Optical sensor and image forming apparatus equipped therewith

Abstract

To provide an optical sensor that can suppress increases in height. [Solution] The light sensor comprises a circuit board having a first surface and a second surface opposite to the first surface, a light-emitting element and a light-receiving element, and a connector having a connection surface 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 arranged on the first surface of the circuit board.

Description

Technical Field

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

Background Art

[0002] An optical sensor including a light emitting element that emits measurement light to be irradiated onto a measurement object and a light receiving element that receives reflected light of the measurement light is known. The optical sensor is used, for example, for detecting a patch image for measuring toner density or color shift, which is formed on an intermediate transfer belt of a tandem type image forming apparatus. Patent Document 1 discloses an optical sensor including a light emitting element and a light receiving element for detecting regular reflection light from a patch image, a lens unit that transfers light between these elements, a circuit board, and a connector. The circuit board has a first surface and a second surface opposite to the first surface. The light emitting element and the light receiving element are mounted on the first surface of the circuit board. On the other hand, the connector is mounted on the second surface of the circuit board.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above optical sensor, since the light emitting element, the light receiving element, and the lens unit are mounted on the first surface of the circuit board, and the connector is mounted on the second surface opposite to the first surface, the height of the optical sensor may increase.

[0005] An object of the present disclosure is to provide an optical sensor capable of suppressing an increase in height.

Means for Solving the Problems

[0006] An optical sensor according to one aspect of the present disclosure comprises a circuit board having a first surface and a second surface opposite to the first surface, a light-emitting element and a light-receiving element, and a connector having a connection surface 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 arranged on the first surface of the circuit board.

[0007] An image forming apparatus relating to another aspect of the present disclosure comprises an image forming unit that forms an image, and the above-described optical sensor that irradiates light onto the image formed by the image forming unit and detects predetermined characteristics. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide an optical sensor capable of suppressing an increase in height, and an image forming apparatus equipped with the optical sensor. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic cross-sectional view showing the internal structure of a color printer to which the optical sensor of this disclosure is applied. [Figure 2] Figure 2 is a cross-sectional view showing a part of an optical sensor according to one embodiment of the present disclosure. [Figure 3] Figures 3(A) and (B) are perspective views showing the external appearance of a part of an optical sensor according to one embodiment of the present disclosure. [Figure 4] Figure 4(A) is a top view of a portion of the optical sensor shown in Figure 3, Figure 4(B) is a bottom view, and Figure 4(C) is a side view. [Figure 5] Figure 5 is a cross-sectional view of the VV line in Figure 4(B). [Figure 6] Figure 6 is a plan view of a concentration sensor according to one embodiment of the present disclosure. [Figure 7] Figure 7 is a side view of a concentration sensor according to one embodiment of the present disclosure. [Figure 8] Figure 8 is a bottom view of a concentration sensor according to one embodiment of the present disclosure. [Figure 9] Figure 9 is a side view of a concentration sensor related to a reference example. [Modes for carrying out the invention]

[0010] The optical sensor of this disclosure will be described below with reference to the drawings. The optical sensor of this disclosure is a module that measures the physical properties of an object by irradiating it with measurement light and receiving the reflected light. There are no particular restrictions on the object to be measured, and it can be a solid, semi-solid, liquid, powder, etc. There are also no particular restrictions on the physical properties to be measured, as long as they can be analyzed from the reflected light. For example, the optical sensor of this disclosure is suitable for measuring the color and density of an object to be measured. In the embodiment described below, an optical sensor assembled into a color printer for detecting the density of toner for image formation will be given as an example.

[0011] [Description of color printer] First, the configuration of a color printer to which the optical sensor of this disclosure is applied will be described. Figure 1 is a schematic cross-sectional view showing the internal structure of a tandem-type color printer 1. The color printer 1 includes image forming units (image forming sections) 2Y, 2C, 2M, 2Bk, an optical scanning device 23, an intermediate transfer unit 28, and a fuser 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 feed tray 13 is provided on the side wall of the main body housing 10, and a paper feed cassette 14 for accommodating sheets such as automatic feeders is provided at the bottom of the main body housing 10. The main body housing 10 is an example of an "external device" in this disclosure.

[0012] The 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 predetermined intervals in the horizontal direction. Each image forming unit 2Y, 2C, 2M, and 2Bk includes a photoreceptor drum 21 having a circumferential surface for carrying an electrostatic latent image and a toner image, a charger 22 for charging the circumferential surface of the photoreceptor drum 21, a developer 24 for depositing developer onto the electrostatic latent image to form a toner image, toner containers 25Y, 25C, 25M, and 25Bk for supplying toner of each color to the developer 24, a primary transfer roller 26 for primary transfer of the toner image formed on the photoreceptor drum 21, and a cleaning device 27 for removing residual toner from the circumferential surface of the photoreceptor drum 21. The optical scanning device 23 scans the circumferential surface of each color photoreceptor drum 21 with a beam in the main scanning direction, and forms an electrostatic latent image on the circumferential surface for forming a toner image.

[0013] The intermediate transfer unit 28 performs primary transfer of the toner image formed on the photoreceptor drum 21. The intermediate transfer unit 28 includes a transfer belt 281 that circulates while in contact with the circumferential surface of each photoreceptor drum 21, and a drive roller 282 and a driven roller 283 over which the transfer belt 281 is stretched. The toner images on each color photoreceptor drum 21 are superimposed on the same location on the transfer belt 281 and primary transferred. This forms a full-color toner image on the transfer belt 281. Opposite the drive roller 282, a secondary transfer roller 15 is positioned to form a secondary transfer nip T across the transfer belt 281. The full-color toner image on the transfer belt 281 is secondary transferred onto the sheet at the secondary transfer nip T.

[0014] The fixing unit 29 includes a fixing roller 291 with a built-in heat source and a pressure roller 292 that, together with the fixing roller 291, forms a fixing nip section N. The fixing unit 29 performs a fixing process on the sheet onto which the toner image has been transferred in the secondary transfer nip section T, by heating and pressurizing the sheet in the fixing nip section N, thereby welding the toner to the sheet. The sheet that has undergone the fixing process is discharged from the sheet discharge port 12 toward the output tray 11.

[0015] Inside the main body housing 10, a density sensor 16 is arranged. The density sensor 16 is an example of the "optical sensor" of the present disclosure. The density sensor 16 is arranged to face the outer peripheral surface of the transfer belt 281 on which the toner image is carried in the vicinity of the secondary transfer nip portion T. 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.

[0016] [Detection principle of toner] FIG. 2 is a cross-sectional view showing the density sensor 16 according to the present 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 measurement object of the density sensor 16 is a toner patch printed on the toner-carrying surface 28T of the transfer belt 281.

[0017] 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 the "sensor unit" in the present disclosure.

[0018] The element group 3E includes a first light emitting and receiving pair 31 for detecting black toner BT and a second light emitting and receiving pair 32 for detecting color toner CT. The first light emitting and receiving pair 31 is composed 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 and receiving pair 32 is composed 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 that of the first light emitting and receiving pair 31.

[0019] The first light-emitting element 33 and the second light-emitting element 35 are LEDs (Light Emitting Diodes) that emit light of a predetermined wavelength. The first photodetector 34 and the second photodetector 36 are PDs (Photo Diodes) that output a current corresponding to the amount of light received. Each element of the element group 3E is arranged in a straight line. Specifically, each element of the element group 3E is arranged in a line on the mounting surface 3M in the order of the first light-emitting element 33, the first photodetector 34, the second photodetector 36, and the second light-emitting element 35. Each element of the element group 3E does not necessarily have to be arranged in a strictly straight line; it may be arranged in a row with an offset that can be considered equivalent to a straight line.

[0020] The lens unit 4 is positioned in front of the mounting surface 3M, that is, between the sensor substrate 3 and the toner-carrying surface 28T. The lens unit 4 includes a first lens section 41, a second lens section 42, a third lens section 43, and a fourth lens section 44 as lens sections for focusing light. The lens sections are located in the optical path between the light-emitting element and the light-receiving element. In the optical path of the first light-emitting pair 31, the first lens section 41 is positioned in front of the first light-emitting element 33, and the second lens section 42 is positioned behind the first light-receiving element 34. In the optical path of the second light-emitting pair 32, the third lens section 43 is positioned in front of the second light-emitting element 35, and the fourth lens section 44 is positioned behind the second light-receiving element 36. The lens unit 4 further includes a holder section 40 for holding each lens section.

[0021] The first lens unit 41 focuses the light emitted by the first light-emitting element 33 to create a first measurement light L11 that is spot-illuminated at a predetermined position on the toner-carrying surface 28T. The second lens unit 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 unit 43 focuses the light emitted by the second light-emitting element 35 to create a second measurement light L12 that is spot-illuminated at a predetermined position on the toner-carrying surface 28T. The fourth lens unit 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 light image of the diffusely reflected light L3 created by the fourth lens unit 44.

[0022] The first light-shielding wall 51 and the second light-shielding wall 52 are opaque materials that do not allow light to pass through. The first light-shielding wall 51 is positioned 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 prevents light emitted from the first light-emitting element 33 from going directly to the first light-receiving element 34 without passing through the toner-carrying surface 28T. In other words, it prevents light before it is focused by the first lens portion 41 from being received by the first light-receiving element 34. The second light-shielding wall 52 is positioned 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 prevents light emitted from the second light-emitting element 35 from going directly to the second light-receiving element 36. In other words, it prevents light before it is focused by the third lens portion 43 from being received by the second light-receiving element 36.

[0023] An open space OS is provided in front of the mounting surface 3M between the first light-receiving pair 31 and the second light-receiving pair 32, and 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 substantially 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 perfect space, and may contain small protrusions or structures that do not affect the optics.

[0024] [Description of some of the external appearance of the concentration sensor (external appearance of the sensor board, lens unit, and housing)] Figure 3(A) is a bottom perspective view showing a part of the external appearance of the concentration sensor 16 according to this embodiment, and Figure 3(B) is a top perspective view. Figure 4(A) is a top view of a part of the concentration sensor 16, Figure 4(B) is a bottom view, and Figure 4(C) is a side view.

[0025] The density sensor 16 includes a housing 6 in addition to the aforementioned sensor substrate 3 and lens unit 4. The housing 6 and lens unit 4 are examples of "cover members" in this disclosure. As shown in Figure 4(B), 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-receiving pair 31 for detecting black toner BT and a second light-receiving pair 32 for detecting color toner CT. The element group 3E is arranged in a line in the order of 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.

[0026] 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 Figure 5). These four lens portions 41, 42, 43, and 44 are arranged in the direction of the arrangement of the element group 3E and constitute a lens mass. The holder portion 40 has a rectangular parallelepiped shape that surrounds the lens mass, and the upper surface of the holder portion 40 is recessed in the portion of the lens mass.

[0027] The lens unit 4 includes a pair of first pillars 45 and a pair of second pillars 46 for positioning the lens portion 4R. For example, each of the pair of first pillars 45 and the pair of second pillars 46 is cylindrical. The pair of first pillars 45 and the pair of second pillars 46 protrude from the lower surface of the holder portion 40. Each first pillar 45 and each second pillar 46 extends from the lens portion 4R toward the circuit board 70 described later. Each first pillar 45 is projected near one diagonal corner of the rectangular lens unit 4. Each second pillar 46 is provided near the other diagonal corner of the lens unit 4 and is a convex portion that protrudes less from the lower surface of the holder portion 40 than the first pillars 45. The first pillars 45 are mainly positioning projections for the lens unit 4 in the horizontal direction (along the substrate). The second pillars 46 are positioning projections for the lens unit 4 in the height direction.

[0028] The housing 6 is a rectangular parallelepiped housing that includes a bottom plate 61 and side plates 62 and has a cavity capable of housing the lens unit 4. The lens unit 4 is fitted into the housing 6. The bottom plate 61 faces the bottom surface of the lens unit 4. The side plates 62 are erected from the periphery of the bottom plate 61 and cover the sides of the lens unit 4. The bottom plate 61 and the side plates 62 are bonded and fixed together at the outer circumference of the bottom plate 61, forming a single unit.

[0029] [Description of some internal structures of the concentration sensor (light-shielding wall and lens unit)] Figure 5 is a cross-sectional view of the VV line in Figure 4(B). The lens unit 4 is fitted into the housing 6 such that the lens portion 4R covers the bottom plate 61 on the sensor substrate 3. The first light-shielding wall 51 has a smaller protrusion height from the bottom plate 61 than the second light-shielding wall 52. For this reason, the lens portion 4R, which is positioned 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. The four lens portions 41, 42, 43, and 44 of the lens portion 4R each have a convex lens surface on both the upper and lower sides of the lens unit 4.

[0030] Figure 5 shows the state in which the first measurement light L11 and the second measurement light L12 are emitted from the density sensor 16 to the density detection position DP where the object to be measured TG is printed on the toner-carrying surface 28T of the transfer belt 281. It also shows the state in which specular reflected light L2 and diffuse reflected light L3 from the object to be measured TG are incident on the density sensor 16. As previously described, the object to be measured TG is black toner BT and color toner CT.

[0031] The first lens section 41 is positioned opposite the first aperture 613 of the bottom plate 61. The first lens section 41 collects the light emitted from the first light-emitting element 33 and passing through the first aperture 613, and irradiates the density detection position DP as the first measurement light L11. The second lens section 42 and the fourth lens section 44 are positioned opposite the third aperture 615 via an open space OS. The second lens section 42 collects the specularly reflected light L2 of the first measurement light L11 from the density detection position DP and directs it into the first photodetector 34. The first light-shielding wall 51 blocks the light emitted from the first light-emitting element 33 that is directed directly towards the first photodetector 34.

[0032] The third lens section 43 is positioned opposite the second aperture 614. The third lens section 43 collects the light emitted from the second light-emitting element 35 and passing through the second aperture 614, and irradiates the density detection position DP with the second measurement light L12. The fourth lens section 44 collects a portion of the diffusely reflected light generated at the density detection position DP of the second measurement light L12 and directs it onto the second photodetector 36 as diffusely reflected light L3. The second light-shielding wall 52 blocks the light emitted from the second light-emitting element 35 that is directed directly towards the second photodetector 36.

[0033] In this embodiment, the arrangement order of the element group on the sensor substrate 3 is the arrangement order shown in Figure 2 above. Therefore, specular reflected light L2 and diffuse reflected light L3 pass through the open space OS. In the open space OS, that is, between the first light-shielding wall 51 and the second light-shielding wall 52, there are substantially no objects that reflect light. Therefore, it is difficult for unnecessary reflected light to be generated between the first light-shielding wall 51 and the second light-shielding wall 52. Accordingly, it is possible to suppress stray light other than the specular reflected light L2 or diffuse reflected light L3 that should be detected from entering the first light-receiving element 34 or the second light-receiving element 36. Note that other arrangement orders of element group 3E different from the above may also be applied to this embodiment. For example, each element of element group 3E may be arranged in a line on the mounting surface 3M in the order of first light-receiving element 34, first light-emitting element 33, second light-receiving element 36, and second light-emitting element 35.

[0034] [Description of the remaining part of the concentration sensor (the circuit board)] Next, the substrate portion 7 of the concentration sensor 16 will be described in detail. In addition to the sensor substrate 3, lens unit 4, and housing 6 described above, the concentration sensor 16 further comprises the substrate portion 7. Figure 6 is a plan view of the concentration sensor 16 according to this embodiment. Figure 7 is a side view of the concentration sensor 16 according to one embodiment of the present disclosure. Figure 8 is a bottom view of the concentration sensor 16 according to one embodiment of the present disclosure. In Figures 6 to 8, the directional relationships will be explained using mutually orthogonal XYZ Cartesian coordinates. One side in the X direction will be referred to as the "+X side," and the other side opposite to the one side in the X direction will be referred to as the "-X side." One side in the Y direction will be referred to as the "+Y side," and the other side opposite to the one side in the Y direction will be referred to as the "-Y side." One side in the Z direction will be referred to as the "+Z side," and the other side opposite to the one side in the Z direction will be referred to as the "-Z side."

[0035] Figures 6 to 8 show the X, Y, and Z directions, respectively. These directions are shown for convenience to explain the structure of the concentration sensor 16 according to this embodiment and do not limit the manner in which the concentration sensor 16 can be used according to this disclosure. Furthermore, the +X direction corresponds to an example of the "first direction" and "predetermined direction" in this disclosure. Also, the -X direction corresponds to an example of the "second direction" in this disclosure.

[0036] Multiple electronic components for operating each element of the sensor board 3 are mounted on the substrate section 7. These multiple electronic components include an IC chip 71 and a connector 72. Although other electronic components smaller than the IC chip 71 and connector 72 are also mounted on the substrate section 7, their description is omitted here. As shown in Figures 6 to 8, the substrate section 7 comprises a circuit board 70 and the IC chip 71 and connector 72 mounted on the circuit board 70.

[0037] The circuit board 70 consists 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 dimensions that extend longer on both sides than the housing 6 described above. The circuit board 70 has a first surface S1 and a second surface S2 which is the surface opposite to the first surface S1. The first surface S1 and the second surface S2 are surfaces that extend in the longitudinal direction and the 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.

[0038] As an example, the circuit board 70 is made of epoxy glass. The circuit board 70 also has wiring 81 arranged inside the circuit board 70 or on the second surface S2 (see Figure 8). The wiring 81 is electrically connected to the circuit pattern on the substrate 30, the IC chip 71, and the connector 72, respectively. 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.

[0039] Furthermore, 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. More specifically, each of the first surface S1 and the second surface S2 of the circuit board 70 further has 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. In other words, each of the first surface S1 and the second surface S2 of the circuit board 70 has a second component mounting area M2, which will be described later, in addition to the first component mounting area M1. These areas are arranged from the -X side to the +X side in the order of 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 long in the longitudinal direction of the circuit board 70. More specifically, the area of ​​the first component mounting area M1 is larger than the area of ​​the sensor substrate 3.

[0040] Furthermore, the circuit board 70 has a first visual pattern 70A, a second visual pattern 70B, and a third visual pattern 70C formed on it. For example, the circuit board 70 is made of a green substrate, and each of the first visual pattern 70A, the second visual pattern 70B, and the third visual pattern 70C is a white linear portion applied to the substrate. Note that each of the first visual pattern 70A, the second visual pattern 70B, and the third visual pattern 70C may be a groove or the like formed on the circuit board 70.

[0041] The first visual pattern 70A, the second visual pattern 70B, and the third visual pattern 70C are arranged in the +X direction in that order. The area between the second visual pattern 70B and the third visual pattern 70C corresponds to the first component mounting area M1. The area between the first visual pattern 70A and the second visual pattern 70B corresponds to the first component mounting prohibited area N1. Furthermore, the area positioned in the +X direction relative to the placement position of the third visual pattern 70C on the circuit board 70 corresponds to the second component mounting prohibited area N2. In addition, the area positioned in the -X direction relative to the placement position of the first visual pattern 70A on the circuit board 70 corresponds to the second component mounting area M2.

[0042] As described above, the sensor substrate 3 includes a substrate 30 and a group of elements 3E mounted on the substrate 30. The substrate 30 is a rectangular plate-shaped member with its length 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 arranged 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 Figure 4(B)). Specifically, the longitudinal center line of the first component mounting area M1 coincides with the longitudinal center line of the sensor substrate 3.

[0043] A circuit pattern for mounting the element group 3E is printed on the mounting surface 3M of the substrate 30. The light-receiving element and light-emitting element constituting the element group 3E are mounted on the circuit pattern. In other embodiments of the substrate 30 according to this disclosure, a sensor substrate 3 may be used in which a semiconductor substrate such as a silicon substrate is used as the element group 3E, and each element is directly formed on the semiconductor substrate. Alternatively, the element group 3E may be mounted on a circuit board 70 instead of on the substrate 30.

[0044] The housing 6 covers the sensor substrate 3. As described above, the housing 6 includes a bottom plate 61 and side plates 62. The housing 6 is mounted on the first component mounting area M1 on the first surface S1 of the circuit board 70. As a result, the housing 6 protrudes from the first surface S1 of the circuit board 70 along the Z direction by the height HA of the bottom plate 61 and side plates 62. The housing 6 houses the lens unit 4. As described above, the lens unit 4 mainly includes a pair of first support columns 45 which are positioning protrusions in the X and Y directions (direction along the substrate) of the lens unit 4, and a pair of second support columns 46 which are positioning protrusions in the Z direction of the lens unit 4.

[0045] A first hole K1 and a second hole K2 are formed in the first component mounting area M1. For example, the first hole K1 is circular, and the second hole K2 is formed as an elongated hole along the longitudinal direction of the circuit board 70. The tip of the first support column 45 is inserted through each of the first hole K1 and the second hole K2. The inner diameter of the first hole K1 and the inner diameter of the second hole K2 in the short direction are set to correspond to the outer diameter of the tip of the first support column 45. The first hole K1 is formed on the -X direction side and the +Y direction side of the first component mounting area M1. On the other hand, 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 columns 45 in the X and Y directions and are responsible for positioning the lens unit 4.

[0046] Furthermore, a pair of contact portions K3 are formed in the first component mounting area M1. Each contact portion K3 is 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 and -Y side of the first component mounting area M1. The other contact portion K3 is formed on the +X and +Y side of the first component mounting area M1. The lens unit 4 is positioned in the Z direction by the tip surface of the second support column 46 contacting each contact portion K3.

[0047] Furthermore, the first hole K1 and the second hole K2 are not necessarily limited to those that penetrate the circuit board 70, but may be recesses (holes) that open at least on the first surface S1 side. Also, the number of holes is not limited to two, but may be one or three or more. The same applies to the contacted portion K3.

[0048] Next, we will describe the multiple electronic components necessary to operate each element of the sensor board 3. 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 (Figure 7). Specifically, the IC chip 71 is mounted on the -X side of the first component mounting area M1. The IC chip 71 is mounted on the circuit board 70 using COB (Chip On Board) mounting and is electrically connected by wire bonding. The IC chip 71 is a relatively large component among the multiple electronic components, but it is smaller than the connector 72, which will be described later. In particular, in the Z direction, the height HC of the IC chip 71 is lower than the height HB of the connector 72.

[0049] Connector 72 accepts the mating connector terminals (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. Connector 72 is, for example, a block-type terminal block. On the other hand, the mating connector terminals are, for example, a connection connector that can be attached to and detached from the block-type terminal block.

[0050] The connector 72 is mounted on the first surface S1 of the circuit board 70. In other words, both the sensor board 3 and the connector 72 are 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 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 along the +Z direction.

[0051] 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 higher than the height HC of the IC chip 71. Also, in a plane perpendicular to the Z direction, the area of ​​the connector 72 is larger than the area of ​​the IC chip 71. On the other hand, in the Z direction, the height HB of the connector 72 is lower than the height HA of the housing 6 covering the sensor substrate 3.

[0052] 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 are examples of "terminals" in this disclosure. For example, the housing 721 is a rectangular parallelepiped housing.

[0053] The connector 72 is fixed to the circuit board 70 via a plurality of legs 723. Each of the multiple legs 723 is electrically connected to the wiring 81 of the circuit board 70. Specifically, each of the multiple 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 in a way different from wire bonding. In addition, the portion of the multiple legs 723 on the first surface S1 is covered with a sealing material 82. The sealing material 82 must be non-conductive and is formed, for example, from silicone resin. Note that although an example has been shown in which each of the multiple legs 723 of the connector 72 is inserted into a hole formed in the first surface S1 of the circuit board 70, it is not limited to this. For example, each of the multiple legs 723 of the connector 72 may be placed on the wiring 81 of the circuit board 70 to which solder paste has been applied and then soldered by reflow soldering.

[0054] As described above, in this embodiment, since both the housing 6 and the connector 72 are provided on the first surface S1 of the circuit board 70, it is possible to suppress an increase in the height of the concentration sensor 16 in the Z direction. For example, the height HA of the housing 6 is higher than the height HB of the connector 72, and the height HB of the connector 72 is higher than the height HC of the IC chip 71. The IC chip 71 is mounted on the first component mounting area M1 on the second surface S2 of the circuit board 70. Here, Figure 9 is a side view of a concentration sensor 16 according to a reference example. Figure 9 shows an example in which the connector 72 is arranged on the second surface S2. As shown in Figure 9, 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. In contrast, as shown in Figure 7, when both the housing 6 and the connector 72 are mounted on the first surface S1 of the circuit board 70, the height of the concentration sensor 16 becomes 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, it is possible to suppress the height of the concentration sensor 16 from becoming too high. In other words, the height of the concentration sensor 16 can be reduced.

[0055] Furthermore, when attaching the density sensor 16 to the main housing 10 of the image forming unit, the connector 72 can be prevented from interfering with the attachment process.

[0056] 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 and the connector 72 face each other. However, since the portion of the multiple legs 723 on the first surface S1 is covered with the sealing material 82, it is possible to suppress the attraction of toner in the toner patch to the multiple legs 723 due to the action of static electricity or the like. As a result, even if the connector 72 is provided on the first surface S1 of the circuit board 70, a decrease in electrical reliability can be suppressed.

[0057] Next, the connection surface 722 of the connector 72 will be described in detail. The housing 721 has a connection surface 722 to which the mating connector terminals are connected. The connection surface 722 is oriented in the -X direction.

[0058] The connecting surface 722 has a detachment opening 724. The mating connector terminals are detached from the detachment opening 724. The detachment opening 724 is open and faces the -X direction. The detachment opening 724 is, for example, a rectangular parallelepiped-shaped hole. As a result, the direction in which the mating connector terminals are detached from the connector 72 is parallel to the first surface S1. Specifically, the mating connector terminals are inserted into the detachment opening 724 along the +X direction. On the other hand, the mating connector terminals are withdrawn from the detachment opening 724 along the -X direction.

[0059] As described above, in this embodiment, since the direction in which the mating connector terminals are attached to and detached from the connector 72 is parallel to the first surface S1, it is possible to suppress tilting of the circuit board 70 relative to the main body 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 will be generated in the area where the connector 72 is located in the direction of insertion into the connector 72, causing the area where the connector 72 is located to move in the insertion direction. Consequently, there is a risk that the area where the connector 72 is not located will move in the opposite direction 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 will act parallel to the first surface S1. As a result, it is possible to suppress tilting of the circuit board 70 relative to the main body housing 10 (transfer belt 281) of the color printer 1. Therefore, the transfer belt 281 and the circuit board 70 can be kept parallel. Therefore, adverse effects on the optical characteristics of the concentration sensor 16 can be suppressed.

[0060] Next, we will explain in detail how to fix the density sensor 16 to the main body housing 10 of the color printer 1. The circuit board portion 7 further has a fixing hole H1 and a notch H2.

[0061] The substrate portion 7 is fixed to the main body housing 10 of the color printer 1 by fixing holes H1 and notches H2. Specifically, fixing bolts, screws, etc. (fixing members) are inserted through the fixing holes H1 and notches H2, respectively, when the density sensor 16 is fixed to the main body housing 10 of the color printer 1.

[0062] 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 positioned in the X direction with respect to the placement position of the connector 72 on the first surface S1. Also, the fixing hole H1 is positioned in the -X direction with respect to the placement position of the sensor board 3 on the first surface S1. In detail, the fixing hole H1 is positioned between the connector 72 and the sensor board 3.

[0063] As described above, in this embodiment, the fixing hole H1 is located on the inner side in the direction in which the mating connector terminal is inserted into the connector 72. Therefore, when the mating connector terminal is inserted into the connector 72, it is possible to suppress the movement of the concentration sensor 16 relative to the main housing 10.

[0064] 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 notch H2 is open on the +X side. As a result, there is a degree of freedom in the position of the concentration sensor 16 relative to the main housing 10, and the concentration sensor 16 can be easily fixed to the main housing 10. Furthermore, after the substrate portion 7 is fixed to the main housing 10, the notch H2 acts as a buffer against thermal expansion of the circuit board 70, suppressing warping of the circuit board 70.

[0065] Furthermore, the notch H2 is positioned in the +X direction relative to the position of the connector 72 on the first surface S1, similar to the fixing hole H1. More specifically, the notch H2 is positioned 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 spaced further apart from the fixing hole H1 relative to the connector 72.

[0066] As described above, in this embodiment, since the fixing hole H1 is located closer to the connector 72 than the notch H2, it is possible to suppress the movement of the concentration sensor 16 relative to the main body housing 10 when the mating connector terminal is inserted into the connector 72.

[0067] More specifically, the connector 72, the fixing hole H1, the notch H2, and the sensor substrate 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 terminals are attached to and detached from the connector 72. As a result, the movement of the sensor substrate 3 relative to the main housing 10 when the mating connector terminals are inserted into the connector 72 can be further suppressed. That is, the fixing member inserted through the fixing hole H1 also receives the insertion load of the mating connector terminals, so the movement of the concentration sensor 16 in the +X direction is suppressed.

[0068] In detail, 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 from the second surface S2 side of the circuit board 70 into the fixing holes H1 and notches H2, respectively. As a result, the circuit board portion 7 is installed relative to the main housing 10 with the first surface S1 of the circuit board 70 as the height reference. In other words, the element group 3E of the circuit board portion 7 is installed relative to the object to be measured TG with the first surface S1 of the circuit board 70 as the height reference. Therefore, it is possible to suppress the effect of errors due to the thickness of the circuit board 70 on the detection accuracy of the element group 3E.

[0069] Furthermore, in this embodiment, the color printer 1 includes an image forming unit that forms an image, and a density sensor 16 (light sensor) that irradiates light onto the image formed by the image forming unit and detects predetermined characteristics. With this configuration, the density sensor 16 can be placed in a small gap within the main housing 10 of the image forming unit.

[0070] The density sensor 16 (optical sensor) and the color printer 1 equipped therewith have been described above, but the disclosure is not limited thereto. [Explanation of Symbols]

[0071] 1. Color printer 10 Main Housing 16. Concentration sensor (light sensor) 3. Sensor board (sensor part) 3E element group 3M mounting surface 30 circuit boards 31, 32 First light-receiving pair, second light-receiving pair 33, 34 First light-emitting element, first photodetector 35, 36 Second light-emitting element, second photodetector 4 Lens Units 45 1st pillar 46 Second pillar 6. Housing (cover component) 61 Bottom plate 7 circuit boards 70 Circuit boards 71 IC chips (electronic components) 72 Connectors (Electronic Components) 721 cabinet 722 terminals 723 Connection surface 724 Detachment port H1 fixing hole H2 Notch K1 1st hole K2 2nd hole K3 Abutted part S1 page 1 S2 side 2

Claims

1. A circuit board having a first surface and a second surface opposite to the first surface, A light-emitting element and a light-receiving element, A connector having a connection surface that connects to a mating connector, Equipped with, The connector is electrically connected to the light-emitting element and the light-receiving element, Each of the light-emitting element, the light-receiving element, and the connector is arranged on the first surface of the circuit board, forming an optical sensor.

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

3. The circuit board further has fixing holes that penetrate the circuit board in the thickness direction, The fixing holes are arranged in a first direction with respect to the position of the connector on the first surface. The optical sensor according to claim 1, wherein the connection surface is arranged to face a second direction opposite to the first direction.

4. The circuit board further has a notch that is open on the first direction side, The optical sensor according to claim 3, wherein the notch is arranged in a first direction with respect 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. The sensor further comprises the light-emitting element and the light-receiving element arranged in the sensor section. The optical sensor according to claim 1, wherein a fixing hole is disposed between the connector and the sensor portion, the fixing hole penetrating the circuit board in the thickness direction.

8. The aforementioned circuit board is The circuit board has a fixing hole that penetrates in the thickness direction, A notch that is open on the side in a predetermined direction, It further possesses, The optical sensor according to claim 1, which 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 with respect to the connector.

10. The light-emitting element and the light-receiving element are further covered by a cover member, The optical sensor according to claim 1, wherein the height of the connector is lower than the height of the cover member.

11. The circuit board further has wiring that is electrically connected to each of the light-emitting element and the light-receiving element, either internally or on the second surface. The connector has a housing and terminals protruding from the housing. The terminal is electrically connected to the wiring, The optical sensor according to claim 1, wherein the portion of the terminal on the first surface is covered with a sealing material.

12. An image forming unit that forms an image, The optical sensor according to claim 1, which irradiates light onto the image formed by the image forming unit and detects predetermined characteristics, An image forming apparatus comprising:

Images