JP6350049B2 - Detection apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a detection device and an image forming apparatus.

  A so-called electrophotographic image forming apparatus such as a digital copying machine or a laser printer transfers a toner image onto a recording material such as recording paper, and records the toner image on recording paper or the like by heating and pressing under predetermined conditions. An image is formed by fixing on a material.

In such an image forming apparatus, it is necessary to consider conditions such as a heating amount and a pressure when fixing a toner image. In particular, when forming a high-quality image, the toner image is fixed. It is necessary to individually set the conditions for this according to the type of recording material.
This is because the image quality recorded on the recording material is greatly influenced by the material, thickness, humidity, smoothness, coating state, and the like of the recording material. For example, with regard to smoothness, depending on the conditions during fixing, the toner fixing rate in the recesses is lowered due to the degree of unevenness in the recording material, and a high-quality image cannot be obtained.

  In other words, color unevenness and the like cannot be obtained unless fixing is performed under conditions according to the smoothness of the recording material on which an image is formed.

On the other hand, with recent advances in image forming apparatuses and diversification of expression methods, there are several hundred types of recording materials, and there are a wide variety of recording materials depending on differences in basis weight, thickness, etc. The brand exists.
Therefore, in order to form a high-quality image, it is necessary to set detailed fixing conditions and the like according to the type and brand of the recording material.
Examples of such recording materials include plain paper, gloss coated paper, mat coated paper, coated paper such as art coated paper, OHP sheets, etc., as well as special paper with an embossed surface. Such recording materials are increasing.
In the above description, recording paper or the like is described as the recording material, but there are recording materials other than recording paper or the like.

By the way, in the current image forming apparatus, it is necessary for the user to set the fixing conditions in the image forming apparatus. For this reason, the user needs to know various types of recording materials.
Further, since it is necessary for the user himself to set the fixing conditions, it is troublesome when performing printing or the like. Furthermore, if the fixing conditions are set incorrectly, a desired high-quality image cannot be obtained.
Therefore, in the image forming apparatus, a recording material identification sensor capable of automatically selecting the type of the recording material and such a recording material identification sensor are mounted, and the recording material is automatically selected to form an image. A technique relating to a possible image forming apparatus is being studied.

  For example, Patent Document 1 includes a light source and a light detector that irradiates the recording material with light emitted from the light source and detects the intensity of specularly reflected light on the recording material. The angle of the incident light with respect to the normal line of the recording material is 80 ° or more and 88 ° or less. Since the angle of the light incident on the recording material from the light source with respect to the normal line of the recording material is 80 ° or more and 88 ° or less, specular reflection light according to the smoothness of the recording material can be obtained. Smoothness can be determined.

  However, as the angle of the incident light with respect to the normal line of the recording material increases, the variation in the distance from the recording material leads to a decrease in the output of the sensor. For this reason, when a paper smoothness sensor is installed in the recording material conveyance path, the distance between the sensor and the recording material varies due to the fluttering of the recording material. When installed on a paper feed tray or the like other than the recording material conveyance path, there is a problem that the apparatus becomes large in order to secure space, and a mechanism for bringing the sensor into contact with the recording material on the tray is necessary, leading to an increase in cost. is there.

  Therefore, an object of the present invention is to increase the detection accuracy and prevent the occurrence of a jam.

In order to solve the above problem, the invention according to claim 1 is a detection device that senses a recording material passing through a conveyance path with an optical sensor, wherein the optical sensor includes a light source and light emitted from the light source. A light detector that irradiates the recording material and detects the intensity of specularly reflected light in the recording material, and the angle of the light incident on the recording material from the light source with respect to the normal of the recording material is 80 degrees or more and 88 degrees or less, the light source and the light detector are installed in a housing, and the housing prevents the recording material from entering the housing ; At least one of the light from the light source is closed and the opening surface for irradiating the recording material, the intrusion preventing means is provided over the downstream side from the upstream side in the transport direction of the recording material of the opening surface, A through hole was formed on the optical path It is a tab-shaped recording material conveyance guide .

  According to the present invention, it is possible to increase detection accuracy and prevent jamming.

1 is an explanatory diagram illustrating a schematic configuration of an image forming apparatus according to an invention which is a premise of the present invention. FIG. 2 is an enlarged schematic view of a place where a smoothness sensor used in the image forming apparatus shown in FIG. 1 is installed. It is a perspective view of the smoothness sensor 40-1. It is a schematic diagram which shows the structure of the smoothness sensor 40-1. It is explanatory drawing which shows operation | movement of the smoothness sensor 40-1. FIG. 6 is a characteristic diagram showing the operation performance of the smoothness sensor 40-1. It is a block diagram of the smoothness sensor 40-2 of Embodiment 1. (A)-(d) is operation | movement explanatory drawing of the smoothness sensor 40-2 shown in FIG. (A), (b) is a characteristic view which shows the operation | movement performance of the smoothness sensor 40-2 shown in FIG. It is a block diagram of the smoothness sensor 40-1 used as the premise of this invention. It is a perspective view of the smoothness sensor 40-2 of Embodiment 2. It is a perspective view of smoothness sensor 40-4 of this embodiment. In this embodiment, the recording material 20 is pressed against the smoothness sensor 40-4 of the present embodiment by using the regulating member 70. 6 is a conceptual diagram of a smoothness sensor 40-5a that detects the smoothness of the recording material 20. FIG. It is a front view of the smoothness sensor 40-5. It is a perspective view of the smoothness sensor 40-5 shown in FIG. It is the XVII-XVII sectional view taken on the line of FIG. FIG. 17 is an arrow view in the direction of arrow P1 in FIG. FIG. 17 is an arrow view in the direction of arrow P2 in FIG. 16. FIG. 17 is an arrow view in the direction of arrow P3 in FIG. 16. It is a figure which shows the state which the recording material 20 tends to enter into the opening part of the smoothness sensor 40-5. It is a specific explanatory view about the scooping shape of the inclined portion. FIG. 15 is a conceptual diagram when the smoothness sensor shown in FIG. 14 is viewed from the front in a sensor not using the present invention. It is the XXIV-XXIV sectional view taken on the line of FIG. The recording material as a sheet is conveyed and the recording material enters the opening of the smoothness sensor. It is explanatory drawing of the edge of the recording material as a paper.

Hereinafter, an embodiment in which an optical sensor as a detection apparatus according to the present invention is used as a smoothness sensor for detecting the smoothness of a recording material on which an image is formed by an image forming apparatus will be described. In addition, the same code | symbol was used for the same member.
<Invention on which the present invention is based>
FIG. 1 is an explanatory diagram showing a schematic configuration of an image forming apparatus according to the invention as a premise of the present invention.
The image forming apparatus shown in FIG. 1 employs an electrophotographic system. An image reading apparatus 200 is installed on the image forming apparatus main body 100, and a duplex unit 300 is attached to the right side of the image forming apparatus main body 100 in the drawing.
The image forming apparatus main body 100 includes an intermediate transfer device 10. The intermediate transfer device 10 includes an endless belt-shaped intermediate transfer belt 11 stretched around a plurality of support rollers, and causes the intermediate transfer belt 11 to run counterclockwise in the drawing. Below the intermediate transfer device 10, four image forming devices 12c, 12m, 12y, and 12k corresponding to the respective colors of cyan (c), magenta (m), yellow (y), and black (k) are intermediate transfer. It is installed along the belt 11 side by side. Each of the image forming devices 12c, 12m, 12y, and 12k includes a drum-shaped photosensitive member that rotates clockwise in the drawing, and a charging device, a developing device, a transfer device, and a cleaning device arranged around the photosensitive member. Including.
An exposure device 13 is installed below the image forming devices 12c, 12m, 12y, and 12k. A paper feeding device 14 is installed below the exposure device 13. The paper feeding device 14 is provided with two paper feeding cassettes 15 for storing the recording material 20. At the upper right of each paper feed cassette 15, there is provided a paper feed roller 17 that feeds the recording material 20 in each paper feed cassette 15 one by one and feeds it to the recording material conveyance path 16.

The recording material conveyance path 16 conveys the recording material with the right side in the figure in the image forming apparatus main body 100 facing from the bottom to the top, and is finally formed between the image forming apparatus main body 100 and the image reading apparatus 200. It is formed so as to be discharged to the inner paper discharge unit 18. In the recording material conveyance path 16, a registration roller 19, a secondary transfer roller 21 facing the intermediate transfer belt 11, a fixing device 22, a paper discharge roller 23, and the like are provided. On the upstream side of the registration roller 19 in the recording material conveyance direction, the recording material 20 re-feeded from the duplex unit 300 or manually fed from the manual sheet feeder 36 across the duplex unit 300 is transferred to the recording material conveyance path 16. A paper feed path 37 to be joined is provided. Further, on the downstream side in the recording material conveyance direction of the fixing device 22, a branch is formed between a discharge path toward the in-body sheet discharge unit 18 and a refeed conveyance path 24 toward the duplex unit 300.
When creating a copy with the image forming apparatus, first, the image reading apparatus 200 reads a document image and the exposure apparatus 13 writes it. Each color toner image is formed on the respective photoreceptors of the image forming devices 12c, 12m, 12y, and 12k, and the toner images are sequentially transferred onto the intermediate transfer belt 11 by the primary transfer devices 25c, 25m, 25y, and 25k. A color image is formed.

On the other hand, one of the paper feeding rollers 17 is selectively rotated, and the recording material 20 is fed out from the paper feeding cassette 15 corresponding to the paper feeding roller 17 and fed into the recording material conveyance path 16, or from the manual paper feeding device 36. The manual feed recording material is fed into the paper feed path 37.
The recording material 20 is conveyed by the registration roller 19 through the recording material conveyance path 16, and is sent to the secondary transfer position with timing. Then, the color image formed on the intermediate transfer belt 11 is transferred onto the recording material 20 by the secondary transfer roller 21.
The recording material 20 after the image transfer is fixed by the fixing device 22, discharged by the discharge roller 23, and stacked on the in-body discharge unit 18.
When an image is also formed on the back surface of the recording material 20, it is placed in the refeed conveyance path 24, reversed by the duplex unit 300, re-feeded through the feed path 37, and separately formed on the intermediate transfer belt 11 The image is secondarily transferred to the recording material 20. After the secondary transfer, the image is fixed again by the fixing device 22 and discharged to the in-body discharge unit 18 by the discharge roller 23.

FIG. 2 is an enlarged schematic view of a place where the smoothness sensor used in the image forming apparatus shown in FIG. 1 is installed.
The image forming apparatus main body 100 is provided with a smoothness sensor 40 for detecting the type of the recording material 20 conveyed to the secondary transfer position, more specifically, the smoothness of the recording material 20. The smoothness sensor 40 of the present embodiment transports the recording material 20 from the paper feeding cassette 15 and the recording material 20 from the manual paper feeding device 36, but does not pass the recording material 20 from the duplex unit 300. It is installed at the location of the road 16. The recording material 20 from the paper feeding cassette 15 or the recording material 20 from the manual paper feeding device 36 is sandwiched by the conveying roller pair 26 and sent out, so that the recording material 20 is along the recording material facing surface of the smoothness sensor 40. Is guided to be conveyed.

<Smoothness sensor>
Next, the configuration of a smoothness sensor that detects the smoothness by sensing a recording material on which an image is formed by the image forming apparatus with an optical sensor will be described.
FIG. 3 is a perspective view of the smoothness sensor 40-1. FIG. 4 is a schematic diagram showing the configuration of the smoothness sensor 40-1.
The smoothness sensor 40-1 is composed of a reflective optical sensor. Specifically, a light emitting unit 41 as a light source, a collimating lens 44 as a lens member, a light receiving unit 42 for detecting the intensity of light as a regular reflection light detector, a lens 45, and a housing as an optical path adjacent member 43.
The collimating lens 44 is a lens having a function of collimating the irradiation light emitted from the light emitting unit 41.
The regular reflection light detector 42 has a function of detecting regular reflection light that is regularly reflected on the surface of the recording material 20, and includes a photodiode or the like.
The lens 45 is a lens for causing only a predetermined angle of light to enter the specular reflection light detector 42.

  In the housing 43, an opening surface 46 is formed on a measurement object facing surface as a recording material facing surface that faces the recording material 20 that is a measurement target. The irradiation light L1 from the light emitting unit 41 passes through the collimating lens 44 through the irradiation light path space 47 formed inside the housing 43 and is emitted from the opening surface 46 toward the surface of the recording material 20. Further, the regular reflection light L2 from the surface of the recording material 20 enters the inside of the housing 43 through the opening surface 46, passes through the lens 45 through the regular reflection optical path space 48 formed inside the housing 43, and Light is received by the light receiving unit 42.

  The light emitting unit 41 is positioned in the housing 43 so that the angle θ1 of the optical axis of the irradiation light L1 with respect to the normal line N of the opening surface 46 is in the range of 80 ° to 88 °. As described above, since the recording material 20 that is the measurement object is conveyed along the recording material facing surface where the opening surface 46 is formed, the smoothness sensor 40 emits light to the surface of the recording material 20. Is configured so that the incident angle falls within the range of 80 ° to 88 °. Incidentally, the incident angle of the irradiated light with respect to the surface of the recording material 20 is configured to be about 81.7 °.

  In the smoothness sensor 40-1, an LED (Light Emitting Diode) can be suitably used as the light source of the light emitting unit 41. As the LED, a chip type having an outer shape of about 3 mm square can be used. As the light emission wavelength of the LED, an infrared ray of 850 nm is used. This is because the sensitivity of the specular reflection light detector 42 is higher in infrared rays. However, other emission wavelengths such as visible light may be used. The LED of the light emitting unit 41 is directly fixed to a housing 43 formed of ABS (Acrylonitrile Butadiene Styrene copolymer) resin or the like.

  Further, since the recording material 20 is preferably irradiated with collimated light with high accuracy, a collimating lens 44 is provided in the irradiation light path space. For example, a collimating lens 44 having a focal length f of 9 mm and a diameter of 2 mm can be used, and is arranged so that the light emitting point of the light emitting unit 41 is positioned at the focal position of the collimating lens 44. The collimating lens 44 is fixed to the housing 43 with a fixing margin of about 5 mm. A line connecting the light emitting point of the light emitting unit 41 and the center of the collimating lens 44 is the optical axis of the irradiation light.

  The light receiving unit 42 as a regular reflection light detector is also fixed in the housing 43 as in the case of the light emitting unit 41. For the light receiving unit 42, a photodiode (PD) is used. A PD having a size of about 5 mm square and a light detection surface serving as a light receiving surface of 2.5 mm square can be used. For example, a lens 45 having a focal length f of 9 mm and a diameter of 3 mm can be used as the lens 45 for making light incident on the light receiving unit 42, and the PD light receiving surface of the light receiving unit 42 is located at the focal position of the lens 45. Are arranged as follows. Thereby, the taking-in angle width of the light incident on the regular reflection light detector 42 is about 5 °. A line connecting the center of the lens 45 and the center of the light receiving surface of the PD serving as the light receiving unit 42 is the optical axis of the regular reflection light.

  The housing 43 is formed of black ABS resin or the like that absorbs light, and disturbance light is removed by the housing 43. Inside the housing 43, the light emitting unit 41, the collimating lens 44, the regular reflection light detector 42, the lens 45, and the like are formed so as to be fixed. The size of the housing 43 depends on the size of the collimating lens 44 and the lens 45 and the like.

  The smoothness sensor 40-1 has a configuration in which only a light receiving unit that receives specularly reflected light from the recording material 20 is provided. However, a configuration in which a light receiving unit that receives diffusely reflected light is additionally provided may be employed.

FIG. 5 is an explanatory diagram showing the operation of the smoothness sensor 40-1. FIG. 6 is a characteristic diagram showing the operational performance of the smoothness sensor 40-1, where the horizontal axis shows the target value and the vertical axis shows the output ratio.
By the way, as described above, the smoothness sensor 40-1 of the present embodiment has a configuration in which the incident angle θ of the irradiation light with respect to the surface of the recording material 20 has a large value in the range of 80 ° to 88 °. . As shown in FIGS. 5 and 6, when the recording material 20 moves to the position of the recording material 20 ′ and the distance (Gap) from the smoothness sensor 40-1 fluctuates, the optical axis path L2 of specularly reflected light is L2. A big shift to '. As a result, the specularly reflected light entering the PD may decrease, and the detection accuracy of the smoothness sensor 40-1 may decrease.

<Embodiment 1>
Next, Embodiment 1 will be described with reference to the drawings.
FIG. 7 is a configuration diagram of the smoothness sensor 40-2 of the first embodiment.
Therefore, in the smoothness sensor 40-2 of the first embodiment, as shown in FIG. 7, the casing 43 is a measurement object facing surface as a recording material facing surface that faces the surface of the recording material 20 that is the measurement target. Are provided with recording material conveyance guides 50-1, 50-4, and 50-5.
FIG. 7 is a schematic diagram showing the configuration of the smoothness sensor 40-2. 8A to 8D are operation explanatory diagrams of the smoothness sensor 40-2 shown in FIG. FIGS. 9A and 9B are characteristic diagrams showing the operation performance of the smoothness sensor 40-2 shown in FIG. 7, where the horizontal axis indicates the target value and the vertical axis indicates the output ratio.
As shown in FIGS. 8A to 8D, the smoothness sensor 40-2 has a recording material conveyance path that is narrow by the size of the recording material conveyance guides 50-1 to 50-5. Become. For this reason, the distance D−the distance D ′ which is the flapping width of the recording material 20 can be reduced, and the decrease in the output ratio V can be suppressed as shown in FIGS. 9A and 9B. As a result, the detection accuracy of the smoothness sensor 40-2 can be increased.
Furthermore, even if the curled recording material 20 contacts the smoothness sensor 40-2, the recording material conveyance guides 50-1 to 50-5 do not enter the inside, and therefore, jamming can be suppressed. .

<Embodiment 2>
The second embodiment will be described with reference to the drawings.
FIG. 10 is a configuration diagram of the smoothness sensor 40-1 as a premise of the present invention, and FIG. 11 is a perspective view of the smoothness sensor 40-2 of the second embodiment.
As described above, the smoothness sensor 40-3 of the present embodiment has a configuration in which the incident angle θ1 of the irradiation light with respect to the surface of the recording material 20 has a large value in the range of 80 ° to 88 °. Therefore, as shown in FIG. 10, it is necessary to provide a wide opening surface 46 for securing the optical axis paths of the irradiation light L1 and the regular reflection light L2. In order not to block the opening surface 46, as shown in FIG. 11, the recording material transport guides 50-1 to 50-5 are divided into a protruding shape on the upstream surface 46 in the transport direction of the recording material 20 as shown in FIG. Recording transport guides 51-1 to 51-5.
With this configuration, the smoothness sensor 40-3 can freely set the installation positions of the recording material conveyance guides 51-1 to 51-5, and the conveyance property of the recording material 20 is improved.

<Embodiment 3>
A third embodiment will be described with reference to the drawings.
FIG. 12 is a perspective view of the smoothness sensor 40-4 of the present embodiment.
As shown in FIG. 12, the tab-shaped recording material conveyance guides 50-2 and 50-3 have through holes in the optical axis path portion in order to secure the optical axis paths of the irradiation light L1 and the regular reflection light L2.
With such a configuration, the smoothness sensor 40-4 has a configuration in which the conveyance guide of the recording material 20 is not divided and does not block the optical path, and the conveyance property of the recording material 20 is improved.

<Embodiment 4>
A fourth embodiment will be described with reference to the drawings.
FIG. 13 shows the recording material 20 pressed against the smoothness sensor 40-4 of the present embodiment using a regulating member 70. FIG. That is, the regulating member 70 that guides the recording material 20 to the recording material conveyance guide side is provided in the vicinity of the position facing the recording material conveyance guides 50-1 to 50-5 in the conveyance path of the recording material 20.
By providing the regulating member 70 that guides to the recording material conveyance guide 50 side in the recording material conveyance path, the distance between the recording material 20 and the smoothness sensor 40-4 is kept constant, and the output of the smoothness sensor 40-4. Reduction can be reduced.

  As described above, a guide shape such as a transport rib is provided on the casing of the smoothness sensor, and a guide for bringing the recording material into contact with the smoothness sensor is provided on the transport path so that the distance between the smoothness sensor and the recording material is constant. The detection accuracy can be increased.

<Embodiment 5>
A fifth embodiment will be described with reference to the drawings.
The invention of the fifth embodiment has the following characteristics in the case of an optical sensor having a large opening installed on the paper conveyance path.
In short, by providing an inclination for scooping up the recording material at the opening of the smoothness sensor, jamming can be prevented even if the edge of the recording material pierces the opening of the sensor. Hereinafter, it explains in detail using a drawing.
FIG. 14 is a conceptual diagram of a smoothness sensor 40-5a that detects the smoothness of the recording material 20.
The smoothness sensor 40-5a is composed of a reflective optical sensor, and has an incident angle θ of 75 ° to 85 °.
The optical sensor includes a light emitting unit 41 and a light receiving unit 42. A light emitting unit 41 and a collimating lens 44 for collimating the light emitted from the light emitting unit 41, a light receiving unit 42 for receiving light reflected from the recording material 20 as a sheet, and a lens 45 for collecting the light on the light receiving unit 42 are provided. Including. Reference numeral 49 denotes a collimating lens.
The optical sensor is installed in the casing 51, and the casing 51 has a recording material entering the surface of a part of the optical path adjacent member of the optical path from the light emitting section 41 as a light source to the light receiving section 42 as a light detector. In this case, inclined portions 61 and 62 for scooping up the paper are provided. The inclined portions 61 and 62 function as entry preventing means.
The inclined portion 61 has a surface parallel to the optical axis going from the light emitting portion 41 to the recording material (not shown), and the inclined portion 62 has a surface parallel to the optical axis going from the recording material to the light receiving portion 42. The angle θ with respect to the normal line N of the recording material not shown in the drawing of the inclined portion 61 is formed to be equal to the angle with respect to the normal line N of the recording material not shown in the drawing of the inclined portion 62. The inclined portion 61 and the inclined portion 62 are integrally formed, and the light emitting portion 41, the lenses 44, 45, 49, and the light receiving portion 42 are accommodated therein.

The inclined portion 61 and the inclined portion 62 shown in FIG. 14 are integrally formed, but the present invention is not limited to this, and the inclined portion 61 and the inclined portion 62 are shown in FIGS. 15 and 16. And may be formed separately through a rectangular flat portion 64.
FIG. 15 is a front view of the smoothness sensor 40-5.
FIG. 16 is a perspective view of the smoothness sensor 40-5 shown in FIG.
17 is a cross-sectional view taken along line XVII-XVII in FIG.
18 is a view in the direction of arrow P1 in FIG. 16, FIG. 19 is a view in the direction of arrow P2 in FIG. 16, and FIG. 20 is a view in the direction of arrow P3 in FIG. .
In the smoothness sensor 40-5 shown in FIG. 17, an inclined portion 62 is disposed on the upper side of the housing 60 on the recording material 20 side. The inclined portion 62 has an inclined surface 62a that is folded back to the inside of the housing 60 with respect to the paper conveyance direction that is the conveyance direction of the recording material 20, and is inclined to the inside of the housing. The inclination angle of the inclined surface is preferably an acute angle with respect to the paper conveyance direction, for example, 45 ° or less. A piece facing the inclined portion 62 of the housing 60 has an inclined surface 63 that is folded upward by about 45 °. The housing 60 is formed in a box shape, and a light emitting unit 41 and a light receiving unit 42 not shown in the figure are arranged therein. That is, the light emitted from the light emitting unit 41 (not shown) is irradiated onto the recording material 20 from the gap between the inclined portion 62 and the inclined surface 63, and the reflected light is again between the inclined portion 62 and the inclined surface 63. It enters into the light-receiving part 42 which is not shown in the figure from the gap.
Reference numerals 71 and 72 denote conveyance guide plates, which smoothly convey the recording material 20 in the paper conveyance direction. Further, the recording material is not caught by the sensor.

FIG. 21 is a diagram illustrating a state where the recording material 20 is about to enter the opening of the smoothness sensor 40-5.
As shown in FIG. 21, even when the recording material 20 tries to enter the opening, the recording material 20 is not caught by the smoothness sensor 40-5 due to the scooping shape of the inclined portion 61.

FIG. 22 is a specific explanatory diagram of the scooping shape of the inclined portion.
When the experiment was conducted with the angles formed by the surfaces formed by the conveyance guide plates 71 and 72 and the inclined portions being 30 ° and 45 °, both had the effect of preventing jamming. The smaller the angle, the smaller the occurrence of jams, so it was confirmed that the effect is effective at 45 ° or less.

  FIG. 23 is a conceptual diagram of the sensor when the present invention is not used and the smoothness sensor shown in FIG. 14 is viewed from the front. It is necessary to cut through the housing so as not to block the light path.

  24 is a cross-sectional view taken along line XXIV-XXIV in FIG. The housing is cut away so as not to block the light path.

FIG. 25 shows a state in which the recording material as a sheet is conveyed and the recording material enters the opening of the smoothness sensor.
FIG. 26 is an explanatory diagram of an edge of a recording material as a sheet.
When the recording material is stuck in the opening of the smoothness sensor, a jam occurs in the image forming apparatus. In many cases, the edge of the recording material 20 (FIG. 26) is stuck in the opening of the smoothness sensor.

  As described above, according to the present embodiment, by providing the recording material scooping inclined portion in the smoothness sensor opening, even if the edge of the paper pierces the sensor opening, the recording material does not enter the inside, Jam can be prevented. As a result, when the smoothness sensor is installed on the paper conveyance path, it is possible to prevent a jam from occurring due to the paper edge being stuck in the gap of the paper smoothness sensor opening.

  In the present invention, a guide shape such as a transport rib is provided on the housing of the sensor installed in the transport path of the recording material, and a guide for bringing the recording material into contact with the sensor is provided on the transport path, thereby reducing the distance between the sensor and the paper. It is possible to obtain a sensor with high detection accuracy that is kept constant.

<Effect>
The sheet is liable to be caught at the joint between the slope portion of the smoothness sensor having a rake shape and the end of the opening, that is, the end portion of the rake slope portion. On the other hand, in the image forming apparatus, it can be assumed in which part the edge comes depending on the size of the recording material. By arranging the end position of the inclined portion at a position where the edge of the recording material does not come, jamming can be prevented.

The depth of the opening on the light emitting part side can be made shallower than that on the light receiving part side. If the depth of the opening is shallow, the recording material is hardly caught. Further, since the recording material is regulated by the conveying roller at the conveyance center, the recording material is less likely to be caught by the smoothness sensor.
On the contrary, if the recording material is separated from the transport center, the recording material is easily caught by the smoothness sensor. That is, if the layout is such that the light emitting unit side is disposed outside the transport center, the recording material is less likely to get caught.

  At the conveyance center, the sheet is regulated by the conveyance roller, so that the edge of the recording material is not easily stuck. On the contrary, the edge of the recording material is easily pierced when coming out of the conveyance center. Since the depth of the opening on the light emitting part side can be made shallower than that on the light receiving part side, the recording material is less likely to get caught if the light emitting part side is arranged outside the transport center.

  The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there.

20 Recording material (paper)
40, 40-1, 40-2, 40-3, 40-4, 40-5 Smoothness sensor 41 Light emitting part 42 Light receiving part 43, 60 Housing 44, 49 Collimating lens 46 Opening surface 50-1 to 50-5 , 51-1 to 51-5 Recording material conveyance guide 61, 62 Inclined portion 62 a, 63 Inclined surface 64 Flat portion 70 Restriction member 71, 72, 73 Conveyance guide plate 100 Image forming apparatus main body 200 Image reading apparatus 300 Double-sided unit

JP 2012-194445 A

Claims (4)

In the detection device that senses the recording material passing through the conveyance path with an optical sensor,
The optical sensor includes a light source, and a light detector that irradiates the recording material with light emitted from the light source and detects the intensity of regular reflection light in the recording material,
The angle of light incident on the recording material from the light source with respect to the normal of the recording material is 80 ° or more and 88 ° or less,
The light source and the photodetector are installed in a housing,
The housing has possess a penetration prevention means the recording material is prevented from entering the housing, and at least one opening surface of the light to irradiate the recording material from the light source,
The detection is characterized in that the entry preventing means is a tab-shaped recording material conveyance guide provided from the upstream side to the downstream side in the conveyance direction of the recording material on the opening surface and having a through hole formed on the optical path. apparatus. The detection apparatus according to claim 1 , further comprising a regulating member that guides the recording material to the recording material conveyance guide side in a vicinity of a position facing the recording material conveyance guide in the conveyance path of the recording material. Detection device. In detecting apparatus according to claim 1, wherein, if the paper plane of part of the optical path adjacent member of an optical path from said light source to said light detector enters, characterized in that a slope portion for scooping the paper Detecting device. An image forming apparatus comprising the detection device according to any one of claims 1 to 3.

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