JPS6366578A - Color image forming device - Google Patents

Abstract

PURPOSE:To facilitate the adjustment of horizontal resists with a simple constitution by detecting the position of an image formed with a light beam. CONSTITUTION:The image of a determined pattern in advance is formed as the toner image on a photosensitive belt 21 by the irradiation of the light beam to the belt 21 and the development. A deviation (l) between the image 35 and a line 34 as an image recording start position designating means is read by a CCD 36. Positions of the line 34 and the image 35 are obtained by counting clocks based on the picture element pitch of the CCD 36. Thereafter, the image 35 is removed by a cleaning device 37 provided on the right of the belt 21. The period from the time, when a synchronous detector detects the light beam, to the image write start time is changed in accordance with the deviation (l) to adjust the horizontal resist. Consequently, the image write start position of each color is adjusted to adjust the horizontal resist of each color with the precision of picture element pitch of the CCD 36.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a color image forming apparatus including a plurality of image carriers such as photoreceptor drums and photoreceptor belts.

(Prior Art) FIG. 11 shows a conventional color image forming apparatus using a color copying machine as an example.

The copying machine includes a scanner section 1 for reading originals, an image processing section 2 that electrically processes image signals output as digital signals from the scanner section 1, and image recording of each color from the image processing section 2. It has a printer section 3 that forms an image on copy paper based on the information. The scanner part 1 has a lamp 5, such as a fluorescent lamp, for scanning and illuminating the document on the document table 4. 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 focused on the guichroic prism 10 by the imaging lens 9, and is separated into lights of 3 [i wavelengths, for example, red R, green G, and blue B. C for red
GDIIR, CCDIIG for green, CCD for blue
It is input to IIB. Each CCDIIR, IIG, IIB
converts the incident light into a digital signal and outputs it, and the output undergoes the necessary processing in the image processing section 2 to record color information for each color, such as 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 other cases, the length of the recording device can be reduced by 1 m compared to the example shown in FIG.

The signal from the image processing section 2 is input to the printer section 3,
The light beams 12Y, 12M, and 12G are sent to the laser beam emitting device 128, which is an exposure system for each color.

In the illustrated example, the printer section includes four sets of recording devices 13C, 1.
3M, 13Y, and 138k are arranged side by side. Since each recording device 13 is made of the same constituent members, in order to simplify the explanation, the recording device for C will be explained, and the explanations for other colors will be omitted. Note that for each color, 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 13C includes a photoreceptor 14C1, such as a photoreceptor drum, which is an image carrier 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 f16c, a transfer charger 17C, and the like 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 by exposure with the laser beam emitting device 12G, and develops it with the developing device 16G to form a developed image. Copy paper is fed by a paper feed roller 18 from a paper feed section 19, for example, from 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 conveyor belt 21 at the same timing by a 0wL feed belt 21. The conveyed copy paper is sequentially sent to the photoreceptors 148 14Y, 14M, and 14C on which a developed image is formed, 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 and then discharged by a paper discharge roller 23.

By being electrostatically attracted to the conveyor belt 21, the copy paper can be accurately conveyed at the speed of the conveyor belt.

FIG. 12 shows a laser beam emitting device 128 which is an exposure system.
2Y, 12M, and a perspective view of the specific configuration of the 12C portions. Each exposure system 128k.

12Y, 12M, and 12G have the same structure, so to explain the exposure system 12C for cyan, 25C is a beam generator that generates a light beam, 27G is a light deflector such as a pyribon mirror or a galvano mirror, and 26G is a beam generator that generates a light beam. is a motor for rotating the optical deflector 27C and deflecting the light beam.

In order to keep the image writing position constant, this exposure system is equipped with a photodetector 28C for detecting the light beam, and after a certain period of time after the photodetector 28C detects the light beam, the photoreceptor 14C is This will start writing the image above.

Adjustment of the image writing position in the above-mentioned apparatus will be explained with reference to FIGS. 13 and 14. Here, each exposure system 12
8, since the mechanisms 12Y, 12M, and 12C are the same, the exposure system 12G for cyan will be explained in this figure as well. The figure shows an example of adjustment using COD. First, a writing unit U consisting of an optical system such as an optical deflector 27C, a motor 26C, a photodetector (not shown), a light beam generator 25C, a lens, a mirror, etc. is set in a dedicated adjustment jig (not shown). The jig also includes a photoreceptor 14.
The CCD 29 is arranged so that the CCD 29 is on the C-equivalent plane (image formation point) and the light receiving part of the CCD 29 is on the beam scanning plane (FIG. 14).

Then, the beam is deflected and scanned on the above-mentioned jig, and the time from when the photodetector 28C, that is, the synchronous detector detects the beam, to the image writing position (when modulation of the beam by the image signal starts) is changed. For example, the clock is adjusted so that the image is written from a preset image recording start point A.

In this way, the image writing position is adjusted, but the adjustment accuracy mentioned above depends on the required image quality, but the maximum
A request for 30 microns is made.

And when the writing unit) U is attached to the jig,
It becomes necessary to suppress the positional deviation when attached to the main body to a few microns, and improving the precision of this attachment increases the cost. Furthermore, if it were possible to attach the C0D29 or the like inside the main body, the attachment would require special parts, and it would be time-consuming to remove the photoreceptor and set the CCD29.

(Objective) The present invention solves the above-mentioned problems of the prior art, and enables easy horizontal registration with a simple configuration! l! It is an object of the present invention to provide a color image forming apparatus that can perform color image formation.

(Structure) In order to achieve the above-mentioned object, the present invention includes a plurality of image carriers, and a light beam provided corresponding to each of these image carriers, and a light beam that is modified with a different color signal to illuminate the image carriers. an image forming means for forming an electrostatic latent image on the image carrier; a developing means for visualizing the latent image formed on the image carrier;
In a color image forming apparatus equipped with a transfer means for transferring a developed image onto a transfer material and a conveyance belt for moving the transfer paper along an image carrier, a recording start position for specifying an image recording start position on the conveyance belt; a specifying means; an image forming means for forming a toner image using a light beam at a predetermined position on the conveyor belt; a designated recording start position on the conveyor belt; and an image position formed by the forming means. The device is characterized in that it includes a position detection means for detecting.

(Example) Hereinafter, the present invention will be specifically explained based on examples.

1 to 6 show a first embodiment of the present invention, FIG. 1 is a plan view of the conveyor belt, FIG. 2 is a side view of the conveyor belt, and FIG. 3 is a perspective view of the conveyor belt. Figure 4 is a partially enlarged plan view of the conveyor belt, Figure 5 is a COD output diagram, and Figure 6 is an enlarged view of a plane of the conveyor belt.
The figure is a contour block diagram.

In FIG. 1.2.3, the conveyor belt 21 is supported by a drive roller 30 and a pair of driven rollers 31 and 32, and is driven by the rotation of the drive roller 30 in response to the driving force of a drive motor 33. . A line 34 indicating an image recording start position is provided on the side of the surface of the conveyor belt 2, and a sensor, for example, a CCD 36, is arranged opposite to this line 34.

During registration adjustment, a predetermined pattern image 35 is irradiated onto the photoreceptor 21 on the conveyor belt 21 with a light beam;
[This explanation describes the adjustment of the Bk (black) recording device, but adjustments are made in the same way for other Y, M, and C.]
.

The pattern image 35 has a line shape extending in the sub-scanning direction at the image writing position set in the exposure system 128, and as shown in FIGS.
The length of the line No. 5 only needs to be long enough to be read by the C0D 36, and the width of the line is the width of one or several dots of the light beam.

Then, the amount of deviation 1 (see FIG. 4) between the pattern image 35 and the line 34, which is the image recording start position designation means, is determined as C0D.
Read by 36. FIG. 5 shows the output of the CCD 36, and the image of the line 34 and the position of the pattern 35 are shown on the CCD 36.
It is determined by counting the number of clocks based on the pixel pitch of 6. For example, in Figure 5, line 3
Assuming that m counts have been made until the detection of image 4 and n counts have been made until the detection of pattern image 35, and the pixel pitch (several microns) of CCD 36 is P, the deviation A' - (
m−n) xp.

After detecting the amount of deviation i in this way, the conveyor belt 21
The pattern image 35 formed on the cleaning surface 37 provided on the right side of the conveyor belt 21, as shown in FIG.
removed by

The horizontal registration is adjusted by changing the time from when the synchronous detector 288k detects the light beam to when the image is written according to the detected deviation amount l.Generally, the deviation ff1l is adjusted to zero. Change the said time to . As a method of changing this time, the synchronization detector 28
There is a method of changing the number of clocks from when the 8k detects the light beam to when the image is written, or a method of delaying the output to the synchronization detector 288 for a certain period of time. By adjusting the image writing position of each color in this way, CC
Horizontal resist #A adjustment for each color can be performed with an accuracy of a pixel pitch of D36.

A more specific control system of the above-mentioned adjustment mechanism will be explained with reference to the control block diagram shown in FIG. 6. In the same figure, COD
Drive circuit 40, CCD 36, edge detection circuit 41, CO
A D address latch 42, an address comparison circuit 43, an image write timing correction circuit 44, an image write timing generation circuit 45, and an exposure system drive modulation circuit 46 are provided, and the light received by the CCD 36 is transmitted to, for example, an edge detection circuit 41. Detects the beam receiving position and COD
The address is latched by the address latch circuit 42. This latched address is compared with the address data of the specified color by the address comparison circuit, and the image writing timing correction circuit 44 adjusts the positional deviation amount corresponding to the difference in the address by increasing or decreasing the number of clocks, etc.
Correct the image export timing.

As the image writing timing generating device 45, one using a counter is already known. In this case, the correction signal from the image writing timing correction circuit 44 is input to the data line of the counter, and the count start address is set in accordance with the amount of positional deviation.

Furthermore, even when performing a sequence using a ROM (memory element), it can be implemented by using the address counter of the ROM in the same manner as described above.

Next, the second embodiment of the present invention is shown in FIGS. 7(a) to (d) and 8.
This will be explained with reference to Figures (a) to (d) and Figures 9 (a) to (dl).

7(a) to (d) are front views showing the movement of the conveyor belt portion, FIGS. 8(a) to (d) are plan views showing the light receiving state of the COD portion, and FIGS. 9(a) to (d). ) is an output diagram of COD.

This embodiment differs from the first embodiment in that a line indicating the image recording start position is not provided in advance on the conveyor belt 50. This will be explained in detail below.

In FIGS. 7(a) to (1), 14Y is applied to each color photoreceptor 148, which is an image carrier on the conveyor belt 50.

Between 14M and 14C, a line CCD 51 is installed near the conveyor belt 50 to read the image on the conveyor belt 50.
8, 51Y, 51M, and 51C are provided. 52
is a cleaning device for removing toner on the conveyor belt 50.

FIG. 7(a) shows that the transfer paper 53 is placed in front of the photoreceptor 148 (the toner image formed on the photoreceptor 14Bk is transferred to the transfer paper 53).
Figures 7(C) and 7(d) show the state in which the transfer paper 53 has been conveyed to the photoconductor 14Y, 14M, respectively.

It is a figure of the state conveyed to before 14G.

In the states shown in Figure 7+8) to (d) above,
A pattern image 54 is formed on the conveyor belt 50 in the same manner as in the first embodiment. FIG. 8(a) shows the exposure system 128k.
The pattern image 5 formed via the photoreceptor 148k by
48k, and FIG. 8(bl indicates the positional relationship between the already formed pattern image 548 and the pattern image 54Y formed by the exposure system 12Y. dl shows a state in which pattern images 54M and 54C are sequentially additionally formed.
4Y, 54M.

54C is a straight line extending in the sub-scanning direction (the moving direction of the conveyor belt 50) so as to be read by the CCDs 51Bk, 51Y, 51M, and 51C.

C of 54Y, 54M, 54C is added to the pattern image 548.
The output from CD51Bk, 51Y, 51M, and 51C is as follows:
Taking the relationships between the pattern images in FIGS. 8(a) to 8(d) as an example, they are as shown in FIGS. 9(a) to (dl).

And 54Y, 54M in each pattern image 548.

The position of 54C is 51Y, 51M,
It is obtained by counting the number of clocks based on the pixel pitch of 51G. For example, exposure system 12Bk (!
The deviation of the image writing position of = 12Y is calculated by assuming that in Fig. 9 (bl), KIIK counts are counted until pattern image 548 is detected, and Kv counts until pattern image 54Y is detected, and the pixel pitch (several microns) of CCD is calculated. When P, the deviation 1lL-<Kv- is obtained by □)xP.

And Bk (pA) for each CCD51Y, 51M, 51C
After detecting □ at the position of the pattern image 548, 4. Find Kc and find the deviation [L] from KBK.

Based on this shift iL, the lateral registration is adjusted in the same manner as in the first embodiment.

In addition, in the above-mentioned embodiment, C0D36,51Bk,
51Y, 51M, and 51C are used to detect the light from a light emitting element (not shown) using a conveyor belt 21.50 and receive the light with a COD, or transmit the light through the conveyor belt and use a CCD. Any model that receives light can be adopted.

In addition, in the first embodiment, as shown in FIG. By forming an image 62 for detecting the amount of deviation on the conveyor belt 63, exposing the deviation 'fi-1 as described in the first embodiment, and feeding back the amount of deviation l to the time changing means, It is possible to obtain an image with small registration deviation (accuracy of pixel pitch of CCD).

In each of the above embodiments, C0D36°518, 51Y, 51M, 51C, 60 and conveyor belts 21,5
Between 0.63 and 0.63, an optical system such as a Selfoc lens array (rinsing) is actually required.

(Effects) As explained above, the present invention has a configuration in which horizontal registration can be adjusted without using a special jig.
Furthermore, it is possible to provide a color image forming apparatus that can be easily formed.

[Brief explanation of the drawing]

1 to 6 show a first embodiment of the present invention, FIG. 1 is a plan view of the conveyor belt, FIG. 2 is a front view of the conveyor belt, and FIG. 3 is a perspective view of the conveyor belt. Figure 4 is a partially enlarged plan view of the conveyor belt, Figure 5 is an output diagram of the CCD, and Figure 6 is an enlarged plan view of a portion of the conveyor belt.
The figure is a control block diagram, Figure 7 (al, (b), (e)
), (d) are front views showing the operation of the conveyor belt portion of the second embodiment, and FIGS. 8(a), (b), (cl, (d)
) is a plan view showing the light receiving state of the CCD part of the second embodiment;
Figure 9 (at, (bl, cl, (di) is an output diagram of the COD of the second embodiment, Figure 10 is a front view of the conveyor belt part of the third embodiment, Figure 11 is a conventional color copying machine. FIG. 12 is a perspective view showing a conventional exposure system; FIG. 13 is a schematic diagram of
14 are diagrams for explaining conventional adjustment. 128, 12C, 12M, 12Y... image forming means;
148, 14C, 14M, 14Y... image carrier;
168, 16c, 16M, 16Y...developing means, 1
78, 17C, 17M, 17Y...transfer means, 21
, 50.63...Transfer belt, 34.548k...
Recording start position designation means, 36,518k. 51Y, 51M, 51C, 60...Position detection means. Figure 1 Figure 2 I Figure 3 Figure 4 Figure 5 Figure 7 Figure 8:) 4M Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Procedural amendment (voluntary) Showa Δ month, 62

Claims (1)

[Claims] a plurality of image carriers, an image forming means provided corresponding to these image carriers and forming an electrostatic latent image on the image carriers with light beams each modulated with a different color signal; A color image comprising a developing means for making an electrostatic latent image formed on a body visible, a transfer means for transferring the developed image onto a transfer material, and a conveyor belt for moving the transfer paper along an image carrier. In the forming apparatus, a recording start position specifying means for specifying an image recording start position on the conveyor belt, an image forming means for forming a toner image by a light beam at a predetermined position on the conveyor belt, and the conveyor belt. A color image forming apparatus comprising: a position detecting means for detecting the recording start position specified above and a position of an image formed by the image forming means.