JPH0419760A - Optical writing device - Google Patents

Abstract

PURPOSE:To accurately make writing positions with a writing light source align even if the attaching position of the writing light source is not accurate by incorporating each writing light source position detecting means into this device, and correcting the writing positions while aligning the position with the actual positions of the writing light sources, respectively. CONSTITUTION:The optical writing device is provided with the writing light source position detecting means 5a and 5b detecting positions in the main scanning directions of plural writing light sources 1a and 1b with respect to a position reference inside the device, and correcting means 12a, 12b, 16a, and 16b carrying out the correction of an optical writing position to a photosensitive body 4 based on detecting signals from the writing light source position detecting means 5a and 5b. When the attaching positions of respective light sources 1a and 1b are varied, and the irradiating position of writing light from the light sources 1a and 1b are deviated caused by this, data reading out timing from image memory 11 is corrected in matching with this deviation, and a mechanical deviation is compensated by an electric processing. Thus, the writing positions coincide with respective light sources, and the degradation of image quality can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical writing device used in an optical printer or the like.

(Background of the Invention) Image forming devices capable of forming multicolor images, such as laser beam printers, generally coat the surface of a cylindrical tram with a highly sensitive selenium-tellurium-based, selenium-arsenic-based, or organic photoreceptor material. The applicant is
When forming a multicolor image, we have developed a method in which a multicolor superimposed image is formed on the surface of the photoreceptor drum as it rotates, and a multicolor image is formed on transfer paper in one transfer (patent application). Hei 2-7697 etc.). An apparatus that forms superimposed images on two photoreceptors has the advantage of being able to reduce the size of the apparatus by eliminating unnecessary members.

However, since the photoreceptor drum is cylindrical, the drum occupies a large volume, and this becomes a bottleneck in pursuing further miniaturization, and there is a limit to miniaturization.

Therefore, the inventors of the present application have developed a technique for suppressing the vertical width of the photoreceptor by using a belt-shaped photoreceptor instead of the cylindrical photoreceptor, thereby promoting miniaturization.

(Problems to be Solved by the Invention) As a result of further study by the inventor of the present invention regarding the technology using a belt-shaped photoreceptor, the following matters became clear.

(1) In order to achieve dramatic speed-up of printing as well as miniaturization of the device, instead of exposing (light writing) one color per rotation of the photoreceptor belt, for example,
Y (yellow) 1M (magenta), C (cyan), K (
It is important to expose all four colors of black. In this case, it is necessary to provide a plurality of writing light sources corresponding to each color and perform multiple optical writing at different positions on the photoreceptor belt.

(2) However, in this case, unless the plurality of writing light sources are extremely accurately fixed at predetermined positions, the writing positions of the respective light sources will be shifted, resulting in a problem that the image quality will deteriorate.

(3) In order to solve the above-mentioned problems, it is necessary to strictly define the position of the light source during manufacturing, that is, to improve mechanical precision. However, the work becomes cumbersome, and it is difficult to use this alone as a sufficient countermeasure.The use of high-precision parts also raises costs, and there are limits to mechanical countermeasures alone.

The present invention has been made in view of the above-mentioned problems, and
The purpose of this is to eliminate the need to strictly control the misalignment of multiple writing light sources during manufacturing in devices that perform multiple writing.
The purpose is to accurately match the writing positions of each light source to prevent deterioration in image quality.

Another object is to achieve the above object while minimizing the complexity of the device.

(Means for Solving the Problems) The present invention incorporates each writing light source position detection means in the device and corrects each writing position according to the actual position of the writing light source. Even if the writing position is not accurate, it is possible to accurately match the writing position by the writing light source.

Further, by using the writing light source itself as the writing light source position detecting means, a highly accurate position detecting means can be easily constructed.

Furthermore, when a point light source such as a laser and an optical/mechanical light scanning means such as a polygon mirror are used as the writing light source, the writing start timing in the main scanning direction of each writing light source may be determined by the writing light source position detection means. There is no need to provide any other sensor (index sensor) for detecting the scanning position of the writing light source.

(Function) The mounting positions of each light source vary, and due to this, when the irradiation position of the writing light from the light source is blurred, the timing of reading data from the image memory is corrected to match this blurring.
Compensate for mechanical deviations by electrical processing.

(Example) Next, an example of the present invention will be described with reference to the drawings.

Example 14 of the overall configuration of an optical printer to which the present invention is applied
As shown in the figure, the optical printer 30 employs a front loading method in which a paper cassette 41 is loaded from the front, and a clamshell method in which the upper part of the developing section etc. is opened diagonally upward to the right around the fulcrum 31. There is.

A photoreceptor is coated on the surface of a belt 4 made of synthetic resin, and this photoreceptor belt 4 is driven by a roller 15. Charging electrode 32. facing the upper surface of photoreceptor belt 4.
35.18 and Y, M, C color developing units 34,3
7.40 is arranged, and on the other hand, a transfer pole 42 is arranged on the left side of the photoreceptor belt 4. Note that, in addition to the seven colors, 1M color, and 0 color, there are usually K (black) developing devices, but these are omitted in this specification to avoid complicating the explanation.

The optical writing system to which the present invention is applied includes racer light sources 1a, 1b, and 1c corresponding to each color, and reflecting mirrors 33, 363.
9.

After the image on the belt photoreceptor 4 is transferred to the transfer paper fed from the paper cassette 41, a fixing process is performed at a fixing section 43, and the paper is discharged via a paper discharge roller 44.

Embodiment 1 FIG. 1 is a diagram showing the configuration of a first embodiment of the optical writing device of the present invention, and FIG. 2 is a diagram showing the cross-sectional configuration of the main part of FIG. 1. In these figures, parts that are the same as or correspond to those in FIG. 14 are given the same reference numerals. Further, the reflecting mirrors 33.3B, :119 in FIG. 14 are generally shown as mirror 3 in FIG.

This simplification is common to the figures described below.

General outline of writing operation In this embodiment, scanning type writing light source units 14a and 14b for the first color and the second color are provided.

The light emitted from the first color racer light source 1a is reflected by one surface of the polygon mirror 2a that rotates at a constant speed, and is reflected by the mirror 3.
a is reflected downward and sequentially scans over the photoreceptor heald 4. The same applies to the second color racer light source 1b.

Writing position correction operation In this embodiment, the mounting positions of the light sources 1a and lb in the main scanning direction are determined by detecting the positions of the side walls of the light source units 14a and 14b. Detection of this side wall position is performed using point light sources (LEDs) Ba and 8b arranged on the side walls of the light source units 4a and 14b, and an array sensor (CC
D) Performed by 5a and 5b. point light source 6a,
[The vertical positional relationship between the fb, the array sensors 5a and 5b, and the light source units 14a and 14b is as shown in FIG. The position of each light source unit 14a, 14b can be determined by determining the boundary with the undetected cell. Since the displacement of the light source unit body directly becomes the displacement of the laser light sources 1a and lb, the result is that the laser light source 1
It is possible to detect the positions of a and [b. According to the second detection result, the optical writing timing in the main scanning direction (the scanning direction of one line of laser light) is adjusted to correct the writing position.

This optical writing position correction can be realized using, for example, a correction mechanism as shown in FIG. That is, the sensors 5a, 5
Based on the detection signal b, the writing position correction signal generation unit 16
a and 16b generate a correction signal, and write light source driving section 12
a, 12b. Writing light source drive unit 12a, 12
b is the image memory 1! at the timing instructed by the correction signal. The image data to be written is read out from the memory, and the writing light sources 1a and lb are driven.

Further, the correction mechanism may be configured to include a common write position correction signal generation section I7, as shown in FIG.

Embodiment 2 This embodiment is a more specific version of the configuration shown in FIG. In this embodiment, the writing position correction operation is performed for each light source in parallel or independently, or the configuration for executing the operation is the same, so only the case of the light source 1a will be described.

The signal P1 from the sensor 5a is sent to the light source position detection means 26a, the light source position is detected, and a signal PS indicating the detection result is generated.
is sent to the write timing determining means 7a and the write control means 13.

The write timing determining means 7a receives the input signal PS.
Adjust the writing start timing of the light source 1a based on
Thereby, the writing position is corrected in accordance with the positional fluctuation of the light source 1a (light source unit 14a).

This adjustment of the write timing is performed by turning on the write enable signal ENI supplied to the AND circuit 9a. That is, this write enable signal EN
When I is turned on, the operating clocks CI and K supplied from the clock generation circuit 8 are supplied to the address counter lOa, and the image data reading main scanning direction address (MSA) is supplied to the address counter lOa.
is sequentially incremented and updated (.As a result, data is read from the memory cell at the specified address in the image memory 11, and is supplied to the drive circuit 12a as input data DIN, and the drive signal DM causes the racer light source 1a to be activated. Each time one scan of the laser light is completed, the write control unit 13 clears the counter loa and increments the read sub-scanning address (SSA) of the image memory 11.

By performing this correction process, the writing of each color is always
It starts from a point equidistant from the ends (side walls) of the light source units 14a, 14b, and the position does not shift.

Embodiment 3 FIG. 6 is a diagram showing the configuration of a third embodiment of the present invention, and FIG. 7 is a diagram showing a cross-sectional configuration of the main part of FIG. 6.

The feature of this embodiment is that an array light source (L) is used as a writing light source.
ED array) 18a and 18b are used, and the writing position is corrected using the reference light-shielding plate 19 for position detection. The vertical positional relationship of each member is as shown in FIG. Array light source 18a, 1
8b consists of an image writing section A and a position detection section (scanning section) B, and the position of the light source L8a18b is determined from the relationship between the scanning timing of the position detection section B and the timing at which the photodiodes 20a and 20b detect light. It will be detected. The second position detection is performed with the end of the light shielding plate 19 as a reference,
By ensuring the flatness and mounting accuracy of the ends of the light shielding plates, the positions of the light sources 18a and 18b can be detected accurately.

FIG. 8 shows an example of a writing position correction mechanism. sensor 20
The writing position correction signal generation section 21 generates a correction signal based on the detection signals of a and 20b, and the writing light source driving section 12
a, 12b. Writing light source drive unit 12a, 12
b reads the image data to be written from the image memory 11 at the timing instructed by the correction signal and drives the writing light sources 18a and 18b. Further, a scanning signal for scanning the position detection section B is generated by the writing position detection scanning signal generation section 24, and a scanning signal for scanning the position detection section B is generated by the writing position detection scanning signal generation section 24.
b.

Example 4 FIG. 9 is a diagram showing the configuration of a fourth embodiment of the present invention.

This embodiment is a more specific version of the example shown in FIG.

The basic operation is the same as that shown in Fig. 5, or the array light source 1
8a and 18b, the scanning signal generation section 2
3a and 23b (however, 23b is not shown) are added, and the scanning signals SC1 and SC2 are respectively applied to the driving means 12 (
12a, 12b) and write timing determining means 7 (
7a, 7b).

Embodiment 5 FIG. 1O is a diagram showing the configuration of a fifth embodiment of the present invention.
FIG. 1 is a diagram showing a cross-sectional configuration of the main part of FIG. 10.

In this embodiment, a writing position correction method using a reference shielding plate 19 for position detection is applied to an optical writing device using racer light sources 1a, lb, lc and a polygon mirror 2.

An example of the writing position correction mechanism of this embodiment is shown in FIG. Based on the detection signals of the sensors 2 [1a, 20b, 20c, the main scanning direction writing start timing generation unit 25a,
25b and 25c generate a start timing and send it to the write light source driving units 12a, 12b, and 12c. The writing light source driving units +2a, 12b, and 12c read image data to be written from the image memory 11 at the instructed timing, and drive the writing light sources 1a, 1b, and 1c.

Embodiment 6 FIG. 13 is a diagram showing the configuration of a sixth embodiment of the present invention.

This embodiment is a more specific version of the example shown in FIG.

The basic operation is the same as that shown in FIG. 5, and the write position is corrected by adjusting the timing of reading data from the image memory 11.

Although the present invention has been described above using six embodiments, the present invention is not limited to these embodiments, and various applications and modifications are possible. For example, the photoreceptor may be belt-shaped, sheet-shaped, or conventionally cylindrical.

In this case, the writing position is prevented from shifting due to positional fluctuation of the writing light source in the axial direction of the photoreceptor.

(Effects of the Invention) As explained above, according to the present invention, the following effects can be obtained.

(1) By providing an automatic writing position correction mechanism,
When multiple writing of each color is performed during one rotation of the photoreceptor, the writing positions of each light source can be made to match without the need for accurate mounting of the light source unit to prevent deterioration in image quality.

(2) By sharing the writing light source as the position detection light source, the writing light source position detection means can be simplified.

(3) There is no need to extremely improve mechanical precision;
Increase in equipment costs can be suppressed.

(4) As a result, it is possible to further reduce the size and increase the speed of devices such as printers that perform multiple writing on a photoconductor without impairing reliability.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a first embodiment of the optical writing device of the present invention, FIG. 2 is a diagram showing the cross-sectional configuration of the main part of FIG. 1, and FIG. 3 is an example of the writing position correction mechanism. 4 is a diagram showing another example of the writing position correction mechanism, FIG. 5 is a diagram showing the configuration of the second embodiment of the present invention, and FIG. 6 is a diagram showing the configuration of the third embodiment of the present invention. 7 is a diagram showing the cross-sectional configuration of the main part of FIG. 6, FIG. 8 is a diagram showing an example of the writing position correction mechanism, and FIG.
The figure shows the configuration of the fourth embodiment of the invention, FIG. 10 shows the configuration of the fifth embodiment of the invention, and FIG.
12 is a diagram showing an example of the writing position correction mechanism, FIG. 13 is a diagram showing the configuration of the sixth embodiment of the present invention, and FIG. 14 is an optical printer. It is a figure showing an example of the whole composition of. 1a, 1b, lc...Each hue racer light source 2 (2a,
2b)...Polygon mirror 3 (3a, 3b)...
・Reflection mirror 4...Photoconductor heald 5a, 5b...Light source position detection means 7 (7a, 7b, 7c) ・Writing timing determination means 8...Clock generation circuit 9 (9a, 9b, 9c)・7> code circuit 10 (10
a, lOb, 10c) - Address counter 11... Image memory 12 (12a, 12b, 12c) - Driving means 13...
-Writing control units 14a, 14b...Light source unit 15 -Rollers 1B (16a, 16b)...Writing position correction signal generation unit 17...Writing position correction signal generation unit 18 (18a, l8b)...Arrayed writing light source (LE
D array) 19. Reference light shielding plate 20 for position detection (20a, 20b). Sensor for writing light source position detection (photodiode) 21.. Writing position correction signal generation unit 22 (22a, 22b) - Light source position detection means 23a,
23b - Scanning signal generation unit 24...Scanning signal generation unit 25 for detecting the writing light source position (
25a, 25b, 25c) - Main scanning direction writing start timing generation section 26 (26a, 213b) - Light source position detection means 30.
...Optical printer 31... Clamshell opening fulcrum 32, 35, 38 Charging electrode 33, 36, 39, Reflection mirror 34, 37, 40... Developing device 4 paper cassette 42, Transfer pole 43 Fixing unit MSA... Main scanning direction address SSA...Sub scanning direction address Paper exit

Claims (3)

[Claims] (1) Multiple writing light sources (1a, 1b, 1c, 18a,
18b), wherein the plurality of writing light sources (1a,
1b, 1c, 18a, 18b) in the main scanning direction;
20), the writing light source position, the detection means (5, 6, 19
, 20) correcting means (7, 8, 9, 1) for correcting the optical writing position on the photoreceptor (4) based on the detection signal from the
0, 11, 12, 13, 16, 21, 24). (2) Writing light source position detection means (5, 6, 19, 20)
A plurality of writing light sources (1a, 1b, 1c,
Claim 1 characterized in that 18a and 18b) are shared.
The optical writing device described. (3) A point light source such as a laser as a writing light source (1a,
1b, 1c) and optical/mechanical light scanning means (2, 3) such as a polygon mirror, each writing light source (1a, 1b, 1
Claim 2, wherein the writing start timing in the main scanning direction of c) is determined based on a signal obtained from a writing light source position detection means (5, 6, 19, 20).
The optical writing device described.