Optical sensor

Abstract

To provide an optical sensor that suppresses stray light without being affected by the presence or absence of light-shielding materials or molding irregularities, while ensuring the mountability of components. [Solution] The light-emitting means has a pattern that extends in a first direction which is substantially parallel to the straight line connecting the centers of two lands connected to the light-emitting means, and is formed on at least one side to the left or right of the straight line connecting the centers of the two lands, and a pattern that extends in a second direction which is substantially perpendicular to the first direction, in the direction between the lands of the light-emitting means.

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 Art

[0002] In an optical sensor that receives the reflected light of the light irradiated from a light emitting means mounted on a substrate with respect to an irradiated portion, unintended light from the light emitting means may be mixed into the light receiving means through the substrate (hereinafter referred to as stray light). If stray light is mixed into the light receiving means, the detection accuracy may deteriorate. Therefore, as a countermeasure to suppress the mixing of stray light into the light receiving means, in Patent Document 1, a black resist, in Patent Document 2, a light shielding paint (silk), and in Patent Document 3, the surface of the substrate is covered with a pattern to suppress the entry of stray light into the substrate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the methods described in Patent Documents 1 and 2, due to equipment constraints and cost considerations in substrate manufacturing, the above-mentioned black resist and light-shielding paint (hereinafter, the black resist and light-shielding paint together are referred to as light-shielding members) cannot be used, or if there are inconsistencies in the formed light-shielding members, light may pass through the inconsistent areas, potentially resulting in insufficient protection against stray light. Therefore, stray light in cases where light-shielding members cannot be used or where formation inconsistencies occur has been a problem. Furthermore, in Patent Document 3, the enlargement of the mounting land raises concerns about mounting defects due to increased heat dissipation during mounting, which has been a problem. Accordingly, the object of the present invention is to provide an optical sensor that suppresses stray light without being affected by the presence or absence of light-shielding members or formation inconsistencies, while ensuring the mountability of components. [Means for solving the problem]

[0005] To solve the above problems, the means of the present invention are: An optical sensor comprising: a light-emitting means for irradiating light toward an object to be irradiated; at least one light-receiving means for receiving reflected light from the object to be irradiated by 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 which is substantially parallel to a straight line connecting the centers of two lands connected to the light-emitting means, and is formed on at least one of the left or right sides of the straight line connecting the centers of the two lands, and a pattern extending in a second direction which is substantially perpendicular to the first direction, in the direction between the lands of the light-emitting means. [Effects of the Invention]

[0006] As described above, the present invention makes it possible to realize an optical sensor that suppresses stray light without being affected by the presence or absence of light-shielding members or unevenness in formation, while satisfying the requirements for mountability. [Brief explanation of the drawing]

[0007] [Figure 1] Schematic diagram of an optical sensor in its implementation configuration. [Figure 2]Stray light countermeasures for optical sensors in implementation example 1 [Figure 3] Stray light area 1 of light irradiated from the LED onto the substrate surface [Figure 4] Stray light area 2 of light projected from the LED onto the substrate surface. [Figure 5] When the LED mounting position is misaligned (to the right) in the optical sensor's stray light countermeasure in Example 1 [Figure 6] Modified form of stray light countermeasure for optical sensor in Example 1 [Figure 7] Stray light countermeasures for optical sensors in Example 2 [Figure 8] When the LED mounting position is misaligned (upward) for stray light countermeasures of the optical sensor in Example 2 [Figure 9] Modified form of stray light countermeasure for optical sensor in Example 2 [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings.

[0009] [Example 1] First, Figure 1 shows a schematic diagram of the optical sensor in this implementation. The numbers in the figure indicate the following: 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 (photo-receiving element); a substrate 105 on which the LED 100 and PD 110 are mounted; an aperture 120 that focuses the light emitted from the LED 100 and received by the PD 110; and a reflector (object to be illuminated) 140 that reflects the light from the LED 100. The light emitted from the LED 100 is focused by the aperture 120 to form an optical path A 160. The light in optical path A 160 is reflected by the reflector 140, and of the reflected light, the light in optical path B 170, which is focused by the aperture, is received by the PD 110. The reflector 140 in this embodiment can be any material that reflects light, so it may be a belt used in an image forming apparatus, etc., and is not limited to this configuration.

[0010] Figure 2 shows a cross-sectional view of the substrate 105. (a) in the figure is a magnified view of the vicinity of the LED 100 from the top surface of the substrate 105. (b) and (c) in the figure show the cross-sections when cut along the dotted lines of cross-section 1 and cross-section 2, respectively. (d) in the figure shows the cross-section when cut along the dotted line of cross-section 3. The numbers in the figure refer to the 35um thick copper foil pattern 104 (hereinafter referred to as "pattern") formed on the surface of the substrate 105, the solder 103 connecting the land of the LED 100 and the pattern (land pattern) 104, and the countermeasure pattern A107 formed as a countermeasure against stray light in this embodiment. The pattern thickness described above is a specific example of dimensions in substrate manufacturing and is not limited to this configuration as manufacturing conditions may be changed.

[0011] Light emitted from LED100 onto the substrate surface radiates from the light-emitting element inside LED100. The light in areas A and B enclosed by solid lines in Figure (a) is dominant as stray light. This invention uses countermeasure pattern A107 to suppress the intrusion (stray light) of light emitted from LED100 into PD110 via substrate 105. Countermeasure pattern A107 has two characteristics. The first is a pattern extending in a first direction that is approximately parallel to the line connecting the centers of the two lands, and is formed on at least one of the left or right sides of the line connecting the centers of the two lands (hereinafter referred to as countermeasure pattern 1). The second is a pattern extending in a second direction that is approximately perpendicular to the first direction, in the direction between the lands of LED100 (hereinafter referred to as countermeasure pattern 2). In this embodiment, one countermeasure pattern 1 is formed on each side.

[0012] Figure 3 shows the light paths from the LED 100 to the substrate surface in Figure 2(b). Path A200 in the figure shows light from the light-emitting element 108 inside the LED 100 reflected by the mold and irradiated onto the substrate surface. Specular reflection is assumed as an example. Path B210 shows light from the light-emitting element 108 passing through the mold 109 and irradiating onto the substrate surface. These two paths are the main cause of stray light through the substrate, and in this embodiment, stray light is suppressed (shielded by countermeasure pattern A107). In this embodiment, the LED substrate 111 is assumed to be opaque. For example, covering as large an area as possible on the top and bottom surfaces of the LED substrate 111 with a substrate pattern, black resist material, silk screen material, or a combination thereof makes it easier to shield from light. In other words, the light irradiated onto the substrate surface by path A200 is limited to the range not shielded by the substrate 111 (greater than or equal to θ1 in the figure). Similarly, the light irradiated onto the substrate surface by path B210 is determined to be within a range that is not blocked by the substrate portion 111 (greater than or equal to θ2 in the figure).

[0013] As an example, let's explain how to calculate area A, where stray light effects are dominant. Let's assume that the distance from the light-emitting element 108 of LED 100 to the top surface of the molded part 109 is ΔA = 0.4 mm, the distance from the top 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 LED 100 is ΔC = 1.1 mm (assuming the thickness of solder 103 can be sufficiently ignored). Also, let's assume that the angle between the angle of incidence and the angle of reflection to the molded part 109 in 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 = 60° between the light perpendicular to the substrate and the light irradiated from the left end of the light-emitting element 108 relative to the left end of the light-emitting element 108, then the distance ΔE from the left end of the light-emitting element 108 to the left end of area A is approximately 1.212 mm (ΔC - ΔA) × tan(θ2). As the angle θ2 approaches 90°, the distance ΔE increases, but as the optical path lengthens, the light intensity decreases, so the stray light effect decreases as you move away from LED 100. Therefore, considering the effect of stray light, ΔE may be set to twice the current optical path (when θ2 = 60° = (√((ΔC - ΔA)^2 + (1.212)^2) ≈ 1.399 mm) (≈ 2.798 mm), so ΔE = (√((ΔC - ΔA)^2 + (2.798)^2) ≈ 2.884 mm. The above values ​​are not limited to this configuration as they depend on the structure and optical characteristics of the LED100 used.

[0014] FIG. 4 is an example showing the range of the dominant area A of stray light influence in FIG. 2(a). The light irradiated from the light-emitting element 108 onto the substrate surface passes through the substrate and becomes stray light when it enters the light-receiving area of PD110. Therefore, as shown in FIG. It is. As an example, assume that the size of the light-emitting element 108 is 0.1 mm × 0.1 mm, the longitudinal length of the light-receiving area of PD110 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. Also, when the center of the light-receiving area and the center of the light-emitting element 108 are on the same straight line and ΔD = 0.473 mm and ΔE = 1.212 mm, then in the figure, ΔF and ΔG are ΔF≒0.245 mm and ΔG≒0.157 mm respectively. When a PD (not shown) different from PD110 is on the opposite side sandwiching the LED100, area B can be obtained in the same manner as the example of area A. On the other hand, even when there is no different PD, although the influence degree of stray light is lower than that of area A, the light irradiated to area B is diffusely reflected in the substrate 105 and mixed into PD110 to become stray light. Therefore, it is also necessary to suppress stray light in area B by the countermeasure pattern A107. Since ΔD and ΔE in area B are obtained in the same way, they are omitted. Regarding ΔF and ΔG, they may be the same as those in area A, or may be determined according to different optical conditions. For example, as described above, since the light intensity decreases as the optical path length increases, it may be determined from the range where the light intensity sufficiently decreases or the range shielded by the LED substrate portion 111.

[0015] In this configuration, in consideration of the above, in order to suppress stray light generated in areas A and B, the countermeasure pattern A107 has countermeasure pattern 1 and countermeasure pattern 2. In countermeasure pattern 1, the distance from the land may be determined by restrictions in substrate manufacturing (for example, the pattern pitch is >= 0.2 mm, etc.). Note that the position of areas A and B changes according to the position of the light-emitting element 108 within the LED100 with respect to the distance from countermeasure pattern 1. Therefore, the distance from countermeasure pattern 1 does not have to be uniform. The width and length of countermeasure pattern 1 only need to be formed so as to cover at least areas A and B shown above. Countermeasure pattern A107 is in the perpendicular direction to countermeasure pattern 1 and has countermeasure pattern 2 extending in the direction between the lands of the LED100. This is to suppress stray light even when the component mounting position of the LED100 is displaced in the left-right direction in Fig. 5(b). Figs. 5(a) to (d) illustrate the case where the component mounting position is displaced to the right as an example. The width and length of countermeasure pattern 2 may be determined in consideration of covering the areas A and B shown in the example and the variation in component mounting position. For example, when the variation in mounting position is ±0.2 mm, a pattern at least 0.2 mm larger than areas A and B may be formed. Patterns extending from one direction of the lands of the LED100 and patterns extending from the other direction may be joined under the LED100.

[0016] In the figures of this embodiment, the junction of countermeasure pattern 1 and countermeasure pattern 2 is a right angle, but it may be smoothly changed. As long as it is possible to suppress stray light in areas A and B, the shape of countermeasure pattern A107 may also be an irregular shape including some diagonal lines or curves, not only perfect parallel and perpendicular as shown in Fig. 6(a). Note that since the area to be shaded changes depending on the arrangement of the light-receiving elements, as shown in Fig. 6(b), the shape of countermeasure pattern A107 may be slightly deformed. As described above, by forming countermeasure pattern A107 on the substrate, it is possible to suppress stray light through the substrate in the vicinity of the LED100 while satisfying the mountability.

[0017] [Embodiment 2] The configuration of this embodiment is the same as that of Embodiment 1. As shown in Figure 7, by making the shape of countermeasure pattern 2 radial from the center of LED 100 (dotted line passing through the center of LED 100), it is possible to suppress stray light even when mounting position misalignment occurs in the vertical direction. Also, (b) and (c) in the figure show the cross-sections when cut along the dotted lines of cross-section 1 and cross-section 2, respectively. (d) in the figure shows the cross-section when cut along the dotted line of cross-section 3. Parts that are the same as in Embodiment 1 are given the same reference numerals and their explanations are omitted. Figure 8 shows the case when the component mounting position misalignment of LED 100 occurs in the vertical direction in Figure 7. When the component mounting position misalignment of LED 100 occurs, the area where stray light influence is dominant shifts, as shown by areas A and B enclosed by solid lines in Figure (a). In this embodiment, by making the shape of countermeasure pattern 2 radial from the center of LED 100 (dotted line passing through the center of LED 100), it is possible to suppress stray light even when the area where stray light influence is dominant shifts when mounting position misalignment occurs in the vertical direction. In Figure 2(a), the reason why the width of countermeasure pattern 2 is not increased is to consider interference with the land of LED 100. In Figure 7(a), the radiation passing through the center of LED 100 can be determined from the vertical mounting variation of LED 100. For example, if the mounting variation is ±0.2 mm, the angle of the radiation can be determined by considering the ±0.2 mm shift in the area where stray light is dominant, as shown by the dotted line in Figure (a). In this embodiment, the light-emitting element 108 within LED 100 is assumed to be at the center of the LED. On the other hand, if the position of the light-emitting element 108 is not at the center of LED 108, the shape of countermeasure pattern 2 can be determined by making it radial from the light-emitting element 108. In this embodiment 2, parallel and perpendicular lines include not only perfectly parallel and perpendicular lines, but also slight obliques and curves. Also, since the area to be shielded changes depending on the arrangement of the light-receiving elements, it is desirable to slightly modify the shape of countermeasure pattern A107. Therefore, in this embodiment, the shape of countermeasure pattern 2 may be formed so as to connect the center of the LED 100 and the light-receiving element.

[0018] Furthermore, if the shape of countermeasure pattern 2 in this embodiment alone is sufficient to suppress stray light in areas A and B, then countermeasure pattern 1 may be omitted. Similarly, as shown in Figure 9, the shape of countermeasure pattern 2 can be irregular as long as it is sufficient 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 line 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 embodiments disclose at least the following booklet manufacturing apparatus and image forming system.

[0020] (Item 1) A light-emitting means that irradiates light toward an object to be irradiated, The light-receiving means includes at least one light-receiving means that receives the reflected light from the irradiated object 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 the light-emitting means and the light-receiving means, and a land pattern formed on the substrate connecting the substrate, A first direction substantially parallel to the line connecting the two land centers connected to the light-emitting means, and a pattern extending in the first direction formed on at least one of the left or right sides of the line connecting the two land centers, An optical sensor characterized by having a pattern extending in the direction between lands of the light-emitting means, which is substantially perpendicular to the first direction.

[0021] (Item 2) The optical sensor described in item 1, An optical sensor characterized by being parallel to the aforementioned substantially parallel first direction and perpendicular to the aforementioned substantially perpendicular second direction.

[0022] (Item 3) The optical sensors described in items 1 to 2, The optical sensor is characterized in that the pattern extending in the first direction, formed on at least one of the left or right sides of a straight line connecting the centers of the two lands, has one pattern on each side and is formed so as to sandwich the land of the light-emitting means.

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

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

[0025] (Item 6) The optical sensors described in items 1 to 5, The optical sensor is characterized in that the pattern extending in the second direction, which is the direction between lands of the light-emitting means, is formed by the coupling of a pattern extending from one direction of the lands of the light-emitting means and a pattern extending from the other direction below the light-emitting means.

[0026] (Item 7) A light-emitting means that irradiates light toward an object to be irradiated, The light-receiving means includes at least one light-receiving means that receives the reflected light from the irradiated object 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 the light-emitting means and the light-receiving means, and a land pattern formed on the substrate connecting the substrate, A pattern extending in the direction between the lands of the light-emitting means, which is a second direction substantially perpendicular to the straight line connecting the centers of the two lands connected to the light-emitting means, The optical sensor is characterized in that the pattern extending in the direction between lands of the light-emitting means, which is the second direction, is formed radially from the center of the light-emitting means.

[0027] (Item 8) The optical sensors described in items 1 to 7, The optical sensor is characterized in that the at least one or more light-receiving means are two in number, each positioned on either side of the light-emitting means.

[0028] (Item 9) Optical sensors as described in items 1 to 8, The optical sensor is characterized in that the pattern extending in the direction between lands of the light-emitting means, which is the second direction, is formed radially along a straight line connecting the center of the light-emitting means and the light-receiving means.

[0029] (Item 10) Optical sensors as described in items 7 to 9, An optical sensor characterized by being perpendicular to the aforementioned substantially perpendicular second direction. [Explanation of Symbols]

[0030] 100 LED 103 Handa 104 patterns 105 circuit board 107 Countermeasure Pattern A 108 light-emitting elements 109 Molded part 110 PD 111 LED board section 120 Aperture 140 Reflector 160 Optical path A 170 Optical path B Route A (200) 210 Route B

Claims

1. A light-emitting means that irradiates light toward an object to be irradiated, The light-receiving means includes at least one light-receiving means that receives the reflected light from the irradiated object 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 the light-emitting means and the light-receiving means, and a land pattern formed on the substrate connecting the substrate, A first direction substantially parallel to the line connecting the two land centers connected to the light-emitting means, and a pattern extending in the first direction formed on at least one of the left or right sides of the line connecting the two land centers, An optical sensor characterized by having a pattern extending in the direction between lands of the light-emitting means, which is substantially perpendicular to the first direction.

2. The optical sensor according to claim 1, characterized in that it is parallel to the aforementioned substantially parallel first direction and perpendicular to the aforementioned substantially perpendicular second direction.

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

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

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

6. The optical sensor according to claim 1, characterized in that the pattern extending in the second direction, which is the direction between lands of the light-emitting means, is formed by a pattern extending from one direction of the lands of the light-emitting means and a pattern extending from the other direction being coupled beneath the light-emitting means.

7. A light-emitting means that irradiates light toward an object to be irradiated, The light-receiving means includes at least one light-receiving means that receives the reflected light from the irradiated object 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 the light-emitting means and the light-receiving means, and a land pattern formed on the substrate connecting the substrate, A pattern extending in the direction between the lands of the light-emitting means, which is a second direction substantially perpendicular to the straight line connecting the centers of the two lands connected to the light-emitting means, The optical sensor is characterized in that the pattern extending in the direction between lands of the light-emitting means, which is the second direction, is formed radially from the center of the light-emitting means.

8. The optical sensor according to any one of claims 1 to 7, characterized in that the at least one or more light-receiving means are two in number, and are each arranged at positions flanking the light-emitting means.

9. The optical sensor according to any one of claims 1 to 7, characterized in that the pattern extending in the direction between lands of the light-emitting means, which is the second direction, is formed radially along a straight line connecting the center of the light-emitting means and the light-receiving means.

10. The optical sensor according to claim 7, characterized in that it is perpendicular to the aforementioned substantially perpendicular second direction.

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