JPH01118864A - Image forming device - Google Patents

Abstract

PURPOSE:To facilitate the alignment of respective colors at the time of adjusting when shipping increases or at the time of readjusting when components are exchanged at a market by displaying the quantity of dislocation of the respective colors. CONSTITUTION:The title device is provided with means for generating a picture signal for a pattern 41, 47a-47c for forming a pattern image for measuring on a transfer belt at every color, a detecting means for detecting the passage of the pattern images of the respective colors, detection timing counting means 42a-42c for counting timings by the detection means, a comparing and arithmetic processing means 44a-44c for comparing the counted value with set values 45a-45c and arithmetically processing the quantity of the deviation as necessary, a display means for displaying a correction quantity with which the arithmetically processed quantity of the deviation or the quantity of the deviation is made to be '0' and a means for generating a writing timing signal of the respective colors which can be changed in setting. When a user corrects the dislocation of the respective colors, he can correct it by adjusting the setting an address setting device only by a value displayed on a dislocation quantity display part. Thus, the color slippage in the transfer carrier direction of each color can be reduced with a simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an image forming apparatus, and particularly to a digital color image forming apparatus having a plurality of photoreceptors.

[Prior art]

In an image forming apparatus that forms color images using multiple photoreceptors, the causes of misalignment in the transfer paper feeding direction (vertical registration) include the mounting position and circumferential speed of each photoreceptor, the exposure position relative to the photoreceptor, and the transfer belt. linear speed, etc., and each was configured to guarantee component accuracy and assembly accuracy, but this resulted in high component costs and assembly costs, and readjustment was required due to changes in each factor over time and variations due to component replacement. becomes.

As a method to solve this problem, a method has been proposed in which the writing timing of each color is obtained by detecting the transfer paper using a sensor installed in front of each transfer position. Due to variations in mounting positions and variations in detection positions of each sensor, it has been difficult to guarantee a positional shift limit (about 0.15k) for color images.

〔the purpose〕

The present invention was made based on such a background, and is a color image forming apparatus that obtains a single color image by superimposing a plurality of color images on a transfer sheet fed by a conveyor belt. An object of the present invention is to provide a digital color image forming apparatus that can reduce color misregistration of each color in the transfer paper conveyance direction with a simple configuration.

〔composition〕

To this end, the present invention provides a pattern image signal generation means for forming a measurement pattern image for each color on a transfer belt, a detection means for detecting passage of each color pattern image, a detection timing counting means by the detection means, Comparison calculating means for comparing the count value by the detection timing counting means with a set value and calculating the deviation amount as necessary, and setting the deviation amount or deviation amount calculated by the comparison calculation means to "0"
The present invention is characterized by having display means for displaying the amount of correction to be made, and false write timing signal generation means whose settings can be changed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and operation of the present invention will be explained in detail below based on embodiments shown in the drawings.

First, FIG. 1 is a schematic diagram of a digital color image forming apparatus to which the present invention is applied.

In FIG. 1, a color copying machine is shown as an example of an image recording device.The copying machine includes a scanner part 1 for reading a document, and electrically processes an image signal output as a digital signal from the scanner part 1. It has an image processing section 2 and a printer section 3 that forms an image on copy paper based on image recording information of each color from the image processing section 2. The scanner part 1 includes a lamp 5 that scans and illuminates the document on the document table 4.
, with, for example, fluorescent lights. The reflected light from the document when illuminated by the fluorescent lamp 5 is reflected by the mirror 6.7.8 and enters the imaging lens 9. The image light is imaged on the guichroic prism lO by the imaging lens 9, and is separated into light of three different wavelengths, for example, red R1 green G1 blue B. For each wavelength light, a light receiver 11, for example, a red CCD 11R1 is sent. It is input to CCDIIG for green and CCDI IB for blue. Each CGDI IR, 11
G.

11B converts the incident light into a digital signal and outputs it,
The output is subjected to necessary processing in the image processing section 2,
Recording color information for each color, e.g. black (hereinafter abbreviated as Bk)
, yellow (abbreviated as Y), magenta (abbreviated as M), and cyan (abbreviated as C).

Although FIG. 1 shows an example of forming four colors, Bk, Y, M, and C, it is also possible to form a color image using only three colors. In that case, the number of recording devices can be reduced by one compared to the example shown in FIG.

The signal from the image processing section 2 is input to the printer section 3,
12G, 1 to the laser beam emitting device 128 of each color.
Sent to 2M and 12Y.

In the example shown in the figure, the printer section includes four sets of recording devices f13Y, 1.
3M, 13C, and 138k are arranged side by side. Each recording deviceff! 13 are made up of the same constituent members, so to simplify the explanation, only the recording device for C will be described, and descriptions of the other colors will be omitted. It should be noted that for each of the other uses, the same parts are given the same reference numerals, and in order to distinguish the configuration of each color, a subscript indicating each color is added to the reference number.

The recording device 13G includes a photoreceptor 14G, for example, a photoreceptor drum, in addition to the laser beam emitting device 12G.

A charger 15C, an exposure position by a laser light emitting device 12G, a developing device 16G, a transfer charger 17C, etc. are attached to the photoreceptor 14C in the same manner as in a known copying apparatus.

Photoreceptor 1 uniformly charged by charger 15C
4C forms a cyan latent image through exposure by the laser beam emitting device 12C, and develops it by the developing device 16G to form a developed image. Copy paper is fed by a paper feed roller 18 from a paper feed unit 19, for example, one of two paper feed cassettes, and the leading edge of the copy paper is aligned by a registration roller 20 and sent to a transfer belt 21 at the same timing. Transfer belt 2
The copy paper conveyed by 1 is sequentially sent to photoreceptors 148, 14C, 14M, and 14Y, each having a developed image formed thereon, and the developed image is transferred under the action of the transfer charger 17. The transferred copy paper is fixed by a fixing roller 22,
The paper is ejected by the paper ejection roller 23.

By being electrostatically attracted to the transfer belt 21, the copy paper can be conveyed with precision at the speed of the transfer belt.

FIG. 2 is a front view of the transfer belt section. Transfer belt 21
is supported by a belt drive roller 24 and a driven roller 25, and moves in the A direction to convey the transfer paper. Further, the cleaning unit 26 removes toner adhering to the belt. A reflective sensor 27 is provided as a pattern image detection means on the downstream side of the photoreceptor 14 in the belt movement direction.

The detection means is provided at the drive roller portion of the transfer belt to prevent the influence of flapping of the transfer belt and to maintain a constant distance from the transfer belt at all times.

FIG. 3 is a system block diagram according to the embodiment.

The system controller 30 controls each module of the scanner 1, image processing unit 2, and printer 3. The control contents include display control on the operation panel 31, manual key processing, and according to the mode set on the operation panel 31.
Sending start signals and scaling ratio designation signals to the scanner 1 and printer 3; image processing mode designation signals to the image processing unit 2 (color conversion, masking, trimming, mirroring, etc.)
transmission, abnormal signals from each module, operating status status signals (Wait, Ready, Busy+5to
p, etc.) to control the entire system.

The scanner scans the original at a scanning speed that matches the magnification specified by the start signal from the system controller 30, reads the original image with a reading element such as a CCD, and converts it into image data of 8 bits each for R, G, and B. 5-LSYNC (horizontal synchronization signal) from image processing unit 2, S-3
It is sent to the image processing section 2 in synchronization with TROBE (image clock) and FGATE (vertical synchronization signal).

The image processing unit 2 receives the R and G signals sent from the scanner 1.

Image processing such as T correction, UCR (undercolor removal), and color correction is performed on each 8-bit B image data to create Y, M, and C images.

Bk is converted into 3-bit image data and sent to the printer 3. Also, according to commands from the system controller 30,
A buffer memory for performing editing processing such as scaling, masking, trimming, color conversion, and mirroring, and for outputting Y, M, C, and Bk image data shifted by the distance between the photoreceptor drums of the printer 3. have.

The printer 3 emits laser light according to 3 bits each of Y, M, C, and Bk image data sent from the image processing section 2 in synchronization with P-LSYNC (horizontal synchronization signal) and P-3TROBE (image clock). The device is modified and a copy image is obtained on the transfer paper by an electrophotographic process.

FIG. 4 shows an example of the detection pattern of the present invention.

In each recording device, the pattern image visualized outside the transfer paper area by the signal from the pattern image signal generating means is transferred to the transfer belt 21, and as shown in FIG. They are located at intervals of . And C, M in the pattern image 288.

Y passes through the sensor 27 sequentially as the belt moves and is detected by the sensor 27. The image interval a is a numerical value that can be arbitrarily selected by setting the exposure timing for each recording device in advance.

In the color copying machine shown in FIG. 1, the transmission of image data of each color from the image processing section 2 must be shifted by the distance between the photosensitive drums of the respective colors.

FIG. 5 is a block diagram showing the configuration of a buffer memory for this purpose and the configuration of a pattern image signal generation means.

FIG. 6 is a timing chart showing the operation of the block diagram in FIG. 5 (waveforms of the portions indicated by Φ to [phase]).

timing chart).

In the color copying machine of this embodiment, Bk and C.

Since the recording devices are arranged in the order of M and Y, the Bk image data is processed by the image processing unit 2 and output as is, and the C, M, and Y image data are , are output with a delay of toe and TIIMITav, respectively.

Figure 7 shows the image data delay time tnc, Tons T
FIG. 2 is an explanatory diagram for setting oy.

The length from the exposure position to the transfer position for each photoreceptor 14 is J, (m), and the linear velocity of the photoreceptor is V, (xl/sec).
, distance between photoreceptors is lz (1M), transfer belt linear speed is vg
(m/sea), time required from exposure to transfer, t, is the same value for each photoreceptor, t+ -1
+ /v+ (sec) If the time to move between each photoreceptor is t, then tt = l
z /vt (sec) That is, in order to form each color image at the same position on the transfer paper, t oc-j! t/vz (see)Ttr
M-21z / vz (ser,)Tov" 3
It becomes e t / VE (sec).

As shown in FIG. 5, the circuit configurations of C, M, and Y are the same, so Bk and C will be explained. A rise detection circuit 40 detects the rise of the vertical synchronization signal FGATE sent from the scanner 1. Since the Bk, C, M, and Y inputs and FGATE are input at the same time, the output of the rise detection circuit 40 is a signal representing the start of Bk image writing. The output of the rising edge detection circuit 40 is input to a Bk pattern signal generation means 41, which outputs a detection pattern. That is, in the case of Bk, the leading edge of the image and the pattern position are the same in the moving direction of the bell 21 (FIG. 4).

The output of the rising edge detection circuit 40 is input to the reset terminal of the address counter C42a via an OR gate, and resets the address counter C42a. The input image data of C is stored in the buffer memory: C43a according to the count value of the address counter 42a.

On the other hand, the output of the address counter 42a is the comparator: C44.
a, the address setter: C45a is compared with the set value, and the output of the address counter 42a is sent to the address setter 4.
When the value matches the set value of 5a, the comparator 44a outputs a match signal. This -defeat signal is inputted to the reset terminal of the buffer memory 43a via an OR gate, and the output of the address counter 42a is reset to 10'' to access the buffer memory 43a at address θ again.

After reading the already stored image data, the buffer memory 43a writes newly input image data to the same address.

Here, if the setting value of the address setting device 45a is set to the drum interval (tDC) of Bk and C,
An image can be created by aligning the k and C images.

The coincidence signal of the comparator: C44a is also input to the delay device: C46a, triggering the delay device 46a, and the matching signal of the comparator: C44a.
After a certain period of time from the matching signal, pattern signal generating means: C
47a outputs a detection pattern.

Since the coincidence signal of the comparator C44a is output at the same time as the leading edge of the C image, the detection pattern of C is outputted with a delay of the delay time (tpc) by the delay device C46a from the leading edge of the image.

Here, the delay device: C46a has a delay time of a(m
) If the time required for movement is set, the detection pattern C can be created with a (m) delay from the leading edge of the image, as shown in FIG.

The same applies to M and Y, and the setting value of the address setter: M45b = toM the setting value of the address setter: Y45c, xi.

Delay device: M46b setting time -jp+<=2a/Vz
Delay device: Y46c setting time -t Pv” 3 a
/ Vt, the leading edge of the image can be matched for each color, and at the same time the detection pattern can be set to a(f) as shown in Figure 4.
l) It is possible to output in pitch.

Here, if the Bk, C, M, and Y image positions shift on the transfer paper due to variations in the position of each photoconductor, variations in the exposure position with respect to the photoconductor, and variations in the linear speed of the photoconductor and transfer belt, the detection The detection pattern also shifts accordingly, and by measuring the interval between the detection patterns, the amount of positional shift of the image can be detected.

FIG. 8 shows an embodiment of the pattern detection circuit according to the present invention. The output current of the phototransistor ph of the reflective sensor 27 is converted into a voltage by the resistor R2 [FIG. 10(a)
waveform shown in Figure 10], the DC component is cut by capacitor C2 and only the AC component is taken out [in Figure 10]
Waveform of 0 part shown in] This signal is voltage follower A
It becomes the input of the inverting amplifier AMP2 via MPI, and is amplified to an appropriate voltage level [Figure 10 (waveform of 0 part shown in C1)].The output of AMP2 is input to the comparator COMP1.
Threshold voltage determined by resistors R8 and R9! 10 (waveform of the 0 part shown in d)). By measuring the pitch of this rectangular wave output, it is possible to know the interval between the detection patterns transferred to the transfer belt 21. .

FIG. 9 shows an embodiment of the pattern interval measuring circuit. 1st
Figure 1 shows a timing chart.

CL from the CPU 60 before starting pattern interval measurement.
The output of the detection circuit which outputs the EAR signal to clear the counters CNT1 to CNT4 is input to the clock terminal of the counter CNT1, and the outputs A and B of CNT1 output the signals shown in FIG.

By ANDing the human output of CNTl and the signal obtained by inverting the B output (ANDI), a signal representing the pattern interval between Bk and C can be obtained.

Also, by taking the exclusive OR of human output and B output (
EORI), a signal representing the Bk and M pattern intervals can be obtained. Furthermore, by ORing the human output and the B output (ORI), a signal representing the Bk and Y pattern intervals is obtained.

Signals representing the pattern intervals of Bk and C, Bk and M, and Bk and y are respectively sent to counters CNT2. It is connected to the enable inputs of CNT3 and CNT4, and the counters CNT2.
CNT3. CNT4 counts the reference clock while the enable input is #H#, and counts Bk, ! :C, Bk and M,
Binary data proportional to the Bk and Y pattern spacing is output.

CNT2. CNT3. When the counting operation of CNT4 is completed, the data selector 61 is controlled by the 5ELO and 5EL1 outputs of the CPU 60 to sequentially count CNT2. C
NT3. FIG. 12 shows a flowchart of the above operation in which the binary data of the CNT4 is taken into the CPU 60.

The CPU 60 compares the captured output value of the counter with a reference value, calculates the difference between the reference value and the measured value, and outputs correction signals C, M, and Y for correcting the difference. This correction signal is sent to the address setter: C, M, Y45 shown in FIG.
By changing the timing at which images are written for Bk, alignment of images of each color can be realized.

Now, if the frequency of the reference clock is F (Hz), then Bk
C, M, Y pattern spacing Lc, LM+ with reference to
Lv is Lc = (Kc /F)Xv2 (m)LH-(K
Il/F)XVt (m)Lv-(Ky/F)X
vt (m) (where KC, , , KY is the number of measured clocks). Therefore, the deviation from the set value of each pattern interval Dc, D, , Dv is DC depth Lc - a (Il [5) DN = LM -2a (m)Dv -Lv
-3a (dragon).

The correction signals Hc, Hx*Hy are Dc, Dn+
The process of the above calculation is shown in FIG. 12), in which Dy is multiplied by a count for converting the amount of deviation on the belt into a memory address to obtain Hc=CXDc HM - CX DM My - CXDY.

In the present invention, the detection patterns are set at intervals of a (ms) using the leading edge of the image of each color as a reference for Bk and C.

Created in the order of M and Y. a (m) means a (1 m) when the belt speed is as designed.
Therefore, if the belt speed deviates from the design value due to component variations, the pattern interval a'
(m) is a'w (vl'/v snow) Xa v: Design value of belt speed v8'; Actual value of belt speed.

However, the time t for detection by the detection sensor is ta'
/V! '-a/V', and the pattern spacing can be accurately measured regardless of the actual belt speed.

FIG. 13 is a control block diagram of the printer section 3. The main control unit 70 is centered around the CPU, and controls the ROM, RAM, and I
It consists of 10 interfaces, etc. On the input side, there is a paper ejection sensor 71 for detecting transfer paper being ejected outside the machine, a paper end sensor 72 for detecting the presence or absence of transfer paper in the cassette, and a paper end sensor 72 for controlling paper feeding to the registration rollers. A registration sensor 73, a cassette size sensor 74 for detecting the size of the cassette, Bk.

There are toner sensors Bk, C, M, and Y 75 for detecting the concentrations of C, M, and Y developers, and a thermistor 76 for detecting the temperature of the fixing heater 79.

On the output side, there is a high voltage power supply 77 for supplying high voltage to various chargers and developing sections, a heater control section 78 for controlling the temperature of the fixing heater 79, and a toner replenishment clutch 80 for replenishing toner to the developing device. , a motor driver 81 for controlling various motors.

Furthermore, there is a polygon motor driver 82 for controlling the polygon motor, a video control section 84 for receiving image data from the image processing device and controlling the LD driver j83 of each trust, and an interface with the system controller.

Furthermore, as an input, the correction signal C from the pattern spacing measurement circuit
, M, and Y, and a deviation amount display section 85 is provided as an output.

Now, the correction signal C obtained by the pattern interval measuring circuit
, M, Y, namely Hc, HM.

Assuming that Hv is HC--15, H = 7, and HV = 0, the pattern interval between cyan (C) and black (B k) is 15 units in memory address conversion with respect to the setting value (ama). It will be narrower.

Conversely, the magenta (M) and black (Bk) pattern spacing is wider than the set value (29■) by 7 units in memory address terms, and the yellow (Y) and black (Bk) pattern spacing is wider than the set value (29■). It is equal to the set value (39m). This means that when looking at the copy image transferred to the transfer paper and considering black as the standard, cyan shifts toward the leading edge of the transfer paper, magenta shifts toward the leading edge of the transfer paper, and yellow remains unchanged.

Here, the Hc, HM, and HvO values may be displayed as they are on the deviation amount display section 85, but it is better for the user to correct the current writing timing of each color to determine the position of each color, rather than displaying the deviation amount itself. It would be easier to understand if the value is displayed as "0" or "0".

Therefore, in this embodiment, values obtained by multiplying each of Hc, HM, and Hv by "-1" are displayed.

In order to correct the positional deviation of each color, the user only needs to adjust the setting of the address setting device shown in FIG. 5 by the value displayed on the deviation amount display section 85.

In other words, the cyan address setter only needs to add 15 to the currently set address, and the magenta address setter only needs to subtract 7 from the currently set address. Yellow! There is no need for adjustment.

〔effect〕

As explained above, according to the present invention, since the amount of positional deviation of each color is displayed, the positioning of each color can be easily adjusted during adjustment at the time of shipment or when readjusting when replacing parts in the market. It can be performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a digital color image forming apparatus to which the present invention is applied, FIG. 2 is a front view of a transfer belt section, FIG. 3 is a system block diagram according to an embodiment of the present invention, and FIG. 4 is a schematic diagram of a digital color image forming apparatus to which the present invention is applied. 5 is a block diagram showing an example of a detection pattern, FIG. 5 is a block diagram for controlling the transmission of image data, FIG. 6 is a timing chart of each part, and FIG. 7 is an explanatory diagram for setting the delay time of image data. , FIG. 8 is a diagram showing an embodiment of the pattern detection circuit according to the present invention, FIG. 9 is a diagram showing an embodiment of the pattern interval measuring circuit, and FIGS. 1O (a) and (b). (C) and (d) are waveform diagrams of the eighth answering section, FIG. 11 is a timing chart in FIG. 9, FIG. 12 is a control flowchart according to the present invention, and FIG. 13 is a control block diagram of the printer section. . 27...Detection means, 41.47...Pattern image signal generation means, CNT1.2.3.4...Detection timing counting means, 60...Comparison calculation means, 21...
- Transfer belt, 85... positional deviation amount display section. Li ;

Claims (1)

[Claims] (1) a photoconductor, a charger that uniformly charges the surface of the photoconductor, an exposure device that projects image light on the photoconductor according to recorded information, and a developing device that develops an electrostatic latent image on the photoconductor; In an image recording device in which a plurality of recording devices each having a transfer means for transferring a developed image of a photoreceptor to a transfer paper are arranged, and the transfer paper is sequentially conveyed to each recording device by a transfer belt having a seam to transfer images in an overlapping manner. , a pattern image signal generation means for forming a measurement pattern image for each color on the transfer belt, a detection means for detecting passage of each color pattern image, a detection timing counting means by the detection means, and a detection timing counting means. A comparison calculation means that compares the count value by the means with a set value and calculates the amount of deviation as necessary, and sets the deviation amount or deviation amount calculated by the comparison calculation means to "0".
What is claimed is: 1. An image forming apparatus comprising: a display means for displaying the amount of correction to be made; and a means for generating a writing start timing signal for each color whose settings can be changed.