JPH0553409A - Image forming device - Google Patents

Abstract

PURPOSE:To perform simple and accurate regulation of the position of a screen filter and to prevent the occurrence of defective evenness in a picture. CONSTITUTION:An image forming device comprises a linear image forming control means 26 to form the linear image of a screen filter on a recording medium 3 during a screen filter position regulation mode, a sensor 25 to detect the size of the line of the linear image, formed on a transfer intermediate substance 5, of the screen filter, a regulating means 18 to regulate the position of the screen filter, and a position regulation control means 27 to regulate the position of the screen filter based on detecting data from the sensor 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a screen filter in the optical path of an exposure optical system for guiding light reflected from a document onto a recording medium.

[0002]

2. Description of the Related Art In a conventional analog type full-color copying machine, for example, an optical path between an exposure optical system and a photoconductor as a recording medium is used to improve gradation and color reproducibility during full-color copying. There was a screen filter inside.

The screen filter is formed by forming a large number of lines having a width of about 65 microns on a transparent film, and the line direction and the rotation direction of the photoconductor coincide with each other at a position about 1 to 2 mm away from the photoconductor. It was set up to do.

With such a screen filter, the reflected light image of the original is linearly decomposed to form an image on the photosensitive member.

[0005]

However, in the above-mentioned conventional image forming apparatus provided with the screen filter, since the screen filter is provided in the optical path, an image is formed due to poor position accuracy due to the inclination of the front side and the back side of the screen filter. And the uniformity was deteriorated.

Further, if it is attempted to accurately position the screen filter, adjustment with extremely high precision is required, which complicates the mechanism and requires a very troublesome work.

[0007]

The present invention has been made to solve the above-mentioned conventional drawbacks, and a screen filter is provided in the optical path of an exposure optical system that guides reflected light from a document onto a recording medium. In the image forming apparatus, a line image forming control unit that forms a line image of the screen filter on the recording medium, a sensor that detects the line thickness of the line image of the screen filter, and the position of the screen filter are adjusted. Adjusting means, and position adjusting control means for operating the adjusting means based on the data detected by the sensor to adjust the position of the screen filter.

[0008]

According to the above-mentioned image forming apparatus, the line image of the screen filter is formed on the recording medium, the thickness of the line formed on the recording medium is detected by the sensor, and based on the detected data. Since the position adjustment of the screen filter can be automatically performed, the position adjustment work that requires high precision can be easily and accurately performed. Therefore, it is possible to prevent the deterioration of the image uniformity due to the poor positional accuracy of the screen filter by eliminating the complicated mechanism and the troublesome adjustment work.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings by taking a full-color copying machine as an example. FIG. 1 is a sectional view showing a schematic configuration of a full-color copying machine according to the present invention.

In the drawings, reference numeral 1 is a transparent document placing table,
2 is an exposure optical system, 3 is a sheet-shaped photoreceptor, 4a, 4b,
4c is a developing tank for each component, 5 is a sheet-shaped transfer intermediate,
6a and 6b are sheet feeding cassettes of different sizes, 7 is a charging charger, 8a and 8b are transfer rollers, and 10 is a fixing device.

The exposure optical system 2 includes a light source lamp 2a for irradiating the original 11 placed on the original table 1 with light, and the original 1.
The reflected light from the photosensitive member 3 is, for example, as indicated by a dashed line in FIG.
It is provided with a plurality of reflecting mirrors 2b that guide upwards, an imaging lens 2c arranged on the optical path, and a color separation filter 2d having color filters of three primary colors (red, green, blue).

The screen filter 2e is located in the optical path of the exposure optical system 2 at a position 1 to 2 mm above the photoconductor 2, that is, 1.7 ± 0.2 mm in this embodiment. Is provided.

The screen filter 2e is, for example, 110 lines / inch having a width of 65 microns formed on a transparent film. The screen filter 2e having such slits has a line in the direction of rotation of the photosensitive member 3. It is provided above the photoconductor 3 so as to be oriented.

The photoconductor 3 has two rollers 12a and 12a.
It is driven to rotate by b, and developing tanks 4a to 4c are arranged in a non-contact state near the center of the upper surface of the photoconductor 3. A charging charger 7 or the like is arranged on the side of the first roller 12a of the photoconductor 3, and a cleaning mechanism 13 for removing toner remaining on the photoconductor 3 is provided on the lower surface of the photoconductor 3 on the side of the first roller 12a. It is arranged.

The transfer intermediate 5 comprises three rollers 14a.
14c to 14c, and is disposed on the side of the second roller 12b of the photoconductor 3.

The second roller 12b side of the photoconductor 3 is pressed against one side surface of the transfer intermediate 5, and the transfer roller 8a is provided on the back side of the transfer intermediate 5 at the position where the photoconductor 3 is pressed. A transfer roller 8b is disposed on the lower surface of the transfer intermediate body 5.

Further, a reflective small optical sensor 25 is attached toward the transfer intermediate 5 below the photoconductor 3 above the transfer intermediate 5 on the downstream side of the transfer roller 8a ( (See FIG. 4).

The structure of the position adjusting means 18 for adjusting the position of the screen filter 2e will be described below. 2A is a top view of the position adjusting means 18 with a screen filter attached, and FIG. 2B is a side view thereof. Further, FIG. 3A shows the position adjusting means 1 shown in FIG.
8 is a partially exploded perspective view of FIG. 8, (b) is a top view of the cam portion. In the figure, the screen filter 2e is attached and fixed to the fixed frame 23. On both side surfaces of the fixed frame 23 in a direction orthogonal to the line direction of the screen filter 2e, a shaft 24 ...
Is provided so as to project.

A cam and a gear integrally provided on each of the four shafts 24 are rotatably attached.

Among the above-mentioned cams, the ones 19a and 19a which are driven to rotate by the motors 21 and 21 are provided with gears 20a and 20b on both surfaces of the cam, and the cam 19 on the driven side is provided.
Gear b is provided only on one surface of b. The gears 20a, 20a are meshed with the gears 20c, 20c attached to the rotary shafts of the motors 21, 21. On the other hand, two pairs of gears located on the screen filter 2e side, that is, the rotating gear 20b and the driven gear 20b.
An endless belt 22 is wound around between and.

With the above structure, the height position of the screen filter 2e on the front side of the copying machine is rotated by the rotation of the motor 21 on the front side so that the cam 19a is rotated and the rotational force thereof is changed to the gear 20b. Is transmitted to the driven gear 20b from the endless belt 22 and the cam 19b is rotated in the same direction as the cam 19a to be adjusted.

On the other hand, the height position of the filter 2e on the back side is the same as that on the front side by the motor 21 on the back side.
It is adjusted independently of the front side.

Next, the operation of the full-color copying machine having the above structure will be briefly described. First, the original 11 placed on the original placing table 1 is illuminated by the light source 2a and scanned several times, and the image forming lens 2c and the color separation filter 2d are reflected by the reflecting mirror 2b.
The optical image is separated for each color component via.

Color separation filter 2 by scanning several times
Each optical image of each color component transmitted through each color filter of d is linearly decomposed by the screen filter 2e, and sequentially imagewise exposed to the photoconductor 3 uniformly charged by the charging charger 7.

The latent images for each color component, which are sequentially created here, are the developing tanks 4a to 4a each having a developer of a complementary color (yellow, magenta, cyan) of each color filter of the color separation filter 2d.
After being developed by each of the developers 4c and visualized, they are sequentially transferred to the transfer intermediate 5 by the transfer roller 8a. In this manner, by superposing the toner images for the respective color components on the transfer intermediate body 5, one completed color toner image is created.

This color toner image is transferred to the paper feed cassette 6
The transfer roller 8b transfers the image to the recording medium 15 which is taken out from either a or 6b and is brought into close contact with the lower surface of the transfer intermediate 5.

After that, the recording medium 15 is separated from the transfer intermediate 5, and is introduced into the fixing device 10 through the conveying path 16 so that the color image transferred to the recording medium 15 is fixed.

Next, the screen filter adjusting mode for adjusting the position of the screen filter 2e in the above-described full-color copying machine will be described. First, a document having a uniform density of the entire image is placed on the document table 1. Here, instead of preparing a new original, the white plate on the back of the original cover was used as it was.

Next, as in the copying operation, the optical system 2 performs exposure scanning based on the signal from the control means 26 to form a latent image of the line of the screen filter 2e on the photoconductor 3, The developing device 4 visualizes it.

The visualized filtered line image is transferred onto the transfer intermediate 5 by the transfer roller 8a. As the process conditions at this time, the exposure voltage was the same as that in the copying operation, and the surface potential of the photoconductor was raised to about 550V.

Next, the thickness of the line image formed on the transfer intermediate 5 is read by the small reflective sensor 25. At this time, only the thicknesses of part of the line images on the front side and the back side are read.

The thickness of the line on the front side thus read and the thickness of the line on the back side are compared, and if there is a difference between them, the heights of the front side and the back side of the screen filter 2e are determined. It is determined that they are tilted differently, and based on the signal from the position adjustment control means 27, the filter position adjustment means 18
The front side motor 21 or the rear side motor 21 is separately driven to rotate the cam 19a via the gears 20c and 20a, and the rotational force thereof simultaneously rotates the rear side cam 19b via the belt 22. And adjust the height position.

A stepping motor is used as the motor 21, and the amount of rotation is determined based on the value of the line thickness detected by the sensor 25 to set the height position of the screen filter 2e to a preset position. adjust.

With the above structure, the position of the screen filter can be accurately adjusted with a simple structure without requiring a complicated position adjusting mechanism. Therefore, it is possible to easily prevent deterioration of image uniformity due to poor positional accuracy of the screen filter.

[0035]

According to the image forming apparatus of the present invention, the position adjustment work of the screen filter, which requires high precision, can be performed easily and accurately. Therefore, it is possible to prevent the deterioration of the image uniformity due to the poor positional accuracy of the screen filter by eliminating the complicated mechanism and the adjustment work.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a full-color copying machine according to the present invention.

2A and 2B are views showing a position adjusting means of a screen filter, wherein FIG. 2A is a top view thereof and FIG. 2B is a side view thereof.

3A is a partially exploded perspective view of FIG. 2, and FIG. 3B is a top view of a cam portion thereof.

FIG. 4 is a perspective view of a transfer intermediate portion according to the present invention.

[Explanation of symbols]

 2 exposure optical system 3 recording medium 18 adjusting means 25 sensor 26 line image forming control means 27 position adjusting control means

Claims (1)

[Claims] 1. An image forming apparatus having a screen filter in an optical path of an exposure optical system for guiding reflected light from a document onto a recording medium, wherein a line image is formed on the recording medium to form a line image of the screen filter. Control means, a sensor for detecting the line thickness of the line image of the screen filter, adjusting means for adjusting the position of the screen filter, and the adjusting means operated based on the data detected by the sensor An image forming apparatus comprising: a position adjusting unit that adjusts a position of a screen filter.