JPH10104898A - Carrying belt unit for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the detection accuracy of a pattern for color slurring detection formed on a carrying belt high for a long time. SOLUTION: Ring grooves 9rR and 9rL are provided on rollers 9, 13a and 13b supporting the carrying belt 10 carrying a transfer material along the array of plural photoreceptors on a peripheral surface opposed to pattern forming areas 10PaR and 10PaL(not shown in figure) for detecting color slurring on the carrying belt, so that the deterioration of light reflection and light transmissivity on the pattern forming areas is prevented. The pattern forming area has high optical reflection performance. Or, the bottom surface of the ring groove has the high optical reflection performance. The pattern is detected by a reflection or a transmission type optical sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an electrostatic latent image by exposing a plurality of photosensitive members with light beams modulated by different color signals, and developing each of the electrostatic latent images with a corresponding color signal. The present invention relates to a color image forming apparatus which superimposes (multicolor superimposes) each visualized image obtained by developing with an agent on transfer paper supported by a conveyor belt and conveyed in the direction in which the photoconductors are arranged, and in particular,
The present invention relates to a transport belt unit that transports transfer paper. This transport belt unit is used, for example, in a color copying machine, a color printer, and the like.

[0002]

2. Description of the Related Art In a color image forming apparatus for performing multi-color superposition, an adjustment method such as changing a writing (exposure) timing has been devised in order to eliminate a positional shift between respective colors on a transfer sheet. For this adjustment, it is necessary to grasp the positional shift (color shift) between the colors. The color misregistration can be grasped to some extent by looking at the transfer paper on which the image has been formed, but it is time-consuming to perform all of the image forming process (up to multi-color transfer onto the transfer paper) in order to grasp the misregistration. As a result, not only is the transfer paper wasted, but also it is difficult to quantitatively detect the color shift automatically.

The problem is that a visible image (measurement pattern) for detecting a transfer position is formed by one photosensitive member and is transferred to a transfer belt, and the measurement pattern on the transfer belt is moved in the belt moving direction. At a predetermined position, the position with respect to the reference point is calculated, and this is executed for each of the photoconductors to calculate the positional deviation of each measurement pattern, and these positional deviations become zero. Thus, by adjusting the exposure timing for each photoconductor, it is improved. In this case, since the measurement pattern is transferred to the transfer belt for each color (without overlapping between colors), the automatic detection of the transfer position shift of each color becomes easy and accurate, and the waste of the transfer paper is reduced. Absent.

The measurement pattern is detected by a reflection type or transmission type optical sensor disposed at a predetermined position in the moving direction of the conveyor belt. When a reflection type optical sensor is used, the measurement pattern
In order to increase the detection accuracy of the transfer belt, the transfer belt shall be light-transmissive, and the back of the measurement pattern formation area (transferred image transfer area for confirming the transfer position) of the transfer belt shall be coated or plated with paint. It is preferable to obtain a higher light reflectance. When a transmission type optical sensor is used, it is assumed that the transport belt has a light transmissive property, and the light emitting element and the light receiving element (photoelectric conversion element) of the optical sensor are opposed to each other with the light transmitting element interposed therebetween.

[0005]

However, in order to detect the measurement pattern on the conveyor belt with high accuracy, it is necessary to reduce noise as much as possible. Foreign matter such as paper dust and toner enters between the supporting rollers (the driving roller and the driven roller) with the passage of time, and stains or damages the rear surface of the transport belt, thereby increasing noise when detecting the measurement pattern. However, there is a problem that the detection accuracy is lowered.

When a reflection type optical sensor is used, a transparent or translucent resin film such as PET, polyurethane, or PVDF is used as a material of the transport belt to increase the light transmittance of the transport belt, and to diffuse light when detecting a measurement pattern. Although the pattern position is detected based on the difference in the amount of light from the reflected light, if the transport belt is scratched, it becomes opaque and the transmittance decreases, so that the accuracy of detecting the measurement pattern decreases.

Further, when a transmission type optical sensor is used, the light receiving element is brought close to the conveyor belt, and a slit for detecting a measurement pattern is interposed therebetween to reduce a gap between the conveyor belt, the slit and the light receiver. Thus, the pattern can be detected with higher accuracy, but the gap cannot be reduced too much due to the waving of the conveyor belt or the like.

Therefore, it is conceivable to take measures to make the color of the measurement pattern forming area (the visible image transfer area for confirming the transfer position) white or the like. There is a problem that a cleaning mechanism is required because of the contamination, and it is difficult to completely remove the contamination even after cleaning. Even when measures are taken on the back surface of the belt, there is a problem in that the coloring and peeling occur over time due to contact with the driving and driven rollers, and the detection accuracy is reduced.

It is a first object of the present invention to reduce contamination of a measurement pattern forming area of a conveyor belt and to increase a detection accuracy of a measurement pattern. The third object is to maintain the value as high as possible for as long as possible.

[0010]

[Means for Solving the Problems]

(1) The present invention provides a plurality of photoreceptors (6a to 6d), and an electrostatic latent image formed on the photoreceptor by a light beam provided corresponding to each of the photoreceptors and modulated by a different color signal. Exposure means (5) for forming, developing means (7a-7d) for visualizing the formed electrostatic latent image, and transfer for transferring a visualized image obtained by being visualized by the developing means to transfer paper Means (11a-11d)
A transport belt of an image forming apparatus (PTR) comprising: a transport belt (10) for moving the transfer paper along the photoreceptor; and a roller (9) for supporting the transport belt. The roller diameter of the peripheral surface (9rR, 9rL) of the roller (9) facing the visible image transfer area (10PaR, 10PaL) for transfer position confirmation on the transport belt (10), It is characterized in that the roller diameter is smaller than the roller diameter of the peripheral surface facing the outside of the visual image transfer area for confirming the transfer position.

To facilitate understanding, symbols in the parentheses corresponding to corresponding elements or corresponding parts of the embodiment shown in the drawings and described later are added for reference.

According to this, the visible image transfer area (10 PaR, 10 Pa
L) does not come into contact with the peripheral surface (9rR, 9rL) of the roller (9), so that foreign substances such as paper dust and toner may bite over time, or the back surface of the area may rub against the foreign substances, and The roller-facing surface (back surface) of the region (10 PaR, 10 PaL) is not stained or damaged, and substantially no increase in noise at the time of detection of a measurement pattern due to a foreign substance or a scratch, particularly, an increase in aging is caused. The detection accuracy of the measurement patterns (TPiR, TPiL) is maintained high for a long time.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(2) At least the visible image transfer area (10PaR, 10PaL) for confirming the transfer position of the transport belt (10) has translucency,
The peripheral surface of the small diameter portion of the roller (9) is covered with a high light reflectance layer (SL, HS), and a visible image transfer area (10 PaR, 10 PaL) for confirming a transfer position facing the high light reflectance layer. It further includes a reflection type optical sensor (20) for detecting an image.

According to this, since the high light reflectivity layer (SL, HS) increases the amount of diffuse reflection light in the visible image transfer area (10 PaR, 10 PaL), the measurement pattern (T
(PiR, TPiL) makes it easier to detect the decrease in light amount, and the detection accuracy of the measurement pattern increases. When a seal (HS) or the like is used for the high light reflectivity layer, the high light reflectivity layer can be regenerated (exchanged) by peeling off from the peripheral surface of the roller when replacing the transport belt. Easy to repair for drop.

(3) At least a visible image transfer area (10 PaR, 10 PaL) for confirming a transfer position of the transfer belt (10) has a high light reflectance, and a reflection type optical sensor (20) for detecting a visible image in the area. ).

According to this, even when the back surface of the belt is colored with high light reflectance, the amount of diffuse reflection light increases and the colored portion
Since the peripheral surface (9rR, 9rL) of the roller (9) does not contact the (10PaR, 10PaL), the colored portion (10PaR, 10PaR) of the roller (9) and the conveyor belt (10)
(PaL) and no color peeling occurs with time. Therefore, the detection accuracy of the measurement pattern is high over a long period of time.

(4) A visible image transfer area (10P
aR, 10PaL) further comprising a sensor (20) for detecting a visible image,
At least the visible image transfer area (10 PaR, 10 PaL) for confirming the transfer position of the transport belt (10) is translucent, and is provided in the space of the small diameter portion (9rR, 9rL) of the roller (9). A light receiving element (20aR) of the sensor (20) and a slit (15) for limiting light incident on the element are provided, and the light emitting element (20aR) of the sensor is transferred to a visible image transfer area (10 PaR , 10 PaL) to irradiate the slit (15) with light.

According to this, the small-diameter portion (9rR, 9r
(L) has a light receiving element (20aR) and a slit (15), and the conveyor belt (10) is tensioned by the roller (9). The light receiving element (20aR) and the light emitting element (20aR) can be arranged close to the vicinity of the transport belt (10), and the detection accuracy of the measurement pattern is improved.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0020]

【Example】

First Embodiment FIG. 1 shows a color printer PTR equipped with a transport belt unit according to a first embodiment of the present invention. Scanner SCR
A light source 1 irradiates a color original (not shown) on a contact glass 2 with light from a light source 1, and the reflected light is guided to a color-magnification CCD 3 through a rinse, and the CCD 3 changes the image color of the color original. An electric signal (image signal) of the three primary colors (R, G, B) of the light to be displayed is generated. The image signal of each color is converted into digital data (image data) by the image processing unit IPU, and further, Bk (black), C (cyan), M (magenta),
After being processed into color recording binary image signals for each of Y (yellow), they are sent to the exposure device 5 of the printer PTR. The exposure device 5 determines Bk, C,
A laser beam light modulated by a binary image signal for Bk, C, M, and Y recording is scanned and projected on each of the photosensitive drums 6a, 6b, 6c, and 6d for M and Y recording to form an electrostatic latent image. Form. Each electrostatic latent image is developed by each of Bk, C, M, and Y toners by each of the developing units 7a, 7b, 7c, and 7d to form a toner image (visible image) of each color.

On the other hand, the transfer material is conveyed from a paper feed cassette 8 onto a conveyor belt 10, and each color image (developed image) developed and formed on each photosensitive drum is transferred to a transfer unit 11a, 11b, 11b.
The toner images are sequentially transferred onto the transfer material at c and 11d, and after being superposed, are fixed by the fixing device 12. The transfer material after fixing is discharged outside the apparatus.

The conveyor belt 10 is an endless belt supported by a driving roller 9, a tension roller 13a and a driven roller 13b. Since the tension roller 13a pushes down the belt 10 with a spring (not shown), Belt 1
The tension of 0 is substantially constant.

FIG. 2 shows rollers 9, 13a and 13b, a conveyor belt 10 stretched over the rollers 9, 13a and 13b, and a photosensitive drum 6a.
6 to 6b. In order to prevent the above-described color shift in the superimposed transfer, the printer PTR uses the exposure device 5 to move the front (front side in FIG. 2) and back (back side in FIG. 2) on each of the photosensitive drums 6a, 6b, 6c and 6d. The test patterns TPiR and TPiL (FIG. 3) transferred to the conveyor belt 10 are written and developed with a test pattern (for example, a + mark) for position detection on the side). , The writing position deviation, inclination, magnification, and the like of the exposure device 5 with respect to each of the photosensitive drums 6a, 6b, 6c, and 6d are detected. Is configured to correct the writing timing and the like.

As shown in FIGS. 3A and 3B, test patterns TPiR, T
The outer diameter of the driving roller 9 at the portions 9rR and 9rL where the PiL and the driving roller 9 for driving the belt 10 overlap is small. Similarly, the other rollers (the tension roller 13a and the driven roller 13b) also have small diameter portions that overlap the pattern forming regions 10PaR and 10PaL (not shown) of the conveyor belt 10. . Thereby, the pattern forming regions 10PaR and 10PaL of the belt 10 and the respective rollers 9 and
The small diameter portions 9rR and 9rL are hardly contaminated because they do not come into contact with the first and second pattern portions 13a and 13b.
The back surface of PaL is also hard to be stained.

In this embodiment, the transport belt 10 is transparent or translucent, and the reflection type optical sensor 20 includes two reflection type optical sensors (20a) as shown in FIG.
E, 20aR) and (20bR, 20bR).
The light emitting element 20aE of the pair of optical sensors projects light toward the small diameter portion 9rR of the ring groove shape, and the light receiving element 20aR receives the reflected light of the pattern formation region 10PaR of the belt 10. The light emitting element 20bE of the second set of optical sensors projects light toward the ring groove-shaped small diameter portion 9rL, and the light receiving element 20bR receives the reflected light of the pattern forming region (10PaR: not shown) of the belt 10. . Each roller 9 over time,
No foreign matter (biting) occurs between the small-diameter portions 9rR and 9rL of the belts 13a and 13b and the pattern formation regions 10PaR and 10PaL of the belt 10, and the pattern formation region 10
No dirt or scratches occur on the back surface of PaR or 10 PaL.

The small-diameter portions 9rR and 9rL are ring grooves, and their edges, that is, the boundaries between the large-diameter portions and the small-diameter portions of the rollers 9, 13a and 13b are rounded as shown in FIG. Thus, scratches due to contact with the roller edge (groove edge) of the belt 10 and a decrease in durability of the belt 10 are small.

As shown in FIG. 4A, the light emitting device 20
aE (similarly to 20bE) is installed obliquely so that the specularly reflected light from the conveyor belt 10 does not hit the light receiving element 20aR (20bR). In the case where a transparent or translucent resin film is used for the transport belt, the reflectance is lowered by increasing the transmittance with respect to the light from the light source, and the pattern position is detected based on the difference in diffusely reflected light when the pattern passes [FIG. (C)], when the belt 10 is flawed, the flaws cause the belt to become cloudy and reduce the transmittance, so that the reflected light of the belt increases by that amount and erroneous pattern detection occurs. In the above-described first embodiment, the possibility of erroneous pattern detection is low because dirt and scratches are unlikely to occur as described above.

-Modification 1 of the first embodiment-The color of the portion of the light emitting element 20aE (20bE) to which light is applied, that is, the small-diameter portions 9rR and 9rL is made white to increase the amount of diffused reflected light, and at the time of passing a pattern. (See FIG. 4B), it is possible to prevent erroneous detection due to a scratch on the belt. The colored portion of the driving roller 9 matches the pattern forming portion on the conveyor belt 10 and has a smaller diameter than the outer diameter of the driving roller 9. As for the coloring method, painting and plating SL are performed on the small diameter portions 9rR and 9rL as shown in FIG. The driving roller 9 itself may be white. Further, as shown in FIG. 4E, a seal HS may be attached. The color is preferably white. The same applies to the tension roller 13a and the driven roller 13b. When the seal HS is attached to the small-diameter portions 9rR and 9rL, the seal is regenerated (replaced) by peeling off the peripheral surface of the roller and exchanging a new seal HS when replacing the conveyor belt. Therefore, it is easy to repair the decrease in light reflectance over time.

Since the small-diameter portions 9rR and 9rL of the roller face the pattern forming regions 10PaR and 10PaL of the conveyor belt 10 and do not come into contact with each other, and the surface property of the colored portion does not change, the reflectance is always stabilized. Can be kept.

As shown in FIG. 5, the small-diameter portions 9rR and 9rL of the rollers 9, 13a and 13b and the color of the rollers themselves are not changed, and the pattern forming region 10PaR of the belt 10 is not changed. , 10 PaL on the back surface (white in this embodiment). Small diameter part 9r
Since the peripheral surfaces of R and 9rL are separated from the back surface of the belt 10, coloring does not occur due to contact between the belt 10 and each of the rollers 9, 13a and 13b. By coloring, the reflectance of the belt 10 can be increased, and the detection accuracy of the measurement pattern can be increased. The test pattern TPiR applied to the conveyor belt 10,
This effect is high when a high light reflectivity layer is formed by painting or plating on the back surface of the pattern forming regions 10PaR and 10PaL of the belt 10 so as not to impair the transferability of TPiL.

Second Embodiment As shown in FIG. 6A, the small-diameter portion 9 of the roller 9 facing the pattern forming region (10 PaR) of the conveyor belt 10 is used.
By arranging the slit 15 and the light receiving element 20aR between the peripheral surface of the rR and the transport belt 10, the gap variation between the test pattern due to the waving of the transport belt 10 and the light receiving element 20aR and the light emitting element 20aE is suppressed. It is possible to always perform stable detection. Light receiving element 2
OaR faces the light emitting element 20aE with the transport belt 10 interposed therebetween. That is, the first set of optical sensors (20aE, light receiving element 20aR) of the optical sensor 20 is a transmission type optical sensor. The second set of optical sensors (not shown) has the same structure, and has another pattern forming area (1
0PbR) and another small-diameter portion (9
rL).

Further, as shown in FIG.
It is also possible to dispose the optical sensor at a position slightly shifted from the center of the axis. Note that the transport belt 10 and the slit 15 may be in contact with the transport belt 10 even when the slit 15 is a member having low sliding friction resistance.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a mechanism of a color printer PTR equipped with a transport belt unit according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an arrangement of a transport belt 10, a photosensitive drum, and an optical sensor 20 of the color printer PTR shown in FIG.

3A is a perspective view of the transport belt 10 shown in FIG. 1, and FIG. 3B is an enlarged plan view of a portion B shown in FIG.

4A is an enlarged cross-sectional view showing a cut surface of a roller supporting portion of the belt 10 shown in FIG. 3, and FIG. 4B shows a light detection signal generated by a light receiving element 20aR shown in FIG. Graph,
(C) shows the light receiving element 20aR assuming that the light emitted from the light emitting element 20aE shown in (a) is arranged at a position where regular reflection light from the belt 10 is detected.
It is a graph which shows the light detection signal which R generates. (D)
Is an enlarged perspective view of an end of a modified example of the roller 9;
(E) is an enlarged perspective view of an end of another modification of the roller 9.

5A is a perspective view illustrating an appearance of a modification of the transport belt 10, and FIG. 5B is a perspective view illustrating the transport belt 10 illustrated in FIG.
FIG. 4 is an enlarged cross-sectional view showing a cut surface at a roller support portion of FIG.

FIG. 6A is a side view showing a main part of a transport belt unit according to a second embodiment of the present invention, and FIG. 6B is a side view showing a modification of the main part.

[Explanation of symbols]

1: Light source 2: Contact glass 3: CCD IPU: Image processing device 5: Exposure device 6a, 6b, 6c, 6d: Photosensitive drum 7a, 7b, 7c, 7d: Developing device 8: Paper cassette 9: Driving roller 9rR , 9rL:
Small diameter part 10: Conveyor belt 10PaR, 10
PaL: pattern forming portions 11a, 11b, 11c, 11d: transfer device 12: fixing device 13a: tension roller 13b: driven roller 15: slit 20: optical sensor 20aE, 20bE: light emitting element 20aR, 20b
R: light receiving element TPiR, TPiL: test pattern SL: white paint or plating HS: white seal

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshio Shimazaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Hiroshi Ono 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Inside Ricoh Company, Ltd. (72) Kenichiro Asada, Inventor Kenichiro Asada 1-3-6, Nakamagome 1-chome, Ota-ku, Tokyo (72) Inventor Takuto Isobe 1-chome Nakamagome, Ota-ku, Tokyo No. 3-6 Ricoh Co., Ltd.

Claims (4)

[Claims] A plurality of photoconductors, an exposure unit provided corresponding to the photoconductors, and an exposure unit for forming an electrostatic latent image on the photoconductors by light beams modulated by different color signals, respectively; Developing means for developing the developed electrostatic latent image, and transfer means for transferring a visualized image obtained by the developing means to a transfer paper; A transport belt unit comprising: a transport belt that moves along a photoreceptor; and a roller that supports the transport belt, wherein the roller opposes a visible image transfer area for confirming a transfer position on the transport belt. A conveyor belt unit characterized in that the roller diameter of the peripheral surface of the roller is smaller than the roller diameter of the peripheral surface facing outside the visible image transfer area for confirming the transfer position. 2. A high-reflectivity layer covering a peripheral surface of a small-diameter portion of the roller, wherein at least a visible image transfer area for confirming a transfer position of the transport belt is translucent. The transport belt unit according to claim 1, further comprising a reflection-type optical sensor that detects a visible image in a visible image transfer area for confirming a transfer position facing the efficiency layer. 3. The transport belt according to claim 1, further comprising a reflection type optical sensor configured to have a high light reflectance in at least a visible image transfer area for confirming a transfer position of the transport belt and to detect a visible image in the area. unit. 4. A sensor for detecting a visible image in a visible image transfer area for confirming a transfer position, wherein at least the visible image transfer area for confirming a transfer position of the transport belt is translucent; A light receiving element of the sensor and a slit for limiting light incident on the element are provided in a space of the small diameter portion of the roller, and the light emitting element of the sensor is transmitted to the slit through a visible image transfer area for confirming a transfer position. The transport belt unit according to claim 1, wherein the transport belt unit is disposed at a position where light is irradiated.