Optical sensor and image forming apparatus provided with same

Abstract

An optical sensor (16) comprises: a circuit board (70) having a first surface (S1) and a second surface (S2) on the opposite side to the first surface (S1); a light-emitting element and a light-receiving element; and a connector (72) having a connection surface connected to a counterpart connector. The connector (72) is electrically connected to each of the light-emitting element and the light-receiving element. Each of the light-emitting element, the light-receiving element, and the connector (72) is disposed on the first surface (S1) of the circuit board (70).

Description

Optical sensor and image forming apparatus equipped with the same

[0001] The present disclosure relates to an optical sensor and an image forming apparatus including the same.

[0002] An optical sensor is known that includes a light-emitting element that emits measurement light to irradiate a measurement object and a light-receiving element that receives reflected light from the measurement light. The optical sensor is used, for example, to detect patch images formed on an intermediate transfer belt of a tandem image forming apparatus for measuring toner concentration and color shift. Patent Document 1 (JP-A-2005-102626) discloses an optical sensor that includes a light-emitting element and a light-receiving element for detecting specularly reflected light from the patch image, a lens unit that transmits light between these elements, a circuit board, and a connector. The circuit board has a first surface and a second surface opposite the first surface. The light-emitting element and the light-receiving element are mounted on the first surface of the circuit board. Meanwhile, the connector is mounted on the second surface of the circuit board.

[0003] Japanese Patent Application Laid-Open No. 2021-128983

[0004] According to one aspect of the present disclosure, there is provided an optical sensor including a circuit board having a first surface and a second surface opposite to the first surface, a light emitting element, a light receiving element, and a connector having a connection surface for connection to a mating connector. The connector is electrically connected to each of the light emitting element and the light receiving element. The light emitting element, the light receiving element, and the connector are each disposed on the first surface of the circuit board.

[0005] An image forming apparatus according to another aspect of the present disclosure includes an image forming unit that forms an image, and the optical sensor described above that irradiates light onto the image formed by the image forming unit and detects predetermined characteristics.

[0006] FIG. 1 is a cross-sectional view schematically illustrating the internal structure of a color printer to which an optical sensor according to the present disclosure is applied. FIG. 2 is a perspective view illustrating an example of the arrangement of a density sensor, which is an example of an optical sensor. FIG. 3A is a schematic diagram illustrating the principle of detection of black toner. FIG. 3B is a schematic diagram illustrating the principle of detection of black toner. FIG. 4A is a schematic diagram illustrating the principle of detection of color toner. FIG. 4B is a schematic diagram illustrating the principle of detection of color toner. FIG. 5 is a cross-sectional view illustrating a portion of an optical sensor according to an embodiment of the present disclosure. FIG. 6A is a perspective view illustrating the appearance of a portion of an optical sensor according to an embodiment of the present disclosure. FIG. 6B is a perspective view illustrating the appearance of a portion of an optical sensor according to an embodiment of the present disclosure. FIG. 7A is a top view of a portion of the optical sensor shown in FIGS. 6A and 6B. FIG. 7B is a bottom view of a portion of the optical sensor shown in FIGS. 6A and 6B. FIG. 7C is a side view of a portion of the optical sensor shown in FIGS. 6A and 6B. FIG. 8A is a perspective view of a bottom view of a housing bottom plate of an optical sensor according to an embodiment of the present disclosure. FIG. 8B is a perspective view of a top view of a housing bottom plate of an optical sensor according to an embodiment of the present disclosure. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 7B. Fig. 10 is a cross-sectional view taken along line XX in Fig. 8B, showing a state before the sensor substrate is attached. Fig. 11 is a plan view of a concentration sensor according to an embodiment of the present disclosure. Fig. 12 is a side view of a concentration sensor according to an embodiment of the present disclosure. Fig. 13 is a bottom view of a concentration sensor according to an embodiment of the present disclosure. Fig. 14 is a side view of a concentration sensor according to a reference example.

[0007] The optical sensor of the present disclosure will be described below with reference to the drawings. The optical sensor of the present disclosure is a module that measures the physical properties of an object by irradiating the object with measurement light and receiving the reflected light. There are no particular limitations on the object to be measured, and solids, semi-solids, liquids, powders, etc. can be the object. There are also no particular limitations on the physical properties to be measured, as long as they can be analyzed from reflected light. For example, the optical sensor of the present disclosure is suitable for measuring the color and density of an object to be measured. In the embodiment described below, an optical sensor that is installed in a color printer to detect the density of toner used in image formation is exemplified.

[0008] [Description of Color Printer] First, the configuration of a color printer to which the optical sensor of the present disclosure is applied will be described. FIG. 1 is a cross-sectional view that schematically shows the internal structure of a tandem color printer 1. The color printer 1 includes image forming units (image forming sections) 2Y, 2C, 2M, and 2Bk, an optical scanning device 23, an intermediate transfer unit 28, and a fixing unit 29, all housed in a main body housing 10. A paper output tray 11 is provided on the top surface of the main body housing 10. A sheet output port 12 opens opposite the paper output tray 11. A manual paper feed tray 13 is provided on a side wall of the main body housing 10, and a paper feed cassette 14 that stores sheets for automatic paper feed, etc., is provided at the bottom of the main body housing 10. The main body housing 10 corresponds to an example of an "external device" in this disclosure.

[0009] Image forming units 2Y, 2C, 2M, and 2Bk are units that form toner images of yellow, cyan, magenta, and black, respectively, and are arranged in tandem at a predetermined interval in the horizontal direction. Each image forming unit 2Y, 2C, 2M, and 2Bk includes a photosensitive drum 21 having a circumferential surface that supports an electrostatic latent image and a toner image, a charger 22 that charges the circumferential surface of the photosensitive drum 21, a developer 24 that forms a toner image by attaching developer to the electrostatic latent image, yellow, cyan, magenta, and black toner containers 25Y, 25C, 25M, and 25Bk, respectively, that supply toner of each color to the developer 24, a primary transfer roller 26 that performs primary transfer of the toner image formed on the photosensitive drum 21, and a cleaning device 27 that removes residual toner from the circumferential surface of the photosensitive drum 21. An optical scanning device 23 scans the circumferential surface of the photosensitive drum 21 of each color as a scanned surface with a beam in the main scanning direction, forming an electrostatic latent image on the circumferential surface for forming a toner image.

[0010] The intermediate transfer unit 28 performs primary transfer of the toner images formed on the photosensitive drums 21. The intermediate transfer unit 28 includes a transfer belt 281 that rotates while contacting the circumferential surface of each photosensitive drum 21, and a drive roller 282 and a driven roller 283 around which the transfer belt 281 is wound. The toner images on the photosensitive drums 21 of each color are primarily transferred and superimposed onto the same location on the transfer belt 281. As a result, a full-color toner image is formed on the transfer belt 281. A secondary transfer roller 15 is disposed opposite the drive roller 282, sandwiching the transfer belt 281 to form a secondary transfer nip T. The full-color toner image on the transfer belt 281 is secondarily transferred onto a sheet at the secondary transfer nip T.

[0011] The fixing unit 29 includes a fixing roller 291 with a built-in heat source, and a pressure roller 292 that forms a fixing nip N together with the fixing roller 291. The fixing unit 29 applies heat and pressure to the sheet, onto which a toner image has been transferred in the secondary transfer nip T, in the fixing nip N, thereby performing a fixing process in which the toner is fused to the sheet. The sheet that has undergone the fixing process is discharged from the sheet discharge port 12 toward the paper discharge tray 11.

[0012] A density sensor 16 is disposed inside the main body housing 10. The density sensor 16 is an example of the "optical sensor" of the present disclosure. The density sensor 16 is disposed near the secondary transfer nip T, facing the outer peripheral surface of the transfer belt 281 on which the toner image is carried. The density sensor 16 optically detects the density of the toner image formed on the transfer belt 281 and converts it into an electrical signal.

[0013] FIG. 2 is a perspective view showing an example of the arrangement of the density sensor 16. In FIG. 2, the density sensor 16 is illustrated as a first density sensor 16A and a second density sensor 16B spaced apart from each other in the main scanning direction. The first density sensor 16A is disposed at a first density detection position DP1 on the toner carrying surface 28T of the transfer belt 281, and the second density sensor 16B is disposed at a second density detection position DP2, facing each other. The two density sensors 16A and 16B optically detect toner detection patches dp carried on the toner carrying surface 28T. The toner detection patches dp include, for example, density detection patches for detecting the toner concentration of each color and position detection patches for detecting the printing position of each color. The transfer belt 281 rotates in the direction indicated by the white arrow in FIG. 2. The first density sensor 16A detects the toner concentration along a first inspection line DL1 extending from the first density detection position DP1 in the sub-scanning direction. The second density sensor 16B detects the toner density along a second inspection line DL2 that extends in the sub-scanning direction from the second density detection position DP2. Only one of the first density sensor 16A and the second density sensor 16B may be disposed opposite the transfer belt 281.

[0014] [Toner Detection Principle] Next, the principle of optically detecting toner on transfer belt 281 will be described with reference to Figures 3 and 4. Figure 3 is a schematic diagram showing the detection principle for black toner BT, and Figure 4 is a schematic diagram showing the detection principle for color toner CT. A light-emitting element E1 and a light-receiving element E2 are arranged facing the toner carrying surface 28T of transfer belt 281. The light-emitting element E1 is, for example, an LED (Light Emitting Diode) capable of emitting light of a predetermined wavelength. The light-receiving element E2 is, for example, a PD (Photo Diode) that receives light, photoelectrically converts it, and outputs a current corresponding to the amount of light.

[0015] 3A shows the light emission and reception state when there is no black toner BT on the transfer belt 281. The toner carrying surface 28T is a smooth surface that generates specular reflection when irradiated with light. Measurement light L1 is emitted from the light-emitting element E1. The measurement light L1 is irradiated at a predetermined emission angle θ1 toward the density detection position DP on the toner carrying surface 28T. The measurement light L1 is reflected by the toner carrying surface 28T, generating specularly reflected light L2. The specularly reflected light L2 is incident on the light-receiving element E2. The light-receiving element E2 outputs a current AM1 corresponding to the amount of light received.

[0016] 3B shows the light emission and reception state when black toner BT is present on the transfer belt 281. A portion of the measurement light L1 irradiated toward the toner carrying surface 28T is absorbed by the black toner BT. In other words, in the area of ​​the toner carrying surface 28T where black toner BT is present, substantially no specularly reflected light L2 is generated. As a result, the amount of specularly reflected light L2 incident on the light receiving element E2 decreases. The light receiving element E2 outputs a current AM2 corresponding to the reduced amount of light. Naturally, the relationship AM1 > AM2 holds. Whether or not black toner BT is present is detected based on the fluctuation in the current output of the light emitting element E1 accompanying such a change in the amount of specularly reflected light L2 received.

[0017] 4A shows the light emission and reception state when no color toner CT is present on the transfer belt 281. Measurement light L1 is emitted from the light-emitting element E1. The measurement light L1 emission optical system is adjusted so that measurement light L1 is irradiated onto the concentration detection position DP at an emission angle θ2 that is larger than the emission angle θ1 in FIG. 3A. Measurement light L1 is reflected by the toner carrying surface 28T, generating specularly reflected light L2. Light-receiving element E2 is positioned at a position where specularly reflected light L2 does not enter. Therefore, the output of light-receiving element E2 is substantially zero.

[0018] 4B shows the light emission and reception state when color toner CT is present on the transfer belt 281. A portion of the measurement light L1 irradiated toward the toner carrying surface 28T is irradiated onto the color toner CT and diffusely reflected. In other words, not all of the measurement light L1 becomes specularly reflected light L2, but a portion becomes diffusely reflected light L3. A portion of the generated diffusely reflected light L3 is incident on the light receiving element E2. The light receiving element E2 outputs a current AM3 corresponding to the amount of diffusely reflected light L3 received. The color toner CT is detected based on the change in output of the light receiving element E2 from 0 to AM3. The optical sensor described in the following embodiments applies the above-described detection principle.

[0019] 5 is a cross-sectional view showing the density sensor 16 according to this embodiment. The density sensor 16 includes a sensor substrate 3, a lens unit 4, a first light-shielding wall 51, and a second light-shielding wall 52. The object to be measured by the density sensor 16 is a toner patch printed on the toner carrying surface 28T of the transfer belt 281.

[0020] The sensor substrate 3 includes a substrate 30 having a mounting surface 3M, and an element group 3E arranged in a row on the mounting surface 3M. The sensor substrate 3 corresponds to an example of a "sensor section" in the present disclosure.

[0021] The element group 3E includes a first light-emitting / light-receiving pair 31 for detecting black toner BT and a second light-emitting / light-receiving pair 32 for detecting color toner CT. The first light-emitting / light-receiving pair 31 is made up of a first light-emitting element 33 and a first light-receiving element 34 arranged at a predetermined interval on the mounting surface 3M. The second light-emitting / light-receiving pair 32 is made up of a second light-emitting element 35 and a second light-receiving element 36 arranged at a predetermined interval on the mounting surface 3M at a position different from the first light-emitting / light-receiving pair 31.

[0022] The first light-emitting element 33 and the second light-emitting element 35 are LEDs that emit light of a predetermined wavelength. The first light-receiving element 34 and the second light-receiving element 36 are PDs that output a current according to the amount of light received. The elements of the element group 3E are arranged in a linear fashion. Specifically, the elements of the element group 3E are arranged in a line on the mounting surface 3M in the order of the first light-emitting element 33, the first light-receiving element 34, the second light-receiving element 36, and the second light-emitting element 35. The elements of the element group 3E do not necessarily have to be arranged in a strict linear fashion; they may be arranged in a row with an offset that is equivalent to a straight line.

[0023] The lens unit 4 is disposed in front of the mounting surface 3M, i.e., between the sensor substrate 3 and the toner carrying surface 28T. The lens unit 4 includes a first lens portion 41, a second lens portion 42, a third lens portion 43, and a fourth lens portion 44 as lens portions that condense light. The lens portions are located between the light-emitting element and the light-receiving element. On the optical path of the first light-emitting / light-receiving pair 31, the first lens portion 41 is disposed in front of the first light-emitting element 33, and the second lens portion 42 is disposed behind the first light-receiving element 34. On the optical path of the second light-emitting / light-receiving pair 32, the third lens portion 43 is disposed in front of the second light-emitting element 35, and the fourth lens portion 44 is disposed behind the second light-receiving element 36. The lens unit 4 further includes a holder portion 40 that holds each lens portion.

[0024] The first lens 41 focuses the light emitted by the first light-emitting element 33 to generate a first measurement light L11 that is irradiated as a spot at a predetermined position on the toner carrying surface 28T. The second lens 42 focuses the specularly reflected light L2 of the first measurement light L11 from the toner carrying surface 28T and guides it to the first light-receiving element 34. In other words, the first light-receiving element 34 is positioned to receive the specularly reflected light L2. The third lens 43 focuses the light emitted by the second light-emitting element 35 to generate a second measurement light L12 that is irradiated as a spot at a predetermined position on the toner carrying surface 28T. The fourth lens 44 focuses the diffusely reflected light L3 of the second measurement light L12 from the toner carrying surface 28T and guides it to the second light-receiving element 36. The second light-receiving element 36 is positioned to receive the optical image of the diffusely reflected light L3 generated by the fourth lens 44.

[0025] The first light-shielding wall 51 and the second light-shielding wall 52 are non-transparent members that do not allow light to pass through. The first light-shielding wall 51 is disposed in front of the mounting surface 3M, between the first light-emitting element 33 and the first light-receiving element 34. The first light-shielding wall 51 reduces the possibility that light emitted from the first light-emitting element 33 will travel directly toward the first light-receiving element 34 without passing through the toner carrying surface 28T. In other words, the first light-shielding wall 51 reduces the possibility that light before being condensed by the first lens unit 41 will be received by the first light-receiving element 34. The second light-shielding wall 52 is disposed in front of the mounting surface 3M, between the second light-emitting element 35 and the second light-receiving element 36. The second light-shielding wall 52 reduces the possibility that light emitted from the second light-emitting element 35 will travel directly toward the second light-receiving element 36. In other words, the second light-shielding wall 52 reduces the possibility that light before being condensed by the third lens unit 43 will be received by the second light-receiving element 36.

[0026] An open space OS is provided in front of the mounting surface 3M between the first light-emitting and light-receiving pair 31 and the second light-emitting and light-receiving pair 32, or in this embodiment, between the first light-receiving element 34 and the second light-receiving element 36. The open space OS is a non-light-shielding space in which there are essentially no light-shielding members. The open space OS is partitioned by the first light-shielding wall 51, the second light-shielding wall 52, and the lens unit 4. Note that the open space OS does not have to be a complete space, and small protrusions or structures that have no optical effect may be present.

[0027] If a light-blocking object (not shown) is present in the open space OS, in addition to the light that should be received and detected, reflected components from the light-blocking object may be incident on the first light-receiving element 34 and the second light-receiving element 36. In this case, stray light generated for some reason between the second lens unit 42 and the first light-receiving element 34 may be reflected by the light-blocking object and incident on the first light-receiving element 34. For example, stray light may be generated when a component of the first measurement light L11 that is diffusely reflected from the toner carrying surface 28T passes through the second lens unit 42, or when a portion of the specularly reflected light L2 is reflected by the light-receiving surface or mounting surface 3M of the first light-receiving element 34. Furthermore, stray light generated for some reason between the fourth lens unit 44 and the second light-receiving element 36 may be reflected by the light-blocking object and incident on the second light-receiving element 36.

[0028] In contrast, in the density sensor 16 shown in Figure 5, an open space OS is formed in front of the mounting surface 3M between the first light receiving element 34 and the second light receiving element 36. Because the open space OS is free of light-reflecting objects such as light-blocking objects, unwanted reflected light is less likely to occur. Therefore, stray light other than the specularly reflected light L2 or diffusely reflected light L3 that should be detected is prevented from entering the first light receiving element 34 or the second light receiving element 36. This allows for a density sensor 16 with improved sensing accuracy.

[0029] [Description of Appearance of Part of Concentration Sensor (Appearance of Sensor Substrate, Lens Unit, and Housing)] Fig. 6A is a perspective view from below showing the appearance of part of concentration sensor 16 according to this embodiment, Fig. 6B is a perspective view from above, Fig. 7A is a top view of part of concentration sensor 16, Fig. 7B is a bottom view, and Fig. 7C is a side view.

[0030] The concentration sensor 16 includes a housing 6 in addition to the sensor substrate 3 and lens unit 4 described above. The housing 6 and lens unit 4 correspond to an example of a "cover member" in this disclosure. As shown in FIG. 7B , the sensor substrate 3 includes a substrate 30 and an element group 3E mounted on the substrate 30. As described above, the element group 3E includes a first light-emitting / light-receiving pair 31 for detecting black toner BT and a second light-emitting / light-receiving pair 32 for detecting color toner CT. The element group 3E is arranged in a line in the following order: a first light-emitting element 33, a first light-receiving element 34, a second light-receiving element 36, and a second light-emitting element 35.

[0031] The lens unit 4 includes a lens portion 4R that focuses light and a holder portion 40 that holds the lens portion 4R. As described above, the lens portion 4R includes a first lens portion 41, a second lens portion 42, a third lens portion 43, and a fourth lens portion 44 (see FIG. 9 ). These four lens portions 41, 42, 43, and 44 are arranged consecutively in the arrangement direction of the element group 3E to form a lens block. The holder portion 40 has a rectangular parallelepiped shape that surrounds the lens block, and the top surface of the holder portion 40 is recessed where the lens block is located.

[0032] The lens unit 4 includes a pair of first support columns 45 and a pair of second support columns 46 for positioning the lens unit 4R. For example, each of the pair of first support columns 45 and the pair of second support columns 46 is a cylindrical body. The pair of first support columns 45 and the pair of second support columns 46 protrude from the underside of the holder section 40. Each of the first support columns 45 and each of the second support columns 46 extends from the lens unit 4R toward the circuit board 70 (described below). Each of the first support columns 45 protrudes near one diagonal corner of the rectangular lens unit 4. Each of the second support columns 46 is provided near the other diagonal corner of the lens unit 4 and is a convex portion that protrudes less from the underside of the holder section 40 than the first support columns 45. The first support columns 45 are mainly positioning protrusions for the lens unit 4 in the horizontal direction (direction along the board). The second support columns 46 are positioning protrusions for the lens unit 4 in the height direction.

[0033] The housing 6 is a rectangular parallelepiped housing that includes a bottom plate 61 and side plates 62 and has a cavity capable of accommodating the lens unit 4. The lens unit 4 is fitted into the housing 6. The bottom plate 61 faces the underside of the lens unit 4. The side plates 62 stand upright from the periphery of the bottom plate 61 and cover the side surfaces of the lens unit 4. The bottom plate 61 and the side plates 62 are adhesively fixed at the outer periphery of the bottom plate 61 and are integrated together.

[0034] 8A is a perspective view of the bottom plate 61 of the housing 6 as viewed from below, and FIG. 8B is a perspective view of the same as viewed from above. The above-mentioned first light-shielding wall 51 and second light-shielding wall 52 are provided upright on the top surface 61A of the bottom plate 61. The side ends of the first light-shielding wall 51 and the second light-shielding wall 52 are connected by a pair of side walls 53. As a result, a rectangular cylindrical space is formed above the top surface 61A by the first light-shielding wall 51, the second light-shielding wall 52, and the pair of side walls 53. This rectangular cylindrical space is the open space OS in this embodiment.

[0035] [Explanation of Part of the Internal Structure of the Concentration Sensor (Light-Shielding Walls and Lens Unit)] Figure 9 is a cross-sectional view taken along line IX-IX in Figure 7B. Figure 10 is a cross-sectional view taken along line X-X in Figure 8B, showing the state before the sensor board 3 is attached to the board accommodating portion 612 of the bottom plate 61. The lens unit 4 is fitted into the housing 6 with the lens portion 4R covering the bottom plate 61 on the sensor board 3. The first light-shielding wall 51 protrudes less from the bottom plate 61 than the second light-shielding wall 52. Therefore, the lens portion 4R, which is disposed so as to straddle the first light-shielding wall 51 and the second light-shielding wall 52, is inclined so that the side facing the first light-shielding wall 51 is lower. Each of the four lens portions 41, 42, 43, and 44 included in the lens unit 4R has a convex lens surface on both the upper and lower sides of the lens unit 4.

[0036] 9 shows a state in which the first measurement light L11 and the second measurement light L12 are emitted from the density sensor 16 toward a density detection position DP where the measurement object TG is printed on the toner carrying surface 28T of the transfer belt 281. It also shows a state in which the specularly reflected light L2 and the diffusely reflected light L3 from the measurement object TG are incident on the density sensor 16. As described above, the measurement object TG is black toner BT and color toner CT.

[0037] The first lens unit 41 is disposed opposite the first opening 613 of the bottom plate 61. The first lens unit 41 condenses light emitted from the first light-emitting element 33 and passing through the first opening 613, and irradiates the first measurement light L11 at the concentration detection position DP. The second lens unit 42 and the fourth lens unit 44 are disposed opposite the third opening 615 across the open space OS. The second lens unit 42 condenses specularly reflected light L2 of the first measurement light L11 from the concentration detection position DP, and directs the light to the first light-receiving element 34. The first light-shielding wall 51 blocks light emitted from the first light-emitting element 33 that is directed directly toward the first light-receiving element 34.

[0038] The third lens unit 43 is disposed at a position facing the second opening 614. The third lens unit 43 collects light emitted from the second light-emitting element 35 and passing through the second opening 614, and irradiates the second measurement light L12 at the concentration detection position DP. The fourth lens unit 44 collects a portion of the diffusely reflected light of the second measurement light L12 generated at the concentration detection position DP, and causes the diffusely reflected light L3 to be incident on the second light-receiving element 36. The second light-shielding wall 52 blocks light emitted from the second light-emitting element 35 that directly travels toward the second light-receiving element 36.

[0039] In this embodiment, the arrangement order of the element groups on the sensor substrate 3 is the same as that shown in FIG. 5 . Therefore, the specularly reflected light L2 and the diffusely reflected light L3 pass through the open space OS. There are substantially no light-reflecting objects in the open space OS, i.e., between the first light-shielding wall 51 and the second light-shielding wall 52. Therefore, unnecessary reflected light is less likely to occur between the first light-shielding wall 51 and the second light-shielding wall 52. This reduces the possibility that stray light other than the specularly reflected light L2 or the diffusely reflected light L3 that should be detected will be incident on the first light-receiving element 34 or the second light-receiving element 36. Note that other arrangement orders of the element groups 3E may also be applied to this embodiment. For example, the elements of the element group 3E may be arranged in a row on the mounting surface 3M in the order of the first light-receiving element 34, the first light-emitting element 33, the second light-receiving element 36, and the second light-emitting element 35.

[0040] [Description of the Remaining Part of the Concentration Sensor (Substrate)] Next, the substrate 7 of the concentration sensor 16 will be described in detail. The concentration sensor 16 further includes the substrate 7 in addition to the sensor substrate 3, lens unit 4, and housing 6 described above. FIG. 11 is a plan view of the concentration sensor 16 according to this embodiment. FIG. 12 is a side view of the concentration sensor 16 according to an embodiment of the present disclosure. FIG. 13 is a bottom view of the concentration sensor 16 according to an embodiment of the present disclosure. Note that in FIGS. 11 to 13, directional relationships are described using mutually orthogonal XYZ Cartesian coordinates. One side in the X direction is referred to as the "+X side," and the other side opposite the one side in the X direction is referred to as the "-X side." One side in the Y direction is referred to as the "+Y side," and the other side opposite the one side in the Y direction is referred to as the "-Y side." One side in the Z direction is referred to as the "+Z side," and the other side opposite the one side in the Z direction is referred to as the "-Z side."

[0041] 11 to 13 show the X, Y, and Z directions, but these directions are shown for the sake of convenience in explaining the structure of the concentration sensor 16 according to this embodiment and do not limit the manner of use of the concentration sensor 16 according to the present disclosure. Furthermore, the +X direction corresponds to an example of the "first direction" and "predetermined direction" in this disclosure. Furthermore, the -X direction corresponds to an example of the "second direction" in this disclosure.

[0042] The substrate unit 7 is mounted with a plurality of electronic components for operating each element of the sensor substrate 3. The plurality of electronic components include an IC chip 71, a connector 72, and the like. Note that other electronic components smaller than the IC chip 71 and the connector 72 are also mounted on the substrate unit 7, but their description will be omitted here. As shown in FIGS. 11 to 13 , the substrate unit 7 includes a circuit board 70 and an IC chip 71 and a connector 72 mounted on the circuit board 70. The IC chip 71 is an example of an "electronic component disposed in an area of ​​the second surface S2 corresponding to the rear surface of the contact portion K3." In one embodiment of the present disclosure, a case will be described in which the "electronic component disposed in an area of ​​the second surface S2 corresponding to the rear surface of the contact portion K3" is the IC chip 71. However, if two connectors are mounted, a single connector may be used.

[0043] The circuit board 70 is made of a rectangular plate-like member extending in a predetermined longitudinal direction. In this embodiment, the predetermined longitudinal direction is the X direction. The circuit board 70 has a dimension that extends longer on both sides outward than the aforementioned housing 6. The circuit board 70 has a first surface S1 and a second surface S2 that is the surface opposite the first surface S1. The first surface S1 and the second surface S2 each extend in the longitudinal direction and width direction of the circuit board 70. In this embodiment, the width direction is the Y direction. In other words, the first surface S1 and the second surface S2 are arranged on opposite sides of each other in the thickness direction of the circuit board 70. In this embodiment, the thickness direction is the Z direction.

[0044] As an example, the circuit board 70 is made of epoxy glass. The circuit board 70 further includes wiring 81 disposed inside the circuit board 70 or on the second surface S2 (see FIG. 13 ). The wiring 81 is electrically connected to the circuit pattern of the substrate 30, the IC chip 71, and the connector 72. In other words, the wiring 81 electrically connects the first light-emitting element 33, the first light-receiving element 34, the second light-emitting element 35, the second light-receiving element 36, the IC chip 71, and the connector 72.

[0045] The circuit board 70 is divided into four areas: a first component mounting area M1, a second component mounting area M2, a first component mounting prohibited area N1, and a second component mounting prohibited area N2. Specifically, each of the first surface S1 and the second surface S2 of the circuit board 70 further includes a first component mounting area M1, a second component mounting area M2, a first component mounting prohibited area N1, and a second component mounting prohibited area N2. That is, each of the first surface S1 and the second surface S2 of the circuit board 70 includes a second component mounting area M2 (described below) in addition to the first component mounting area M1. These areas are arranged from the -X side to the +X side in the following order: second component mounting area M2, first component mounting prohibited area N1, first component mounting area M1, and second component mounting prohibited area N2. For example, the shape of the first component mounting area M1 is a rectangle that is elongated in the longitudinal direction of the circuit board 70. In detail, the area of ​​the first component mounting region M1 is larger than the area of ​​the sensor substrate 3.

[0046] Furthermore, a first visual pattern 70A, a second visual pattern 70B, and a third visual pattern 70C are formed on the circuit board 70. As an example, the circuit board 70 is made of a green base material, and the first visual pattern 70A, the second visual pattern 70B, and the third visual pattern 70C are each white linear portions formed on the board. Note that the first visual pattern 70A, the second visual pattern 70B, and the third visual pattern 70C may each be a groove or the like formed in the circuit board 70.

[0047] The first visual inspection pattern 70A, the second visual inspection pattern 70B, and the third visual inspection pattern 70C are arranged in this order in the +X direction. The area sandwiched between the second visual inspection pattern 70B and the third visual inspection pattern 70C corresponds to the first component mounting area M1. The area sandwiched between the first visual inspection pattern 70A and the second visual inspection pattern 70B corresponds to the first component mounting prohibited area N1. The area arranged in the +X direction with respect to the arrangement position of the third visual inspection pattern 70C on the circuit board 70 corresponds to the second component mounting prohibited area N2. The area arranged in the -X direction with respect to the arrangement position of the first visual inspection pattern 70A on the circuit board 70 corresponds to the second component mounting area M2.

[0048] As described above, the sensor substrate 3 includes the substrate 30 and the element group 3E mounted on the substrate 30. The substrate 30 is made of a rectangular plate-like member elongated in the X direction. The first light-emitting element 33, the first light-receiving element 34, the second light-emitting element 35, and the second light-receiving element 36 are aligned in the X direction. The sensor substrate 3 is mounted on the first surface S1 of the circuit board 70, approximately in the center of the first component mounting area M1 (see FIG. 7B ). Specifically, the longitudinal center line of the first component mounting area M1 and the longitudinal center line of the sensor substrate 3 coincide with each other.

[0049] A circuit pattern for mounting the element group 3E is printed on the mounting surface 3M of the substrate 30. The light receiving elements and light emitting elements that make up the element group 3E are mounted on the circuit pattern. As another aspect of the substrate 30 according to the present disclosure, a semiconductor substrate such as a silicon substrate may be used as the element group 3E, and a sensor substrate 3 may be used in which each element is directly formed on the semiconductor substrate. Note that the element group 3E may be mounted on a circuit board 70 instead of on the substrate 30.

[0050] The housing 6 covers the sensor board 3. As described above, the housing 6 includes a bottom plate 61 and a side plate 62. The housing 6 is mounted on the first surface S1 of the circuit board 70 in the first component mounting area M1. As a result, the housing 6 protrudes in the Z direction from the first surface S1 of the circuit board 70 by a height HA of the bottom plate 61 and the side plate 62. The housing 6 houses the lens unit 4. As described above, the lens unit 4 mainly includes a pair of first support posts 45 that serve as positioning protrusions for the lens unit 4 in the X and Y directions (directions along the board), and a pair of second support posts 46 that serve as positioning protrusions for the lens unit 4 in the Z direction.

[0051] A first hole K1 and a second hole K2 are formed in the first component mounting area M1. As an example, the first hole K1 is circular, and the second hole K2 is elongated along the longitudinal direction of the circuit board 70. The tip of the first support 45 is inserted into each of the first hole K1 and the second hole K2. The inner diameter of the first hole K1 and the inner diameter in the lateral direction of the second hole K2 are set to correspond to the outer diameter of the tip of the first support 45. The first hole K1 is formed on the −X direction side and the +Y direction side of the first component mounting area M1. Meanwhile, the second hole K2 is formed on the +X direction side and the −Y direction side of the first component mounting area M1. As a result, the first hole K1 and the second hole K2 restrain the pair of first support 45 in the X direction and the Y direction and position the lens unit 4.

[0052] Furthermore, a pair of contact portions K3 are formed in the first component mounting area M1. Each contact portion K3 is a part of the first surface S1 of the circuit board 70. The contact portions K3 may be positioned with a slight step relative to the first surface S1. One of the pair of contact portions K3 is formed on the −X direction side and the −Y direction side of the first component mounting area M1. Meanwhile, the other of the pair of contact portions K3 is formed on the +X direction side and the +Y direction side of the first component mounting area M1. Each contact portion K3 positions the lens unit 4 in the Z direction when the tip surface of the second support 46 abuts against it.

[0053] The first hole K1 and the second hole K2 are not necessarily limited to holes that penetrate the circuit board 70, but may be recesses (holes) that open at least on the first surface S1 side. The number of holes is not limited to two, but may be one or three or more. The same applies to the contact portion K3.

[0054] Next, the multiple electronic components for operating each element on the sensor board 3 will be described. The IC chip 71 includes a core chip, which is an integrated circuit. The IC chip 71 is mounted on the first component mounting area M1 on the second surface S2 of the circuit board 70 ( FIG. 12 ). Specifically, the IC chip 71 is mounted on the −X direction side of the first component mounting area M1. The IC chip 71 is mounted on the circuit board 70 using COB (chip-on-board) technology and is electrically connected by wire bonding. The IC chip 71 is a relatively large component among the multiple electronic components, but is smaller than the connector 72, which will be described later. In particular, the height HC of the IC chip 71 in the Z direction is smaller than the height HB of the connector 72.

[0055] The connector 72 receives a mating connector terminal (not shown) extending from the main body housing 10 of the color printer 1, enabling the supply of drive voltage and the transmission and reception of various signals between the main body housing 10 and the density sensor 16. The connector 72 is, for example, a block-type terminal block. On the other hand, the mating connector terminal is, for example, a connector that can be attached to and detached from the block-type terminal block.

[0056] The connector 72 is mounted on the first surface S1 of the circuit board 70. In other words, the sensor board 3 and the connector 72 are each provided on the first surface S1 of the circuit board 70. Specifically, the connector 72 is mounted in the second component mounting area M2 on the first surface S1 of the circuit board 70. More specifically, the connector 72 is mounted in the center of the second component mounting area M2 on the first surface S1 of the circuit board 70. As a result, the connector 72 protrudes in the +Z direction from the second component mounting area M2 on the first surface S1 of the circuit board 70 by a height HB of the connector 72.

[0057] Furthermore, the connector 72 is the largest component among the multiple electronic components. Specifically, in the Z direction, the height HB of the connector 72 is greater than the height HC of the IC chip 71. Furthermore, in a plane perpendicular to the Z direction, the area of ​​the connector 72 is greater than the area of ​​the IC chip 71. Meanwhile, in the Z direction, the height HB of the connector 72 is less than the height HA of the housing 6 that covers the sensor board 3.

[0058] The connector 72 is electrically connected to each element of the element group 3E. Specifically, the connector 72 has a housing 721 and a plurality of legs 723 protruding from the housing 721. The plurality of legs 723 corresponds to an example of a "terminal" in the present disclosure. For example, the housing 721 is a rectangular parallelepiped housing.

[0059] The connector 72 is fixed to the circuit board 70 via a plurality of legs 723. Each of the legs 723 is electrically connected to a wiring 81 of the circuit board 70. Specifically, each of the legs 723 is inserted into a hole (not shown) formed in the first surface S1 of the circuit board 70 and electrically connected to the wiring 81 of the circuit board 70. In other words, the connector 72 is fixed to the circuit board 70 by a method other than wire bonding. Furthermore, the portions of the legs 723 on the first surface S1 are covered with a sealing material 82. The sealing material 82 must be non-conductive and may be formed, for example, of a silicone resin. Note that, although an example in which each of the legs 723 of the connector 72 is inserted into a hole formed in the first surface S1 of the circuit board 70 has been shown, this is not limiting. For example, each of the legs 723 of the connector 72 may be placed on the wiring 81 of the circuit board 70 coated with cream solder and then reflow soldered.

[0060] As described above, in this embodiment, both the housing 6 and the connector 72 are provided on the first surface S1 of the circuit board 70, thereby reducing the possibility that the height of the concentration sensor 16 in the Z direction will be increased. For example, the height HA of the housing 6 is greater than the height HB of the connector 72, which in turn is greater than the height HC of the IC chip 71. The IC chip 71 is mounted in the first component mounting area M1 on the second surface S2 of the circuit board 70. FIG. 14 is a side view of the concentration sensor 16 according to a reference example. FIG. 14 illustrates an example in which the connector 72 is disposed on the second surface S2. As shown in FIG. 14 , when the housing 6 is provided on the first surface S1 of the circuit board 70 and the connector 72 is provided on the second surface S2 of the circuit board 70, the height of the concentration sensor 16 is the sum of the height HA of the housing 6, the thickness HD of the circuit board 70, and the height HB of the connector 72. 12, if both the housing 6 and the connector 72 are provided on the first surface S1 of the circuit board 70, the height of the concentration sensor 16 will be the sum of the height HA of the housing 6, the thickness HD of the circuit board 70, and the height HC of the IC chip 71. As a result, the possibility that the height of the concentration sensor 16 will be increased can be reduced. In other words, the height of the concentration sensor 16 can be reduced.

[0061] Furthermore, when the density sensor 16 is attached to the main body housing 10 of the image forming unit, the possibility that the connector 72 will affect the attachment work can be reduced.

[0062] Furthermore, in this embodiment, since the connector 72 is provided on the first surface S1 of the circuit board 70, the toner patch printed on the toner carrying surface 28T faces the connector 72. However, since the portions of the legs 723 on the first surface S1 are covered with the sealing material 82, the possibility that toner in the toner patch will be attracted to the legs 723 due to static electricity or the like can be reduced. As a result, even if the connector 72 is provided on the first surface S1 of the circuit board 70, the possibility of a decrease in electrical reliability can be reduced.

[0063] The circuit board 70 has a first hole K1 and a second hole K2 that are opened on the first surface S1 and through which the first support 45 is inserted, and a contact portion K3 that receives the contact of the second support 46 along the thickness direction of the circuit board 70 on the first surface S1. The IC chip 71 is disposed in an area of ​​the second surface S2 that corresponds to the rear surface of the contact portion K3. Therefore, for example, when heat from the IC chip 71 is transmitted to the second support 46 via the circuit board 70, the second support 46 undergoes slight thermal expansion, thereby stabilizing the contact of the second support 46 with the contact portion K3. This prevents the contact of the second support 46 with the contact portion K3 from becoming unstable due to a slight tilt of the lens unit 4, and the height position of each lens portion of the lens unit 4 can be stably maintained. Furthermore, the positions of the lens portions relative to the light-emitting elements and light-receiving elements of the sensor substrate 3 can be stabilized, and variations in sensing performance can be suppressed.

[0064] The first hole K1 and the second hole K2 do not necessarily have to penetrate the circuit board 70, but may be recesses (holes) that open at least to the first surface S1 side. The contacted portion K3 and the electronic component on its back surface do not necessarily have to completely overlap, but may at least partially overlap. The electronic component on the second surface S2 of the circuit board 70 does not have to be mounted in close contact with the second surface S2, but may be mounted with a gap therebetween. Even in this case, heat can be transferred to the second support 46 side via slight heat transfer or conduction. The number of holes is not limited to two, but may be one, three, or more. The same applies to the contacted portion K3.

[0065] Furthermore, with the above configuration, it is possible to ensure sufficient space on the back surface of the circuit board 70 for mounting each electronic component.

[0066] Furthermore, in this embodiment, an IC chip 71 is disposed as an electronic component on the back surface of the contact portion K3. With this configuration, heat generated by the IC chip 71 (driver IC) is transferred to the first surface S1 of the circuit board 70, and unnecessary heat can be dissipated on the second surface S2.

[0067] Next, a detailed description will be given of the connection surface 722 of the connector 72. The housing 721 has the connection surface 722 to which the mating connector terminal is connected. The connection surface 722 is oriented in the −X direction.

[0068] The connection surface 722 has a detachable opening 724. A mating connector terminal is attached to and detached from the detachable opening 724. The detachable opening 724 is open and oriented in the -X direction. The detachable opening 724 is, for example, a rectangular parallelepiped hole. As a result, the direction in which the mating connector terminal is attached to and detached from the connector 72 is parallel to the first surface S1. Specifically, the mating connector terminal is inserted into the detachable opening 724 along the +X direction. On the other hand, the mating connector terminal is removed from the detachable opening 724 along the -X direction.

[0069] As described above, in this embodiment, the direction in which the mating connector terminals are attached to and detached from the connector 72 is parallel to the first surface S1, thereby reducing the possibility of the circuit board 70 tilting relative to the main housing 10 (transfer belt 281) of the color printer 1. For example, if the direction in which the mating connector terminals are attached to and detached from the connector 72 is perpendicular to the first surface S1, stress is generated in the region where the connector 72 is located in the direction of insertion into the connector 72, causing the region where the connector 72 is located to move in the insertion direction. As a result, there is a risk that the region where the connector 72 is not located will move in the direction opposite to the insertion direction. In contrast, if the direction in which the mating connector terminals are attached to and detached from the connector 72 is parallel to the first surface S1, even if stress is generated in the direction of insertion into the connector 72, the stress acts parallel to the first surface S1. As a result, the possibility of the circuit board 70 tilting relative to the main housing 10 (transfer belt 281) of the color printer 1 can be reduced. Therefore, the transfer belt 281 and the circuit board 70 can be maintained parallel to each other. Therefore, the possibility that the optical characteristics of the density sensor 16 will be adversely affected can be reduced.

[0070] Next, a detailed description will be given of a method for fixing the density sensor 16 to the main body housing 10 of the color printer 1. The substrate portion 7 further has a fixing hole H1 and a notch H2.

[0071] The substrate 7 is fixed to the main body housing 10 of the color printer 1 by the fixing hole H1 and the notch H2. Specifically, when the density sensor 16 is fixed to the main body housing 10 of the color printer 1, fixing bolts, screws, etc. (fixing members) are inserted into the fixing hole H1 and the notch H2, respectively.

[0072] The fixing hole H1 is formed in the first component mounting prohibited area N1. The fixing hole H1 penetrates the circuit board 70 in the thickness direction. The fixing hole H1 is a circular opening in the circuit board 70. The fixing hole H1 is arranged in the X direction with respect to the arrangement position of the connector 72 on the first surface S1. The fixing hole H1 is also arranged in the −X direction with respect to the arrangement position of the sensor board 3 on the first surface S1. Specifically, the fixing hole H1 is arranged between the connector 72 and the sensor board 3.

[0073] As described above, in this embodiment, the fixing hole H1 is located on the far side in the direction in which the mating connector terminal is inserted into the connector 72. This reduces the possibility that the concentration sensor 16 will move relative to the main body housing 10 when the mating connector terminal is inserted into the connector 72.

[0074] On the other hand, the notch H2 is formed in the second component mounting prohibited area N2. The notch H2 is a U-shaped notch with an open portion at the +X side edge of the circuit board 70. In other words, the +X side of the notch H2 is open. As a result, there is a degree of freedom in the position of the concentration sensor 16 relative to the main body housing 10, and the concentration sensor 16 can be easily fixed to the main body housing 10. Furthermore, after the board portion 7 is fixed to the main body housing 10, the notch H2 acts as a buffer against thermal expansion of the circuit board 70, reducing the possibility of warping of the circuit board 70.

[0075] Similarly to the fixing hole H1, the notch H2 is also disposed in the +X direction relative to the position of the connector 72 on the first surface S1. More specifically, the notch H2 is disposed in the +X direction relative to the position of the fixing hole H1 on the first surface S1. In other words, the notch H2 is farther away from the connector 72 than the fixing hole H1.

[0076] As described above, in this embodiment, the fixing hole H1 is located closer to the connector 72 than the cutout H2, thereby reducing the possibility of the concentration sensor 16 moving relative to the main housing 10 when the mating connector terminal is inserted into the connector 72.

[0077] Specifically, the connector 72, fixing hole H1, notch H2, and sensor board 3 are arranged in a straight line. More specifically, both the fixing hole H1 and the notch H2 are located in the direction in which the mating connector terminal is attached to or detached from the connector 72. As a result, the possibility of the sensor board 3 moving relative to the main body housing 10 when the mating connector terminal is inserted into the connector 72 can be further reduced. In other words, the fixing member inserted into the fixing hole H1 also bears the insertion load of the mating connector terminal, reducing the possibility of the concentration sensor 16 moving in the +X direction.

[0078] Specifically, the first component mounting prohibited area N1 and the second component mounting prohibited area N2 on the first surface S1 side of the circuit board 70 are brought into contact with the wall of the main housing 10, and fixing bolts, screws, etc. are inserted into the fixing holes H1 and the notches H2 from the second surface S2 side of the circuit board 70. As a result, the board unit 7 is installed relative to the main housing 10, with the first surface S1 of the circuit board 70 serving as a height reference. In other words, the element group 3E of the board unit 7 is installed relative to the measurement target TG, with the first surface S1 of the circuit board 70 serving as a height reference. This reduces the possibility that errors due to the thickness of the circuit board 70 will affect the detection accuracy of the element group 3E.

[0079] In this embodiment, the color printer 1 includes an image forming unit that forms an image, and a density sensor 16 (optical sensor) that irradiates light onto the image formed by the image forming unit and detects a predetermined characteristic. With this configuration, the density sensor 16 can be placed in a small gap in the main body housing 10 of the image forming unit.

[0080] The density sensor 16 (optical sensor) according to the present disclosure and the color printer 1 including the same have been described above, but the present disclosure is not limited to this.

[0081] <Summary of the present disclosure> In one embodiment, (1) an optical sensor includes a circuit board having a first surface and a second surface opposite the first surface, a light-emitting element and a light-receiving element, and a connector having a connection surface to be connected to a mating connector, the connector being electrically connected to each of the light-emitting element and the light-receiving element, and each of the light-emitting element, the light-receiving element, and the connector being arranged on the first surface of the circuit board.

[0082] (2) In the optical sensor of (1) above, the direction in which the mating connector is attached to or detached from the connector may be parallel to the first surface.

[0083] (3) In the optical sensor of (1) or (2) above, the circuit board may further have a fixing hole penetrating the circuit board in the thickness direction, the fixing hole may be arranged in a first direction relative to the position of the connector on the first surface, and the connection surface may be arranged facing a second direction opposite to the first direction.

[0084] (4) In the optical sensor of (3) above, the circuit board further has a notch that is open on the first direction side, and the notch can be positioned in the first direction relative to the position of the connector on the first surface.

[0085] (5) In the optical sensor of (4) above, the connector, the fixing hole, and the notch may be arranged in a straight line.

[0086] (6) In the optical sensor of (4) above, the connector, the fixing hole, the notch, the light emitting element, and the light receiving element may be arranged in a straight line.

[0087] (7) An optical sensor according to any one of (1) to (6) above, further comprising a sensor section in which the light-emitting element and the light-receiving element are arranged, and a fixing hole penetrating the circuit board in the thickness direction can be arranged between the connector and the sensor section.

[0088] (8) In the optical sensor of (1) or (2) above, the circuit board further has a fixing hole penetrating the circuit board in the thickness direction and a notch that is open on a predetermined side, and the circuit board can be fixed to an external device by the fixing hole and the notch.

[0089] (9) In the optical sensor of (8) above, the notch may be spaced apart from the fixing hole with respect to the connector.

[0090] (10) Any of the optical sensors described in (1) to (9) above may further include a cover member that covers the light-emitting element and the light-receiving element, and the height of the connector may be lower than the height of the cover member.

[0091] (11) In any of the optical sensors (1) to (10) above, the circuit board may further have wiring electrically connected to each of the light-emitting elements and the light-receiving elements inside or on the second surface, the connector may have a housing and terminals protruding from the housing, the terminals may be electrically connected to the wiring, and the portions of the terminals on the first surface may be covered with a sealing material.

[0092] (12) Any of the optical sensors (1) to (9) above may further include a lens portion located between the optical paths of the light-emitting element and the light-receiving element, a cover member including a first support and a second support extending from the lens portion toward the circuit board, and an electronic component mounted on the second surface of the circuit board, wherein the circuit board has a hole portion through which the first support is inserted and an abutment portion on the first surface against which the second support abuts along the thickness direction of the circuit board, and the electronic component may be arranged in an area of ​​the second surface corresponding to the back surface of the abutment portion.

[0093] (13) In the optical sensor of (12) above, the electronic component can be an IC chip.

[0094] (14) In the optical sensor of (12) or (13) above, the cover member has a pair of the first pillars and a pair of the second pillars, and the circuit board has a pair of the hole portions through which the pair of first pillars are inserted and a pair of the abutment portions against which the pair of second pillars abut, and when viewed from a direction perpendicular to the first surface, a straight line connecting the pair of hole portions and a straight line connecting the pair of abutment portions intersect with each other.

[0095] In one embodiment, (15) an image forming device includes an image forming unit that forms an image, and an optical sensor of any one of (1) to (14) that irradiates light onto the image formed by the image forming unit and detects a predetermined characteristic.

[0096] REFERENCE SIGNS LIST 1 color printer 10 main body housing 16 density sensor (light sensor) 3 sensor board (sensor section) 3E element group 3M mounting surface 30 board 31, 32 first light emitting / receiving pair, second light emitting / receiving pair 33, 34 first light emitting element, first light receiving element 35, 36 second light emitting element, second light receiving element 4 lens unit (cover member) 45 first support 46 second support 6 housing (cover member) 61 bottom plate 7 board 70 circuit board 71 IC chip (electronic component) 72 connector (electronic component) 721 housing 722 terminal 723 connection surface 724 attachment / detachment opening H1 fixing hole H2 notch K1 first hole (hole) K2 second hole (hole) K3 contact portion S1 first surface S2 second surface

Claims

1. An optical sensor comprising: a circuit board having a first surface and a second surface opposite the first surface; a light-emitting element and a light-receiving element; and a connector having a connection surface to be connected to a mating connector, wherein the connector is electrically connected to each of the light-emitting element and the light-receiving element, and each of the light-emitting element, the light-receiving element, and the connector is disposed on the first surface of the circuit board.

2. The optical sensor according to claim 1, wherein the direction in which the mating connector is attached to or detached from the connector is parallel to the first surface.

3. An optical sensor as described in claim 1 or claim 2, wherein the circuit board further has a fixing hole penetrating the circuit board in the thickness direction, the fixing hole is arranged in a first direction relative to the position of the connector on the first surface, and the connection surface is arranged facing a second direction opposite to the first direction.

4. The optical sensor according to claim 3, wherein the circuit board further has a notch that is open on the first direction side, and the notch is positioned in the first direction relative to the position of the connector on the first surface.

5. The optical sensor according to claim 4, wherein the connector, the fixing hole, and the notch are arranged in a straight line.

6. The optical sensor according to claim 4, wherein the connector, the fixing hole, the notch, the light emitting element, and the light receiving element are arranged in a straight line.

7. An optical sensor according to any one of claims 1 to 6, further comprising a sensor section in which the light-emitting element and the light-receiving element are arranged, and a fixing hole penetrating the circuit board in the thickness direction is arranged between the connector and the sensor section.

8. An optical sensor as described in claim 1 or claim 2, wherein the circuit board further has a fixing hole penetrating the circuit board in the thickness direction and a notch that is open on a predetermined side, and the circuit board is fixed to an external device by the fixing hole and the notch.

9. The optical sensor according to claim 8, wherein the notch is spaced apart from the fixing hole relative to the connector.

10. An optical sensor according to any one of claims 1 to 9, further comprising a cover member that covers the light-emitting element and the light-receiving element, and the height of the connector is lower than the height of the cover member.

11. An optical sensor as described in any one of claims 1 to 10, wherein the circuit board further has wiring electrically connected to each of the light-emitting elements and the light-receiving elements inside or on the second surface, the connector has a housing and terminals protruding from the housing, the terminals are electrically connected to the wiring, and the portions of the terminals on the first surface are covered with a sealing material.

12. An optical sensor as described in any one of claims 1 to 9, further comprising: a cover member including a lens portion located between the optical paths of the light-emitting element and the light-receiving element, and a first support and a second support extending from the lens portion toward the circuit board; and an electronic component mounted on the second surface of the circuit board, wherein the circuit board has a hole portion through which the first support is inserted, and an abutment portion on the first surface against which the second support abuts along the thickness direction of the circuit board, and the electronic component is arranged in an area of ​​the second surface corresponding to the back surface of the abutment portion.

13. The optical sensor of claim 12, wherein the electronic component is an IC chip.

14. An optical sensor as described in claim 12 or claim 13, wherein the cover member has a pair of the first supports and a pair of the second supports, the circuit board has a pair of holes through which the pair of first supports are inserted and a pair of abutment portions against which the pair of second supports abut, and when viewed from a direction perpendicular to the first surface, a straight line connecting the pair of hole portions and a straight line connecting the pair of abutment portions intersect with each other.

15. An image forming apparatus comprising: an image forming unit that forms an image; and an optical sensor according to any one of claims 1 to 14 that irradiates light onto the image formed by the image forming unit and detects a predetermined characteristic.

Images