JPH1115218A - Pattern detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern detection device whose fitting place is not restricted and which is constituted so that a transparent or a semi-transparent belt can be used for a transfer belt or a carrying belt and the accurate and stable detecting action of a pattern can be executed by preventing the effect of the vibration and the electrification of the belt from being exerted on the detecting action. SOLUTION: The reflection type pattern detection device 12 detecting the pattern by receiving light emitted from a light emission part by a light receiving part is arranged near the transfer paper carrying side of the transfer paper carrying belt 2. Besides, a pair of rollers and an opposed belt laid between a pair of rollers are arranged on the rear surface side of the belt 2 opposed to the light emission part and the light receiving part of the detection device 12. Then, the pattern is detected in an area interposed between a pair of rollers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern detecting device, and more particularly to a pattern detecting device formed on a transfer paper conveying belt or an intermediate transfer belt of a conveying device of an image forming apparatus such as a copying machine, a printer, a facsimile or the like for forming a multicolor image. The present invention relates to a pattern detection device that detects a detected pattern.

[0002]

2. Description of the Related Art An image forming apparatus having a plurality of photosensitive members and capable of forming a multicolor image is widely used in, for example, an electrophotographic apparatus, a laser beam printer or a multicolor printing apparatus. In such an image forming apparatus, when the images formed by the image forming units of a plurality of photoconductors are sequentially transferred and combined, if the transfer position of the image is deviated from a predetermined position for each image forming unit, the tint is reduced. Good image quality cannot be obtained because the image is different from the original document or the image has a color shift.

Usually, in order to eliminate the color shift, adjustments such as changing the timing of writing on the photosensitive member are performed. At this time, in order to measure the deviation between the colors, a pattern for measuring the deviation is formed on the transfer belt or the transport belt, and a pattern detecting device for detecting the pattern is provided. The timing is adjusted to make the color match exactly.

As such a pattern detecting device, a reflection type which irradiates a position formed by a pattern formed on a transfer belt or a conveyor belt with light and detects a change in reflected light due to the passage of the pattern is detected. And JP-A-9-2
2199 and the like.

[0005] Among them, the transmission type has an advantage that it is strong against noise and is inexpensive. However, since the light emitting unit and the light receiving unit need to be located on the opposite side of the transfer belt or the transport belt, there is a limitation on the installation place. When the light-receiving unit comes close to the belt, the sensitivity increases.However, when the light-receiving unit comes too close to the belt, the sensitivity greatly fluctuates due to the vibration of the transfer belt or the conveyance belt. There is a problem that the pattern is disturbed due to the triboelectric charging and stable detection cannot be performed.

The reflection type has an advantage that the light-emitting portion and the light-receiving portion can be set relatively far from the transfer belt or the conveyance belt, so that there is little restriction on a place where the pattern detection device is installed. To improve efficiency,
There is a restriction that a black transfer belt or transport belt must be used. However, when a black belt is used, there is a problem that pattern detection of an image formed with black toner becomes difficult.

[0007]

As described above, a conventional pattern detecting apparatus used in an image forming apparatus capable of forming a multicolor image has many restrictions on a mounting place in a transmission type and a reflection type in a reflection type. However, there was a restriction that a black belt had to be used.

The present invention solves this problem, and the transfer belt or the transport belt can be made of a transparent or translucent one without being restricted by the mounting place. It is an object of the present invention to realize a pattern detection device capable of performing highly accurate and stable pattern detection while preventing the influence of charging or the like.

[0009]

According to one aspect of the present invention, there is provided a pattern detecting apparatus for detecting a pattern formed on a transfer paper transport belt or an intermediate transfer belt of an image forming apparatus. A light emitting unit and a light receiving unit provided near the transfer paper holding side of the transfer paper transport belt or the image holding side of the intermediate transfer belt, and the light emitted from the light emitting unit is received by the light receiving unit. And a pair of roller means provided on the back side of the transfer paper transport belt or the intermediate transfer belt facing the light emitting section and the light receiving section of the reflection type pattern detecting means. And an opposing belt means stretched between the pair of roller means, and detecting the pattern in an area sandwiched between the pair of roller means. And butterflies.

According to a second aspect of the present invention, the material of the opposing belt means applied between the roller means is the same as the material of the transfer paper transport belt or the intermediate transfer belt in terms of charging system, or It is made of a material that is charged to a polarity opposite to the polarity of the transfer electric field on the transfer paper or the intermediate transfer belt.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a pattern detecting device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a configuration diagram of a color printer as an image forming apparatus for performing multi-color superposition using an embodiment of the pattern detection apparatus of the present invention. In FIG. 1, 1 is a transfer paper, 2 is a transfer paper transport belt, and 3 to 6 are image formations for forming respective color images of, for example, black (Bk), magenta (M), yellow (Y), and cyan (C). Station, 7 is a transfer paper separating position, 7a is a separation claw, 8a to 8d are drum-shaped photoconductors installed in each of the image forming stations 3 to 6, and 9a to 9d are photoconductors 8a of each of the image forming stations 3 to 6. A transfer roller 10 for transferring the image of each color formed on the transfer paper 1 to the transfer paper 1;
b is a driven roller, 11a and 11b are belt static eliminators, 1
2 is a pattern detection device of the present invention, and 14 is a registration roller.

The operation of the color printer will be described with reference to FIG. 1. Transfer paper 1 is fed from a paper feeder (not shown) through a transport path and a registration roller 14 to a driving roller 10.
is transferred to the transfer paper transport belt 2 stretched between the transfer roller a and the driven roller 10b, and is attracted to the surface of the transfer paper transport belt 2 and transported. Then, the transfer paper 1 on the transfer paper transport belt 2
Is sequentially transferred from the first image forming station 3 to the fourth image forming station 6 while being conveyed by the transfer paper conveying belt 2, during which the toner images on the photoconductors 8a to 8d are sequentially transferred by the transfer devices 9a to 9d. It is superimposed and transferred. Then, the sheet is finally separated from the transfer sheet transport belt 2 at the transfer sheet separation position 7, the image is fixed via a fixing device (not shown), and sent to a sheet discharging device (not shown).

In each of the image forming stations 3 to 6, a charging device (not shown), an exposure device (optical writing device), a developing device, a cleaning device, and a static elimination device are arranged around the drum-shaped photoconductors 8a to 8d. And each of the photoconductors 8a to 8d
Is rotated clockwise, and a toner image of each color, for example, a toner image of each color of black, magenta, yellow, and cyan, is sequentially formed on each of the photoconductors 8a to 8d through respective steps of charging, exposure, and development. .

When the transfer paper 1 conveyed by the transfer paper conveyance belt 2 passes from the first image forming station 3 to the fourth image forming station 6, the toner images on the photoconductors 8a to 8d of the respective stations are formed. Is the transfer device 9
The images are sequentially transferred onto the transfer paper 1 by a to d. After the transfer step, residual toner and the like adhering to the surfaces of the photoconductors 8a to 8d are removed and cleaned by a cleaning device (not shown), and the residual charge is removed by a charge removing device.

FIG. 2 is a schematic configuration diagram around the pattern detecting device of the image forming apparatus shown in FIG. 2, the same components as those in FIG. 1 are indicated by the same numbers. The transfer paper transport belt 2 is driven to rotate by a driving roller 10a.
After the transfer paper 1 transported by the transfer paper transport belt 2 is separated at the transfer paper separation position 7, the belt static eliminators 11a, 11
The charge is removed by b.

Although not shown, a belt cleaning means is provided downstream of the belt neutralization devices 11a and 11b in the belt traveling direction, and removes toner adhered to the belt during transfer and a pattern image 13 described later. You can do it.

In each of the image forming stations 3 to 6, an image is formed using different colors, for example, black, magenta, yellow and cyan toners. Then, in order to detect the deviation of the image forming position in each of the image forming stations 3 to 6, the pattern image 13 for the deviation measurement is transferred by the toner at each of the image forming stations 3 to 6 by the toner at the timing set in advance. The pattern image 13 is detected by the pattern detection device 12 to perform image forming position adjustment. This pattern is set so as to be between the sheets of the transfer paper 1 so as not to affect the transfer of the transfer paper 1 and the transfer of the image.

The pattern detecting device 12 of the present invention includes a reflection type sensor 12a having a light emitting portion and a light receiving portion near the front side (transfer paper transport side) of the transfer paper transport belt 2, and a back surface of the transfer paper transport belt 2. It is composed of a pair of rollers 12b concealed on the side and an opposing belt 12c hung on the rollers 12b.

The pattern detecting device 12 includes a sensor 1
The reflected light of the light emitted from the light emitting unit provided inside 2a is received by the light receiving unit also provided inside sensor 12a, and the pattern formed on transfer paper transport belt 2 is detected. is there.

Since the roller 12b is set so as to give an appropriate tension to the transfer paper transport belt 2, it suppresses the detection portion of the transfer paper transport belt 2 from waving or the transfer paper transport belt 2 from vibrating. be able to. Further, when the transfer paper transport belt 2 is transparent, the opposing belt 12b can select a color that can provide a large detection output of the reflected light, and the roller 12b and the opposing belt 12c can be selected.
Can be rotated only by the tension with the transfer paper transport belt 2, the load on the belt can be reduced as much as possible, and the influence of scratches and dirt on the transfer paper transport belt 2 can be reduced. Become.

FIG. 3 is an enlarged view of a part of the pattern detection device 12 of the present invention shown in FIG. In this example, the toner forming the pattern image 13 on the surface of the transfer paper transport belt 2 is negatively charged, while the surface of the transfer paper transport belt 2 is positively charged. The transfer paper transport belt 2 is rotationally driven by a driving roller 10a and rubs against the opposing belt 12c. The opposing belt 12c is equivalent to the material of the transfer paper transport belt in terms of the charging sequence, or the transfer electric field of the pattern image 13 is The polarity is made of a material whose surface is charged to the opposite polarity. In this case, it is positively charged during the rubbing.

At this time, the back side of the transfer paper transport belt 2 is negatively charged, and the front side is positively charged. However, since the toner forming the pattern image 13 is negatively charged, the toner does not scatter. .

FIG. 4 shows a pattern detecting device 12 according to the present invention.
FIG. 3 is a configuration diagram of a sensor 12a. This has exactly the same configuration as the barcode scanner used for reading barcodes. The sensor 12a is configured such that reflected light of light output from the light emitting unit 15 is condensed by the plastic lens 16 and received by the light receiving unit 17. With this configuration, the sensor 12a can be formed relatively small, and an existing product used as a barcode scanner can be diverted as it is, thereby reducing the cost.

FIG. 5 is a configuration diagram of another example of the sensor 12a. This sensor includes a lens 18, a light receiving unit 19, and a light emitting unit 20. The reflected light of the light output from the light emitting unit 20 is collected by the lens 18 and received by the light receiving unit 19.

[0026]

As described above, according to the first aspect of the present invention, there is provided a pattern detecting device for detecting a pattern formed on a transfer paper transport belt or an intermediate transfer belt of an image forming apparatus. A light emitting portion and a light receiving portion are provided near the transfer paper holding side or the image holding side of the intermediate transfer belt, and the light emitted from the light emitting portion is received by the light receiving portion to detect a pattern. A mold pattern detecting device, a pair of rollers provided on the back side of the transfer paper conveyance belt or the intermediate transfer belt facing the light emitting portion and the light receiving portion of the reflection type pattern detecting device, and a belt stretched between the pair of rollers. An opposing belt is provided, and a pattern is detected in a region sandwiched between the pair of rollers.

Thus, tension can be applied to the transfer paper conveyance belt or the intermediate transfer belt by the pair of rollers, and the vibration and waving of the transfer paper conveyance belt or the intermediate transfer belt can be suppressed. Further, by selecting the color of the opposed belt, a large detection output can be obtained, and the pattern image of the toner can be detected with high accuracy. In addition, since the opposing belts are provided between the rollers, the load applied to each belt can be reduced, and a configuration can be provided that does not scratch or contaminate the belts.

According to the invention of claim 2 of the present invention, the material of the opposing belt applied between the rollers is the same as the material of the transfer paper transport belt or the intermediate transfer belt in terms of the charging system.
Alternatively, it is characterized by a material whose surface is charged to a polarity opposite to the polarity of the transfer electric field generated on the transfer paper or the intermediate transfer belt.

As described above, by selecting the belt material to be applied to the pair of rollers that come into contact with the transfer paper transport belt or the intermediate transfer belt, the toner for pattern detection formed on the transfer paper transport belt or the intermediate transfer belt by triboelectric charging is selected. Image disturbance can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a multicolor image forming apparatus using a pattern detection device of the present invention.

FIG. 2 is a configuration diagram of a pattern detection apparatus according to an embodiment of the present invention used in the image forming apparatus shown in FIG.

FIG. 3 is an enlarged view of a part of the pattern detection device shown in FIG. 2;

FIG. 4 is a configuration diagram of an embodiment of a sensor of the pattern detection device shown in FIG. 2;

FIG. 5 is a configuration diagram of another embodiment of the sensor of the pattern detection device shown in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transfer paper 2 Transfer paper conveyance belt 3 Image forming station corresponding to black (Bk) 4 Image forming station corresponding to magenta (M) 5 Image forming station corresponding to yellow (Y) 6 Image corresponding to cyan (C) Forming station 7 Transfer paper separation position 7a Separation claw 8a Photoconductor 8b corresponding to black (Bk) 8c Photoconductor corresponding to magenta (M) 8c Photoconductor corresponding to yellow (Y) 8d Photoconductor corresponding to cyan (C) 9a Transfer device corresponding to black (Bk) 9b Transfer device corresponding to magenta (M) 9c Transfer device corresponding to yellow (Y) 9d Transfer device corresponding to cyan (C) 10a Drive roller 10b Followed roller 11a, 11b Belt Static eliminator 12 Pattern detector 13 Pattern image 14 Registration roller 15 Light emission 16 plastic lens 17 light receiving portion 18 the lens 19 the light receiving unit 20 emitting portion

Claims (2)

[Claims] 1. A pattern detecting device for detecting a pattern formed on a transfer paper transport belt or an intermediate transfer belt of an image forming apparatus, comprising: a transfer paper holding side of the transfer paper transport belt or a belt of the intermediate transfer belt. A reflective pattern detecting unit that includes a light emitting unit and a light receiving unit near the image holding side, and detects a pattern by receiving light emitted from the light emitting unit by the light receiving unit; A pair of roller means provided on the back side of the transfer paper transport belt or the intermediate transfer belt facing the light emitting unit and the light receiving unit; and an opposing belt means stretched between the pair of roller means. A pattern detecting device for detecting the pattern in a region sandwiched between the pair of roller means. 2. The material of the opposing belt means applied between the roller means is the same as the material of the transfer paper transport belt or the intermediate transfer belt in terms of the charging system, or the surface thereof is on the transfer paper or the intermediate transfer belt. 2. A pattern detecting apparatus according to claim 1, wherein said pattern detecting apparatus is made of a material which is charged to a polarity opposite to the polarity of said transfer electric field.