JP2012093547A - Light detection device, belt device, transfer device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light detection device capable of obtaining stable detection accuracy even when being disposed so as to face a part other than a part where a belt is wound around, by a simple structure.SOLUTION: A light detection device 24 irradiates on an endless belt 8 wound around a plurality of supporting members with light to detect reflection light of the light with which a detection object on the belt 8 is irradiated. The light detection device 24 includes a light emitting part and a light receiving part disposed so as to face a part where the belt is not wound around the supporting members, and reflecting means 25 for reflecting light emitted from the light emitting part to a part E where the belt is wound around the support member and reflecting the reflection light from the belt 8 to the light receiving part.

Description

  The present invention relates to a light detection device that detects reflected light of light irradiated to a detection target on a belt, a belt device including the light detection device, a transfer device, and an image forming apparatus.

  In an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a complex machine of these, in order to appropriately control the density and position of a toner image, a toner pattern for toner density detection or toner position detection has been conventionally used as an intermediate. A widely used method is to detect the density or position of a toner pattern by forming it on the surface of an endless belt such as a transfer belt, irradiating it with detection light and receiving reflected light.

  In general, as the detection means for detecting the toner pattern, a reflection type optical sensor having a light emitting unit that emits light and a light receiving unit that receives reflected light is used. In order to correct image density and positional deviation with high accuracy, the sensor pattern detection accuracy of the sensor must be stable above all. However, there are cases where the distance from the sensor to the toner pattern on the belt changes due to wrinkling (waving) or vibration of the belt, and accurate detection cannot be ensured.

  In order to solve such a problem, some countermeasures have been conventionally proposed. For example, in the image forming apparatus disclosed in Patent Document 1 below, a sensor is disposed to face a portion of a belt that is wound around a support roller, and is detected at a position where the belt is not easily wrinkled or vibrated. I am doing so.

  Further, in the image forming apparatus disclosed in Patent Document 2 below, a flat contact member is brought into contact with the back side of the detection area detected by the sensor on the belt, so that the belt hardly vibrates in the detection area. is doing.

  Further, in the image forming apparatus shown in Patent Document 3 below, instead of the flat contact member, a small belt wound around a pair of rollers is brought into contact with the back surface of the belt to be detected, thereby Tension is applied to the belt to suppress wrinkling and vibration of the belt.

  However, the configuration of the image forming apparatus disclosed in Patent Document 1 is reduced in size because there is a restriction that a sensor, a base, and the like must be disposed so as to face a portion around which a belt is wound around a support roller. For example, there is a drawback that it is difficult to cope with the layout design in the apparatus. For example, in the configuration in which the belt 400 is wound around the two support rollers 200 and 300 as shown in FIG. 9, when the sensor 500 is disposed outside the portion where the belt 400 is wound around the one support roller 200, There is a problem that the size of the apparatus increases in the longitudinal direction of the belt 400 (the left-right direction in the drawing).

  In the image forming apparatus disclosed in Patent Document 2, a flat contact member is brought into contact with the back surface of the belt. However, when the belt is wrinkled, it is insufficient to suppress the influence. There is a risk of false detection. In order to solve this problem, in order to prevent the belt from being wrinkled, a mechanism for relaxing the tension of the belt at the time of non-driving is required, which causes a problem that the apparatus becomes large. Further, since the contact member is in contact with the back surface of the belt, there are problems such as wear of the belt and a decrease in driving energy efficiency due to load applied to the belt.

  Further, in the image forming apparatus disclosed in Patent Document 3, since a small belt wound around a pair of rollers is disposed inside the belt, the number of parts increases, resulting in complicated structure and occupied space. There is a problem of increase of

  SUMMARY OF THE INVENTION In view of such circumstances, the present invention provides a photodetection device capable of obtaining stable detection accuracy even if it is disposed facing a portion other than a portion around which a belt is wound, with a simple configuration, and the photodetection device A belt device, a transfer device, and an image forming apparatus provided with the above are provided.

  The invention according to claim 1 is a light detection device that irradiates light onto an endless belt wound around a plurality of support members and detects reflected light of light irradiated to a detection target on the belt. A light emitting portion and a light receiving portion disposed to face a portion of the belt that is not wound around the support member, and light emitted from the light emitting portion is wound around the support member of the belt. Reflecting means for reflecting the reflected light from the belt and reflecting the reflected light from the belt to the light receiving section.

  As a result, the light from the light emitting unit can be irradiated to the portion of the belt wound by the reflecting means and the reflected light can be received, so that it can be detected at a place where the belt is not easily wrinkled or vibrated. it can. For this reason, it is possible to prevent erroneous detection due to belt wrinkling or vibration, and it is possible to detect with high accuracy. Further, by using the reflecting means, the light emitting unit and the light receiving unit are irradiated with light on the surface of the belt-wound portion without reflecting the light-wound portion and the light-receiving portion against the belt-wound portion. Light can be received. In this way, with a simple configuration in which the reflecting means is simply provided at a predetermined position, stable detection accuracy can be obtained even if the light emitting portion and the light receiving portion are arranged to face each other than the portion around which the belt is wound.

  According to a second aspect of the present invention, in the light detection device according to the first aspect, the support member that wraps the portion irradiated with the light on the belt is a rotatable roller member, and the belt from the reflecting means to the belt The reflection means is disposed so that an extension line of the light path of the light reflected to the light passes through the rotation center of the roller member.

  By arranging the reflecting means so that the extension line of the optical path of the light reflected from the reflecting means to the belt passes through the rotation center of the roller member, light directed from the reflecting means to the belt and light directed from the belt to the reflecting means. And will go through the same light path. Thereby, the light irradiated from the light emission part can be returned to a light-receiving part via a reflection means.

  According to a third aspect of the present invention, in the light detection device according to the second aspect, the holding member that holds the reflecting means is configured to be swingable, and the holding member is urged by the urging means to the roller member. It is made to contact.

  With this configuration, even if the roller member is displaced, the holding member swings following the roller member, so that the relative position between the surface of the belt wound around the roller member and the reflecting means can be reduced. Variations can be suppressed. As a result, it is possible to prevent erroneous detection due to displacement of the roller member.

  According to a fourth aspect of the present invention, in the light detection device according to the second aspect, the holding member that holds the reflecting means is configured to be swingable, and the holding member is urged by the urging means to This is in contact with a roller provided at the shaft end.

  In this case, even if the axial position of the roller member is displaced, the holding member swings following the roller, so that erroneous detection due to the displacement of the roller member can be prevented.

  According to a fifth aspect of the present invention, in the light detection device according to the third aspect, the holding member is brought into contact with a surface of the roller member on which the belt is not wound.

  When the roller member is eccentric, when the roller member rotates, the surface position of the belt wound around the roller member also fluctuates. In this case, the holding member swings following the surface of the roller member. Therefore, it is not affected by noise due to the eccentricity. Thereby, erroneous detection can be prevented.

  According to a sixth aspect of the present invention, in the light detection device according to any one of the first to fifth aspects, the holding member that holds the reflecting means and the holding member that holds the light emitting unit and the light receiving unit are integrated. It is composed.

  By integrally configuring the holding member, the number of parts can be reduced and detection accuracy can be improved.

  A seventh aspect of the invention is the light detection device according to any one of the first to sixth aspects, wherein the reflecting surface of the reflecting means is formed as a flat surface.

  By forming the reflecting surface as a flat surface, it is possible to suppress the shift of the incident position of light due to the tolerance of components and the like, and it is possible to improve the detection accuracy.

  The invention according to claim 8 is the light detection device according to any one of claims 1 to 7, wherein the surface roughness Ra of the reflecting surface of the reflecting means is set to 0.05 [μm] or less. is there.

  By setting the surface roughness Ra of the reflecting surface of the reflecting means to 0.05 [μm] or less, erroneous detection can be prevented.

  According to a ninth aspect of the present invention, there is provided an endless belt wound around a plurality of support members, and light detection for detecting reflected light of light irradiated on a detection target on the belt by irradiating the belt with light. The belt apparatus provided with the apparatus is provided with the light detection device according to any one of claims 1 to 8 as the light detection device.

  Since the belt device includes the light detection device according to any one of claims 1 to 8, the above-described effects of these light detection devices can be obtained.

  The invention according to claim 10 is a transfer device for transferring an image formed on an image carrier onto a recording medium using a belt device including an endless belt that is wound around a plurality of support members and driven to rotate. The belt device according to claim 9 is used as the belt device.

  Since the transfer device uses the belt device according to the ninth aspect, the effect of the light detection device according to any one of the first to eighth aspects can be obtained.

  According to an eleventh aspect of the present invention, there is provided an image carrier that carries an image, an image forming unit that forms an image on the image carrier, and a transfer device that transfers an image formed on the image carrier to a recording medium. The image forming apparatus provided includes the transfer device according to claim 10 as the transfer device.

  Since the image forming apparatus includes the transfer device according to claim 10, the above-described effect of the light detection device according to any one of claims 1 to 8 can be obtained.

  According to the present invention, the light-emitting unit and the light-receiving unit are wound around the belt without being disposed opposite the belt-wound portion by a simple configuration in which the reflection means is provided at a predetermined position. It is possible to irradiate the surface of the portion and receive the reflected light, and to detect with high accuracy. In addition, since the light emitting unit and the light receiving unit do not have to be disposed opposite to the portion around which the belt is wound, the degree of freedom of the arrangement of the light emitting unit and the light receiving unit is increased, so It becomes easy to cope with layout design.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view of a transfer device mounted on the image forming apparatus, showing a configuration according to the first embodiment of the present invention. It is a figure which shows the relationship between surface roughness Ra of a reflective surface, and the detection voltage deviation | shift amount of a density | concentration detection sensor. It is a figure which shows the structure of 2nd Embodiment of this invention. It is a figure which shows the structure of 3rd Embodiment of this invention. It is a figure which shows the structure of 4th Embodiment of this invention. It is a figure which shows the structure of 5th Embodiment of this invention. It is a figure which shows the structure of 6th Embodiment of this invention. It is a figure which shows arrangement | positioning of the conventional sensor.

  Hereinafter, the present invention will be described with reference to the accompanying drawings. In the drawings for explaining the present invention, components such as members and components having the same function or shape are denoted by the same reference numerals as much as possible, and once described, the description will be given. Omitted.

FIG. 1 is a schematic configuration diagram of a color image forming apparatus according to the present invention.
The image forming apparatus shown in FIG. 1 includes a tandem type image forming unit in which four process units 1Y, 1C, 1M, and 1Bk as image forming units are arranged side by side. Each of the process units 1Y, 1C, 1M, and 1Bk is configured to be detachable from the image forming apparatus main body 100, and yellow (Y), cyan (C), magenta (M), and magenta (M) corresponding to the color separation components of the color image. The configuration is the same except that toners of different colors of black (Bk) are accommodated.

  Specifically, each of the process units 1Y, 1C, 1M, and 1Bk includes a photosensitive member 2 as an image carrier, a charging device that includes a charging roller 3 that charges the surface of the photosensitive member 2, and the like. The image forming apparatus includes a developing device 4 that supplies toner (developer) to the surface, and a cleaning device that includes a photoconductor cleaning blade 5 for cleaning the surface of the photoconductor 2. In FIG. 1, only the photoconductor 2, the charging roller 3, the developing device 4, and the cleaning blade 5 included in the yellow process unit 1 </ b> Y are denoted by reference numerals, and the other process units 1 </ b> C, 1 </ b> M, and 1 </ b> Bk are denoted by reference numerals. Omitted.

The photosensitive member 2 is a cylindrical photosensitive drum having a diameter of 24 mm, and is rotated at a peripheral speed of 100 to 180 mm / s by a driving source (not shown).
The charging roller 3 is in pressure contact with the surface of the photoconductor 2 and is driven to rotate by the rotation of the photoconductor 2. The charging roller 3 is applied with a DC bias or a bias in which AC is superimposed on DC from a high voltage power source (not shown).
The developing device 4 contains a one-component developer made of toner. The developing device 4 is configured to supply the developer to the photoconductor 2 with a predetermined developing bias supplied from a high voltage power source (not shown).

  In FIG. 1, an exposure device 6 as an exposure means for exposing the surface of the photoreceptor 2 is disposed above each process unit 1Y, 1C, 1M, 1Bk. The exposure device 6 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each photoreceptor 2 with laser light based on image data.

  A transfer device 7 is disposed below each process unit 1Y, 1C, 1M, 1Bk. The transfer device 7 has an intermediate transfer belt 8 constituted by an endless belt as a transfer body. As the intermediate transfer belt 8, a conductive material such as PVDF (vinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), TPE (thermoplastic elastomer) or the like is used. A resin film-like endless belt is used by dispersing a functional material. In the present embodiment, a belt having a thickness of 90 to 160 μm and a width of 230 mm is further used which has a tensile modulus of 1000 to 2000 MPa.

  The intermediate transfer belt 8 is wound and stretched around a driving roller 9 and a tension roller 10 as support members. The drive roller 9 is rotationally driven by a drive source (not shown). When the drive roller 9 rotates counterclockwise in the figure, the intermediate transfer belt 8 runs in the direction indicated by the arrow in the figure ( Rotate. The tension roller 10 is made of an aluminum pipe having a diameter of φ16 to φ20 mm, and both ends thereof are pressed against the intermediate transfer belt 8 by a biasing member such as a spring, whereby a predetermined tension is applied to the intermediate transfer belt 8. Has been granted. Further, flanges having a diameter of 22 mm are press-fitted at both ends of the tension roller 10 so as to restrict the meandering of the intermediate transfer belt 8. Further, both ends of the driving roller 9 and the driven roller 10 are supported by side plates (not shown).

  Four primary transfer rollers 11 as primary transfer means are disposed at positions facing the four photoconductors 2. Each primary transfer roller 11 presses the inner peripheral surface of the intermediate transfer belt 8 at each position, and a primary transfer nip is formed at a location where the pressed portion of the intermediate transfer belt 8 and each photoconductor 2 are in contact with each other. ing. Here, a metal roller having a diameter of φ8 to φ12 mm is used as the primary transfer roller 11. In place of the metal roller, a conductive sponge roller or a conductive blade may be applied. Each primary transfer roller 11 is connected to a power source (not shown), and a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to the primary transfer roller 11.

  A secondary transfer roller 12 as a secondary transfer unit is disposed at a position facing the drive roller 9. The secondary transfer roller 12 has a diameter of φ19 to φ22 mm and a width of 222 mm by covering a metal core such as SUS having a diameter of φ6 mm with an elastic body such as urethane adjusted to a predetermined resistance value by a conductive material. It is configured. As the material, a conductive roller, an electronic conductive type roller (EPDM) or the like is used. In this embodiment, a roller having a diameter of 20 mm and an Asker C hardness of 35 to 50 ° is used. The resistance value of the secondary transfer roller 12 is measured from the value of current that flows when a roller is installed on a conductive metal plate and a voltage of 100 to 1 kV is applied between the metal core and the metal plate. Calculated. The secondary transfer roller 12 presses the outer peripheral surface of the intermediate transfer belt 8, and a secondary transfer nip is formed at a location where the secondary transfer roller 12 and the intermediate transfer belt 8 are in contact with each other. Similarly to the primary transfer roller 11, a power source (not shown) is connected to the secondary transfer roller 12, and a predetermined DC voltage (DC) and / or AC voltage (AC) is applied to the secondary transfer roller 12. It has come to be.

  A belt cleaning device 13 for cleaning the surface of the intermediate transfer belt 8 is disposed on the outer peripheral surface of the intermediate transfer belt 8 on the right end side in the drawing. The belt cleaning device 13 has a cleaning blade 13a as a cleaning member. The cleaning blade 13 a is in a counter direction with respect to the surface of the intermediate transfer belt 8 at a position facing the metal cleaning counter roller 21 (the tip of the cleaning blade 13 a is opposite to the rotation direction of the intermediate transfer belt 8). (Facing) As the cleaning blade 13a, urethane rubber having a thickness of 1.5 to 3 mm and a rubber hardness of 65 to 80 ° is used. Further, by applying a lubricant to at least one of the contact portion of the cleaning blade 13a on the intermediate transfer belt 8 or the contact portion of the cleaning blade 13a at the time of assembly, it is possible to prevent the blade from rolling up at the cleaning nip portion. It is possible to improve the cleaning performance by forming a dam layer in the cleaning nip. A waste toner transfer hose (not shown) extending from the belt cleaning device 13 is connected to the entrance of a waste toner container 14 disposed below the transfer device 7.

  A paper feed cassette 15 that accommodates a sheet-like recording medium P such as paper or OHP is disposed below the image forming apparatus main body 100. The paper feed cassette 15 is provided with a paper feed roller 16 for feeding out the stored recording medium P. On the other hand, a pair of paper discharge rollers 17 for discharging the recording medium to the outside and a paper discharge tray 18 for stocking the discharged recording medium are disposed on the upper portion of the image forming apparatus main body.

  In the image forming apparatus main body 100, a transport path R for transporting the recording medium P from the paper feed cassette 15 through the secondary transfer nip to the paper discharge tray 18 is provided. In the conveyance path R, a pair of registration rollers 19 are disposed upstream of the position of the secondary transfer roller 12 in the recording medium conveyance direction. A fixing device 20 is disposed downstream of the position of the secondary transfer roller 12 in the recording medium conveyance direction.

The basic operation of the image forming apparatus will be described below with reference to FIG.
When the image forming operation is started, the photoconductors 2 of the process units 1Y, 1C, 1M, and 1Bk are rotationally driven clockwise in the drawing, and the surface of each photoconductor 2 is uniformly made to have a predetermined polarity by the charging roller 3. Is charged. Based on image information of a document read by a reading device (not shown), the exposure device 6 irradiates the charged surface of each photoconductor 2 with laser light, and an electrostatic latent image is formed on the surface of each photoconductor 2. . At this time, the image information to be exposed on each photoconductor 2 is monochromatic image information obtained by separating a desired full-color image into color information of yellow, cyan, magenta, and black. As the electrostatic latent image formed on the photosensitive member 2 is supplied with toner by each developing device 4, the electrostatic latent image is visualized (visualized) as a toner image.

  A drive roller 9 that stretches the intermediate transfer belt 8 is driven to rotate, causing the intermediate transfer belt 8 to run in the direction of the arrow in the figure. Also, a primary transfer nip between each primary transfer roller 11 and each photoreceptor 2 is applied to each primary transfer roller 11 by applying a constant voltage or a voltage controlled by a constant current opposite to the charging polarity of the toner. A transfer electric field is formed. Then, the toner images of the respective colors on the respective photoconductors 2 are sequentially superimposed and transferred onto the intermediate transfer belt 8 by the transfer electric field formed in the primary transfer nip. Thus, the intermediate transfer belt 8 carries a full-color toner image on its surface. Further, the toner on each photoreceptor 2 that could not be transferred to the intermediate transfer belt 8 is removed by the cleaning blade 5.

  When the image forming operation is started, the paper feed roller 16 rotates and the recording medium P is carried out from the paper feed cassette 15. The unloaded recording medium P is timed by the registration roller 19 and sent to the secondary transfer nip between the secondary transfer roller 12 and the intermediate transfer belt 8. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the intermediate transfer belt 8 is applied to the secondary transfer roller 12, thereby forming a transfer electric field in the secondary transfer nip. Then, the toner image on the intermediate transfer belt 8 is collectively transferred onto the recording medium P by the transfer electric field formed in the secondary transfer nip. Thereafter, the recording medium P is sent to the fixing device 20 and the toner image is fixed on the recording medium P. Then, the recording medium P is discharged to the paper discharge tray 18 by the pair of discharge rollers 17. The toner remaining on the intermediate transfer belt 8 after the image transfer is removed by the cleaning blade 13a of the belt cleaning device 13, and the removed toner is conveyed to the waste toner container 14 and collected.

  The above description is an image forming operation when a full-color image is formed on a recording medium. A single-color image is formed using any one of the four process units 1Y, 1C, 1M, and 1Bk, and 2 Two or three process units can be used to form a two or three color image.

Hereafter, the characteristic part of this invention is demonstrated.
FIG. 2 is an enlarged view of a transfer device mounted on the image forming apparatus of the present invention, and shows a configuration according to the first embodiment of the present invention.
As shown in FIG. 2, on the outer periphery of the intermediate transfer belt 8 on the tension roller 10 side, a density detection sensor 24 for detecting the toner density, a sensor holder 26 as a holding member for holding the density detection sensor 24, and light A reflecting plate 25 as reflecting means for reflecting and a reflecting plate holder 27 as a holding member for holding the reflecting plate 25 are provided. The density detection sensor 24 is a reflective light detection device having a light emitting unit and a light receiving unit. Light (infrared rays) emitted from the light emitting unit is incident and reflected in the order of arrows A → B → C → D in the figure and received by the light receiving unit. That is, the light emitted from the light emitting unit to the reflection plate 25 is reflected by the reflection plate 25 to the surface of the intermediate transfer belt 8, and the reflected light from the intermediate transfer belt 8 is reflected by the reflection plate 25 to the light receiving unit and received. It has become so.

  In FIG. 2, if the range indicated by the symbol E is a portion wound by the tension roller 10 of the intermediate transfer belt 8 (a portion in contact with the tension roller 10), the density detection sensor 24 is wound around the portion. It is disposed at a position excluding the portion E. That is, the density detection sensor 24 is disposed to face a portion of the intermediate transfer belt 8 that is not wound around the tension roller 10 (and the driving roller).

On the other hand, the reflection plate 25 is disposed to face the portion E around which the intermediate transfer belt 8 is wound. The direction of the reflecting plate 25 is set so as to reflect the light from the light emitting portion of the density detection sensor 24 toward the portion E wound around the intermediate transfer belt 8. Further, the extension line S of the light path of the light reflected from the reflecting plate 25 to the intermediate transfer belt 8 is set so as to pass through the rotation center (axial center) Q of the tension roller 10. By arranging the reflection plate 25 in this manner, light traveling from the reflection plate 25 to the intermediate transfer belt 8 (light in the direction of arrow B) and light traveling from the intermediate transfer belt 8 to the reflection plate 25 (in the direction of arrow C). ) Through the same optical path. In addition, thereby, an incident angle θ _{1 of} light (light in the direction of arrow A) from the light emitting portion to the reflecting plate 25 and an incident angle θ of light (light in the direction of arrow C) from the intermediate transfer belt 8 to the reflecting plate 25. ₂ is the same, the light emitted from the density detection sensor 24 (light emitting section) returns to the density detection sensor 24 (light receiving section) again via the reflector 25.

  In the present embodiment, the reflecting plate 25 having a reflecting surface formed on a flat surface is used. In the case of using a curved reflecting surface, if the light incident position deviates from the target position due to the tolerance of parts or the like, the amount of deviation of the light incident position on the intermediate transfer belt 8 increases. On the other hand, when the reflecting surface is a flat surface, it is possible to suppress the shift of the incident position of light due to the tolerances of the components, and therefore the flat reflecting surface is preferable in terms of improving detection accuracy.

FIG. 3 shows the relationship between the surface roughness Ra of the reflecting surface and the detected voltage deviation amount of the density detection sensor.
As shown in FIG. 3, as the surface roughness of the reflecting surface increases, the detection voltage deviation amount also increases. This is because as the surface roughness of the reflecting surface increases, the light diffuses and the amount of light decreases. Further, when the detected voltage deviation amount becomes large, an error such as erroneous detection of toner density or inability to detect may occur. Therefore, it is desirable that the surface roughness of the reflecting surface is small. Specifically, in the example shown in FIG. 3, an error such as erroneous density detection occurs when the surface roughness Ra is greater than 0.05, and thus the surface roughness Ra is 0.05 [μm]. The following is desirable. In the present embodiment, the surface roughness Ra of the reflecting surface is set to 0.02 [μm] or less.

  The toner density is detected by the density detection sensor 24 by irradiating the toner pattern for toner density detection formed on the surface of the intermediate transfer belt 8 with light and receiving the reflected light. Specifically, light is emitted from the light emitting portion of the density detection sensor 24, and the light is reflected by the reflection plate 25 and irradiated onto the portion of the intermediate transfer belt 8 wound around the tension roller 10. Then, the reflected light at each of the pattern forming portion on which the toner pattern is formed on the intermediate transfer belt 8 and the other portion (belt background portion) is received by the light receiving portion via the reflection plate 25, and each of the light at that time is received. The image density is obtained from the ratio of the detected output values of the light reflectance of the portion.

  The pattern forming means for forming the toner pattern is composed of a photoreceptor, a charging roller, a developing device, an exposure device, a CPU as a control means for controlling these, and the like image forming process similar to the normal image forming described above. After that, a toner pattern is formed on the intermediate transfer belt 8. Further, based on the detected image density, various image forming conditions (parameters) such as a developing bias of the developing device, a charging bias of the charging device, and a laser power of the exposure device are controlled and adjusted to be optimal.

FIG. 4 is a diagram showing the configuration of the second exemplary embodiment of the present invention.
In the second embodiment of the present invention, a holding member that holds the density detection sensor 24 and a holding member that holds the reflection plate 25 are integrally configured, and both are held by a single integrated holder 28. Other than that, the configuration is the same as in the first embodiment. Thus, by integrally configuring the holding member, the number of parts can be reduced and detection accuracy can be improved. As a result, erroneous detection of toner density can be prevented, and a high-quality image forming apparatus can be provided.

FIG. 5 is a diagram showing the configuration of the third exemplary embodiment of the present invention.
In the third embodiment of the present invention, the reflection plate holder 33 that holds the reflection plate 25 is configured to be swingable in the direction of arrow F in the figure with the fulcrum 29 as the center. The upper end of the reflector holder 33 is urged toward the roller 30 provided at the shaft end of the tension roller 10 by a spring 32 as an urging means provided on the wall surface 31 of the image forming apparatus main body. As a result, the upper end portion of the reflector holder 33 is maintained in contact with the roller 30. In addition, the contact surface 33 a that contacts the roller 30 of the reflector holder 33 is formed into a circular or substantially circular curved surface along the outer peripheral surface of the roller 30. Since the configuration other than the configuration described above is the same as that of the first embodiment, description thereof will be omitted.

  With the configuration described above, even if the axial position of the tension roller 10 is displaced for adjusting the tension of the intermediate transfer belt 8, the reflector holder 33 swings following the roller 30, so that the tension roller 10 The fluctuation of the relative position between the surface of the belt portion wound around 10 and the reflecting plate 25 can be suppressed. As a result, it is possible to prevent erroneous detection of the toner density due to the displacement of the tension roller 10, and to provide a high-quality image forming apparatus.

FIG. 6 is a diagram showing the configuration of the fourth exemplary embodiment of the present invention.
As in the third embodiment shown in FIG. 5, the fourth embodiment of the present invention has a swingable holder 34 that follows a roller 30 provided on the tension roller 10, and the holder 34 further increases the concentration. The detection sensor 24 and the reflection plate 25 are integrally held. Other than that, the configuration is the same as in the third embodiment.

  In this case, in addition to the same operations and effects as in the third embodiment, since the density detection sensor 24 and the holding member for the reflection plate 25 are integrally formed, the number of parts can be reduced and detection accuracy can be improved. As a result, erroneous detection of toner density can be prevented more reliably, and a high-quality image forming apparatus can be provided.

FIG. 7 is a diagram showing the configuration of the fifth exemplary embodiment of the present invention.
In the fifth embodiment of the present invention, the reflecting plate holder 36 is configured to be swingable in the direction of arrow J in the figure with the fulcrum 37 as the center, and the reflecting plate holder 36 is attached to the intermediate transfer belt of the tension roller 10 by a spring 32. 8 is made to contact | abut to the end part surface which is not wound. Further, the contact surface 36 a that contacts the tension roller 10 of the reflection holder 36 is formed into a circular or substantially circular curved surface along the outer peripheral surface of the tension roller 10.

  In this case, even if the tension roller 10 is eccentric, the reflection plate holder 36 swings following the surface of the tension roller 10, so that the density detection sensor 24 is noise caused by the eccentricity of the tension roller 10. Not affected. For this reason, erroneous detection of the toner density can be prevented, and a high-quality image forming apparatus can be provided.

FIG. 8 is a diagram showing the configuration of the sixth exemplary embodiment of the present invention.
As in the fifth embodiment shown in FIG. 7, the sixth embodiment of the present invention has a swingable holder 38 that follows the surface of the tension roller 10, and further, the density detection sensor 24 is provided by the holder 38. And the reflector 25 are integrally held. Other than that, the configuration is the same as in the fifth embodiment.

  In this case, in addition to the same operations and effects as in the fifth embodiment, since the density detection sensor 24 and the holding member for the reflecting plate 25 are integrally formed, the number of parts can be reduced and detection accuracy can be improved. As a result, erroneous detection of toner density can be prevented more reliably, and a high-quality image forming apparatus can be provided.

  As described above, according to the configuration of each embodiment of the present invention, the light from the density detection sensor 24 is irradiated onto the portion of the intermediate transfer belt 8 wound around the tension roller 10 by the reflection plate 25, and the reflected light is irradiated. Can be detected at locations where the intermediate transfer belt 8 is not easily wrinkled or vibrated. For this reason, erroneous detection of the density detection sensor 24 can be prevented, and the toner density can be detected with high accuracy.

  Further, according to the present invention, the density detection sensor 24 (light emitting portion and light receiving portion) is wound around the tension roller 10 of the intermediate transfer belt 8 with a simple configuration in which the reflector 25 is provided at a predetermined position. Even if it is not disposed so as to face the surface, it is possible to irradiate the portion around the intermediate transfer belt 8 with light and receive the reflected light. This eliminates the restriction that the density detection sensor 24 must be disposed opposite to the portion of the intermediate transfer belt 8 wound around the roller in order to obtain stable detection accuracy. The degree of freedom increases, and it becomes easy to cope with the layout design in the apparatus for downsizing and the like.

  For example, in the configuration in which the intermediate transfer belt 8 is wound around two support rollers (the driving roller 9 and the tension roller 10) as in the embodiment shown in FIG. 1, the configuration of the present invention is applied by applying the configuration of the present invention. The size can be reduced in the longitudinal direction of the intermediate transfer belt 8 (left-right direction in the figure). Further, although the reflector 25 is disposed on the outer periphery of the portion around which the intermediate transfer belt 8 is wound, since the reflector 25 is formed thinner than the density detection sensor 24, the increase in the apparatus size is minimized. To the limit.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention. In the above-described embodiment, the case where the configuration of the present invention is applied to the density detection sensor that detects the toner pattern for density detection on the intermediate transfer belt has been described as an example. However, the sensor for detecting the toner pattern for position detection is described. The configuration of the present invention is also applicable. The configuration of the present invention can also be applied to a light detection device that receives reflected light by irradiating a detection target on the belt with detection light in another belt device. Further, the image forming apparatus according to the present invention is not limited to the one shown in FIG. 1, but may be another copying machine, a printer, a facsimile, or a complex machine thereof.

7 Transfer Device 8 Intermediate Transfer Belt 9 Drive Roller 10 Tension Roller 24 Density Detection Sensor 25 Reflector Plate 26 Sensor Holder 27 Reflector Holder 28 Holder 30 Roller 32 Spring 33 Reflector Holder 34 Holder 36 Reflector Holder 38 Holder Q Rotation Center S Optical Path Extension line

JP 2006-235469 A JP-A-11-223976 Japanese Patent Laid-Open No. 11-15218

Claims (11)

A light detection device that irradiates light on an endless belt wound around a plurality of support members and detects reflected light of light irradiated on a detection target on the belt,
A light emitting portion and a light receiving portion disposed to face a portion of the belt that is not wound around the support member;
Reflecting means for reflecting light emitted from the light emitting portion to a portion of the belt wound around the support member and reflecting light reflected from the belt to the light receiving portion. Photodetector. The support member that wraps the portion irradiated with light on the belt is a rotatable roller member,
The light detection device according to claim 1, wherein the reflection unit is disposed so that an extension line of an optical path of light reflected from the reflection unit to the belt passes through a rotation center of the roller member.   The photodetecting device according to claim 2, wherein a holding member that holds the reflecting unit is configured to be swingable, and the holding member is urged by an urging unit to be brought into contact with the roller member.   The holding member that holds the reflecting means is configured to be swingable, and the holding member is urged by an urging means to be brought into contact with a roller provided at a shaft end portion of the roller member. Photodetector.   The light detection device according to claim 3, wherein the holding member is in contact with a surface of the roller member on which the belt is not wound.   The photodetecting device according to claim 1, wherein a holding member that holds the reflecting unit and a holding member that holds the light emitting unit and the light receiving unit are integrally configured.   The light detection device according to claim 1, wherein a reflection surface of the reflection unit is formed as a flat surface.   The light detection device according to claim 1, wherein the surface roughness Ra of the reflection surface of the reflection means is set to 0.05 [μm] or less. In a belt device comprising an endless belt wound around a plurality of support members, and a light detection device that irradiates light on the belt and detects reflected light of light irradiated on a detection target on the belt. ,
A belt device comprising the light detection device according to claim 1 as the light detection device. In a transfer device for transferring an image formed on an image carrier to a recording medium using a belt device provided with an endless belt that is wound around a plurality of support members and driven to rotate,
A transfer device using the belt device according to claim 9 as the belt device. In an image forming apparatus comprising: an image carrier that carries an image; an image forming unit that forms an image on the image carrier; and a transfer device that transfers an image formed on the image carrier to a recording medium.
An image forming apparatus comprising the transfer device according to claim 10 as the transfer device.

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