Reflection-type photoelectric encoder chip capable of uniformly emitting light

Abstract

The invention provides a reflective photoelectric encoder chip capable of uniformly emitting light, which comprises a chip body, and the chip body comprises an LED light source; the bare chip is provided with a photosensitive area; the light guide plate is used for adjusting the path of the light emitted by the LED light source, so that the light is uniformly emitted in a set area; the light guide plate comprises a light reflection area and a light emission area, and the LED light source is arranged on the lower portion of the center in the light reflection area. The light emitting area is provided with a plurality of light guide points, and light emitted by the LED light source is reflected to the light guide points through the top face of the light reflecting area and is evenly emitted perpendicular to the light emitting area. The light shielding plate is used for shielding light and at least comprises a light guide plate light shielding area and a bare chip light shielding area, the light guide plate light shielding area is located above the light reflection area and covers the light reflection area, and the bare chip light shielding area is located above the bare chip and covers the part, except the light sensing area, of the bare chip; and the light-transmitting sheet is used for covering the photosensitive area of the bare chip and allowing light to transmit.

Description

Technical Field

[0001] The present invention relates to the technical field of encoder chips, and in particular to a reflective photoelectric encoder chip capable of uniformly emitting light. Background Art

[0002] Photoelectric encoder chips with built-in LED light sources usually use LED light sources as light-emitting devices 101. The light emitted by the LED light source is reflected by the code disk 103 and then irradiated to the light-receiving device 102 of the chip. The chip receives the light signal and then converts it into an electrical signal for processing and output. The principle is as follows: Figure 1 shown.

[0003] The light emitted by the LED light source itself is not uniform, but presents characteristics similar to the Lambert curve, such as Figure 2 This characteristic causes the LED light intensity received at different positions of the code disk to be unequal, and the light intensity reflected to the light receiving device 102 of the chip is also different, resulting in differences in the amplitude of the signal output by the chip, reducing the accuracy of the chip output signal, requiring signal conditioning at the back end of the chip to improve the signal accuracy, and increasing the circuit size and complexity.

[0004] Therefore, it is necessary to provide a reflective photoelectric encoder chip that can emit light evenly to effectively solve the above problems. Summary of the invention

[0005] The present invention provides a reflective photoelectric encoder chip capable of uniformly emitting light, optimizes the structure, and arranges a light guide plate and a light shielding plate, so that the light of an LED light source is uniformly emitted from a set area, thereby improving the accuracy of measurement.

[0006] An embodiment of the present invention provides a reflective photoelectric encoder chip capable of uniformly emitting light, including a chip body, wherein the chip body includes:

[0007] LED light source for emitting light;

[0008] A bare chip is provided with a photosensitive area, wherein the photosensitive area is used to receive the light emitted by the LED light source and reflected back by the code disk, and the bare chip outputs an electrical signal according to the received light;

[0009] A light guide plate, used to adjust the path of the light emitted by the LED light source so that the light is uniformly emitted in a set area; the light guide plate includes a light reflection area and a light emission area, the LED light source is arranged at the lower part of the center of the light reflection area; the light emission area is provided with a plurality of light guide points, the light guide points are semi-ellipsoidal, and the plurality of light guide points are distributed in an array, and the light emitted by the LED light source is reflected from the top surface of the light reflection area to the light guide points and is uniformly emitted from the light emission area;

[0010] A light shielding plate, used for shielding light, at least comprising a light guide plate light shielding area and a bare chip light shielding area, wherein the light guide plate light shielding area is located above the light reflection area and covers the light reflection area, and the bare chip light shielding area is located above the bare chip and covers the bare chip except the photosensitive area;

[0011] A light-transmitting sheet, used to cover the photosensitive area of ​​the bare chip and allow light to pass through;

[0012] The light guide plate is in a U-shape as a whole and surrounds the bare chip. The light emitting areas are two and are respectively arranged on both sides of the bare chip. The light reflecting area is located at one end of the bare chip and connects the two light emitting areas.

[0013] Preferably, the light shielding plate further comprises a positioning area, the positioning area is located at a side of the bare chip that does not contact the light guide plate, and the positioning area and the light guide plate surround and fix the bare chip.

[0014] Preferably, the shading plate is integrally formed, and the top surface of the shading plate is a plane; a mounting hole matching the photosensitive area is provided in the middle of the bare chip shading area, and the light-transmitting sheet is provided in the mounting hole.

[0015] Preferably, the light reflecting area and the light emitting area of ​​the light guide plate are integrally formed, and the bottom surface of the light guide plate is a plane; the light guiding point is formed by etching the bottom surface of the light emitting area.

[0016] Preferably, the height of the light reflecting area of ​​the light guide plate is the same as the height of the bare chip, the height of the light emitting area is equal to the height of the bare chip plus the height of the bare chip shading area of ​​the shading sheet and is equal to the height of the light reflecting area plus the height of the light guide plate shading area of ​​the shading sheet, so that the top surface of the chip body is flush.

[0017] Preferably, the light guide points are in multiple groups, each group includes multiple light guide points, and the multiple groups of light guide points are arranged at equal intervals in the longitudinal direction away from the LED light source; the multiple light guide points in each group are arranged at intervals in the transverse direction, and the number of light guide points in each group increases with the increase of the distance from the LED light source.

[0018] Preferably, the number of each group of light guide points on a unit area rectangle is calculated by the following formula:

[0019]

[0020] Wherein, N is the number of a group of light guide points on a unit area rectangle, a 2is the area of ​​the light emitting area, y is the vertical distance between a group of the light guide points and the LED light source, Δs is the area of ​​a single light guide point, k is the proportionality coefficient, and I0 is the initial light intensity of the LED light source.

[0021] Preferably, the side edges of the light guide plate are coated with a reflective medium.

[0022] Preferably, the top surface of the light reflecting area is coated with a reflective medium.

[0023] Preferably, the shading plate is made of a light-opaque black packaging material, the light guide plate is made of PMMA, and the light-transmitting sheet is made of glass.

[0024] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0025] A reflective photoelectric encoder chip that can emit light uniformly provided in an embodiment of the present invention is provided with a light guide plate and a light shielding plate. The light guide plate includes a light reflection area and a light emission area. The light emission area is provided with multiple light guide points. The light emitted by the LED light source is reflected to the light guide points via the top surface of the light reflection area and is emitted uniformly perpendicular to the light emission area; the light shielding plate includes at least a light guide plate light shielding area and a bare chip light shielding area. The light guide plate light shielding area is located above the light reflection area and covers the light reflection area. The bare chip light shielding area is located above the bare chip and covers the bare chip except the photosensitive area. The light shielding plate cooperates with the light guide plate to achieve uniform output of the light intensity of the LED light source, eliminate the difference in chip output signal caused by uneven light emission at different positions of the LED light source, improve the quality of the chip output signal, reduce the signal conditioning circuit on the single board, and reduce the product cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are some embodiments of the present invention, not all embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor.

[0027] Figure 1 This is a schematic diagram of the working principle of an existing photoelectric encoder chip;

[0028] Figure 2 It is a schematic diagram of the light intensity of an existing LED light source;

[0029] Figure 3 A schematic diagram of a reflective photoelectric encoder chip capable of uniformly emitting light provided by an embodiment of the present invention;

[0030] Figure 4 A side cross-sectional view of a reflective photoelectric encoder chip capable of uniformly emitting light provided by one embodiment of the present invention;

[0031] Figure 5 An exploded diagram of a reflective photoelectric encoder chip capable of uniformly emitting light provided by one embodiment of the present invention;

[0032] Figure 6 A schematic diagram of the structure of a conduit plate provided for one embodiment of the present invention;

[0033] Figure 7 A schematic diagram of light from an LED light source propagating in a light guide plate provided in one embodiment of the present invention.

[0034] In the figure:

[0035] 1. Chip body; 2. LED light source; 3. Bare chip; 4. Photosensitive area; 5. Light guide plate; 6. Light shielding plate; 8. Transparent sheet;

[0036] 51. Light reflection area; 52. Light emission area; 53. Light guide point;

[0037] 61. Light guide plate shading area; 62. Bare chip shading area; 63. Positioning area; 64. Mounting hole;

[0038] 101. Light emitting device; 102. Light receiving device; 103. Code disk. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0041] Based on the problems existing in the prior art, an embodiment of the present invention provides a reflective photoelectric encoder chip that can emit light evenly, optimizes the structure, and sets a light guide plate and a light shielding plate, so that the light of the LED light source is evenly emitted from the set area, thereby improving the accuracy of measurement.

[0042] Figure 3 A schematic diagram of a reflective photoelectric encoder chip capable of uniformly emitting light provided by an embodiment of the present invention; Figure 4A side cross-sectional view of a reflective photoelectric encoder chip capable of uniformly emitting light provided by one embodiment of the present invention; Figure 5 An exploded diagram of a reflective photoelectric encoder chip capable of uniformly emitting light provided by one embodiment of the present invention; Figure 6 A schematic diagram of the structure of a conduit plate provided for one embodiment of the present invention; Figure 7 A schematic diagram of light from an LED light source propagating in a light guide plate provided in one embodiment of the present invention.

[0043] View now Figures 3 to 7 The embodiment of the present invention provides a reflective photoelectric encoder chip capable of uniformly emitting light, including a chip body 1, wherein the chip body 1 includes:

[0044] LED light source 2, for emitting light;

[0045] The bare chip 3 is provided with a photosensitive area 4, and the photosensitive area 4 is used to receive the light emitted by the LED light source 2 and reflected back by the code disk, and the bare chip 3 outputs an electrical signal according to the received light;

[0046] The light guide plate 5 is used to adjust the path of the light emitted by the LED light source 2 so that the light is evenly emitted in the set area; the light guide plate 5 includes a light reflection area 51 and a light emission area 52, and the LED light source 2 is arranged at the lower part of the center of the light reflection area 51; the light emission area 52 is provided with a plurality of light guide points 53, the light guide points 53 are semi-ellipsoidal, and the plurality of light guide points 53 are distributed in an array, and when the light is irradiated on the light guide points 53, scattering occurs; the plurality of light guide points scatter the light multiple times, so that the entire light emission area 52 becomes a light-emitting surface, thereby controlling the distribution of light and making the light emission area 52 emit light evenly; the light emitted by the LED light source 2 is reflected to the light guide points 53 via the top surface of the light reflection area 51 and is evenly emitted from the light emission area 52;

[0047] The light shielding plate 6 is used to shield light, and at least includes a light guide plate light shielding area 61 and a bare chip light shielding area 62. The light guide plate light shielding area 61 is located above the light reflection area 51 and covers the light reflection area 51. The bare chip light shielding area 62 is located above the bare chip 3 and covers the bare chip 3 except the photosensitive area 4.

[0048] A light-transmitting sheet 8, used to cover the photosensitive area 4 of the bare chip 3, allowing light to pass through;

[0049] The light guide plate 5 is in a U-shape as a whole and surrounds the bare chip 3 . The light emitting areas 52 are two and are respectively arranged on both sides of the bare chip 3 . The light reflecting area 51 is located at one end of the bare chip 3 and connects the two light emitting areas 52 .

[0050] Specifically, a light guide point 53 is formed at the bottom of the light emitting area 52 by laser engraving and etching.

[0051] In some embodiments, the light shielding plate 6 further includes a positioning area 63 , which is located on a side of the bare chip 3 that does not contact the light guide plate 5 . The positioning area 63 and the light guide plate 5 surround and fix the bare chip 3 .

[0052] In some embodiments, the shading plate 6 is integrally formed, and the top surface of the shading plate 6 is a plane; a mounting hole 64 matching the photosensitive area 4 is provided in the middle of the bare chip shading area 62 , and the light-transmitting sheet 8 is provided in the mounting hole 64 .

[0053] In some embodiments, the light reflecting area 51 and the light emitting area 52 of the light guide plate 5 are integrally formed, the bottom surface of the light guide plate 5 is a plane, and the light guiding point 53 is formed by etching the bottom surface of the light emitting area 52 .

[0054] In some embodiments, the height of the light reflecting area 51 of the light guide plate 5 is the same as the height of the bare chip 3, the height of the light emitting area 52 is equal to the height of the bare chip 3 plus the height of the bare chip shading area 62 of the shading sheet 6 and is equal to the height of the light reflecting area 51 plus the height of the light guide plate shading area 61 of the shading sheet 6, so that the top surface of the chip body 1 is flush.

[0055] In some embodiments, the light guide points 53 are divided into multiple groups, each group includes multiple light guide points 53, and the multiple groups of light guide points 53 are arranged at equal intervals in the longitudinal direction away from the LED light source 2; the multiple light guide points 53 in each group are arranged at intervals in the transverse direction, and the number of light guide points 53 in each group increases with the increase of the distance from the LED light source 2.

[0056] Assuming a rectangle of unit area, which contains a row of light guide points 53, the area of ​​the rectangle is approximately equal to the sum of the areas of all light guide points 53 in the rectangle, and its area S is expressed by the following formula:

[0057] S=N*Δs

[0058] Wherein, N is the number of light guiding points 53 on a unit area rectangle, and Δs is the area of ​​a single light guiding point 53;

[0059] Then the light guide point density f per unit area of ​​the rectangle is calculated by the following formula:

[0060]

[0061] Among them, a 2 is the area of ​​the light emitting region 52;

[0062] The light intensity of the light emitting area 52 is related to the distribution of the light guide points 53 and can be expressed by the following formula:

[0063] B=k*E*f

[0064] Wherein, k is the proportionality coefficient, B is the light intensity of the light emitting area 52, and E is the brightness of the light emitting surface of the light emitting area 52;

[0065] The brightness E of the light emitting surface of the light emitting area 52 is calculated by the following formula:

[0066]

[0067] Wherein, y is the vertical distance between a certain group of light guiding points 53 and the LED light source 2 , and I0 is the initial light intensity of the LED light source 2 .

[0068] It can be seen from the above formula that the number N of each group of light guide points 53 on the unit area rectangle can be calculated by the following formula:

[0069]

[0070] Wherein, N is the number of a group of light guide points 53 on a unit area rectangle, a 2 is the area of ​​the light emitting region 52 , y is the vertical distance between a group of light guiding points 53 and the LED light source 2 , Δs is the area of ​​a single light guiding point 53 , k is the proportionality coefficient, and I0 is the initial light intensity of the LED light source 2 .

[0071] In some embodiments, the side of the light guide plate 5 is coated with a reflective medium, which is a nano-coating, to prevent light from leaking from the side of the light guide plate 5 and improve light utilization.

[0072] In some embodiments, the top surface of the light reflection area 51 is coated with a reflective medium, which is a nano coating, so that more light is reflected to the light guide point 53, thereby improving light utilization. The light intensity can also be enhanced by increasing the forward current of the LED light source 2.

[0073] In some embodiments, the shading plate 6 is made of opaque black packaging material, the light guide plate 5 is made of PMMA (Polymethyl methacrylate), the light transmittance of the light guide plate 5 is required to be greater than or equal to 90%, and the light-transmitting sheet 8 is made of glass.

[0074] In summary, an embodiment of the present invention provides a reflective photoelectric encoder chip that can emit light uniformly, and a light guide plate 5 and a light shielding plate 6 are provided. The light guide plate 5 includes a light reflection area 51 and a light emission area 52. The light emission area 52 is provided with multiple light guide points 53. The light emitted by the LED light source 2 is reflected to the light guide points 53 via the top surface of the light reflection area and is uniformly emitted perpendicular to the light emission area 52; the light shielding plate 6 includes at least a light guide plate light shielding area 61 and a bare chip light shielding area 62. The light guide plate light shielding area 61 is located above the light reflection area 51 and covers the light reflection area 51. The bare chip light shielding area 62 is located above the bare chip 3 and covers the bare chip 3 except the photosensitive area 4. The light shielding plate 6 cooperates with the light guide plate 5 to achieve uniform light intensity output of the LED light source 2, eliminate the chip output signal difference caused by uneven light emission at different positions of the LED light source 2, improve the chip output signal quality, reduce the signal conditioning circuit on the single board, and reduce product cost.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A reflective photoelectric encoder chip capable of uniformly emitting light, characterized in that: The chip body includes: LED light source for emitting light; A bare chip is provided with a photosensitive area, wherein the photosensitive area is used to receive the light emitted by the LED light source and reflected back by the code disk, and the bare chip outputs an electrical signal according to the received light; A light guide plate, used to adjust the path of the light emitted by the LED light source so that the light is uniformly emitted in a set area; the light guide plate includes a light reflection area and a light emission area, the LED light source is arranged at the lower part of the center of the light reflection area; the light emission area is provided with a plurality of light guide points, the light guide points are semi-ellipsoidal, and the plurality of light guide points are distributed in an array, and the light emitted by the LED light source is reflected from the top surface of the light reflection area to the light guide points and is uniformly emitted from the light emission area; A light shielding plate, used for shielding light, at least comprising a light guide plate light shielding area and a bare chip light shielding area, wherein the light guide plate light shielding area is located above the light reflection area and covers the light reflection area, and the bare chip light shielding area is located above the bare chip and covers the bare chip except the photosensitive area; A light-transmitting sheet, used to cover the photosensitive area of ​​the bare chip and allow light to pass through; The light guide plate is in a U-shape as a whole and surrounds the bare chip. The light emitting areas are two and are respectively arranged on both sides of the bare chip. The light reflecting area is located at one end of the bare chip and connects the two light emitting areas.

2. The reflective photoelectric encoder chip capable of uniform light emission according to claim 1, characterized in that: The shading plate further comprises a positioning area, the positioning area is located at a side of the bare chip that does not contact the light guide plate, and the positioning area and the light guide plate surround and fix the bare chip.

3. The reflective photoelectric encoder chip capable of uniform light emission according to claim 1, characterized in that: The shading plate is integrally formed, and the top surface of the shading plate is a plane; a mounting hole matching the photosensitive area is arranged in the middle of the bare chip shading area, and the light-transmitting sheet is arranged in the mounting hole.

4. The reflective photoelectric encoder chip capable of uniform light emission according to claim 1, characterized in that: The light reflecting area and the light emitting area of ​​the light guide plate are integrally formed, and the bottom surface of the light guide plate is a plane; the light guiding point is formed by etching the bottom surface of the light emitting area.

5. The reflective photoelectric encoder chip capable of uniform light emission according to claim 1, characterized in that: The height of the light reflecting area of ​​the light guide plate is the same as the height of the bare chip, the height of the light emitting area is equal to the height of the bare chip plus the height of the bare chip shading area of ​​the shading sheet and is equal to the height of the light reflecting area plus the height of the light guide plate shading area of ​​the shading sheet, so that the top surface of the chip body is level.

6. The reflective photoelectric encoder chip capable of uniform light emission according to claim 1, characterized in that: The light guide points are divided into multiple groups, each group includes multiple light guide points, and the multiple groups of light guide points are arranged at equal intervals in the longitudinal direction away from the LED light source; the multiple light guide points in each group are arranged at intervals in the transverse direction, and the number of light guide points in each group increases with the increase of the distance from the LED light source.

7. The reflective photoelectric encoder chip capable of uniform light emission according to claim 6, characterized in that: The number of each group of light guide points on a unit area rectangle is calculated by the following formula: Wherein, N is the number of a group of light guide points on a unit area rectangle, a 2 is the area of ​​the light emitting area, y is the vertical distance between a group of the light guide points and the LED light source, Δs is the area of ​​a single light guide point, k is the proportionality coefficient, and I0 is the initial light intensity of the LED light source.

8. The reflective photoelectric encoder chip capable of uniform light emission according to claim 1, characterized in that: The side edges of the light guide plate are coated with a reflective medium.

9. The reflective photoelectric encoder chip capable of uniform light emission according to claim 1, characterized in that: The top surface of the light reflecting area is coated with a reflective medium.

10. The reflective photoelectric encoder chip capable of uniform light emission according to claim 1, characterized in that: The shading plate is made of opaque black packaging material, the light guide plate is made of PMMA, and the light-transmitting sheet is made of glass.

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