large memory capacity, the board becomes large, making it difficult to store it in the copier itself, and making it difficult to respond flexibly to changes in specifications. However, there are problems such as high cost and so on.

Therefore, in this copying machine, a technology that can be shared with other models or devices such as a CRT controller is used as a remote to distribute the CPU to cope with the increase in the amount of data.

The electrical hardware is as shown in Figure 3.
It is roughly divided into three types: UI system, sys system, and MCB system. The UI system includes a UI remote 70, and the sys system includes an F/P remote 72 that controls the F/P, an IIT remote 73 that reads originals, and an IPS remote 74 that performs various image processing. IIT remote 73 is an II for controlling the imaging unit.
T controller 73a and VIDEO circuit 73 that digitizes the read image signal and sends it to the IPS remote 74
b, and is controlled by the VCPUT 4a together with the IPS remote 74. SYS (System+) is used to centrally manage each remote mentioned above and below.
A remote 71 is provided at the tail.

Since the SYS remote 71 requires a huge memory capacity for programs and the like to control the screen transitions of the UI, an 808B equipped with a 16-bit microcomputer is used. Note that in addition to 808G, for example, eaooo, etc. can also be used.

In addition, in the MCB system, the video signal used to form a latent image on the photosensitive material belt with a laser is received from the IPS remote 74, and a raster output scan (Raster Output 5can) is performed to send it to the IOT.
RO8) interface, VCB (Video
Control Board) remote 76, RCB remote 77 for the servo of the transfer device (turdle)
, even more! IOB remote 78 as I10 boat for tIOT, ADF1)-9, accessories
and accessory-remote 79, and MCB (Master Co., Ltd.) is used to centrally manage them.
ntrol Board) remote 75 is provided.

Note that each remote in the figure is composed of one board. Also, the thick solid line in the figure is 187°5 kbp
s LNET high-speed communication network, the thick broken line is 9800t) ps
The figure shows a master/slave type serial communication network, and the thin solid line shows a hot line which is a control signal transmission path. In addition, 7 [i, 8 kbps in the figure means that graphic information drawn on the edit pad, copy mode information input from the memory card, and graphic information in the editing area are transmitted from the U I IJ mote 70 to the IPS remote 74. This is a dedicated line for notifications. Furthermore, CCC (C
ommunlcatl.

n Control Chip) is an IC that supports the protocol of the high-speed communication line LNET.

As mentioned above, the hardware architecture can be roughly divided into three types: UI system, sys system, and MCB system.The division of processing among these systems can be explained as follows with reference to the software architecture in Figure 4. It is. Note that the arrows in the figure indicate data exchange via the 187.5 kbps LNET high-speed communication network and 91700 bps master/slave type serial communication network shown in Figure 3, or control signals carried out via the hotline. shows the transmission relationship.

The UI remote 70 is LLU I (Low Level
(old) module 80, and a module (not shown) that processes the edit pad and memory card.
It consists of The LLUI module 80 is usually C
It is similar to what is known as an RT controller, and is a software module for displaying a screen on a color CRT.What kind of picture is displayed on the screen at any given time is determined by the 5YSUI module 81 or MCBU.
Controlled by I module 86. It is clear that this allows the UI remote to be shared with other models or devices. This is because the screen configuration and screen transitions vary depending on the model.
This is because the CRT controller is used integrally with the CRT.

SYS remote 71 and 5YSDI module 81,
SYSTEM module 82, and SYS, DIAG
It is composed of three modules: module 83;

The 5YSU t module 81 is a software module that controls screen transitions, and the SYSTEM module 82 is a F/F (Feature) that recognizes which screen and which coordinates of the soft panel have been selected, that is, what kind of job has been selected. Function)
Selection software, job confirmation software that ultimately checks the job to see if there are any inconsistencies in the copy execution conditions, and various information such as F/F selection, job recovery, machine state, etc. with other modules. This is a module that includes software that controls communication for sending and receiving data.

The SYS, DIAG module 83 is a module that operates in the customer simulation mode in which a copy operation is performed in a diagnostic state that performs self-diagnosis. Since the customer simulation mode operates in the same way as a normal copy, The SYS, DIAG module 83 is essentially the same as the SYSTEM module 82, but since it is used in a special state called diagnostic, the SYSTEM module 83 is
It is written separately from 2, but partially overlaps with it.

In addition, the IIT remote 73 includes an IIT remote controller that controls the stepping motor used in the imaging unit.
The IPS remote 74 stores an IPS module 85 that performs various processes related to IPS, and these modules are controlled by the SYSTEM module 82 .

On the other hand, the MCB remote 75 includes an MCBUI module 86, which is software that controls screen transitions in the event of faults such as diagnostics, Audltron, and jams, controls the photosensitive material belt, controls the developer, and controls the user. IOT module 901 ADF that performs the necessary processing when copying etc.
The ADF module θ1 for controlling the sorter, the 5ORTER module 92 for controlling the sorter, the Cobia executive module 87 for managing them, the diagnostic executive module 88 for performing various diagnoses, and the electronic counter can be accessed by reciting the i code. It houses an audiotron module 89 that performs charge processing.

Further, the RCB remote 77 stores a turdle servo module 93 that controls the operation of the transfer device, and the turdle servo module 93 is under the control of the IOT module 90 in order to control the transfer process of the xerography cycle. It is located in The reason why the copier executive module 87 and the diagnostic executive module 88 overlap in the figure is the same as the reason why the SYSTEM module 82 and the SYS and DIAG modules 83 overlap.

FIG. 5 is a diagram showing the relationship between the system and other remotes.

As mentioned above, the remote 71 is equipped with the 5YSUI module 81 and the SYSTEM module 82, and the 5Y
SU I 81 and SYSTEM! .

Data is exchanged between the module 82 and the SYSTEM module 82 through an inter-module interface.
IT73 and IPS74 are connected via a serial communication interface, and MCB75, RO376, and RAIB
79 is connected to the LNET Shisoku double-speed communication network.

Next, the module configuration of the system will be explained.

FIG. 6 is a diagram showing the module configuration of the system.

In this copying machine, each module such as IIT and IPSl 10T is considered to be a component, and each module of the system that controls these is considered to have a brain. Adopting a distributed CPU system, the system side is in charge of per-original processing and job programming processing, and correspondingly has control rights to manage the initialization state, standby state, set-up state, and cycle state, as well as control rights to manage these states. Since the user has the UI master right to use the UI in this state, the system is configured with the corresponding modules.

The system main 100 takes in the received data from the 5YSUI, MCB, etc. to the internal buffer, clears the data stored in the internal buffer, and clears the data stored in the internal buffer.
It calls each module below 0 and passes the processing to update the system state.

The M/C initialization control module 101 controls the initialization sequence from when the power is turned on until the system enters a standby state, and is activated when the power-on processing for performing various tests after the power-on by the MCB is completed.

The M/C set-up control module 103 controls the set-up sequence from when the start key is pressed until starting the MCB that processes the copy layer. M/ to achieve the requirements of
A jib mode is created based on the instruction items for C), and a setup sequence is determined according to the created job mode.

M/C standby control module 102 is M/C
It controls the sequence during C standby, and specifically accepts start keys, controls color registration, and enters diagnostic mode.

The M/C copy cycle control module 104 controls the copy sequence from when the MCB is started until it is stopped, and specifically sends a paper feed count notification, determines the end of a JOB and requests IIT startup, and sends a request to start up the MCB. It determines whether to stop and issues a request to shut down the IPS.

It also has the function of notifying the remote destination of through commands that occur while the M/C is stopped or in operation.

Fault control module 106 is IIT11
Monitors the cause of the shutdown from the PS and activates the MCB when the cause occurs.
Specifically, llT1 IPS
Shutdown is performed using the fail command from M.
After a shutdown request is issued from the CB, recovery is determined when the M/C is stopped, and recovery is performed by, for example, a jam command from the MCB.

Communication scene control mosule 107 is I
It sets the IIT ready signal from IT and enables/disables communication in the image area.

The DIAG control module 108 controls the input check mode and the output check mode in the DIAG mode.

(I-4 image ring system S Figure 7 is IPS
FIG. 2 is a diagram showing an overview of the module configuration of FIG.

IPS receives 8 bibt data (256 tones) from IIT for each B, G, and R color separation signal.
is input, converted to YlM, C, and K toner signals, selects the process color toner signal It is. During this time, various data processing is performed to improve color reproducibility, gradation reproducibility, definition reproducibility, and the like.

END conversion (Equivalent Neutral
Denslty (equivalent neutral concentration conversion) module 30
1 is a module for adjusting (converting) the optical reading signal of a color original obtained at IIT into a gray-balanced color signal, and when reading a gray original, it adjusts (converts) the optical reading signal of a color original, and when reading a gray original, it B at always equal gradation,
There are 16 conversion tables for converting and outputting G and H color separation signals.

Color masking module 302! t, Bt　G.

It converts an R color separation signal into a Yl Ml C toner signal, and is determined by matrix calculation or using a table.

The document size detection module 308 performs document size detection during pre-scanning and platen color erasing (frame erasing) processing during document reading and scanning. If the document is tilted or not rectangular, the maximum and minimum values (xLx2, l, 72) of the top, bottom, left and right are detected and stored.

The color conversion module 305 performs conversion processing using a specified color in a specific area, and if it is not a color conversion area, it converts YlM, C of the document according to the area signal input from the area image control module.
When it enters the color conversion area, it detects the color specified as 1 and sends out the conversion colors YlM and C.

UCR (Under Co1or Removal
: Undercolor removal) & black generation module 305 generates an appropriate amount of K to prevent color turbidity, and Yl according to the amount.
This is a process of reducing M and C by equal amounts (undercolor removal) to prevent ink from being mixed in and a decrease in saturation of low brightness and high chroma colors.

The spatial filter module 306 generates halftone dot removal information and edge enhancement information using a digital filter and a modulation table, and smoothes the document with photographs or halftone dot printing, and performs edge enhancement with the document containing text or line drawings. It is something to do.

10T is Y according to the on/off signal from the IPS.
Four copy cycles (in the case of 4 full-color copies) are executed using each process color of IM, C, and K, making it possible to reproduce full-color originals, but in reality, the colors calculated theoretically through signal processing are To faithfully reproduce the data, delicate adjustments are required that take into account the characteristics of the IOT.

TRC (Tone Reproduction Con
trol (color tone correction control) module 307 is for improving reproducibility, and performs editing such as density adjustment according to area signals, hill contrast adjustment, negative/positive inversion, color balance adjustment, character mode, watermark composition, etc. It has a function.

The reduction/enlargement processing module 308 performs reduction/enlargement processing in the main scanning direction by thinning out and supplementing data when reading/writing data using a line buffer.

In addition, shifting image processing in the main scanning direction can be performed by reading data written to the line buffer from the middle or by reading it with delayed timing, and by repeatedly reading data, it is possible to perform repeated processing, and from the opposite direction. Mirror image processing can also be performed by reading. In the sub-scanning direction, the IIT scan speed is varied from 2x speed to 1/4x speed and 50%
It is scaled up from 400%.

The screen generator 309 converts the gradation toner signal of the process color into an on/off binary toner signal and outputs it, and performs the binarization process by comparing the threshold matrix and the gradation-expressed data value. and performs error diffusion processing. In the IOT, this binary toner signal is input, and the width is approximately 80 μm vertically to correspond to 16 dots/mm.
A half-tone image is reproduced by turning on/off an elliptical laser beam with a diameter of 60 μm and a width of 60 μm. In addition, error diffusion processing is performed by detecting and feeding back the quantization error between the on/off binary signal generated by the screen generator and the input gradation signal, thereby improving the gradation from a macro perspective. Improves reproducibility.

The area image control module 311 is capable of setting seven rectangular areas and their priorities, and area control information is set corresponding to each area. The control information includes color conversion, color mode such as monochrome or full color, modulation selection information for photos and text, TRC selection information, screen generator selection information, etc., and the color masking module 302, color conversion module 304, UCR module 305, spatial filter 306, TRC module 3
Used for control of 07.

The editing control module reads a manuscript that is not a rectangle but a pie chart, for example, and enables coloring processing in which a specified area of any shape is filled with a specified color, and commands 0 to 15 are used as a fill pattern, It is set and processed as a command to process fill logic, logos, etc.

In the IPS of the present invention, as described above, the IIT original reading signal is first subjected to END conversion and then color masking, and processes such as original size, border erasure, and color conversion, which are more efficient when processing with full color data, are performed. After removing the undercolor and generating ink, I focused on process colors.

However, processing such as spatial filtering, color modulation, and TRC1 reduction can be done by processing process color data, which reduces the amount of processing compared to processing full color data, and reduces the number of conversion tables used by 1/3. At the same time, we have increased the number of types to increase adjustment flexibility, color reproducibility, gradation reproducibility, and definition reproducibility.

-5 Image Terminal ■0 Figure 8 is a diagram showing the schematic configuration of the image output terminal.

This device uses a photoreceptor as a photoreceptor.

A developing machine 404 consisting of 1M, C, and Y for full-color printing, and a transfer device (Tow Roll Tr) that conveys the paper to the transfer section.
ansfer Loop) 40 B, a vacuum conveyance device (V
acum Traosfer) 407, paper tray 41
0.412, a paper conveyance path 411 is provided, and the three units of a photosensitive material belt, a developing device, and a transfer device are configured to be pulled out to the front side.

Information light obtained by modulating the laser light from the laser light source 40 is irradiated onto the sensitive material 41 via the mirror 40d to perform exposure and form a latent image.

The image formed on the photosensitive material is developed by a developing device 404 to form a toner image. The developing machine 404 is M
It consists of IC and Y, and is arranged in the positional relationship as shown in the figure. For example, the relationship between dark decay and the characteristics of each toner,
The arrangement is done taking into consideration the difference in influence due to the mixing of other toners with the black toner. However, the driving order for full color copying is Y-+C+M-+
It is.

On the other hand, 41o1 and other 2 consisting of two elevator trays
The paper fed from the tray 412 of the stage is transported through the conveyance path 411.
It is supplied to the transfer device 40B through the transfer device 40B. Transfer device 406
is placed in the transfer section and consists of two rolls connected by a timing chain or belt and a gripper bar as described below.The gripper bar grips the paper and transports the paper, transferring the toner image on the photosensitive material. Transfer it to paper. 4
In the case of full color, the paper rotates 4 times in the transfer unit, and the Y
Images of lolM and K are transferred in this order. After the transfer, the paper is released from the gripper bar, transferred from the transfer device to a vacuum conveyance device 407, fixed by a fixing device 408, and then discharged.

The vacuum conveyance device 407 is connected to the transfer device 406 and the fixing device 40.
It absorbs the speed difference with 8 and maintains synchronization. In this device, the transfer speed (process speed) is 190 mm/
Sea is set, and the fixing speed is 90. (2)/secC, so the transfer speed and fixing speed are different.

In order to ensure the degree of fixation, the process speed is reduced, and on the other hand, to achieve 1.5 kVA, power cannot be given to the user.

Therefore, in the case of small paper such as B5 or A4, the transferred paper is released from the transfer device 406 and transferred to the vacuum conveyance device 40.
7, the speed of the vacuum transfer device is increased to 190 mm/
sea to 90 ms/sec to make it the same as the fixing speed. However, in this device, the distance between the transfer device and the fixing device is made as short as possible to make the device more compact, so if A3 paper cannot fit between the transfer point and the fixing device, the speed of the vacuum conveyance device will be reduced. Otherwise, since the rear edge of the A3 sheet is being transferred, the brakes will be applied to the paper, resulting in color misregistration. Therefore, a baffle plate 409 is provided between the fixing device and the vacuum conveying device,
In the case of A3 paper, the baffle plate is tilted downward to make the paper draw a loop to lengthen the conveyance path, and the vacuum conveyance device is set at the same speed as the transfer speed so that the leading edge of the paper reaches the fixing device after the transfer is complete. In this way, the speed difference is absorbed. Further, in the case of OHP, heat conduction is poor, so the same method as in the case of A3 paper is used.

In addition, this device is capable of copying not only full color but also black without reducing productivity. In the case of black, there is less toner layer and it is possible to fix even with a small amount of heat, so the fixing speed is 190 mm/sec. Do not reduce the speed using the vacuum transfer device. In addition to black, this toner layer is IJi like a single color! In this case, the fixing speed does not need to be reduced, so the same procedure is used. and,
When the transfer is completed, the toner remaining on the photosensitive material is scraped off by a cleaner 405.

-6 User Interface UI In order to improve operability, the U/I is equipped with a 12-inch color display 51 monitor and a 71-door control panel 52 next to it, as shown in FIG.

The color display is designed to provide the user with a menu that is easy to see and understand, and the color display 51 is combined with an infrared touch board 53 to allow direct access using soft buttons on the screen. In addition, by efficiently distributing operation contents to the note buttons on the hard control panel 52 and the soft buttons displayed on the screen of the color display 51, it is possible to simplify operations and efficiently configure the menu screen. ing.

FIG. 9 is a diagram showing the hardware configuration of the U/I.

The U/I board consists of two boards, a UICB 521 and a BPIB 522, as shown in FIG.

The UICB 521 controls the UL node and has an edit pad 513 and a memory card 514.
In order to drive, there is also a touch screen 503
Two CPUs (
For example, the EPI B522 uses Intel's 8085 equivalent and 6845 equivalent), and since 8 bits is insufficient for drawing in the bitmap area,
6-bit CPU (e.g. Intel's 80C198K)
Use A) to DM the bitmap area drawing data.
Functional distribution is achieved by configuring A to transfer to the UICB 521.

In the U/I of the present invention, a compact size display is used, and the display screen and its control are devised. For example, by broadly classifying the information displayed on the screen and dividing it into multiple screens, and then, for each screen, creating a pop-up with detailed information and omitting it from the primary screen, the screen can be configured concisely with the minimum necessary information. We are trying to do this. On a screen containing a plurality of pieces of information, features of color display and highlighted display are devised to make it easier to recognize and identify the necessary information on the screen.

FIG. 10 is a diagram showing an example of the configuration of a display screen,
Figure (a) is a diagram showing the basic copy screen.
FIG. 6(b) is a diagram showing an example of the basic copy screen in which the pop-up screen is expanded.

In the U/I of the present invention, a basic copy screen for setting a copy mode as shown in FIG. 10 is displayed as an initial screen. The copy mode setting screen includes a 117-inch soft control panel and a message area A.
It is divided into two parts: and / Nl Sway Bl.

Message area A uses the top three lines of the screen,
The first line is for state messages, and the second and third lines are for guidance messages when there is a contradiction in function selection, messages regarding abnormal conditions of the device, and warning information messages at the right end of the message area A. is a number display area, and displays the set number of copies input using the numeric keypad and the number of sheets being copied.

Pathway B is an area for selecting various functions,
Base 7 copy Edit at feature marker,
It has busways for business editing, free online editing, creative editing, and tools, and a busway tab C is displayed corresponding to each busway. Additionally, each pathway has a pop-up to improve operability. Busway B has a soft button D1 that is an option and selects a function when touched, an icon (picture) E1 that changes depending on the selected function and displays that function, an indicator F that displays the zoom ratio, etc. Items that are displayed and can be popped up using soft button D are marked with a △ pop-up mark G. And pathway tab C
By touching , the pathway can be opened, and by touching soft button D, the function can be selected. The selection of functions by touching the soft button D is designed to be operated in order from the upper left to the lower right in consideration of operability.

As mentioned above, the basic floppy screen and others are separated to maximize commonality with other models and hard console panels, and the editing screen provides screens and functions tailored to the skill level of the operator. It has a multi-layer structure so that Furthermore, by combining such a screen configuration with a pop-up function, a screen that is easy to use in a variety of ways is provided, such as displaying advanced or complex functions within a single screen as a pop-up.

FIG. 10(b) shows the screen when a pop-up is opened by pressing the magnification soft button in the zoom/enlarge function.

Note that the screen display has a width of 3, excluding the bitmap area.
It uses tiled display with mm (8 pixels) and height Etmm (16 pixels), with 80 tiles horizontally and 25 tiles vertically. The bitmap area is displayed with 151 pixels vertically and 216 pixels horizontally.

As shown in Figure 2, the hard control panel is installed on the right side of the color display at an angle that points further toward the center than the screen. , language buttons are attached.

In addition to the above-mentioned buttons, LED (light emitting diode) lamps are appropriately attached to display the operation status of the buttons.

-7 Film As shown in FIG. 2, the film image reading device is composed of a film projector (F/P) 84 and a mirror unit (M/U) 65.

Fig. 11 is a perspective view of the F/P, Fig. 12 is a perspective view of the M/U, and Fig. 13 is a diagram showing the schematic configuration of the F/P and the relationship between the F/P, M/U, and IIT. .

The F/P 64 has a housing 601 as shown in FIG.
This housing 601 includes an operation confirmation lamp 602, a manual ramp switch 803, and an autofocus/manual focus switch (AF
/MF selector switch) 804. and manual focus operation switch (M/F operation switch) 80
5a and 605b are provided. Also, housing 6
01 includes an opening/closing part 608 that can be opened and closed. A film holding case 607 holding an original film 633 is mounted on the top and side surfaces of this opening/closing part 606.
Holes 608 and 609 are formed, respectively, in a size that allows the housing 601 to be inserted into the housing 601 vertically or horizontally depending on how the subject is to be photographed as recorded in the housing 601.

A hole (not shown) through which the film holding case 607 can protrude is also provided on the opposite side of the holes 608 and 809. The opening/closing part 606 is rotatably attached to the housing 801 by a hinge, or detachably attached to the housing E301. By making the opening/closing part 606 freely openable and closable, the hole 60
8. When a small foreign object enters the housing 601 from the 809, the foreign object can be easily removed.

The film holding case 607 includes a case for a 351m negative film and a case for a positive film. Therefore, F/P64 is designed to be compatible with these films. Furthermore, the F/P64 is designed to be compatible with 8cIIX6cm and 41nch x 51nch negative films. In that case, transfer this negative film to M/U85 and platen glass 3.
1 so as to be in close contact with the platen glass 31.

In the diagram of the housing 601, the projection lens 6 is on the right side.
A projection lens holding member 611 holding the lens 10 is slidably supported.

Further, inside the housing 601, a beam flap 612 and a light source lamp 613 made of a halogen lamp or the like are arranged coaxially with the projection lens 610. A cooling fan 614 for cooling the lamp 613 is provided near the lamp 613. Further, on the right side of the lamp 813, an aspherical lens 615 for converging the light from the lamp 613, a heat ray absorption filter 616 for cutting light rays of a predetermined wavelength, and a convex lens 617 are arranged coaxially with the projection lens 610. is placed on top.

To the right of the convex lens 617 is a correction filter holder that supports a correction filter 635 (the correction filter for one film is shown in the figure) for adjusting the film density of, for example, 35m11 negative film and positive film. A member 618, a motor 619 for driving the correction filter holding member 618, and first and second position detection sensors 62 that detect the rotational position of the correction filter holding member 618.
An automatic correction filter exchange device is provided, each having a control device (provided in the F/P 84 but not shown) for controlling the 0° 621 and the drive motor 619. Of the correction filters 635 supported by the correction filter holding member 618, the original film 63
The correction filter 635 corresponding to No. 3 is automatically selected so as to match the use position coaxially with each lens such as the projection lens 610. The correction filter 635 of this correction filter automatic exchange device can be placed anywhere on the optical axis of the projection light, such as between the platen glass 31 and the imaging unit 37, for example.

Further, an autofocus sensor including a light emitter 623 and a light receiver 624 for an autofocus sensor that are linked to the projection lens holding member 611, and a sliding motor 625 that slides the projection lens holding member 811 of the projection lens 610 with respect to the housing 801. A focus device is provided. When the film holding case 607 is inserted into the housing 601 through the hole 608 or 609, the original film 633 supported by the film holding case 607 is placed between the correction filter holding member 618, the light emitter 623, and the light receiver 624. Being located.

A film cooling fan 626 for cooling the original film 633 is provided near the position where the original film 635 is set.

The power supply for this F/P 84 is provided separately from the power supply for the base machine 30, but is housed within the base machine 30.

As shown in FIG. 12, the M/U 65 includes a bottom plate θ27 and a cover 6 whose one end is rotatably attached to the bottom plate 627.
It is equipped with 28. A pair of support pieces 629°629 are pivotally mounted between the bottom plate 627 and the cover 628.
These support pieces 629 and 629 support the cover 628 so that the angle formed between the cover 628 and the bottom plate 627 is 45 degrees when the cover 628 is opened to the maximum.

A mirror 630 is provided on the back surface of the cover 628. Further, a large opening is formed in the bottom plate 627, and a Fresnel lens 631 and a diffusion plate 632 are provided so as to close this opening.

The Fresnel lens 631 and the diffuser plate 632 are made of a single acrylic plate, as shown in FIG.
A Fresnel lens 631 is formed on the front surface of this acrylic plate, and a diffuser plate 632 is formed on the back surface. The Fresnel lens 631 has a function of preventing the periphery of the image from becoming dark by converting the projected light that is reflected by the mirror 830 and tends to be diffused into parallel light. Further, the diffusing plate 632 has a Fresnel lens 631
In order to prevent the line sensor 226 from detecting the shadow of the SELFOC lens 224 in the imaging unit 37, which is formed by the parallel light from the imaging unit 37, it has a function of diffusing the parallel light by a minute amount.

When the M/U 65 is not making color copies using the F/P 64, it is folded and stored in a predetermined storage location. Then, when the M/Uf 35 is used, it is opened and placed at a predetermined location on the platen glass 31 of the base machine 30.

The main functions of the film image reading device are automatic correction filter replacement function, original film insertion direction detection function, autofocus function (AF function), manual focus function (MF function), manual lighting function of the light source lamp,
It has automatic magnification change function, automatic scan area change function, automatic shading correction function, and automatic image quality adjustment function.

■ Image Terminal 11 An embodiment of the present invention will be explained using an image input terminal of a copying machine as an example.

Imaging Unit FIG. 14 shows a perspective view of the imaging unit drive mechanism.

The imaging unit 37 is movably mounted on two slide shafts 202 and 203, and both ends thereof are fixed to wires 204 and 205. The wires 204 and 205 are wound around drive pulleys 206 and 207 and tension pulleys 208 and 209, and tension is applied to each of the tension pulleys 208 and 209 in the direction of the illustrated arrow. Said drive pulley 206.2
A reduction pulley 211 is attached to the drive shaft 210 to which the motor 07 is attached, and is connected to an output shaft 214 of a stepping motor 213 via a timing belt 212. Note that the limit switches 215 and 21B are sensors for detecting abnormal operation of the imaging unit 37, and the registration sensor 217 is a sensor for setting a reference point for the original reading start position.

The reason for employing the stepping motor 213 to drive the imaging unit 37 as described above is as follows.

That is, in order to obtain one full-color copy of Y, M, C, and K, the imaging unit 37
requires repeating 4 scans; in this case, 4
A major challenge is how to reduce synchronization and positional deviations during multiple scans.To achieve this, it is necessary to suppress fluctuations in the stop position of the imaging unit 37 and to suppress fluctuations in the arrival time from the home position to the register position. thing,
It is important that scan speed fluctuations are reproducible.

When using a DC servo motor, it is difficult to suppress such fluctuations in the stop position of the imaging unit 37 and fluctuations in the arrival time from the home position to the register position. A stepping motor is used because it is better at suppressing these fluctuations than a motor.

However, the stepping motor 213 has greater vibration and noise than a DC servo motor, and is also susceptible to mechanical problems such as aging of the timing belt 212 and wires 204 and 205, and viscous resistance between the slide pad and slide rail 202 and 203. Vibration is also caused by unstable factors. Therefore, countermeasures are required to improve the image quality and speed of the image recording apparatus.

To this end, in this embodiment, two slide shafts 202 (203) are provided in parallel, and as shown in FIG. 15, between the imaging unit housing 37a and the slide shafts 202 (203), Angle 37b! Vibration of the imaging unit 37 in the main scanning direction is restricted by interposing the oil-impregnated pad P with the spring 37c.

FIG. 16(a) of the stepping motor shows a drive circuit of the stepping motor 213. This drive circuit uses pentagonal wiring, in which the motor windings are connected in a pentagonal pattern.
The connection points are each connected to the positive side or negative side of the power supply using two transistors, and bipolar drive is performed using ten switching transistors. Furthermore, by feeding back the current flowing to the motor, the current supplied to the motor is controlled to be constant. In the excitation sequence, as shown in FIG. 16(b), when four phases are excited, the remaining one phase is short-circuited at the same positive or negative potential.

Next, the control circuit of the driver will be explained with reference to FIG. 16(C). In Figure 16 (C), 5TART
Signal and forward rotation clock CW or reverse rotation clock CCW
is input to the 5-phase pulse divider 271, the 5-phase pulse divider 271 controls the driver 2 according to the input clock.
The driver 272 supplies a current to the stepping motor 213 to drive it. The current i flowing through the stepping motor 213 is detected by the current detector 27.
3 and converted to voltage ■. This voltage V,
The comparator 274 compares the reference voltage v1 or V2 preset by the reference voltage generator 275, and if the voltage V becomes larger than the reference voltage Vl or 2, the
276 is turned off, the driver 272 is turned off, and the current supplied to the stepping motor 213 is controlled to be constant.

The reference voltages preset by the reference voltage generator 275 include a high voltage V I (FULL) and a voltage V2 that is about half of the high voltage V I (FULL).
(IIALF), the high voltage V1 is set when the stepping motor 213 is accelerating and torque is required, and when the clock frequency is high during return, and the voltage v2 is set when the acceleration is finished and the steady scan is performed. Ru. In addition,
Although the 5TART signal is input to the pulse divider 271, if the forward rotation clock CW or reverse rotation clock CCW is not input, the current flows only to the transistor of the driver 272 and it is destroyed, so the low frequency detector
This is detected and a signal is sent to the reference voltage generator 275 to lower the reference voltage to v3.

FIG. 17(a) shows a scan cycle of the imaging unit 37 driven by the stepping motor 213.
7 shows the relationship between speed and frequency applied to the stepping motor. During acceleration, the frequency applied to the stepping motor is increased one cycle at a time by multiplying 259 Hz, for example, to a maximum of about 11 to 12 KHz, as shown in FIG. 2(b). By imparting regularity to the pulse train in this way, pulse generation can be simplified.

Also, if you do this, as shown in Figure (a), 2
A trapezoidal profile with regular stepwise acceleration can be created at 59pps/3.9m5ec. Further, a pause time is provided between the scan operation and the return operation, and between the return operation and the scan operation, to wait for the vibration of the IIT mechanism system to decrease, and to synchronize with the image output in the IOT.

On the other hand, when reading a color original, the imaging unit 37 is scanned four times to read four color signals, so the major issue is how to reduce the color shift between the four colors. Imaging unit 37
It is important to suppress fluctuations in the stop position of the camera, to suppress fluctuations in the arrival time from the home position to the register position, and to suppress fluctuations in the scan speed.

FIG. 18 is a diagram for explaining the cause of color shift caused by the occurrence of vibration. As shown in FIG. 18 (a), the position where the imaging unit returns and stops after completing scanning is Δ If the difference is too much, the time to the registration position will be different when starting the next time, resulting in color misregistration. In addition, as shown in the same figure (b), if there is a transient vibration of the stepping motor within 4 scans, that is, a speed fluctuation until reaching a steady speed, the time to reach the registration position will shift by Δt, resulting in color shift. occurs. In addition, as shown in the same figure (C), the variation in the constant speed scanning characteristics from passing through the registration position to the tail edge is as follows. It's bigger than the variation. In consideration of the above, in this embodiment, during the first scan, yellow, which causes less noticeable color shift, is developed.

-3 Imaging unit (A) Overall configuration FIG. 19 shows a cross-sectional view of the imaging unit 37.

The original 220 is set on the platen glass 31 so that the image surface to be read faces downward, and the imaging unit 37 moves its lower surface in the direction of the arrow shown in the figure to adjust the original surface using the daylight color changing light 222 and the reflecting mirror 223. to expose. Then, the reflected light from the original 220 is passed through a SELFOC lens 224 and a cyan filter 225.
An erect, same-size image is formed on the light receiving surface of the CCD line sensor 226. The SELFOC lens 224 is a compound lens consisting of four rows of fiber lenses, and has the advantage of being bright and having high resolution, allowing the power of the light source to be kept low, and being compact. The imaging unit 37 also includes a CCD sensor drive circuit, a CO
A circuit board 227 including a D sensor output buffer circuit and the like is mounted.

In addition, 228 is a lamp heater, 229 is a flexible cable for control signals, and 230 is a flexible cable for illumination power supply. A circuit board 227 is attached to the lower part of the housing 37a to which the line sensor 226 is fixed, and the circuit board 227 and the housing 37a
A heat radiating plate 250 is attached between them to cover the protrusion 250b, and a punching metal 251 for electromagnetic shielding is further attached to cover the heat radiating plate 250. circuit board 2
A drive IC chip 252 is disposed at 27, and the line sensor 226 is electrically connected to a circuit board 227 through a connection pin 226a.

FIG. 20 shows a detailed view of the daylight color changing light lamp 222, in which a reflective film 222b is formed on the inner surface of the glass tube 222a except for the surface with a 7-vertical angle α (approximately 50 degrees), and a reflective film 222b is further formed on the inner surface of the glass tube 222a. A light film 222C is formed. Thereby, the light m of the fluorescent film 222 is efficiently irradiated onto the document surface, thereby reducing power consumption. The reason why the fluorescent film 222C is formed on the entire inner surface and the reflective film 222b is formed on the surface other than the surface at the aperture angle is to reduce the peak of the bright line of mercury, although the amount of light is reduced. Further, a lamp heater 228 and a heat sink (heat radiating member) 222d are provided on the outer peripheral surface of the fluorescent film 222, and the lamp heater 228 and the cooling fan are controlled by temperature detection by the thermistor 222e.

(B) CCD line sensor FIG. 21 shows an example of the arrangement of the CCD line sensor 226, and as shown in FIG.
θa to 226e are arranged in a staggered manner in the main scanning direction X. This is because it is difficult to form a large number of light-receiving elements without missing parts and with uniform sensitivity due to the size of the wafer, yield, and cost. This is because if they are arranged side by side, it is difficult to configure pixels to both ends of the line sensor, resulting in unreadable areas.

The sensor section of this line sensor 226 has three color filters of R (red), G (green), and B (blue) repeated in this order on the surface of each pixel of the line sensor 226, as shown in [Q(b)]. Three adjacent bits constitute one pixel during reading. The reading pixel density of each color is 1
If 6 dots/1 ugliness and the number of pixels per chip is 2928, then the length of 1 chip is 2928/(16X3)=
61. .

Therefore, the total length of 5 chips is 61×5:305 m. Therefore, this provides a line sensor of equal magnification that is capable of reading A3 size. Furthermore, each R and GlB pixel is arranged at a 45 degree angle to reduce moiré.

In this way, when the plurality of line sensors 226a to 226e are arranged in a staggered manner, adjacent line sensors scan different document surfaces.

That is, when the line sensor is moved in the sub-scanning direction Y orthogonal to the main-scanning direction X of the line sensor and the document is read,
The first row of line sensors 228b scans the original in advance.
There is a time lag between the signal from line sensor 1-228d and the subsequent signal from line sensor 228a122e3C1226e in the second row, which corresponds to the positional deviation between adjacent line sensors.

(C) Staggered correction Therefore, in order to obtain one line of continuous signal from the image signals divided and read by multiple line sensors, it is necessary to
The signal from b1226d is stored and sent to the second row line sensor 226at 2280% 22 f3
Staggered correction is required to read out in synchronization with the signal output from e. In this case, for example, if the amount of deviation is 250 μm,
Assuming a resolution of 16 dots/definition, a delay of 4 lines is required.

Further, in general, reduction/enlargement in an image reading device is performed in the main scanning direction by thinning out and increasing the amount of data in the video circuit, and by other processing, and in the sub-scanning direction by increasing/decreasing the moving speed of the imaging unit 37. Therefore, the reading speed (the number of lines read per unit time) in the image reading device is fixed, and the resolution in the sub-scanning direction is changed by changing the moving speed. That is, for example, if the scaling factor is 10
If the resolution is 16 dots/cup at 0%, the relationship will be as follows. Therefore, as the reduction/enlargement ratio increases, the resolution increases, and accordingly, the number of line memories required to correct the staggered arrangement difference of 250 μm also increases. FIG. 22 shows the relationship between the scaling factor and the amount of deviation, and one line is corrected every time one pixel shifts due to a change in the scaling factor.

Correction for each line causes a maximum deviation of 31 μm, but
There is no effect on the output image.

-4I Control IIT Remote has sequence control, service support function, self-diagnosis function, and fail-safe function for each full-length copy operation. IIT sequence control is divided into normal scan, sample scan, and initialization. ■Various commands for IT control,
Parameters are sent from the SYS remote 71 via serial communication.

FIG. 23(a) shows a timing chart of normal scanning.

In normal scanning, the extension and magnification are set as scan length data from 0 to 432 times (1 step).
The scan speed is set by the magnification (50% to 400%), and the prescan length (distance from the stop position to the registration position) data is also set by the magnification (50% to 400%).

In a normal scan, first, when a scan command is received, the fluorescent lamp is turned on by the FL-ON signal, and the
The motor driver is turned on by the CN-RDY signal, and after a predetermined timing, the shading correction pulse WHT-R is activated.
Generate EF' and start scanning. When the register position is reached, the image area signal IMG-AREA becomes low level for a predetermined scan length, and in synchronization with this, the IIT
- Output the PS signal to the IPS.

FIG. 23(b) shows a timing chart of sample scan.

The sample scan is used for color detection during color conversion, color balance correction and shading correction when using F/P. In this sample scan, the imaging unit was first moved to the target sample position and paused, or the micro-movement was repeated multiple times, based on data on the stop position, movement speed, number of micro-movements, and step interval from the register position. After that, stop it and collect sample data.

FIG. 23(C) shows a timing chart of initialization.

In initializing the IIT, when a command is received from the SYS remote when the power is turned on, the registration sensor is checked, the imaging unit operation is checked by the registration sensor, and the home position of the imaging unit is corrected by the registration sensor.

Video (A) Overview of the configuration of the video signal processing system As shown in FIG. 24, a CCD line sensor 226 is used to read a color original as a reflectance signal for each R, G1B, and convert this into a digital density signal. The video signal processing circuit will be explained below.

In FIG. 24, a read data adjustment/conversion circuit 232 samples and holds an analog video signal, performs gain adjustment and offset adjustment, and converts it into a digital signal. Out.

matlc Ga1n Control) 232 b
s Automatic offset adjustment circuit A OC (Automa
tic 0fset Control) 232c, A
/D conversion circuit 232d. The white signal (signal read from the white reference plate) and black signal (output signal during dark) of the COD line sensor usually vary depending on each chip and each pixel within the chip. In AGC232b,
Align the maximum value (peak value) of the white signal of each channel to the standard value, for example "200" with 258 gradations, and use AOC232.
In C, the minimum value of the black signal is set to a reference value, for example "10" in 256 gradations. In other words, AOC2
32c, if the minimum value is greater than the reference value of the A/D output level, it is lowered to that reference value, and if the minimum value is smaller than the reference value of the A/D output level, it is raised to that reference value.

I T G (TIT Tllng Generat
or) 238 controls the delay amount setting circuit 233 and separation/synthesis circuit 234 that perform staggered correction, controls the delay amount of staggered correction according to the contents of the register set by the VCPU 74a, and controls the delay amount of the 5 channels. C.C.
Adjust the timing of the output of the D line sensor 226, and
, G, and R color separation signals. ITG23g has a register that sets the staggered correction amount corresponding to the magnification value, a register that sets the IPS pipeline delay correction value, a register that sets the registration correction value in the main scanning direction, and a register that sets the effective pixel width in the main scanning direction. A register, a register for setting a staggered correction adjustment value, a register for setting a dark output timing adjustment value, etc. are provided. Then, when the power is turned on, "4" corresponding to 100% magnification is displayed.
'' is set in the register as the staggered correction amount, and at the start, the staggered correction amount according to the selection magnification is determined and set.

The delay amount setting circuit 233 is a so-called zigzag correction circuit that corrects the mounting deviation amount of the CCD line sensor 226 in the sub-scanning direction as explained in FIGS. 21 and 22.

The first row of CCD line sensors 228b and 228 consist of a FIFO-configured line memory and scan the original in advance.
The second row of CCD line sensors 228 a+ 226 ct 228 e
It outputs in synchronization with the signal output from the ITG.
The number of delay lines is controlled according to the setting of the delay amount according to the reduction/enlargement ratio in H.238.

The separation and synthesis circuit 234 performs BGRBGR and BGRBGR of each channel.
The consecutive 8-bit data strings are R, G.

After separating the signals into B signals and storing them in a line memory, the signals of each channel are serially combined into R, G, and B signals and output.

The conversion table 236 is a logarithmic conversion tape h for converting a reflected signal into a density signal as shown in FIG. 25(a).
L U T (Look UpTable) r
It has two tables: IJ and through conversion table LUT "0" as shown in FIG.
It is stored in . Then, the reflectance R, G, and B signals obtained by reading the original are converted into one-time R, G, and B signals corresponding to the amount of recording material, for example, the amount of toner.

The shading correction units 235 and 237 include a shading correction circuit 235a1237a and an SRAM 235.
b, 237b, and performs pixel shift correction, shading correction, image data input adjustment, etc.

Pixel shift correction is a process that performs weighted averaging between pixel data, and as mentioned above, in the signal processing circuit, R, G
, B's data is imported in parallel, but the second
R, G as shown in Figure 1 (b).

Since the B filter position is shifted, the R, G, and B outputs at the same pixel are shifted as shown in FIG. 26(a), and when the black line K is read, they are shifted. For this purpose, the weighting is performed by averaging processing, by shifting R to the right by 273 pixels and shifting B by 173 pixels to the right, so that the black lines K are made to coincide as shown in FIG. 2B.

For example, if the input data of the n-th pixel is Dnl and the output data is dn, as shown in FIG. 26(a), R1G,
According to the B signal, dn = Dn (no correction) dn = (Dn-1+2Dn) /3do = (
2Dn-1+Dn) /3 pattern is selected.

Shading correction is a process that subtracts the image data written in SRAM as reference data from the image input data after pixel misalignment correction and outputs the result.It is a process that subtracts and outputs the image data written in SRAM as reference data from the image input data after pixel shift correction. Corrects and corrects variations in the optical system due to dirt, etc., and variations in sensitivity between pits of the CCD line sensor. The shading correction circuit 235a is connected to the front stage of the conversion table 236 and outputs the dark level (dark output when the fluorescent lamp is turned off).
The shading correction circuit 237a
is connected to the rear stage of the conversion table 236 to correct the read output of the white reference plate. Therefore, as the reference data, the dark output data and the read data of the white reference plate are written into the respective SRAMs.

(B) Overview of operation of video signal processing system Next, an overview of the operation of the circuit will be explained along the flow of image signals.

First, the original is placed in the five CCs in the imaging unit 37.
5 consisting of CH2-CH2 by the D line sensor 226
It is divided into channels and read, and from each channel GBRGBR... as shown in Fig. 27 is read.
A serial signal is sent out.

This serial signal is amplified to a predetermined level by the pre-stage amplifier circuit 231, and then held by a sample-and-hold pulse HP in the sample-and-hold circuit 5H232a to remove noise. This held signal is sent to the gain adjustment circuit AGC232b and the offset adjustment circuit AO.
Gain and offset are adjusted through C232c
The signal is converted into a digital signal by the /D conversion circuit 232d. And serial digital signal GBRGBR...
- Line synchronizes each channel in the delay amount setting circuit 233, separates RGB for each channel in the separation/synthesis circuit 234, and then synthesizes the serial digital signal that synthesizes the R of each channel and the G of each channel. A serial digital signal is generated by combining the serial digital signal and B of each channel, and is sent to the shading correction circuit. The shading correction circuit processes image input data according to the mode at the time.

In addition to the copy scan mode mentioned above, there is a color detection sample scan mode, but in this mode,
First, the IIT carriage is moved to a designated color detection point, and original reading density data is written into the SRAM. and,
The data of the specified pixel is taken into the VCPU 74a. To explain this color detection sequence in more detail, in the color detection sequence, when 50 II seconds have elapsed after moving the IIT carriage to a specified point, the WHTR is sent to the ITG785.
EF is issued, ■PS line sync signal I PS-
Write processing to the SRAM is performed in synchronization with the LS.

Then, with the next line sync signal IPS-LS, the ITG issues a WHTINT signal, and the RA of the VCPU784
The pixel data of the specified point is transferred to M. Above 5 Q r
mSec is the time it takes for the IIT carriage to stop vibrating and come to rest. This color detection targets 5 pixels in the main scanning direction and 5 pixels in the g11 scanning direction from the designated point. Therefore, from the pixel data of one line in the main scanning direction written to the SRAM, the specified point and the pixel data of the following 5 points are read into the RAM of the VCPU 74a, and the IIT carriage is moved 4 times with 1 pulse to do the same 5 points at a time. Performs pixel data reading processing. The above is the process when the number of designated points is one. Therefore, if there are multiple designated points, the same process will be repeated for each designated point.

(C) Adjustment of read data The signal level read by the CCD line sensor irradiates the original with light from a light source and reads the reflected signal, so it corresponds to the reflectance and becomes higher as the original becomes whiter. Therefore, for example A
When the input range of the /D conversion circuit is O to 2.5V, it is converted to 1 byte, 8 bits of 0 to 255, the signal level read from the white reference plate should be a value close to 2.5V. This makes it possible to improve the accuracy of reading the original. Therefore, the gain was adjusted so that the signal level read from the white reference plate was about 2.0■, and this
I am trying to divide it into 6 equal parts and convert it to a digital signal, but
As the light intensity of the fluorescent lamp decreases with use, the level of the signal read from the same white reference plate will gradually decrease, and 1
The resolution per bit will decrease. Since the reflectance of the white reference plate is about 80%, if the reading signal level is increased to, for example, 2.degree. 3V, there is a problem that the signal will be saturated with the bright white of the original.

The gain adjustment AGC makes it possible to obtain stable resolution even in such cases, and if the level of the signal read from the white reference plate is set to, for example, 2°0■,
The gain is adjusted so that it is always maintained at this value, and the optimum gain is set for chips with varying sensor sensitivities.

Furthermore, when the fluorescent lamp is turned off, the signal level (dark output level, dark level) output from the COD line sensor reaches the lowest value.

This dark level is not flat even for one chip, but has various curves, and the lowest level differs between chips. Therefore, the offset adjustment AOC is used to increase the minimum value of the dark level to a certain value and guarantee it.

In the gain adjustment, first, read data from the white reference plate is written into, for example, the SRAM of the white shading circuit.

Thereafter, the VCPU 74a samples the read data from this SRAM at predetermined pixel intervals and finds the maximum value for each chip.

Then, the gain is set so that this maximum value becomes 200 in a predetermined manner, for example, 256 gradations. Similarly, in offset adjustment, after writing the dark output to the SRAM of the white aging correction circuit, the VCPU 74a
::17) Sample the read data from the SRAM at predetermined pixel intervals and find the minimum value for each chip. Then, this minimum value is a predetermined output, for example, 1 at 256 gradations.
Set the offset value so that it becomes 0.

However, with this alone, the levels between each pixel and at the edge of the chip will not be uniform, and the image will become rough or have lines in areas of high density. The ΔV dark correction is for correcting such pixel-by-pixel variations in the dark level, and the white shading correction is for correcting the pixel-by-pixel variations in the white level.

In the Δ■ dark correction, after writing the dark output to the SRAM of the white shading correction circuit, the vCPU 74a reads the data from this SRAM, repeats this four times, integrates it, and calculates the average value. Write to the SRAM of the shading correction circuit. Therefore, when making these adjustments, the VCPU 74a
The through conversion table shown in FIG. 5(b) has been selected and set.

Further, by performing gain adjustment, offset adjustment, and ΔV dark correction as described above, it becomes possible to shift to lobby operation. In the copy operation, a logarithmic conversion table is selected, and first, prior to transition to a copy cycle, a process of writing reference data into the SRAM of the white shading correction circuit is performed.

This is a process of writing the read data of the white reference plate after performing the ΔV dark correction in a state where each of the above adjustments has been performed. Therefore, the old data stored in this SRAM is the read data of the white reference plate.
If the correction data written in the SRAM of the dark shading correction circuit is DD, log (DW - DD) is obtained.

Therefore, when we take the difference between the data set in this SRAM by the white shading correction circuit and the document read data in the actual copy cycle, the document read data DX is first subjected to ΔV dark correction in the dark shading correction circuit, so log (DX -DD) -log
(DW - DD). In other words, as a result of correction by the dark shading correction circuit and the white aging correction circuit, the density signal is log(DI - DD) - log (DW - DD).
= log((DX −DD)/(DW −DD
)) = fogR correction processing will be performed, and in the reflected signal, R = (
A correction process of DX - DD )/(DW - DD') will be performed.

In this way, ΔV dark correction, which is a correction based on the black signal, is performed on the reflected signal before logarithmic conversion, and shading correction, which is correction based on white, is performed on the density data after logarithmic conversion. , the correction value is reduced to improve correction efficiency. Furthermore, by storing correction data for one line using SRAM and performing correction processing by subtracting this data, a general-purpose full adder IC can be used, and arithmetic processing can be performed easily. .

Therefore, there is no need to assemble a hard logic divider with a complicated and large-scale circuit as in the past.

Up to now, it has been assumed that the A/D conversion circuit merely digitizes the output of the COD line sensor, and its specific configuration will be described here.

Various A/D conversion methods are known, but
In particular, for example, a parallel A/D conversion circuit as shown in FIG. 28 is used to A/D convert a video signal at high speed.

FIG. 28(a) is a block diagram of an 8-bit parallel A/D conversion circuit, and FIG. 28(b) is a timing chart of the operation. As shown in FIG. 2(b), the sample phase φ2 starts at the falling edge of the externally applied clock, and during the period of φ2, the switch 704 is opened and the 25
Six capacitors 705 are connected to the analog input and charge the analog input voltage VIN. Next, when φ1 is reached, the switch 704 is opened, the switch 703 is opened, and the voltage is switched to the reference voltage VREFIT[1. The reference voltage source is made up of a group of divided resistors, and supplies 256 levels of reference voltage to the corresponding capacitors 705.

As a result, the capacitor 705 outputs to the comparator 1708 the difference between the analog input voltage VIN and the reference voltage VREF, which were being charged during the period φ. Comparator 706 detects whether the difference output is positive or negative and outputs it to latch/encode logic 707 as a binary output. In the latch/encode logic 707, the analog input voltage VI
A code is assigned corresponding to N, and 9-bit digital data including an overflow bit is generated.

These 9-bit codes are transferred to the output register 708 on the falling edge at the end of the φ1 period, and a digital output is obtained as the output of the three-state driver 709 after a digital output delay time Td. When the period φ ends, the period φ2 begins, the next sample phase starts, and this operation is repeated thereafter.

An example of the waveform of a video signal when the parallel A/D conversion circuit shown in FIG. 28 is used in the image reading device of this copying machine is shown in FIG.
As shown in the figure. FIG. 29(a) is a diagram showing the input waveforms of the A/D conversion circuit of the signal when a white original is read and the dark output signal read with the exposure lamp turned off, together with the waveform of the clock signal. However, white and black are R, G,
Since the density difference of B is not extreme and the point-sequential output waveform changes relatively gently as shown in the figure, A/
D conversion is performed well. In addition, the same figure (b), (
c).

(d), (e), and (f) are A/C when reading cyan, magenta, red, green, and blue originals, respectively.
Although it is a diagram showing the input waveform of the D conversion circuit together with the waveform of the clock signal of A/D conversion, in the case of these colors as well, R,
The density difference between G and B is not extreme, and the signal waveform changes gently. Therefore, even when reading such colors, A/D conversion is performed satisfactorily.

In this way, when a parallel A/D conversion circuit as shown in Fig. 28 is used to A/D convert a point-sequential color video signal, good A/D conversion can be achieved for many colors. However, it has been found that when a yellow original is read, noise increases and the S/N ratio deteriorates.

Yellow has a high concentration of blue and low concentration of red and green. Therefore, since the level of the B signal is smaller than that of the R signal and the G signal, the input waveform of the A/D conversion circuit is a waveform with a steep drop in the B signal portion, as shown in FIG. becomes.

By the way, in the parallel A/D conversion circuit shown in FIG.
Since we are looking for the difference between N and the reference voltage VREF, VIN
If V REF is smaller than V REF of each node, the charge flows out and is superimposed on the analog input signal, resulting in noise. This is the so-called kickback phenomenon. Therefore, the lower the input signal level, the more kickback m and the more noise. Moreover, in the case of 8 bits, 256 capacitors 705 are used, so when the amount of kick pack is large and the input signal level is low, deterioration of the S/N is unavoidable.

Therefore, the question is how much noise is generated in the parallel A/D conversion circuit shown in FIG. 28, and the measurement results of the noise will be explained with reference to FIG. 31.

FIG. 31(a) shows a circuit configuration with 1ill+constant noise, and the inverting input of the operational amplifier 712 is connected to the variable resistor 711 from 0 to 3. Input the OV DC voltage. As the A/D conversion circuit 714, a parallel type A/D conversion circuit having the configuration shown in FIG. 28 was used. Note that the reference voltage VREF is 3. O
V, A/D ratio o-7 is 9 MHz. In this configuration, noise was measured at the analog input end of the A/D conversion circuit 713, indicated by 714 in the figure, using the resistor RO as a parameter.

The results are as shown in Figure 31(b), which shows that the lower the input signal level is, the larger the noise amplitude is, and that the resistance R
It can be seen that although the noise amplitude can be somewhat reduced by increasing O, the tendency remains the same. From this, it can be seen that even if the value of the resistor RO is changed, it is difficult to significantly reduce the noise amplitude, and this does not provide an essential solution.

As described above, in a portion where the signal level is low, such as the B signal when reading yellow, there is a lot of noise due to kickback, resulting in a signal with degraded S/H.

Furthermore, as shown in Fig. 30, since the changes from the G signal to the B signal and from the B signal to the R signal are steep, they contain very high frequency components, which may cause waveform distortion. arise. That is, as shown in FIG.
A pre-stage amplifier circuit 231 and an AGC 2 are provided before the /D conversion circuit.
32b% AOC232c and other circuits are provided, but the frequency characteristics of these circuits often do not necessarily follow the high frequencies included in the steep waveforms shown in Figure 30; As a result, distortion occurs in the waveform.

Of course, in each of the waveforms shown in FIGS. 29(a) to 29(f), the noise due to kickback is, for example, as shown in FIG. 29(a).
However, in the case of many colors, there is no extreme difference in the signal levels of R, G, and B, so the signal waveform changes gently. for that,
High frequencies are not included, and the circuit provided before the A/D conversion circuit can follow level changes, so even if kickback or other noise is mixed in, the waveform distortion is small and density errors can be ignored. be.

As mentioned above, when reading yellow, not only does noise due to the kickback phenomenon increase, but also waveform distortion is added to it. However, when performing A/D conversion, a false signal becomes a density signal different from that of the original original, and the relationship between the printed output density (DOUT) and the original density (DIN) is
It does not look like the straight line 714 in the figure, but in the high concentration part,
It changes like 715 or 716 and deviates from the straight line 714. Yellow is originally a difficult color to reproduce, and as mentioned above, DIN/DOUT has a nonlinear characteristic, which causes problems in terms of the quality of the output image.

The above discussion has been about one CCD line sensor, but since this copying machine uses a 5-channel CCD line sensor, in addition to the above problem, there is the added problem of unavoidable variations between channels. As a result, although many colors could be faithfully reproduced, yellow was reproduced as a different density in each channel, and the seams between channels were sometimes noticeable.

We have found that there are two methods to solve this problem:

The first means is to have a circuit configuration as shown in FIG. 1(a). That is, as the A/D conversion circuit 3, the 28th
The parallel A/D conversion circuit shown in figure (a) is used, but A
A CCD line sensor 1 is used as a pre-stage amplifier (corresponding to 231 in FIG. 24) placed before the /D conversion circuit.
An inverting amplifier 2 is used which inverts the polarity of the dot-sequential color video signal output from the circuit 5, and a buffer 4 disposed after the A/D conversion circuit 3 having an inverter function is used.

According to this configuration, in the output of the inverting amplifier 2, the signal level of the high-density portion is high and the signal level of the low-density portion is low, so the level of the B signal when reading a yellow original is high. It becomes unaffected by noise. At this time, the levels of the R signal and the G signal are small, so they are affected by noise, but the R
The signal and G signal are high-level signals at the output of the CCD line sensor, and since they are signals with a good S/N to begin with, even if noise is superimposed due to kickback, it will not have a big effect, and the overall S/N will be reduced. As a result, concentration errors are reduced and
DIN/DOUT characteristics also become better.

It is clear that it is necessary to use a buffer 4 that has an inverter function.

This is because the polarity of the signal is inverted by the inverting amplifier 2, so the output of the A/D conversion circuit 3 cannot be used as is in the subsequent SHC (Figure 24) or IPS, and the polarity is changed to its original state. This is because it is necessary to return to Of course, it is possible to change the subsequent circuit to process digital data with different polarities, but this cannot be shared with conventional circuit components, resulting in an increase in cost. It's not a good idea.

The first means above uses a parallel A/D conversion circuit,
Although the overall S/N ratio is kept good even if noise occurs, it is clear that it is more desirable if the noise generation can be suppressed.

Therefore, it is conceivable to use an A/D conversion circuit that generates less noise 1, but this is the second method, and as shown in FIG. A type A/D conversion circuit is used.

Note that the amplifier 5 outputs the input signal without inverting its polarity, and the buffer 7 also does not have an inverter function.

A schematic configuration of the series/parallel type A/D conversion circuit is shown in FIG. 33. Figure 33(a) shows a 4-bit series-parallel A/D.
The overall configuration diagram of the conversion circuit, (b) is a diagram showing the configuration of the switch block, in which reference voltages V refA and VrefB are applied to terminals 721 and 722, respectively, and the reference voltages V refA and VrefB are applied at equal intervals by reference resistors R1 to R16. The upper two bit comparators 724 (C1, C2, C3
) and lower 2-bit comparator 728 (C4, C5, C
Switch block 727 (81, 8
2, S3. S4). Moreover, the analog human power Vln supplied to the terminal 720 is the top 2
The bit comparator 724 and the other terminal of the switch block 727 are provided. First, compare the top 2 bits! &724, VrefA −vl, v
l ~V'2. V2-V3. V3-VrefB
It is determined whether there is an input signal Vln at position a, and the upper 2 bit encoder 723 obtains a digital output of the upper 2 bits. At the same time, a control signal given from the upper 2-bit encoder 723 closes the portion of the switch block 727 that corresponds to the input signal V1n. When one part of the switch block 727 is closed, the lower 2-bit comparator 726 starts converting, and the lower 2-bit encoder 725 outputs the lower 2-bit digital data. Note that the switch block includes, for example, one transistor 73 constituting a differential amplifier, as shown in FIG. 33(b).
A reference voltage is supplied to the base of the other transistor 731, an analog human power Vln is supplied to the base of the other transistor 731, and a control signal from the upper two bit encoder 723 is supplied to the base of the transistor 732 which serves as a current source. It can be configured by obtaining the output from the collector of 731.

The one shown in Figure 33(a) is a 4-bit series-parallel type A/D.
Although this is a conversion circuit, it is clear that an 8-bit A/D conversion circuit can also be constructed in the same manner.

When performing 8-bit A/D conversion, the parallel type requires 256 comparators and capacitors, whereas the series-parallel type requires 32 comparators (
= 18×2), so the number of capacitors is also 32. Therefore, it can be expected that the occurrence of noise due to kickback will be reduced to the extent that the number of capacitors is small, and this has been confirmed in actual measurements. In other words, 8 series/parallel type
When the noise amplitude was measured using a Bift A/D conversion circuit with a circuit configuration similar to that shown in FIG. 31(a), the results shown in FIG. 34 were obtained. Note that the reference voltage VREF
is 2.5 ■.

From the above, it can be seen that when A/D converting a dot-sequential color video signal, a series-parallel type A/D conversion circuit is more compatible than a parallel type A/D conversion circuit.

As a result, even if the signal obtained by reading the yellow original shown in Fig. 30 is directly input to the A/D conversion circuit, the influence of noise is extremely small, and therefore the DIN/D OUT characteristics also have good linearity. Become.

In the above embodiments, a CCD line sensor was used as the line sensor, but the present invention can also be applied to a case where a line sensor using other charging conversion elements is used.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, even if noise is superimposed, the overall S/N ratio can be maintained good, or the noise itself can be reduced. , - degree error can be reduced compared to the conventional one, so the DIN/D OUT characteristic can be made to have good linearity. As a result, it is possible to obtain a high quality image output. In addition, when using multiple CCD line sensors, in the conventional one,
In addition to variations between channels, concentration errors occurred in the A/D conversion circuit, so in the case of originals containing a lot of yellow, the joints between channels were the eyes, but according to the present invention, the A/D conversion circuit Since the occurrence of density errors is extremely small, variations between channels are only a problem of variations in components, and reliability is improved compared to conventional systems.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an image reading device according to the invention, FIG. 2 is a diagram showing an example of the overall configuration of a color copying machine to which the invention is applied, and FIG. 3 is a diagram showing the hardware architecture. Figure 4 is a diagram showing the software architecture, Figure 5 is a diagram showing the relationship between the system and other remotes, and Figure 6 is a diagram showing the relationship between the system and other remotes.
The figure shows the module configuration of the system, and Figure 7 shows the IP
FIG. 8 is a diagram showing a schematic configuration of IOT. FIG. 9 is a diagram showing a hardware configuration of UI. FIG. 10 is a diagram showing an example of a display screen configuration. The figure is a perspective view of the F/P, FIG. 12 is a perspective view of the M/U, and FIG. 13 schematically shows the configuration of the F/P.
/P,! : Diagram showing the relationship with M/U and IIT, 1st
Figure 4 is a perspective view of the imaging unit drive mechanism, the first
5 is a sectional view of the main part of FIG. 14, FIG. 16(a) is a stepping motor drive circuit diagram, FIG. 16(b) is a diagram showing the excitation sequence, FIG. 16(C) is a driver control circuit diagram, Fig. 17 is a diagram for explaining the scan cycle by the imaging unit, Fig. 18 is a diagram for explaining the cause of color shift in color copying, Fig. 19 is a cross-sectional view of the imaging unit, and Fig. 20 is a diagram for explaining the cause of color shift in color copying. cross section,
21(a) is a diagram showing an example of the arrangement of CCD line sensors, FIG. 21(b) is a diagram showing an example of the arrangement of color filters,
Figure 2 is a diagram showing the relationship between the reduction ratio and the amount of reading deviation, Figure 23 is a diagram for explaining the IIT control mode, and Figure 2
Figure 4 is a video signal processing circuit diagram, Figure 25 is a diagram showing a conversion table, Figure 26 is a diagram explaining pixel shift correction, Figure 2
Figure 7 is a diagram showing the output waveform of the CCD line sensor, No. 28
The figure shows an example of the configuration of a parallel type A/D conversion circuit, Figure 29 shows an example of the waveform of an input signal to the parallel type A/D conversion circuit, and Figure 30 shows a parallel type A when reading a yellow original. /D
Figure 31 is a diagram showing the waveform of the input signal of the conversion circuit, Figure 31 is a diagram showing the circuit configuration and measurement results of noise amplitude measurement of the parallel type A/D conversion circuit, Figure 32 is the diagram showing the circuit configuration and measurement results using the parallel type A/D conversion circuit. FIG. 33 is a diagram showing a configuration example of a series-parallel type A/D conversion circuit, and FIG. 34 is a diagram showing the results of noise amplitude measurement of a series-parallel type A/D conversion circuit. It is. 1... Line sensor, 2... Inverting amplifier, 3...
Parallel type A/D conversion circuit, 4... Buffer 5... Non-inverting amplifier, 6... Series/parallel type A/D conversion circuit, 7...
・Buff applicant Fuji Xerox Co., Ltd.

Claims (6)

[Claims] (1) In an image reading device that includes a line sensor and an A/D conversion circuit that digitizes the output of the line sensor, dark is associated with the MSB side and white is associated with the LSB side. image reading device. (2) The image reading device according to claim 1, wherein the line sensor outputs a point-sequential color video signal. (3) a line sensor, an inverting amplifier that inverts the polarity of the output signal of the line sensor, a parallel A/D conversion circuit that receives the output of the inverting amplifier and converts it into a digital signal of a predetermined bit; An image reading device comprising: a buffer that inverts the polarity of the output of the A/D conversion circuit and outputs the inverted polarity. (4) The image reading device according to claim 3, wherein the line sensor outputs a point-sequential color video signal. (5) a line sensor, an amplifier that outputs the output signal of the line sensor without reversing its polarity, and a series-parallel A/D conversion circuit that receives the output of the amplifier and converts it into a digital signal of predetermined bits; , and a buffer that outputs the output of the serial-parallel type A/D conversion circuit without inverting the polarity thereof. (6) The image reading device according to claim 5, wherein the line sensor outputs a point-sequential color video signal.