JPH0922199A - Pattern detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern detector capable of stably detecting a pattern with high accuracy without damaging an image formed on a transfer paper and an intermediate transfer belt. SOLUTION: In the pattern detecting device detecting the pattern formed on a transfer paper carrying belt (or the intermediate transfer belt) in an image forming device, the pattern detector 12 is provided with a light emitting part 12a installed in the vicinity of the belt front side of the transfer paper carrying belt (or the intermediate transfer belt) 2 and a light receiving part 12b installed on the belt rear side, to receive light emitted by the light emitting part 12a, by the light receiving part 12b on the belt rear side and constituted so that a part of the light receiving part 12b comes into contact with the belt rear side. Thus, the gap between the light receiving part 12b and the pattern formed on the belt 2 can be made smallest and the fluctuation of the gap caused by the waving of the belt 2, etc., can be suppressed as well, so that the pattern can be stably detected with the high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, and in particular, a plurality of color images are sequentially superposed on a transfer paper conveyed by a transfer paper conveying belt. On a transfer paper conveyance belt or an intermediate transfer belt of an image forming device that forms a multicolor image by sequentially superposing a plurality of color images on an image forming device or an intermediate transfer belt that forms a multicolor image The present invention relates to a pattern detection device that detects a formed pattern.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus such as a copying machine, a printer and a facsimile using an electrophotographic system, which can form a multicolor image or a full color image, has been put into practical use. Such an image forming apparatus includes, for example, a plurality of photoconductors, forms a latent image corresponding to each color on each photoconductor, develops the latent image with toner of a corresponding color, and visualizes the latent image. , A multi-color image is formed by sequentially superimposing images of respective colors on a transfer paper conveyed by a transfer paper conveying belt, or an intermediate transfer belt is used, and images of respective colors are sequentially superposed on the intermediate transfer belt. There is known one in which a multicolor image is formed and then collectively transferred to a transfer paper.

In such an image forming apparatus for performing multicolor superposition, adjustment methods such as considering writing timing have been proposed in order to eliminate the deviation between the colors. At this time, in order to measure the deviation between the colors, a pattern detection device has been proposed which forms a deviation measurement pattern on the transfer paper conveyance belt or the intermediate transfer belt and detects or measures this. This pattern detection device is classified into a type that detects reflected light (reflective type) and a type that detects transmitted light (transmissive type). The transmissive type is more resistant to noise and can be constructed at a lower cost than the reflective type. There are advantages. Further, in the transmissive type, the pattern can be detected with higher accuracy by bringing the light receiving section closer to the belt and reducing the gap between the pattern detection slit and the pattern image formed on the belt.

[0004]

By the way, in the above-mentioned transmission type pattern detecting device, when the light receiving portion or the slit is brought close to the belt surface, the influence of the fluctuation of the gap due to the corrugation of the belt becomes large, and the stable pattern is obtained. Cannot be detected. Further, in the pattern image formed on the surface of the belt, when the light receiving portion comes into contact with the back surface of the belt, the pattern image is disturbed due to frictional charging of the belt, which makes it impossible to detect the pattern accurately and reliably.

Further, when the transfer paper or the image passes through the front surface of the belt where the light receiving portion of the transmissive pattern detection device approaches or contacts the back surface of the belt, the transfer paper or the image is transferred onto the transfer paper or the belt and electrostatically adsorbed. The toner image is disturbed by frictional electrification between the light receiving part and the back surface of the belt or the electric field formed by the back surface of the belt and the light receiving part which is close to the back surface of the belt. There is a problem that can not be. In addition, the pattern image formed on the belt is electrostatically attracted to the belt, and when the belt is destaticized, the attraction force is reduced, and the pattern image may be disturbed.
There is a problem that pattern detection cannot be performed stably.

The present invention has been made in view of the above circumstances, and an object thereof is to stably and highly accurately without damaging an image formed on a transfer paper on a transfer paper transport belt or an intermediate transfer belt. An object of the present invention is to provide a pattern detection device capable of performing pattern detection.

[0007]

In order to achieve the above object, the invention of claim 1 is a pattern detection device for detecting a pattern formed on a transfer paper transport belt or an intermediate transfer belt of an image forming apparatus. Light emitted from the light emitting unit includes a light emitting unit installed near the belt surface side (transfer paper carrying side or image carrying side) of the paper transport belt or the intermediate transfer belt and a light receiving unit installed on the back side of the belt. Is a pattern detection device that detects a pattern by receiving light from a light receiving portion on the back surface side of the belt, and is characterized in that part of the light receiving portion is configured to contact the back surface of the belt.

According to a second aspect of the present invention, in the above-mentioned pattern detecting device, the surface of the light receiving portion which contacts the back surface of the belt is made of a material which is equal to the belt material in the charging series or on the side opposite to the polarity of the transfer electric field. It is characterized by

According to a third aspect of the present invention, in the above-described pattern detecting device, the member that comes into contact with the back surface of the belt of the light receiving portion is a sheet material, and a slit for pattern detection is directly printed on the sheet material. There is.

According to a fourth aspect of the present invention, there is provided a pattern detecting device for detecting a pattern formed on a transfer paper carrying belt or an intermediate transfer belt of an image forming apparatus, wherein the transfer paper carrying belt or the intermediate transfer belt has a belt surface side (transfer). A light emitting section installed near the paper carrying side or the image carrying side) and a light receiving section installed on the back side of the belt, and the light emitted from the light emitting section is received by the light receiving section on the back side of the belt to form a pattern. A pattern detection device that detects the light-emitting portion and the light-receiving portion in the belt traveling direction downstream of the transfer paper separation position from the transfer paper transport belt or the image transfer position from the intermediate transfer belt to the transfer paper. It is characterized by being installed on the upstream side of the static elimination means.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus for performing multicolor superposition using the pattern detection apparatus of the present invention. In the figure, reference numeral 1 is a transfer paper, 2 is a transfer paper transport belt, and 3 to 6 are. For example, first to fourth image forming stations for forming each color image of black (Bk), magenta (M), yellow (Y), and cyan (C), 7 is a transfer paper separating position, 7a is a separating claw, 8a to 8d are drum-shaped photoconductors installed in the image forming stations 3 to 6,
Reference numerals 9a to 9d denote photoconductors 8 of the image forming stations 3 to 6, respectively.
A transfer device for transferring the image of each color formed on a to 8d onto the transfer paper 1, 10a is a drive roller for rotationally driving the transfer paper transport belt 2, 10b is a driven roller, 11
Reference numerals a and 11b are belt neutralization devices, 12 is a pattern detection device of the present invention, and 14 is a registration roller.

In FIG. 1, a transfer sheet 1 is sent from a sheet feeding device (not shown) to a transfer sheet conveying belt 2 via a conveying path and a registration roller 14, and is adsorbed on the surface of the transfer sheet conveying belt 2 and conveyed. . Then, the transfer sheet 1 on the transfer sheet transport belt 2 passes from the first image forming station 3 to the fourth image forming station 6 and, during this period, the photoconductors 8a to 8a.
The toner images on d are transferred one after another by the transfer devices 9a to 9d in sequence, separated from the transfer paper transport belt 2 at the transfer paper separating position 7, and the image is fixed through a fixing device (not shown). Not sent to the paper ejection device.

In each of the image forming stations 3 to 6, a charging device, an exposure device (optical writing device), a developing device, a cleaning device, and a charge eliminating device (not shown) are arranged around the drum-shaped photoconductors 8a to 8d. And each photoconductor 8a-8d
Is rotated clockwise, and toner images of respective colors, for example, black, magenta, yellow, and cyan toner images are formed on the respective photoconductors 8a to 8d through respective processes of charging, exposing, and developing. When the transfer sheet 1 conveyed by the transfer sheet conveying 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 transferred to the transfer device. The images are sequentially transferred onto the transfer paper 1 by 9a to 9d. After the transfer process, the 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.

Next, FIG. 2 is a schematic configuration diagram of the main part around the pattern detection device of the image forming apparatus shown in FIG. The transfer paper conveyance belt 2 is rotationally driven by the drive roller 10a, and after separating the transferred transfer paper 1 at the transfer paper separation position 7,
The charge is removed by the belt charge removal devices 11a and 11b. Although not shown, the belt static eliminators 11a and 11b are also provided.
A belt cleaning unit is provided on the downstream side of the belt traveling direction, so that the toner adhering to the belt during the transfer and the pattern image described later can be removed. The image forming stations 3 to 6 form images using toners of different colors, for example, black, magenta, yellow, and cyan. Then, each image forming station 3
In order to detect the deviation of the image forming positions in 6 to 6, a pattern image for measuring the deviation is formed on the transfer paper transport belt 2 by the toner in each of the image forming stations 3 to 6, and is formed on the transfer paper transport belt 2. The pattern image of the octopus pattern image 1
2 is used for detection.

The pattern detection device 12 of the present invention includes a light emitting section 12a installed near the front side (transfer sheet carrying side) of the transfer sheet carrying belt 2 and a light receiving section 12b installed on the back side of the transfer sheet carrying belt 2. The light receiving portion 12b on the back side of the belt receives the light emitted from the light emitting portion 12a to detect the pattern formed on the transfer paper transport belt 2, and a part 12c of the light receiving portion 12b. Is installed so as to contact the back surface of the belt (claim 1). For this reason,
The gap between the light receiving portion 12b and the pattern formed on the transfer paper transport belt can be minimized, and the gap fluctuation due to the corrugation of the transfer paper transport belt can be suppressed.

FIG. 3 is a partially enlarged schematic view of the pattern detection device 12 according to the present invention. In this example, the toner forming the pattern image 13 on the surface of the transfer paper transport belt 2 is negatively charged, and the surface of the transfer paper transport belt 2 is positively charged. The transfer paper transport belt 2 is rotationally driven by the drive roller 10a, and the contact member 1 of the light receiving portion 12b is used.
2c, but the contact member 12c of the light receiving portion is made of a material that is equal to the belt material in the charging series or on the side opposite to the polarity of the transfer electric field (claim 2). The rubbing surface is positively charged. At this time, the back surface side of the transfer paper transport belt 2 is negatively charged and the front surface side is positively charged, but the toner forming the pattern image 13 is negatively charged, so that the toner does not scatter.

Next, FIG. 4 is a perspective view showing a schematic structure of a contact member 12c which comes into contact with the back surface of the belt of the light receiving portion 12b of the pattern detection device 12. The contact member 12c is made of a sheet material and has a slit for pattern detection. The pattern 12d is directly printed on this sheet material, and this is the light receiving portion 12
It is used as a slit for pattern detection of b (claim 3). As a result, the gap between the pattern detection slit 12d and the pattern image 13 formed on the transfer paper transport belt 2 can be made smaller. Further, in this case, the gap between the pattern and the slit is determined only by the thickness of the belt, and the pattern can be detected with high accuracy without being affected by the corrugation of the transfer paper transport belt.

By the way, when the light receiving portion 12b of the pattern detecting device 12 is in contact with the back surface of the transfer paper conveying belt 2, the light receiving portion is installed at a position where the transfer paper 1 passes on the front surface side of the belt. If so, the toner image transferred on the transfer paper and electrostatically adsorbed may be adversely affected.
That is, when the transfer paper 1 passes through the front surface of the belt, the toner image may be disturbed due to frictional charging between the light receiving portion and the back surface of the belt, and a stable and good image may not be obtained.
Further, since the pattern image formed on the belt is only electrostatically attracted to the belt, the pattern detection device 12
Belt neutralizing means 11 on the upstream side of the belt traveling direction
If there are a and 11b, the belt will be the static elimination means 11a and 11b.
When the static electricity is removed by, the attraction force of the pattern image is reduced, the pattern image may be disturbed or scattered, and stable pattern detection may not be possible.

Therefore, in the present invention, as shown in FIGS. 1 and 2, a pattern detecting device 12 including a light emitting portion 12a and a light receiving portion 12b is provided downstream of the transfer paper separating position 7 in the traveling direction of the transfer paper transport belt 2. It is installed on the upstream side of the belt static elimination means 11a and 11b (claim 4). By installing in this way, the pattern detection device 12 does not affect the image on the transfer paper 1 at all, so that the image on the transfer paper 1 is not damaged by the pattern detection device 12. Further, the belt charge eliminating means 11
Since it is installed on the upstream side of a and 11b, the pattern image formed on the transfer paper transport belt 2 is not disturbed by the static eliminator before the detection, so that the pattern can be detected stably and with high accuracy. Can be done.

In the above embodiments, an image forming apparatus for obtaining a multicolor image by directly superimposing each color image on a transfer paper carried and conveyed by the transfer paper conveying belt is used as an example. The pattern detection device for detecting the pattern formed on the transfer paper transport belt has been described, but in FIGS. 1 and 2, the transfer paper transport belt is replaced with an intermediate transfer belt, and the transfer paper separation position 7 is transferred to the transfer paper. A transfer device for transferring the transfer paper is installed at the position of the separating claw 7a in place of the position, and a multicolor image is formed by superimposing each color image on the intermediate transfer belt, and then the intermediate transfer belt is transferred by the transfer device at the transfer position (7). The same operation can be performed as an image forming apparatus of the type that transfers the above image to the transfer sheet all at once. In this case, the pattern detection device 12 detects the pattern formed on the intermediate transfer belt. It can be a pattern detection device known to.

[0021]

As described above, in the pattern detecting device according to the first aspect of the present invention, since the part of the light receiving portion is in contact with the back surface of the belt, the pattern formed on the light receiving portion and the belt. Since the gap between and can be minimized and variation in the gap due to undulation of the belt is suppressed, pattern detection can be performed with higher accuracy and stability.

In the pattern detecting device of the second aspect,
The material that comes into contact with the belt is the same as that of the belt in the charging series or is located on the side opposite to the polarity of the transfer electric field.Therefore, the light receiving part comes into contact with the back surface of the belt and is formed on the belt caused by frictional charging. It is possible to prevent the pattern image from being disturbed or scattered and to perform the pattern detection with higher accuracy and stability.

In the pattern detecting device of claim 3,
Since the slit for pattern detection is printed directly on the sheet material of the light receiving part that contacts the back surface of the belt, the gap between the slit and the pattern formed on the belt can be made smaller, so pattern detection can be performed with higher accuracy. Can be done.

In the pattern detecting device of claim 4,
The installation positions of the light emitting unit and the light receiving unit are located downstream of the transfer paper separating position from the transfer paper transport belt or the image transfer position from the intermediate transfer belt to the transfer paper in the belt traveling direction and upstream of the belt charge removing unit. Therefore, the pattern detection can be performed with high accuracy and stability without damaging the image on the transfer paper carried on the transfer paper transport belt or the image on the intermediate transfer belt.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus that performs multicolor superposition using a pattern detection apparatus of the present invention.

FIG. 2 is a schematic configuration diagram of a main part around a pattern detection device of the image forming apparatus shown in FIG.

FIG. 3 is a partially enlarged schematic view of a pattern detection device according to the present invention.

FIG. 4 is a perspective view showing a schematic configuration of a contact member that comes into contact with the back surface of the belt of the light receiving unit of the pattern detection device according to the present invention.

[Explanation of symbols]

 1: Transfer paper 2: Transfer paper transport belt 3, 4, 5, 6: Image forming station 7: Transfer paper separating position 7a: Separation claws 8a, 8b, 8c, 8d: Drum-shaped photoconductors 9a, 9b, 9c, 9d: transfer device 10a: drive roller 10b: driven roller 11a, 11b: belt static eliminator 12: pattern detection device 12a: light emitting part 12b: light receiving part 12c: contact member (sheet material) 12d: pattern detection slit 13: toner Pattern image by 14: Registration roller

Front page continuation (72) Inventor Naoki Matsuyama 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd.

Claims (4)

[Claims] 1. A pattern detection device for detecting a pattern formed on a transfer paper transport belt or an intermediate transfer belt of an image forming apparatus, comprising: a belt surface side (transfer paper carrying side or image) of the transfer paper transport belt or the intermediate transfer belt. (Carrying side), a light emitting unit installed in the vicinity, and a light receiving unit installed on the back side of the belt,
A pattern detection device for detecting a pattern by receiving light emitted from the light emitting unit at a light receiving unit on the back side of the belt, characterized in that part of the light receiving unit is configured to contact the back side of the belt. Pattern detection device. 2. The pattern detecting device according to claim 1, wherein a surface of the light receiving portion which contacts the back surface of the belt is made of a material which is equal to the material of the belt in terms of charging series or opposite to the polarity of the transfer electric field. A pattern detection device characterized in that 3. The pattern detecting device according to claim 1, wherein the member that comes into contact with the back surface of the belt of the light receiving portion is a sheet material, and a slit for pattern detection is directly printed on the sheet material. The pattern detection device. 4. A pattern detecting device for detecting a pattern formed on a transfer paper carrying belt or an intermediate transfer belt of an image forming apparatus, comprising: a belt surface side of the transfer paper carrying belt or the intermediate transfer belt (transfer paper carrying side or image). (Carrying side), a light emitting unit installed in the vicinity, and a light receiving unit installed on the back side of the belt,
A pattern detection device that detects a pattern by receiving light emitted from the light emitting unit at a light receiving unit on the back side of the belt, the light emitting unit and the light receiving unit being a transfer paper from a transfer paper transport belt in the belt traveling direction. A pattern detection device, which is installed downstream of an image transfer position from a separation position or an intermediate transfer belt to a transfer paper and upstream of a belt charge eliminator.