TWI718040B - Encoder - Google Patents

Abstract

This invention provides an encoder including a light-receiving module package (3) having a package substrate (30) and a light-transmitting resin (33) covering a mounting surface (30a) of the substrate. The light-transmitting resin (33) has a first part (33a) and a second part (33b). The first part (33a) covers an area on the mounting surface (30a) where a light-emitting element (31) is disposed. The second part (33b) covers an area on the mounting surface (30a) where a light-receiving element (32) and a bonding wire (35) connecting the light-receiving element (32) and the substrate are disposed. The thickness in at least a part of the second part (33b) of the light-transmitting resin (33) perpendicular to the mounting surface (30a) is thinner than that of the first part (33a), or the length in at least a part of the second part (33b) of the light-transmitting resin (33) parallel to the mounting surface (30a) and perpendicular to the direction in which the light emitting element (31) and the light receiving element (32) are arranged side by side is shorter than that of the first part (33a).

Description

Encoder

The invention relates to an encoder for detecting the rotation angle of a measurement object.

The optical rotary encoder is an encoder that calculates the rotation angle of the scale based on the light signal incident from the scale. The light-emitting element that irradiates light on the scale and the light-receiving element that receives the light from the scale are covered by a light-transmitting resin, thereby being protected from the external environment. In addition, bonding wires connecting the light-receiving element and the substrate are protected by light-transmitting resin together with the light-receiving element. Generally, the thermal expansion coefficient of the light-transmitting resin and the material of the bonding wire are different, so the bonding wire may sometimes withstand the stress caused by the expansion or contraction of the light-transmitting resin due to temperature changes. Bonding wires sometimes break due to repeated stress.

Patent Document 1 discloses a light-emitting device that has a light-transmitting resin covering a light-emitting element provided on a base substrate, and the substrate is provided with a wire connecting the light-emitting element through Through hole. According to the technology of Patent Document 1, by reducing the amount of light-transmitting resin around the bonding wire, the stress on the bonding wire due to temperature changes is reduced.

[Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Application Publication No. 2012-94612

In the encoder, the more the number of light-receiving elements is increased in order to calculate the rotation angle with high accuracy, the more the number of bonding wires will become. When the technique of Patent Document 1 is applied to the bonding wires connected to the light-receiving element, the more the number of the bonding wires of the substrate on which the light-receiving element is mounted, the greater the number of through holes. As the number of through holes increases, the size of the package made by the light-transmitting resin increases, making it difficult to miniaturize the encoder. In addition, as the number of through holes increases, the processing at the time of encoder manufacturing becomes more complicated. Therefore, according to the technique of Patent Document 1, there is a problem that it is difficult to reduce the breakage of the bonding wire with a small and easily processable structure.

The present invention was developed in view of the above-mentioned problems, and its purpose is to obtain an encoder that can prevent the breakage of the wire connecting the light-receiving element and the substrate by a structure that is small and can be easily processed.

In order to solve the above-mentioned problems and achieve the objective, the encoder of the present invention has: a scale having an optical pattern; and a module package having a substrate and a light-transmitting resin, the substrate The light-emitting element and the light-receiving element are installed. The light-emitting element irradiates light on the scale, and the light-receiving element The light-transmitting resin covers the mounting surface of the substrate on which the light-emitting element and the light-receiving element are mounted; the light-transmitting resin has a first part and a second part, and the first part covers The area on the mounting surface where the light-emitting element is provided, and the second part covers the area where the light-receiving element and the bonding wire connecting the light-receiving element and the substrate are located in the mounting surface; A light-shielding part is provided between the parts to shield light; the part covering the lap line in the second part has a thickness in the first direction perpendicular to the installation surface than the first part in the first direction The thickness is thinner, and a portion with the same thickness in the first direction as that of the first portion is included in the second portion other than the portion covering the lap line.

The encoder of the present invention achieves the effect of preventing the breakage of the wire connecting the light-receiving element and the substrate through a small and easily processed structure.

1: encoder

2: Optical scale

3: Light emitting and receiving module package

4: Control Department

5: Rotation axis

11, 12: signal

13: Signal waveform

14: Threshold level

15: bit stream

16: checklist

17: Phase offset

18: reference pixel

19: Edge pixel position

20: Optical pattern

21: reflection part

22: Non-reflective part

30: Package substrate

30a: Mounting surface

31: Light-emitting element

31a: luminous surface

32: Light receiving element

32a: Light receiving surface

33: Light-transmitting resin

33a: The first part

33b: second part

33c, 33d, 33e: part

34: light-shielding resin

35: Wiring

36: curved surface

41: Angle calculation department

42: Luminous quantity adjustment part

43: Location Information

44: Light distribution correction section

45: Edge Detection Department

46: Rough Inspection Department

47: High-precision detection department

48: Rotation angle detection unit

49: rough absolute rotation angle

L1~L4: length

Fig. 1 is a schematic diagram showing the structure of the encoder of Embodiment 1 of the present invention.

Figure 2 is a perspective view of the module package of the encoder shown in Figure 1.

Figure 3 is a cross-sectional view of the module package included in the encoder shown in Figure 1.

Fig. 4 is a top view of the module package of the encoder shown in Fig. 1.

Fig. 5 is a block diagram showing the structure of the angle calculation unit of the encoder shown in Fig. 1.

Fig. 6 is a schematic diagram showing an example of the signal waveform of the signal input to the light distribution correction unit included in the angle calculation unit shown in Fig. 5.

Fig. 7 is a schematic diagram showing an example of the signal waveform after correction in the light distribution correction unit included in the angle calculation unit shown in Fig. 5.

Fig. 8 is a schematic diagram for explaining the method of calculating the rough absolute rotation angle from the signal waveform shown in Fig. 7.

FIG. 9 is a schematic diagram for explaining a method of calculating a high-precision absolute rotation angle from the rough absolute rotation angle explained by reference to FIG. 8.

FIG. 10 is a cross-sectional view of a module package included in the encoder of Embodiment 2 of the present invention.

Figure 11 is a top view of the module package included in the encoder shown in Figure 10.

Figure 12 is a perspective view of a module package included in the encoder of Embodiment 3 of the present invention.

Figure 13 is a top view of the module package included in the encoder shown in Figure 12.

Hereinafter, the encoder of the embodiment of the present invention will be described in detail based on the drawings. Furthermore, the present invention is not limited to this embodiment. In the diagrams shown below, the scale of each element may be different from reality in some cases, and the same may be the case among the various diagrams. In addition, in the drawings shown below, in order to make it easier to see the drawings, there are cases where no hatching is added to the elements shown by the cross section.

[Implementation Type 1]

Fig. 1 is a schematic diagram showing the structure of the encoder of Embodiment 1 of the present invention. The encoder 1 detects the rotation angle of the rotating body belonging to the measurement object. The encoder 1 is an optical rotary encoder that calculates the rotation angle of the scale based on the light signal incident from the scale, and is an absolute encoder that detects the absolute rotation angle.

The encoder 1 has: an optical scale 2, which is a scale with an optical pattern 20; a light emitting and receiving module package 3, which is a module package with light emitting and receiving functions; and a control unit 4, which controls the encoder 1. The optical scale 2 is connected to a rotating shaft 5 provided in a rotating device such as a motor. The optical scale 2 rotates together with the rotating shaft 5. In Fig. 1, illustration of the rotating device is omitted.

In the optical scale 2, a circular plate is used. The optical pattern 20 is provided in a ring-shaped area, which is the outer peripheral part of the circular shape of the optical scale 2. The optical pattern 20 has reflective parts 21 and non-reflective parts 22 alternately arranged in a direction along the outer circumference of the circular shape. The reflection part 21 is a part that reflects light incident from a light-emitting element described later toward the light emitting and receiving module package 3. The non-reflective portion 22 is a portion that absorbs or scatters light incident from the light emitting element.

Each of the plurality of reflecting portions 21 and the plurality of non-reflecting portions 22 has various widths in the direction along the outer circumference. When the light emitting element irradiates light to the rotating optical pattern 20, reflection for a time corresponding to the width of the reflective portion 21 and non-reflection for a time corresponding to the width of the non-reflective portion 22 are repeated on the optical pattern 20. The light receiving element described later detects the light reflected by the reflection part 21. The intensity of the light detected in the light-receiving element is adjusted according to the arrangement pattern of the reflective part 21 and the non-reflective part 22.

The arrangement pattern of the reflective part 21 and the non-reflective part 22 is set in such a way that the rotation angle of the optical scale 2 is characterized. In this way, the optical scale 2 has a unique optical pattern 20 at the rotation angle. In the optical pattern 20, for example, a so-called M series pseudo random code pattern can be used.

For the plate material constituting the optical scale 2, for example, a metal base material such as stainless steel can be used. The non-reflective portion 22 is formed by applying electroplating treatment to the surface of the metal substrate. The reflection part 21 is formed by applying a mirror finish to the surface of the metal substrate. The reflection part 21 may also be formed by a method other than mirror polishing. The non-reflective portion 22 may also be formed by a method other than the plating process.

The light emitting and receiving module package 3 emits light toward the optical scale 2. In addition, the light emitting and receiving module package 3 detects the light reflected on the optical scale 2. The light emitting and receiving module package 3 outputs a signal corresponding to the detected light to the control unit 4. The control unit 4 has an angle calculation unit 41 that calculates the absolute rotation angle of the optical scale 2 and a light emission amount adjustment unit 42 that adjusts the light emission amount in the light emitting and receiving module package 3.

The angle calculation unit 41 calculates the absolute rotation angle of the optical scale 2 based on the signal output from the light receiving element of the light emitting and receiving module package 3. The absolute rotation angle calculated by the angle calculation unit 41 corresponds to the rotation position of the rotation shaft 5. In this way, the angle calculation unit 41 obtains the rotational position of the rotating shaft 5 based on the signal corresponding to the encoded optical pattern 20. The angle calculation unit 41 outputs position data 43 to an external device. The position data 43 is the calculation result of the absolute rotation angle and is data indicating the rotation position of the rotation shaft 5. The light emission amount adjusting unit 42 adjusts the light emission amount by the light emitting element based on the signal output from the light receiving element. Furthermore, the light-emitting element and the light-receiving element will be described later.

In this way, the encoder 1 calculates the absolute rotation angle by the angle calculation unit 41 from the signal corresponding to the light that has entered the light receiving element. Furthermore, the control unit 4 may perform rotation control of the measurement target based on the absolute rotation angle. Since the encoder 1 does not need to accumulate the pulse signal output from the light-receiving element, there is no need to set the optical scale when the power is turned on The action of the ruler 2 returning to the origin. Therefore, the encoder 1 can be quickly activated when the power is turned on.

Figure 2 is a perspective view of the module package of the encoder shown in Figure 1. Figure 3 is a cross-sectional view of the module package included in the encoder shown in Figure 1. Figure 4 is a top plan view of the module package of the encoder shown in Figure 1. The light emitting and receiving module package 3 has: a light emitting element 31 for irradiating light to the optical scale 2; a light receiving element 32 for detecting light from the optical scale 2; and a package substrate 30 for mounting the light emitting element 31 and The substrate of the light receiving element 32.

The light emitting element 31 and the light receiving element 32 are mounted on the mounting surface 30 a of the package substrate 30. The mounting surface 30a is formed in a rectangular shape. The light emitting and receiving module package 3 is in a state where the mounting surface 30a faces the optical scale 2 and is arranged opposite to the optical pattern 20.

The encoder 1 has an encoder substrate to which a package substrate 30 is connected. In Figures 2 and 3, illustration of the encoder substrate is omitted. In the encoder substrate, various processes on the rear side of the light emitting and receiving module package 3 are executed. The control unit 4 is arranged on the encoder board. Specifically, the encoder substrate has a processing circuit that executes the processing of the control unit 4. The angle calculation unit 41 and the light emission amount adjustment unit 42 are functional units of the control unit 4.

The mounting surface 30a is provided with terminals connected to the encoder board. The terminals are provided on all four sides of the rectangle of the mounting surface 30a. Each terminal is a through hole or a back electrode. By providing terminals on all four sides of the mounting surface 30a, the mounting accuracy of the light emitting element 31 and the light receiving element 32 is improved.

The packaging substrate 30 is preferably composed of the same substrate as the encoder substrate. The encoder substrate is composed of, for example, a glass epoxy substrate. In this case, the packaging substrate 30 is preferably also composed of a glass epoxy substrate.

The light emitting element 31 is an element having a light emitting surface 31a that emits light. The light emitting element 31 is, for example, a point light source LED (Light Emitting Diode) that emits near-infrared light. The light emitting element 31 is joined to the package substrate 30 so that the light emitting surface 31a and the mounting surface 30a become parallel.

The light receiving element 32 is an element having a light receiving surface 32a that receives light. The light-receiving element 32 is, for example, an imaging element of a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor, and has A collection of pixels arranged in a single direction. The light receiving element 32 is joined to the package substrate 30 so that the light receiving surface 32a and the mounting surface 30a become parallel.

The light receiving element 32 outputs a signal corresponding to the intensity of the light incident on the light receiving surface 32a. Specifically, the light receiving element 32 converts the light received on the light receiving surface 32a into an analog voltage signal. The light receiving element 32 further converts the analog voltage signal into a digital voltage signal by an A/D (Analog-to-Digital) converter built in the light receiving element 32. Thereby, the light receiving element 32 generates a signal corresponding to the intensity of the light incident on the light receiving surface 32a. The light receiving element 32 outputs the generated signal to the control unit 4. In Figs. 2 to 4, the illustration of the A/D converter is omitted. The signal output by the light receiving element 32 is a signal corresponding to the light reflected on the optical scale 2 and received by the light receiving element 32. Therefore, the signal received by the control unit 4 corresponds to the rotational position of the optical scale 2.

The light emitting and receiving module package 3 has a light transmissive resin 33 covering the mounting surface 30a. The light-transmitting resin 33 encloses the light-emitting element 31 and the light-receiving element 32. The light-transmitting resin 33 has a first part 33a and a second part 33b. The first part 33a covers the area of the mounting surface 30a where the light-emitting element 31 is provided, and the second part 33b covers the mounting surface 30a. An area where the light receiving element 32 and the bonding wire 35 are provided. The bonding wire 35 connects the light receiving element 32 and the package substrate 30. In FIG. 2, the light-emitting element 31, the light-receiving element 32, and the bonding wire 35 which belong to the constituent elements covered by the light-transmitting resin 33 are indicated by dotted lines. In addition, in FIG. 4, the light-emitting element 31, the light-receiving element 32, and the bonding wire 35, which belong to the constituent elements covered by the light-transmitting resin 33, are represented by solid lines. In order to match the linear expansion coefficient of the light-transmitting resin 33 and the package substrate 30, for example, an epoxy resin is used for the light-transmitting resin 33. The distance between the surface facing the optical scale 2 in the second part 33b and the bonding wire 35 is shorter than the distance between the surface facing the optical scale 2 in the second part 33b and the light receiving surface 32a. In addition, the bonding wire 35 is provided on the mounting surface 30a other than the portion between the light-emitting element 31 and the light-receiving element 32. Thereby, the light emitting and receiving module package 3 can suppress the light incident from the light emitting element 31 to the light receiving element 32 from being hindered by the bonding wire 35.

The light emitting and receiving module package 3 has a light-shielding resin 34 as a light-shielding portion. The light-shielding resin 34 suppresses the penetration of the incident light by absorbing or scattering the incident light. The light-shielding resin 34 is an element for suppressing stray light of unnecessary light propagating in the light emitting and receiving module package 3. The light-shielding resin 34 is provided between the first part 33a and the second part 33b. The light-transmitting resin 33 is divided into a first part 33 a and a second part 33 b by the light-shielding resin 34. In the light-shielding resin 34, an epoxy resin is used in the same manner as the light-transmitting resin 33.

Part of the light emitted from the light emitting element 31 will not be emitted from the light emitting and receiving module package 3 due to Fresnel reflection on the interface of the first part 33a and stay at the first part 33a. In this way, when the light stays at the first part 33a, stray light will be generated in the light emitting and receiving module package 3. The stray light is incident on the light receiving element 32, whereby the signal output from the light receiving element 32 will be mixed with components corresponding to the light incident from the optical scale 2 to the light receiving element 32 and components corresponding to the stray light ingredient. In the encoder 1, stray light enters the light receiving element 32 and it is difficult to calculate the correct rotation angle.

The light-shielding resin 34 blocks the light traveling from the first part 33 a to the second part 33 b to suppress stray light from traveling to the light receiving element 32. The light-shielding resin 34 not only shields the light reflected at the interface of the first part 33a, but also shields the light incident from the light-emitting element 31 without being reflected on the interface, or between the package substrate 30 and the optical scale 2 Light that has undergone multiple reflections.

The light-shielding resin 34 is formed in a plate shape. The first end belonging to one end of the light-shielding resin 34 in the direction perpendicular to the mounting surface 30a is in contact with the mounting surface 30a. The first part 33 a and the second part 33 b are divided on the mounting surface 30 a by the light-shielding resin 34. The second end belonging to the other end of the light-shielding resin 34 in the direction perpendicular to the mounting surface 30a is set so that the position in the direction perpendicular to the mounting surface 30a is opposite to the mounting surface 30a side in the first part 33a The same position on the sides. Therefore, the second end of the light-shielding resin 34 is exposed on the surface of the light emitting and receiving module package 3 facing the optical scale 2.

The light-shielding resin 34 is arranged at a position where it does not shield the light traveling from the light-emitting element 31 to the light-receiving element 32 through reflection on the optical scale 2. Light-shielding resin 34 series The surface of the light-shielding resin 34 on the side of the first site 33a and the surface of the light-shielding resin 34 on the side of the second site 33b are arranged so as to be perpendicular to the mounting surface 30a.

The glass epoxy substrate is known to partially transmit light such as near infrared rays. When a glass epoxy substrate is used for the packaging substrate 30, a part of the light emitted from the light emitting element 31 may propagate to the packaging substrate 30 and reach the light receiving element 32 directly or after being reflected in the first part 33a. In this way, the stray light that has propagated to the package substrate 30 may be incident on the light receiving element 32. In order to suppress the incidence of light into the packaging substrate 30, a black glass epoxy substrate may be used for the packaging substrate 30. Alternatively, on the surface of the packaging substrate 30, a light-shielding layer useful for suppressing the incidence of light into the packaging substrate 30 or the propagation of light inside the packaging substrate 30 may be formed. In the light shielding layer, a metal film, a black resist, or a combination of a metal film and a black resist is used. In this way, the light emitting and receiving module package 3 can prevent stray light from entering the light receiving element 32. Furthermore, as long as it is a method that achieves the same effect as the method using these materials, in order to prevent stray light from entering the light receiving element 32, a method using other materials may also be applied.

Here, regarding the arrangement of the components of the light emitting and receiving module package 3, the X axis, the Y axis, and the Z axis are defined as three mutually perpendicular axes. The Z-axis direction is a first direction, and the first direction is a direction perpendicular to the mounting surface 30a. The X-axis direction is the direction in which the first part 33a and the second part 33b are arranged side by side with the light-shielding resin 34 interposed therebetween. The Y-axis direction is a second direction, and the second direction is a direction perpendicular to the direction in which the first part 33a and the second part 33b are aligned and perpendicular to the first direction. The X-axis direction and the Y-axis direction are directions parallel to the mounting surface 30a. The direction of the arrow indicating the Z-axis direction is the direction facing the mounting surface 30a.

The length L2 of the second part 33b in the Z-axis direction is shorter than the length L1 of the first part 33a in the Z-axis direction. In other words, the second in the direction perpendicular to the mounting surface 30a The thickness of the portion 33b is thinner than the thickness of the first portion 33a in the direction perpendicular to the mounting surface 30a. The effect that can be achieved by making the length L2 shorter than the length L1 will be described later.

The encoder 1 detects the light reflected on the optical pattern 20 and obtains the rotation angle of the optical scale 2. The encoder 1 may also be provided with a configuration for detecting light passing through the optical pattern 20 instead of a configuration for detecting light reflected on the optical pattern 20.

Next, the configuration of the angle calculation unit 41 will be described. Fig. 5 is a block diagram showing the structure of the angle calculation unit of the encoder shown in Fig. 1. The angle calculation unit 41 includes a light quantity distribution correction unit 44, an edge detection unit 45, a rough detection unit 46, a high precision detection unit 47, and a rotation angle detection unit 48. The light receiving element 32 outputs a signal corresponding to the intensity of the light incident on the light receiving surface 32 a to the light quantity distribution correction unit 44.

Fig. 6 is a schematic diagram showing an example of the signal waveform of the signal input to the light distribution correction unit included in the angle calculation unit shown in Fig. 5. The vertical axis of the graph shown in Fig. 6 indicates the signal intensity, and the horizontal axis indicates the position of the pixel. The signal 11 belonging to the level "1" of the peak in the signal waveform corresponds to the reflection part 21 in the optical pattern 20 after encoding. The signal 12 belonging to the level "0" of the bottom of the signal waveform corresponds to the non-reflective portion 22 in the encoded optical pattern 20.

The light distribution of the light-emitting element 31 and the unevenness of the gain in each pixel of the light-receiving element 32 will cause a difference in the signal intensity of the signal 11 for each pixel. In the signal intensity of the signal 12, similar to the signal intensity of the signal 11, a difference occurs for each pixel. The light distribution correction unit 44 performs correction to make the signal intensities of the signals 11 uniform, and correction to make the signal intensities of the signals 12 uniform. Light distribution The correction unit 44 corrects the input signal, thereby obtaining a signal in which the signal strengths of the signals 11 are uniform and the signal strengths of the signals 12 are uniform.

Fig. 7 is a schematic diagram showing an example of the signal waveform after correction in the light distribution correction unit included in the angle calculation unit shown in Fig. 5. The vertical axis of the graph shown in Fig. 7 indicates the signal intensity, and the horizontal axis indicates the position of the pixel. In the corrected signal waveform 13, the signal strength in the peak will be uniform, and the signal strength in the trough will be uniform. In addition, the correction method performed by the light quantity distribution correcting unit 44 may be any method as long as it can suppress the unevenness of the signal intensity due to the light quantity distribution or the like. The light distribution correction unit 44 outputs the corrected signal to the edge detection unit 45.

The edge detection unit 45 calculates the pixel value for each edge based on the corrected signal by the light distribution correction unit 44. The pixel value indicates that the signal intensity is consistent with the threshold level 14 set in advance. value. The edge refers to the boundary between the reflective part 21 and the non-reflective part 22 in the optical pattern 20. The edge detection unit 45 outputs the edge pixel value as the calculated pixel value to the rough detection unit 46. The edge pixel value indicates the position of the edge.

The rough detection unit 46 decodes the bit pattern projected on the light receiving element 32 in the optical pattern 20 according to the input edge pixel value. The rough detection unit 46 decodes the bit pattern to calculate the rough absolute rotation angle 49.

Fig. 8 is a schematic diagram for explaining the method of calculating the rough absolute rotation angle from the signal waveform shown in Fig. 7. The bit stream 15 shown in FIG. 8 is a bit stream corresponding to the signal of the signal waveform 13. The rough detection unit 46 converts the signal of the signal waveform 13 into the bit stream 15 of each coded arrangement of "0" and "1" according to the position of the edge represented by the edge pixel value.

The look-up table 16 establishes a corresponding relationship between the absolute rotation angle of the optical scale 2 and the bit stream and saves it. The checklist 16 is stored in a memory (memory) of the control unit 4 in advance. In Figures 1 to 5, the illustration of the memory is omitted. The rough detection unit 46 reads the absolute rotation angle corresponding to the same bit stream as the bit stream 15 from the check table 16 to obtain the rough absolute rotation angle 49. The rough detection unit 46 outputs the rough absolute rotation angle 49 to the high precision detection unit 47.

The high-accuracy detection unit 47 calculates the phase shift amount of the pattern projected on the light receiving element 32 with high accuracy based on the rough absolute rotation angle 49. The rough absolute rotation angle 49 obtained by the rough detection unit 46 is the absolute rotation angle of the bit unit of the optical scale 2. The high-precision detection unit 47 detects the phase shift amount, which indicates the shift between the rough absolute rotation angle 49 and the high-precision absolute rotation angle.

FIG. 9 is a schematic diagram for explaining a method of calculating a high-precision absolute rotation angle from the rough absolute rotation angle explained by reference to FIG. 8. As shown in FIG. 9, the high-accuracy detection unit 47 detects the phase shift amount 17 from the position of the reference pixel 18 to the edge pixel position 19, which is the position of the edge pixel closest to the reference pixel 18. The reference pixel 18 is a pixel used as a reference when calculating a high-precision absolute rotation angle, and may be any pixel. The phase shift amount 17 corresponds to the difference between the position of the reference pixel 18 and the position of the edge pixel 19. The high-accuracy detection unit 47 outputs the rough absolute rotation angle 49 and the phase shift amount 17 to the rotation angle detection unit 48.

The rotation angle detection unit 48 calculates a high-precision absolute rotation angle with respect to a unit smaller than the 1-bit unit of the optical scale 2 based on the phase shift amount 17. Specifically, the rotation angle detection unit 48 is based on the rough absolute rotation angle calculated by the rough detection unit 46 The degree 49 is added to the phase shift amount 17 calculated by the high-accuracy detection unit 47 to calculate the high-accuracy absolute rotation angle. The rotation angle detection unit 48 outputs the position data 43 belonging to the calculation result of the high-precision absolute rotation angle to an external device.

Next, the effect achieved by making the length L2 of the second part 33b shorter than the length L1 of the first part 33a in the light emitting and receiving module package 3 will be described. The bonding wire 35 is sealed by the light-transmitting resin 33 to obtain protection. Generally, since the thermal expansion coefficients of the materials of the light-transmitting resin 33 and the bonding wire 35 are different, the bonding wire 35 may sometimes withstand the stress caused by the expansion or contraction of the light-transmitting resin 33 due to temperature changes. When the bonding wire 35 is broken due to repeated stress, the light emitting and receiving module package 3 cannot send the signal from the light receiving element 32 to the angle calculation unit 41, and therefore the rotation angle cannot be calculated.

In the first embodiment, the thickness of the second portion 33b in the Z-axis direction is thinner than the thickness of the first portion 33a in the Z-axis direction. Compared with the case where the thickness of the second part 33b is the same as the thickness of the first part 33a, the thickness of the second part 33b is made thinner than the thickness of the first part 33a, which reduces the light in the second part 33b. The amount of penetrating resin 33. In the second portion 33b, by reducing the amount of the light-transmitting resin 33, the amount of expansion and contraction when a temperature change occurs is reduced. As the amount of expansion and contraction decreases, the stress on the bonding wire 35 due to the expansion or contraction of the light-transmitting resin 33 decreases. In this way, the light emitting and receiving module package 3 can reduce the breakage of the bonding wire 35.

In the case where the thickness of the first portion 33a is reduced in the same way as the thickness of the second portion 33b, in the first portion 33a, the light-emitting element 31 passes through the reflection on the interface of the light-transmitting resin 33 and is reflected on the light-emitting element. 31 or reflection of the wiring pattern connected to the light-emitting element 31 The light will increase, so the stray light will increase. The light emitting and receiving module package 3 maintains a thickness capable of suppressing stray light for the first portion 33a.

Compared with the case where a through hole is provided on the package substrate 30 and the bonding wire 35 penetrates through the through hole, it is not necessary to provide the same number of through holes as the bonding wire 35 in the manufacture of the light emitting and receiving module package 3 Processing. Therefore, the light emitting and receiving module package 3 can avoid the problem of complicated processing during manufacturing. In addition, by eliminating the need for through holes, the light emitting and receiving module package 3 can also avoid the problem of enlargement.

The light emitting and receiving module package 3 is formed by forming the light-transmitting resin 33 such that the thickness of the second portion 33b becomes thinner than the thickness of the first portion 33a, thereby forming a structure capable of reducing the breakage of the bonding wire 35. As long as the light-transmitting resin 33 of the first part 33a and the second part 33b have different thicknesses for the light emitting and receiving module package 3, a structure capable of reducing the breakage of the bonding wire 35 can be easily obtained. As a result of the above, the encoder 1 has the effect of reducing the breakage of the bonding wire 35 through a compact and easily processed structure.

[Implementation Type 2]

FIG. 10 is a cross-sectional view of a module package included in the encoder of Embodiment 2 of the present invention. Figure 11 is a top view of the module package included in the encoder shown in Figure 10. In a part of the second part 33b in the second embodiment, the length L2 in the Z-axis direction is shorter than the length L1 of the first part 33a in the Z-axis direction. In the second embodiment, the same symbols are added to the same components as those in the first embodiment, and the description is mainly for the different components from the first embodiment. In FIG. 11, the light-emitting element 31, the light-receiving element 32, and the bonding wire 35, which belong to the constituent elements covered by the light-transmitting resin 33, are represented by solid lines.

The portion 33c of the length L2 in the second portion 33b is a portion other than the portion 33d where the light-receiving surface 32a is provided, and is a portion other than the portion 33e on the first portion 33a side than the light-receiving surface 32a. In the portion 33d and the portion 33e, the length in the Z-axis direction is the length L1. A concave curved surface 36 is formed between the portion 33c and the portion 33d. That is, a slope is provided between the portion 33c and the portion 33d. The surface between the portion 33c and the portion 33d may also be an inclined surface having an inclination with respect to the mounting surface 30a. By providing a slope between the portion 33c and the portion 33d, the light irradiated from the light emitting element 31 and incident on the slope will not enter the light receiving element 32. Therefore, the light emitting and receiving module package 3 can suppress stray light.

Among the light incident on the light-receiving surface 32a, the light reflected on the light-receiving surface 32a and the light reflected around the light-receiving surface 32a may turn toward the light-receiving surface due to Fresnel reflection at the interface of the second part 33b. Stray light of 32a. The thinner the portion 33d where the light-receiving surface 32a is provided, the more the light reflected at the interface of the second portion 33b increases, thereby increasing the stray light. In the second embodiment, the thickness in the Z-axis direction of the portion 33d is the same as the thickness of the first portion 33a, so that the light emitting and receiving module package 3 can suppress stray light toward the light receiving surface 32a.

According to the second embodiment, the thickness of the portion 33c as a part of the second portion 33b is formed to be thinner than the thickness of the first portion 33a. The light emitting and receiving module package 3 can prevent the bonding wire 35 from breaking by reducing the amount of the light-transmitting resin 33 in the second part 33b. In addition, the projecting and receiving module package 3 can suppress stray light toward the light receiving surface 32a by not reducing the thickness of the portion 33d provided with the light receiving surface 32a. In this way, the encoder 1 can calculate the correct rotation angle.

[Implementation Type 3]

Figure 12 is a perspective view of a module package included in the encoder of Embodiment 3 of the present invention. Figure 13 is a top view of the module package included in the encoder shown in Figure 12. In a part of the second part 33b of the third embodiment, the length L4 in the Y-axis direction is shorter than the length L3 of the first part 33a in the Y-axis direction. In Embodiment 3, the same constituent elements in the above-mentioned Embodiment 1 and Embodiment 2 are attached with the same symbols, and the different configurations from Embodiment 1 and Embodiment 2 are mainly described. In FIGS. 12 and 13, the illustration of the package substrate 30 is omitted. In addition, in FIG. 13, the light-emitting element 31, the light-receiving element 32, and the bonding wire 35 which belong to the constituent elements covered by the light-transmitting resin 33 are represented by solid lines.

Compared with the case where the entire length of the second part 33b is the same length L3 as the first part 33a, since the length L4 in a part of the second part 33b is shorter than the length L3 in the first part 33a, This reduces the amount of light-transmitting resin 33 in the second part 33b. The light emitting and receiving module package 3 can reduce the stress of the bonding wire 35 in the Y-axis direction. In this way, the light emitting and receiving module package 3 can reduce the breakage of the bonding wire 35.

Furthermore, in Embodiment 3, regarding the entire second portion 33b, the length in the Y-axis direction can also be set as the length L4. In this case, the light emitting and receiving module package 3 can also reduce the breakage of the bonding wire 35. As long as the light-transmitting resin 33 of the first part 33a and the second part 33b have different lengths in the light-emitting and receiving module package 3, a structure capable of reducing the breakage of the bonding wire 35 can be easily obtained. As a result, the encoder 1 can achieve the effect of reducing the breakage of the bonding wire 35 through a small-sized and easy-to-process structure similar to the case of the first embodiment.

The configuration shown in the above embodiment is an example of the content of the present invention, which can be combined with other known technologies, and part of the configuration can be omitted or changed without departing from the gist of the present invention.

3 Light emitting and receiving module packaging 30 Package substrate 30a Installation surface 31 Light-emitting element 31a Luminous surface 32 Light-receiving components 32a Illuminated side 33 Light-transmitting resin 33a The first part 33b The second part 34 Light-shielding resin 35 Wiring L1, L2 Length

Claims (5)

An encoder is provided with: a scale having an optical pattern; and a module package having a substrate and a light-transmitting resin, the substrate is mounted with a light-emitting element and a light-receiving element, and the light-emitting element irradiates light to the aforementioned A scale, the light-receiving element has a light-receiving surface into which light from the scale is incident, and the light-transmitting resin covers the mounting surface of the substrate on which the light-emitting element and the light-receiving element are mounted; The resin system has a first part and a second part. The first part covers the area on the mounting surface where the light emitting element is provided, and the second part covers the light receiving element on the mounting surface and the light receiving element is connected to the second part. The area of the bonding wire between the component and the substrate; the module package is provided with a light-shielding portion between the first part and the second part to shield light; in the second part, the bonding wire is covered The part whose thickness in the first direction, which is the direction perpendicular to the mounting surface, is thinner than the thickness of the first part in the first direction, and the second part covers the part of the bonding wire outside It includes a portion having the same thickness in the first direction as the thickness of the first portion. The encoder described in claim 1, wherein the part covering the light-receiving surface in the second part is the thickness in the first direction and the thickness of the first part in the first direction The thickness is the same. The encoder described in item 1 or item 2 of the scope of the patent application, wherein, in the second part, the thickness in the first direction is greater than that in the first direction. The portion where the thickness of the portion is thinner is provided with a slope between the portion of the second portion where the thickness in the first direction is the same as the thickness of the first portion in the first direction. An encoder is provided with: a scale having an optical pattern; and a module package having a substrate and a light-transmitting resin, the substrate is mounted with a light-emitting element and a light-receiving element, and the light-emitting element irradiates light to the aforementioned A scale, the light-receiving element has a light-receiving surface into which light from the scale is incident, and the light-transmitting resin covers the mounting surface of the substrate on which the light-emitting element and the light-receiving element are mounted; The resin system has a first part and a second part. The first part covers the area on the mounting surface where the light emitting element is provided, and the second part covers the light receiving element on the mounting surface and the light receiving element is connected to the second part. The area where the component and the aforementioned substrate are connected; the aforementioned module package is provided with a light-shielding portion between the aforementioned first part and the aforementioned second part; at least a part of the aforementioned second part is in the first part The length in the two directions is shorter than the length of the first portion in the second direction, which is perpendicular to the direction in which the light emitting element and the light receiving element are aligned and parallel to the mounting surface. The encoder according to any one of items 1, 2 and 4 in the scope of patent application, wherein the substrate is a substrate made of glass epoxy resin; the light-transmitting resin and the light-shielding portion are epoxy Department resin.

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