JPH0416969A - Optical writing device - Google Patents

Abstract

PURPOSE:To surely prevent the deviation of a writing position with high accuracy and to prevent color slurring in a main scanning direction and the lowering of resolution by adding an automatic writing position correcting mechanism which utilizes a mark put on the inner side of a photosensitive body. CONSTITUTION:The position of the photosensitive body is detected by the reflection type marks 14a and 14b, an LED 15, a lens 16, and a photosensitive body position detecting sensor 17 in an array state. Namely, the position in the main scanning direction of the photosensitive belt 4 is detected according as what cell of the sensor 17 detects the light and judged by a photosensitive body position detecting means 5. A writing timing deciding means 7 receives a position detection signal PS from the means 5 and an index signal ID from an index sensor 6, adjusts writing start timing and corrects the writing position corresponding to the positional deviation of the belt 4. Thus, the deviation of the writing position is surely prevented with high accuracy and the color slurring in the main scanning direction and the lowering of the resolution are surely 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 apparatuses capable of forming multicolor images, such as racer beam printers, generally use highly sensitive selenium-tellurium, selenium-arsenic, or organic photoreceptor materials coated on the surface of a cylindrical drum. 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 while it rotates, and a multicolor image is formed on transfer paper in one transfer (patent application). Hei 2-7697 etc.). This type of device that forms superimposed images on a photoreceptor has the advantage that it can be made more compact by eliminating unnecessary members.

However, since the photosensitive drum is cylindrical, the drum occupies a large volume, and if further miniaturization is pursued, this will be a problem 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.

(Problem to be Solved by the Invention) As a result of further study by the inventor of the present invention regarding the technique of using a belt-shaped photoreceptor, it has been found that when multiple writing is performed to form a multicolor image (one image of each color is superimposed on the photoreceptor) It has been found that when writing at the same time), misalignment of the photoconductor may cause a shift in the writing position, resulting in color shift in the main scanning direction (line scanning direction of the writing beam) and a decrease in resolution. . This is because, since the belt is driven by a separate roller, relative positional deviation is likely to occur due to slipping or the like.

In order to solve this problem, it is necessary to improve the mechanical accuracy, but it is difficult to take this alone as a sufficient countermeasure, and the cost increase due to the use of high-precision parts is also a problem. However, there are limits to what mechanical countermeasures can be taken.

Therefore, the inventor of the present application has researched and variously considered techniques for detecting the photoreceptor position using an optical method and correcting the optical writing position in response to positional fluctuations of the photoreceptor belt. As a result,
The following study results were obtained.

(1) For example, in an optical writing device that writes information on a photoconductor heald 4 using a laser light source 1, a polygon mirror 2, and a mirror 3 as shown in FIG. Consider a writing position correction mechanism in which a detection LED 15 and an array sensor 17 are arranged, and a detection signal from the sensor 17 is sent to the photoreceptor position detection means 5. In this case, as shown in FIG. 16, the end portion of the photoreceptor belt 4 is likely to fluctuate up and down, and the accuracy of detecting the position of the photoreceptor is reduced.

(2) It is conceivable to use the back plate 18 to suppress the vertical fluctuation of the photoconductor 4, but since the end of the photoconductor is used as a reference for position detection, the back plate 18 is However, it is difficult to extend it sufficiently.

The present invention has been made in view of the above-mentioned study results, and its purpose is to highly accurately control the displacement of the writing position without strictly regulating the displacement of the photoreceptor in the main scanning direction when performing multiple writing. The objective is to reliably prevent color blurring and resolution degradation in the main scanning direction. In addition, other purposes are
The object is to achieve the above object while minimizing the complexity of the device.

(Means for Solving the Problems) The present invention uses a light-reflecting or light-transmitting mark provided inward from the end of the photoreceptor to prevent a decrease in accuracy due to shaking of the end of the heald. The positional deviation of the photoreceptor is detected, and based on the detection result, the optical writing position is corrected in accordance with the positional deviation.

As the photoreceptor position detection means, the above-mentioned mark and LED are used.
It is conceivable to use a non-scanning type light source such as the above and an array-shaped position detection optical sensor such as a CCD, or a scanning type light source such as an LED array and a non-array type optical sensor such as a phototransistor.

The present invention is suitable for application to an apparatus using a belt-like or sheet-like photoreceptor, and can also be applied to an apparatus using a cylindrical photoreceptor.

The correction of the writing position may be performed each time one line is written, once or multiple times for one image, or once for multiple images.

By using the light source for image writing as the light source of the optical sensor for detecting the position of the photoreceptor, the position of the photoreceptor can be detected easily and at low cost by adding a light receiving element such as a phototransistor.

It is conceivable to use a point light source such as a laser and an optical/mechanical light scanning means such as a polygon mirror as the light source for writing and detecting the position of the photoreceptor.

In this case, by giving the light receiving element the role of an index sensor that detects the writing start timing, this index sensor becomes unnecessary and an increase in the number of parts can be prevented.

Alternatively, an array light source such as an LED array or a liquid crystal array may be used as the writing light source, and the position of the photoreceptor may be detected by scanning a part or all of the light source and sequentially lighting the light source.

(Function) Even if a belt-like or sheet-like photoconductor fluctuates in the main scanning direction, the optical writing position automatically follows this fluctuation and changes, so that only a deviation of the writing position occurs.

Furthermore, since the positional misalignment of the photoreceptor is detected with reference to the inner side of the end of the photoreceptor, highly accurate detection is possible by eliminating the influence of shaking of the end, and the accuracy of writing position correction is guaranteed.

(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 the paper cassette 31 is loaded from the front, and a clamshell method in which the upper part of the developing section etc. is opened diagonally upward and to the right around a fulcrum 45. There is.

A photoreceptor is coated on the surface of the belt 4 made of synthetic resin, and the second photoreceptor belt 4 is driven by rollers 13a and 13b. Developing units 32, 33, 34, and 35 for each color and a charging electrode 41 are arranged facing the bottom surface of the photoconductor belt 4, while a transfer pole 42 is placed on the left side of the photoconductor heald 4, and a toner box 46 is provided above. It is located.

Is the optical writing system targeted by the present invention a laser beam? 1.1
, f/θ lens 36, and reflecting mirror 37, 38, 39
and a cylinder drill force lens 40.

The transfer paper fed from the paper cassette 31 has the image on the belt photoreceptor 4 transferred thereto, undergoes a fixing process in a fixing section 43, and 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 sectional view taken along line A-A 4g in FIG. 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 37, 38, and 39 in FIG. 14 are generally shown as mirror 3 in FIG. 1, and the f/θ lens 36 and the mirror lens 40 are also omitted. This simplification is common to the figures described below.

General outline of a general writing operation Light emitted from a laser light source 1 is reflected by one surface of a polygon mirror 2 that rotates at a constant speed and is guided onto a photoreceptor belt 4. Writing starts a predetermined time after the laser beam reaches the index sensor 6. At this time,
The reflected light from the polygon mirror 2 is reflected downward by the mirror 3 and sequentially scans the photoreceptor belt 4.

Correcting operation of writing position Marks 14a and 14b having light reflecting characteristics are arranged slightly inward from the end of the photoreceptor heald 4 in parallel to the belt end. The photoconductor position is detected by
4b, an LED L5, a lens 16, and an arrayed photoconductor position detection sensor (CCD) 17.

In order to prevent this detection accuracy from decreasing, the hack plate I8 extends to the bottom surface of the end of the photoreceptor belt 4 (the hack plate 18 is not shown in FIG. 1, but is shown in FIG. 2). ). Even with this arrangement, the same problem occurs because the end of the belt is not used as a reference for position detection, but vertical fluctuations of the photoreceptor heald 4 are thereby reliably prevented.

LED 15 and marks 14a, 14 on photoconductor heald 4
The vertical positional relationship between the photoreceptor belt 4 and the array-like sensor 17 for detecting the position of the photoreceptor is as shown in FIG. Detect the position of the direction. The second determination is made by the photoreceptor position detection means 5.

The write timing determining means 7 includes the photoconductor position detecting means 5.
In response to the position detection signal PS from the index sensor 6 and the index signal (signal that serves as a reference for determining the beginning of writing) ID, the writing start timing is adjusted, thereby adjusting the writing position corresponding to the misalignment of the photoreceptor belt 4. Make corrections. This adjustment of the write timing is performed by turning on the write enable signal EN supplied to the AND circuit 9. That is, when the write enable signal EN is turned on, the operating clock supplied from the clock generation circuit 8 is supplied to the address counter 10, and the read main scanning direction address of the image data is sequentially incremented and updated.

As a result, data is read from the memory cell at the specified address of the image memory (DRAM configuration) 11,
The input data DIN is supplied to the drive circuit 12, and the laser light source 1 is driven by the drive output signal DM.

Every time one scan of the laser beam is completed, the write control unit 4
7 clears the counter IO and increments the read sub-scanning address of the image memory 11.

It is preferable to correct this writing position every time one line is written. In this case, since high-speed processing is required, the writing timing determining means 7 is constructed of dedicated hardware. However, the correction may be performed once or multiple times for writing one image, or once for writing multiple images. In these cases, processing can be performed under control by computer software. In this case, the write timing determining means 7 is realized by a functional block constructed as a result of hardware operating in accordance with software.

Embodiment 2 FIG. 3 is a diagram showing the configuration of a second embodiment of the optical writing device of the present invention, and FIG. 4 is a sectional view taken along the line BB in FIG. 3.

The features of this embodiment are that an array light source (LED array) 19 and a non-array position detection sensor (photodiode) 20 are used as photoreceptor position detection means, and that a scanning signal generator 26 The light sources 19 are scanned by the signals and turned on sequentially.

The vertical relationship between the array light source I9, the light reflective marks 14a and 14b on the photoreceptor belt 4, and the position detection sensor 20 is as shown in FIG. 4, and the position of the photoreceptor heald 4 is , is determined from the relationship between the scanning (on/off) timing of the array light source 19 and the light detection timing of the sensor 20, and this t'l+ disconnection is performed by the photoreceptor position detection means 5.

Embodiment 3 FIG. 5 is a diagram showing the configuration of a third embodiment of the optical writing device of the present invention, and FIG. 6 is a sectional view taken along the line C--C in FIG. 5.

In this embodiment, unlike the above-mentioned embodiments, light-transmitting marks 21a and 21b having a property of transmitting light are used as marks for detecting the position of the photoreceptor 4.

As shown in FIG. 6, an array of sensors 17 is arranged below the photoreceptor belt 4, and the position of the photoreceptor heald 4 can be detected by detecting light from the LED 15.

Embodiment 4 FIG. 7 is a diagram showing the configuration of a fourth embodiment of the optical writing device of the present invention, and FIG. 8 is a sectional view taken along the line DD in FIG. 7.

This embodiment also uses light-transmissive marks 21a and 21b. Further, a scanning array light source I9 is used as a light source for detecting the position of the photoreceptor, and a photodiode 20 is used as a sensor. The position of the photoreceptor belt 4 can be detected from the relationship between the on/off timing of the array light source 19 and the light detection timing of the photodiode 2°.

Embodiment 5 FIG. 9 is a diagram showing the configuration of a fifth embodiment of the optical writing device of the present invention, and FIG. 10 is a sectional view taken along the line E--E in FIG. 9.

In this embodiment, the position of the photoreceptor belt 4 is detected using a reflective mark 14a, an LED 15, and an array sensor 17, as in the first embodiment described above, but the detection position is set on the roller 13a, The hack plate 18 is not required. This simplifies the configuration of the photoreceptor belt 4.

Embodiment 6 FIG. 11 is a diagram showing the configuration of a sixth embodiment of the present invention.

In this embodiment, the reflective mark 14a of the photoreceptor heald 4,
14b, two photodiodes 20a20b
The writing light source 1 also serves as a light source for these photodiodes 20a and 20b. This eliminates the need to provide a light source just for detecting the position of the photoreceptor belt 4, and the number of parts can be reduced.

Embodiment 7 FIG. 12 is a diagram showing the configuration of a seventh embodiment of the present invention.

In this embodiment, the photoconductor position detecting sensors 20a and 20b also play the role of index sensors (that is, the role of determining the writing timing).
The configuration is such that the index sensor 6 is removed from the figure. This allows for further simplification of the configuration.

Embodiment 8 FIG. 13 is a diagram showing the configuration of an eighth embodiment of the present invention.

In this embodiment, an array-shaped write light source 24 such as an LED array is used as the write light source. Accordingly, a scanning signal generating section 2θ is provided, and scanning signals SCI and SC2 are supplied to the driving means 12 and the write timing determining means 7.

Although the present invention has been described above using eight embodiments, the present invention is not limited to these embodiments, and various applications and modifications are possible. For example, the photoreceptor may not only be in the shape of a heald or sheet, but may also be in the form of a conventional cylinder.

In this case, writing position displacement during multiple writing due to play in the thrust (axial) direction can be prevented.

Alternatively, a mark having a color different from that of the photoreceptor belt may be used as the reflective mark, and the photoreceptor position may be detected by image processing based on the difference in light reflectance.

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

(1) By adding an automatic writing position correction mechanism that uses marks provided inside the photoreceptor, even when using a belt-like or sheet-like photoreceptor, it is possible to perform multiple writing such as color images. , it is possible to reliably prevent displacement of the writing position with high precision without strictly regulating the positional displacement of the photoreceptor in the main scanning direction, and it is possible to reliably prevent color blurring and resolution degradation in the main scanning direction.

(By sharing the writing light source as the light source for detecting the position of the 2-pin photoconductor, the photoconductor position can be easily detected. This makes it possible to easily detect the writing position deviation during multiple writing. It can definitely be prevented.Especially,
Writing and photoreceptor position detection 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 detection light source, this can be realized without increasing the number of parts.

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

(4) As a result, devices such as printers that perform multiple writing on a photoconductor can be further miniaturized without sacrificing reliability.

[Brief explanation of the drawing]

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 cross-sectional view taken along line 1-A in FIG.
FIG. 3 is a diagram showing the configuration of a second embodiment of the optical writing device of the present invention, FIG. 4 is a sectional view taken along the line BB in FIG. 3, and FIG. FIG. 6 is a sectional view taken along the line C-C in FIG. 5, FIG. 7 is a diagram showing the configuration of a fourth embodiment of the present invention, and FIG. 7 is a cross-sectional view taken along line D-D in FIG. 7, FIG. 9 is a view showing the configuration of the fifth embodiment of the present invention, and FIG. 10 is a cross-sectional view taken along line E-E in FIG. 9. 11 is a diagram showing the configuration of the sixth embodiment of the present invention, FIG. 12 is a diagram showing the configuration of the seventh embodiment of the present invention, and FIG. 13 is a diagram showing the configuration of the seventh embodiment of the present invention.
FIG. 14 is a diagram showing an example of the overall configuration of an optical printer, and FIG. 5 and FIG. FIG. ]...Racer light source 2...Polygon mirror 3...
・Mirror 4・Photoreceptor belt 5...Photoreceptor position detection means 6...Index sensor 7...Writing timing determination means 8...Clock generation circuit 9...AND circuit 10...
- Counter 11... Image memory 12 - Driving means 13 (13a, 13b) - O-ra 14 (14a, 14b) - Reflective mark 15 - LED for detecting photoconductor position 16... Lens 17... Photosensitive Array sensor 18 for body position detection...
Back plate 19...Array light source 20 (20
a, 20b)...Photoconductor position detection sensor (photodiode) 21 (21a, 21b)/Light transmission mark 24...
LED array 25... Combined optical system 26... Scanning signal generator 30... Optical printer 31... Paper cassettes 32 to 35, Developing device 3[-f/θ lens 3f...
39...Reflection mirror 40...IJ optical lens 4I/Charging electrode 42 Transfer pole 43/Fixing section 44 Paper ejection roller 45...Clam shinir opening support 46/Toner hook 47...Writing control means

Claims (2)

[Claims] (1) The photoreceptor (4) is illuminated by the light of the writing light source (1, 24).
In an optical writing device for writing information on the photoreceptor (4
) for detecting the position of the photoreceptor in the main scanning direction (5, 14, 15, 16, 17, 5, 14, 19,
20) and a mechanism (6, 7, 8, 10, 11, 12, 47) for correcting the optical writing position on the photoconductor (4) based on the detection signal from the photoconductor position detection means. have,
The photoreceptor position detecting means includes a mark (14) having light reflective properties provided inward from the end of the photoreceptor (4).
and a sensor (
17, 20). (2) The photoreceptor position detection means includes a mark (21) having a light transmission characteristic provided inward from the end of the photoreceptor (4), and sensors (17, 20) that detect the transmitted light of the mark. 2. The optical writing device according to claim 1, further comprising the following.