Optical sensor

Abstract

To provide an optical sensor that reduces stray light while components are reliably mountable regardless of whether a light-shielding member is included or unevenly formed.SOLUTION: An optical sensor includes: a pattern extending in a first direction substantially parallel to a line connecting two land centers that are connected to light emitting means, the pattern being formed on at least one of right and left relative to the line connecting the two land centers; and a pattern extending in a direction between lands of the light emitting means, the direction being a second direction substantially perpendicular to the first direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a stray light suppression method for improving the detection accuracy of an optical sensor by suppressing the generation of stray light through a substrate. [Background technology]

[0002] In an optical sensor in which light is irradiated from a light emitting means mounted on a substrate to an irradiated portion and reflected light is received by a light receiving means, unintended light from the light emitting means may enter the light receiving means through the substrate (hereinafter, stray light). If stray light enters the light receiving means, there is a risk of the detection accuracy deteriorating. Therefore, as a measure to prevent stray light from entering the light receiving means, Patent Document 1 uses a black resist, Patent Document 2 uses a light-shielding paint (silk), and Patent Document 3 covers the surface of the substrate with a pattern to prevent stray light from entering the substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-354832 [Patent Document 2] JP 2006-267644 A [Patent Document 3] JP 2019-197072 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the methods described in Patent Document 1 and Patent Document 2, when the above-mentioned black resist and light-shielding paint (hereinafter, the black resist and light-shielding paint are collectively referred to as light-shielding material) cannot be used due to equipment constraints and costs in manufacturing the board, or when the formed light-shielding material has unevenness, light may pass through the uneven parts, and the method may not be a sufficient measure against stray light. Therefore, when the light-shielding material cannot be used or when unevenness in formation occurs, stray light is an issue. In addition, in Patent Document 3, there is a concern that mounting failure may occur due to heat escaping easily during mounting due to the expansion of the mounting land, which is an issue. Therefore, an object of the present invention is to provide an optical sensor that suppresses stray light without being affected by the presence or absence of a light-shielding material or uneven formation while ensuring the mountability of the component. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention provides: An optical sensor comprising: a light-emitting means for irradiating light towards an irradiated object; at least one light-receiving means for receiving light reflected by the irradiated object from the light emitted by the light-emitting means; a substrate on which the light-emitting means and the light-receiving means are mounted; and a land pattern formed on the substrate for connecting the light-emitting means and the light-receiving means to the substrate, characterized in that the optical sensor has a pattern extending in a first direction that is approximately parallel to a straight line connecting the centers of two lands connected to the light-emitting means and formed on at least one of the left and right sides of the straight line connecting the centers of the two lands; and a pattern extending in a direction between the lands of the light-emitting means, which is a second direction that is approximately perpendicular to the first direction. Effect of the Invention

[0006] As described above, according to the present invention, it is possible to realize an optical sensor that satisfies mounting requirements and suppresses stray light without being affected by the presence or absence of a light blocking member or unevenness in formation. [Brief description of the drawings]

[0007] [Figure 1] Schematic diagram of an optical sensor in an implementation [Diagram 2]Countermeasures against stray light in optical sensors in implementation example 1 [Diagram 3] Stray light area 1 of light irradiated from the LED onto the board surface [Figure 4] Stray light area 2 of light irradiated from the LED onto the board surface [Diagram 5] When the LED mounting position is misaligned (to the right) to prevent stray light from the optical sensor in Example 1 [Figure 6] Variation of stray light countermeasures for optical sensors in embodiment 1 [Figure 7] Countermeasures against stray light in optical sensor in embodiment 2 [Figure 8] When the LED mounting position is misaligned (upward) to prevent stray light in the optical sensor in Example 2 [Figure 9] Variation of stray light countermeasures for optical sensors in the second embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] [Example 1] First, FIG. 1 shows a schematic diagram of an optical sensor in this implementation. The numbers in the figure indicate an LED (Light Emitting Diode) 100 which is a light emitting means (light emitting element), a PD (Photo Diode) 110 which is a light receiving means (light receiving element) which receives light, a substrate 105 on which the LED 100 and the PD 110 are mounted, an aperture 120 which narrows the light irradiated from the LED 100 and received by the PD 110, and a reflector (irradiated object) 140 which reflects the light from the LED 100. The light irradiated from the LED 100 is narrowed by the aperture 120 to form an optical path A 160. The light in the optical path A 160 is reflected by the reflector 140, and the light of the optical path B 170 narrowed by the aperture among the reflected light is received by the PD 110. The reflector 140 in this embodiment may be any material that reflects light, and is not limited to this configuration, and may be a belt or the like used in an image forming apparatus.

[0010] FIG. 2 shows a cross-sectional view of the substrate 105. (a) in the figure is an enlarged view of the vicinity of the LED 100 from the top surface of the substrate 105. (b) and (c) in the figure show cross-sections taken along the dotted lines of cross-section 1 and cross-section 2, respectively. (d) in the figure shows cross-section taken along the dotted line of cross-section 3. The numbers in the figure indicate a copper foil pattern 104 (hereinafter, pattern) having a thickness of 35 um formed on the surface of the substrate 105, a solder 103 connecting the land of the LED 100 and the pattern (land pattern) 104, and a countermeasure pattern A 107 formed as a countermeasure against stray light in this embodiment. The above pattern thicknesses show specific examples of dimensions in substrate manufacturing, and are not limited to this configuration because manufacturing conditions may be changed.

[0011] The light irradiated from the LED 100 to the substrate surface draws radiation from the light emitting element inside the LED 100. The light in areas A and B enclosed by solid lines in FIG. (a) is dominant as a stray light effect. In this embodiment, the countermeasure pattern A107 suppresses the light irradiated from the LED 100 from being mixed (stray light) into the PD 110 through the substrate 105. The countermeasure pattern A107 has two features. The first is a pattern (hereinafter referred to as countermeasure pattern 1) extending in a first direction that is approximately parallel to a straight line connecting the centers of the two lands and formed on at least one of the left and right sides of the straight line connecting the centers of the two lands. The second is a pattern (hereinafter referred to as countermeasure pattern 2) extending in a second direction that is approximately perpendicular to the first direction, that is, a direction between the lands of the LED 100. In this embodiment, the countermeasure pattern 1 is formed on each side.

[0012] FIG. 3 shows the path of light irradiated from the LED 100 to the substrate surface in FIG. 2(b). In the diagram, the path A200 is the path in which light from the light emitting element 108 inside the LED 100 is reflected by the molded part and irradiated to the substrate surface. As an example, specular reflection is assumed. In the path B210, the light from the light emitting element 108 passes through the molded part 109 and is irradiated to the substrate surface. The light from these two paths is the main cause of stray light through the substrate, and in this embodiment, this is the part that suppresses stray light (blocked by the countermeasure pattern A107). In this embodiment, the LED substrate part 111 is assumed to be opaque. For example, the LED substrate part 111 is easily blocked by covering as large an area as possible with a substrate pattern, a black resist material or silk material, or a combination thereof on the upper and lower surfaces of the LED substrate part 111. In other words, the light irradiated to the substrate surface by the path A200 is determined to be within the range (θ1 or more in the diagram) that is not blocked by the substrate part 111. Similarly, the light irradiated onto the substrate surface via path B210 is limited to a range that is not blocked by substrate portion 111 (greater than θ2 in the drawing).

[0013] As an example, a method of calculating area A where the influence of stray light is dominant will be described. Suppose that the distance from the light emitting element 108 of the LED 100 to the top surface of the molded part 109 is ΔA=0.4 mm, the distance from the upper part of the LED substrate part 111 to the top surface of the molded part 109 is ΔB=0.5 mm, and the component height of the LED 100 is ΔC=1.1 mm (the thickness of the solder 103 is assumed to be sufficiently negligible). Also, the angle between the angle of incidence and the angle of reflection on the molded part 109 in the path A200 is θ1=35°. In that case, the distance from the left end of the light emitting element 108 to the right end of area A is ΔD=ΔC×tan(θ1 / 2)+ΔA×tan(θ1 / 2)≈0.473 mm. If the angle θ2 between the direction perpendicular to the substrate and the light irradiated from the left end of the light emitting element 108 is 60°, then the distance ΔE from the left end of the light emitting element 108 to the left end of area A is ΔE=(ΔC-ΔA)×tan(θ2)≈1.212 mm. The closer the angle θ2 is to 90°, the greater the distance ΔE becomes, but since the longer the optical path, the lower the light intensity becomes, the further away from the LED 100 the lower the stray light effect becomes. Therefore, taking into account the effects of stray light, ΔE may be limited to twice (≒2.798 mm) the current optical path (when θ2 = 60° = (√((ΔC-ΔA)^2+(1.212)^2) ≒ 1.399 mm), and ΔE = (√((ΔC-ΔA)^2+(2.798)^2) ≒ 2.884 mm). The above values ​​depend on the structure and optical characteristics of the LED 100 used, and are therefore not limited to this configuration.

[0014] FIG. 4 is an example showing the range of area A where the influence of stray light is dominant in FIG. 2(a). Light irradiated from the light emitting element 108 to the substrate surface passes through the substrate and enters the light receiving area of ​​the PD 110, becoming stray light. Therefore, as shown in FIG. 4, the area A is the area surrounded by the dotted line in the figure connecting the outline of the light emitting element 108 and the light receiving area of ​​the PD 110, and the range from the left end of the light emitting element 108 to ΔD or more and ΔE or less. As an example, the size of the light emitting element 108 is 0.1 mm×0.1 mm, the longitudinal side of the light receiving area of ​​the PD 110 is 0.7 mm, and the distance from the left end of the light emitting element 108 to the right end of the light receiving area is 5 mm. In addition, if the center of the light receiving area and the center of the light emitting element 108 are on a straight line and ΔD=0.473 mm and ΔE=1.212 mm, ΔF and ΔG in the figure are ΔF≒0.245 mm and ΔG≒0.157 mm, respectively. In the case where a PD (not shown) different from the PD110 is located on the opposite side of the LED100, the area B may be obtained in the same manner as the example of the area A. On the other hand, even if there is no different PD, the influence of stray light is lower than that of the area A, but the light irradiated to the area B is diffusely reflected in the substrate 105 and mixed with the PD110 to become stray light. Therefore, it is necessary to suppress the stray light in the area B by the countermeasure pattern A107. Since ΔD and ΔE are obtained in the area B in the same manner, they are omitted. ΔF and ΔG may be the same as those in the area A, or may be determined based on other optical conditions. For example, as described above, the longer the optical path, the lower the light intensity, so they may be determined based on the range where the light intensity is sufficiently lowered or the range where the light is blocked by the LED substrate part 111.

[0015] In this configuration, in consideration of the above, the countermeasure pattern A107 has countermeasure pattern 1 and countermeasure pattern 2 to suppress stray light generated in areas A and B. In countermeasure pattern 1, the distance from the land may be determined according to the constraints of board manufacturing (e.g., pattern interval of 0.2 mm or more). The distance from countermeasure pattern 1 changes the positions of areas A and B depending on the position of the light emitting element 108 in the LED 100. Therefore, the distance from countermeasure pattern 1 does not need to be uniform. The width and length of countermeasure pattern 1 need only be formed so as to cover at least areas A and B shown above. The countermeasure pattern A107 has countermeasure pattern 2 that is perpendicular to countermeasure pattern 1 and extends in the direction between the lands of the LED 100. This is to suppress stray light even if the component mounting position of the LED 100 is shifted in the left-right direction in FIG. 5(b). FIGS. 5(a) to (d) show an example in which the component mounting position is shifted to the right. The width and length of countermeasure pattern 2 may be determined so as to cover areas A and B shown in the example, and taking into consideration the variation in component mounting position. For example, if the variation in mounting position is ±0.2 mm, a pattern may be formed that is at least 0.2 mm larger than areas A and B. A pattern extending from one direction of the land of LED 100 and a pattern extending from the other direction may be joined under LED 100.

[0016] In the figure of this embodiment, the joint between countermeasure pattern 1 and countermeasure pattern 2 is at a right angle, but it may be changed smoothly. As long as it is possible to suppress stray light in areas A and B, the shape of countermeasure pattern A107 may be not only perfectly parallel and perpendicular, but also slightly oblique or curved, as shown in FIG. 6(a). Since the area to be shielded changes depending on the arrangement of the light receiving element, the shape of countermeasure pattern A107 may be slightly deformed, as shown in FIG. 6(b). As described above, by forming countermeasure pattern A107 on the substrate, it is possible to suppress stray light through the substrate near LED 100 while satisfying mountability.

[0017] [Example 2] The configuration of this embodiment is the same as that of the embodiment 1, and as shown in FIG. 7, by making the shape of the countermeasure pattern 2 radially from the center of the LED 100 (dotted lines passing through the center of the LED 100), it is possible to suppress stray light even when the mounting position is shifted in the vertical direction. Also, (b) and (c) in the figure show cross sections cut along the dotted lines of the cross sections 1 and 2, respectively. (d) in the figure shows a cross section cut along the dotted line of the cross section 3. The same parts as those in the embodiment 1 are given the same reference numerals and will not be described. FIG. 8 is a diagram showing the case where the component mounting position of the LED 100 in FIG. 7 is shifted upward. When the component mounting position of the LED 100 is shifted, the area where the influence of stray light is dominant shifts as shown by areas A and B surrounded by solid lines in FIG. 7(a). In this embodiment, by making the shape of the countermeasure pattern 2 radially from the center of the LED 100 (dotted lines passing through the center of the LED 100), it is possible to suppress stray light even when the area where the influence of stray light is dominant shifts when the mounting position is shifted in the vertical direction. In FIG. 2(a), the width of the countermeasure pattern 2 is not increased because interference with the land of the LED 100 is taken into consideration. The radiation passing through the center of the LED 100 in FIG. 7(a) may be determined based on the mounting variation in the vertical direction of the LED 100. For example, when the mounting variation is ±0.2 mm, the angle of the radiation may be determined by considering the shift of the area where the influence of stray light is dominant by ±0.2 mm as shown by the dotted line in FIG. 7(a). In this embodiment, the light emitting element 108 in the LED 100 is at the center of the LED. On the other hand, when the position of the light emitting element 108 is not at the center of the LED 108, the shape of the countermeasure pattern 2 may be determined as a radial shape with the light emitting element 108 as the center. The parallel and perpendicular in this embodiment 2 include not only completely parallel and perpendicular, but also slight obliqueness and curves. In addition, since the area to be shielded changes depending on the arrangement of the light receiving element, it is desirable to slightly deform the shape of the countermeasure pattern A107. Therefore, in this embodiment, the shape of the countermeasure pattern 2 may be formed so as to connect the center of the LED 100 and the light receiving element.

[0018] Note that countermeasure pattern 1 may not be necessary if the shape of countermeasure pattern 2 in this embodiment alone is sufficient to suppress stray light in areas A and B. Similarly, as shown in Fig. 9, countermeasure pattern 2 may have an irregular shape as long as it is able to suppress stray light in areas A and B. As described above, by making the shape of countermeasure pattern 2 radial from the center of LED 100 (dotted lines passing through the center of LED 100), stray light can be suppressed even if mounting position misalignment occurs in the vertical direction.

[0019] [Note] The above-described embodiments at least disclose the following booklet producing apparatus and image forming system.

[0020] (Item 1) A light emitting means for irradiating light toward an object to be irradiated; At least one light receiving means for receiving light reflected by the object to be irradiated by the light emitting means; a substrate on which the light emitting means and the light receiving means are mounted; An optical sensor comprising: a land pattern formed on the substrate, the land pattern connecting the light emitting means and the light receiving means to the substrate, a pattern extending in a first direction substantially parallel to a straight line connecting the centers of two lands connected to the light emitting means, the pattern being formed on at least one of the left and right sides of the straight line connecting the centers of the two lands; The optical sensor further comprises a pattern extending in a second direction substantially perpendicular to the first direction, that is, in a direction between the lands of the light emitting means.

[0021] (Item 2) Item 1, an optical sensor comprising: An optical sensor, characterized in that the optical sensor is parallel to the substantially parallel first direction and perpendicular to the substantially perpendicular second direction.

[0022] (Item 3) Item 3. The optical sensor according to items 1 to 2, An optical sensor characterized in that the patterns extending in the first direction formed on at least one of the left and right sides of the straight line connecting the centers of the two lands have one pattern on each side, and are formed to sandwich the land of the light-emitting means.

[0023] (Item 4) 4. The optical sensor according to items 1 to 3, An optical sensor characterized in that a pattern extending in the second direction, that is, a direction between the lands of the light emitting means, is formed radially from the center of the light emitting means.

[0024] (Item 5) 5. The optical sensor according to items 1 to 4, An optical sensor characterized in that the length in the first direction of a pattern extending in the first direction formed on at least one of the left and right sides of a straight line connecting the centers of the two lands is greater than or equal to the range connecting the outline of the light-emitting means and the outline of the light-receiving means.

[0025] (Item 6) 6. The optical sensor according to items 1 to 5, An optical sensor characterized in that a pattern extending in the second direction, which is the direction between the lands of the light-emitting means, is characterized in that a pattern extending from one direction of the lands of the light-emitting means and a pattern extending from the other direction are combined under the light-emitting means.

[0026] (Item 7) A light emitting means for irradiating light toward an object to be irradiated; At least one light receiving means for receiving light reflected by the object to be irradiated by the light emitting means; a substrate on which the light emitting means and the light receiving means are mounted; An optical sensor comprising: a land pattern formed on the substrate, the land pattern connecting the light emitting means and the light receiving means to the substrate, a pattern extending in a direction between the lands of the light emitting means, the second direction being substantially perpendicular to a straight line connecting the centers of the two lands connected to the light emitting means; An optical sensor characterized in that a pattern extending in the second direction, that is, a direction between the lands of the light emitting means, is formed radially from the center of the light emitting means.

[0027] (Item 8) 8. The optical sensor according to items 1 to 7, The optical sensor is characterized in that the at least one light receiving means is two in number, and each light receiving means is disposed at a position sandwiching the light emitting means.

[0028] (Item 9) 9. The optical sensor according to items 1 to 8, an optical sensor comprising: a pattern extending in the second direction, that is, a direction between the lands of the light emitting means, said pattern being formed radially from straight lines connecting the centers of the light emitting means and the light receiving means;

[0029] (Item 10) 10. The optical sensor according to items 7 to 9, The optical sensor is characterized in that the substantially perpendicular second direction is perpendicular. [Explanation of symbols]

[0030] 100 LED 103 Solder 104 Patterns 105 Substrate 107 Countermeasure Pattern A 108 Light emitting element 109 Mold section 110PD 111 LED board section 120 Aperture 140 Reflector 160 Optical path A 170 Optical path B 200 Route A 210 Route B

Claims

1. A light emitting means for irradiating light toward an object to be irradiated; At least one light receiving means for receiving light reflected by the object to be irradiated due to the light emitted by the light emitting means; a substrate on which the light emitting means and the light receiving means are mounted; An optical sensor comprising: a land pattern formed on the substrate, the land pattern connecting the light emitting means and the light receiving means to the substrate, a pattern extending in a first direction substantially parallel to a straight line connecting the centers of two lands connected to the light emitting means, the pattern being formed on at least one of the left and right sides of the straight line connecting the centers of the two lands; The optical sensor further comprises a pattern extending in a second direction substantially perpendicular to the first direction, that is, in a direction between the lands of the light emitting means.

2. 2. The optical sensor of claim 1, wherein the substantially parallel first direction is parallel and the substantially perpendicular second direction is perpendicular.

3. The optical sensor according to claim 1, characterized in that the patterns extending in the first direction formed on at least one of the left and right sides of the straight line connecting the centers of the two lands have one pattern on each side, and are formed so as to sandwich the land of the light-emitting means.

4. 2. The optical sensor according to claim 1, wherein the pattern extending in the second direction, that is, the direction between the lands of the light emitting means, is formed radially from the center of the light emitting means.

5. The optical sensor according to claim 1, characterized in that the length in the first direction of a pattern extending in the first direction formed on at least one of the left and right sides of a straight line connecting the centers of the two lands is greater than or equal to the range connecting the outline of the light-emitting means and the outline of the light-receiving means.

6. The optical sensor according to claim 1, characterized in that a pattern extending in the second direction, which is a direction between the lands of the light-emitting means, is joined under the light-emitting means with a pattern extending from one direction of the land of the light-emitting means and a pattern extending from the other direction.

7. A light emitting means for irradiating light toward an object to be irradiated; At least one light receiving means for receiving light reflected by the object to be irradiated due to the light emitted by the light emitting means; a substrate on which the light emitting means and the light receiving means are mounted; An optical sensor comprising: a land pattern formed on the substrate, the land pattern connecting the light emitting means and the light receiving means to the substrate, a pattern extending in a direction between the lands of the light emitting means, the direction being a second direction substantially perpendicular to a straight line connecting the centers of two lands connected to the light emitting means; An optical sensor characterized in that a pattern extending in the second direction, that is, a direction between the lands of the light emitting means, is formed radially from the center of the light emitting means.

8. 8. The optical sensor according to claim 1, wherein the at least one light receiving means is two in number, and the light receiving means are disposed at positions sandwiching the light emitting means.

9. 8. The optical sensor according to claim 1, wherein a pattern extending in the second direction, which is a direction between the lands of the light-emitting means, is formed radially with straight lines connecting the center of the light-emitting means and the light-receiving means.

10. The optical sensor of claim 7 , wherein the second direction is substantially perpendicular.

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