WO2019162998A1

WO2019162998A1 - Absolute encoder

Info

Publication number: WO2019162998A1
Application number: PCT/JP2018/006018
Authority: WO
Inventors: 琢也野口; 勇治久保; 秀多久島; 茂雄神保
Original assignee: 三菱電機株式会社
Priority date: 2018-02-20
Filing date: 2018-02-20
Publication date: 2019-08-29
Also published as: CN110392820B; KR20190102172A; KR102037786B1; TWI660159B; JP6407502B1; TW201934963A; JPWO2019162998A1; CN110392820A

Abstract

This absolute encoder comprises: an optical scale having an optical pattern; a module package (300B) in which a light-emission element (31) for irradiating light onto the optical scale and a light-reception element (32) for receiving reflected light from the optical scale are covered by a light-transmitting resin (33A); and a control unit for calculating the absolute rotation angle of the optical scale on the basis of a signal output by the light-reception element (32) according to the reflected light. The module package (300B) has light-blocking resin (34B) disposed so as to be exposed at the surface of the light-transmitting resin (33A) facing the optical scale and pass through the intermediate position between the center of the light emission surface (310) of the light-emitting element (31) and the center of the light reception surface (320) of the light-reception element (32).

Description

Absolute encoder

The present invention relates to an absolute encoder that detects an absolute rotation angle of a measurement object.

¡An absolute encoder is one of the rotary encoders that detects the absolute rotation angle of the measurement object. The absolute encoder is an encoder that calculates an absolute rotation angle of the optical scale based on an optical signal reflected by an optical pattern on the optical scale and incident on a light receiving element. In this absolute encoder, when an unnecessary light beam other than the light beam used for the calculation of the absolute rotation angle is incident on the light receiving element, the detection accuracy of the absolute rotation angle is lowered. Therefore, it is desirable to remove the unnecessary light beam.

In the optical encoder of Patent Document 1, a light source, a photodetector, and a light source slit are enclosed in a package, and a light-shielding portion is formed at one end of the light source slit. With this configuration, the optical encoder of Patent Document 1 prevents unnecessary light from traveling at the light shielding portion.

JP 2007-333667 A

However, in Patent Document 1, which is the above-described conventional technique, it is not possible to suppress a decrease in angle detection accuracy due to multiple reflection between the package and the optical scale. The multiple reflection between the package and the optical scale is a phenomenon in which the light beam emitted from the light source is reflected by the optical scale, then reflected by the surface of the package, and further reflected by the optical scale. The detection accuracy is lowered by the multiple reflected light entering the photodetector. Since the light amount and the light beam pattern change according to the rotation of the optical scale, it is difficult to remove the light beam by the multiple reflection by the arithmetic unit. For this reason, in patent document 1, there existed a problem that the absolute rotation angle of a measuring object could not be detected accurately.

The present invention has been made in view of the above, and an object of the present invention is to obtain an absolute encoder that can accurately detect the absolute rotation angle of a measurement object.

In order to solve the above-described problems and achieve the object, the absolute encoder of the present invention receives an optical scale having an optical pattern, a light emitting element that irradiates light to the optical scale, and reflected light from the optical scale. And a control unit that calculates an absolute rotation angle of the optical scale based on a signal output from the light receiving element according to reflected light. Also, the absolute encoder of the present invention is exposed to the module package on the surface facing the optical scale of the light-transmitting resin and has an intermediate position between the center of the light emitting surface of the light emitting element and the center of the light receiving surface of the light receiving element. A light-shielding part is provided.

The absolute encoder according to the present invention has an effect that the absolute rotation angle of the measurement object can be accurately detected.

The figure which shows the structure of the absolute encoder concerning Embodiment 1 of this invention. Sectional drawing which shows the structure of the module package concerning Embodiment 1. FIG. 3 is a top view showing the configuration of the module package according to the first embodiment. FIG. 2 is a block diagram showing a configuration of an angle calculation unit provided in the absolute encoder according to the first embodiment. The figure which shows the example of a waveform of the signal which the angle calculating part of the absolute encoder concerning Embodiment 1 receives from a light receiving element. The figure which shows what the waveform shown in FIG. 5 was correct | amended by uniform distribution The figure for demonstrating the method of calculating a rough absolute rotation angle from the waveform shown in FIG. The figure for demonstrating the method of calculating a fine absolute rotation angle from the rough absolute rotation angle demonstrated in FIG. The figure for demonstrating the example of the stray light which the module package of a comparative example generates The figure for demonstrating the course of the light ray in the module package concerning Embodiment 1 The figure for demonstrating a mode that the module package concerning Embodiment 1 prevents incidence | injection of the multiple reflected light to a light receiving element. FIG. 3 is a diagram illustrating a waveform example of a signal detected by the light receiving element of the module package according to the first embodiment. The figure which shows the waveform example of the signal detected with the light receiving element of the module package of a comparative example The figure for demonstrating the arrangement position of light-shielding resin with which the module package concerning Embodiment 1 is provided. The figure for demonstrating the 3rd example of the stray light which the module package of a comparative example generates The figure for demonstrating the dimensional relationship of the component with which the module package concerning Embodiment 1 is provided. The figure which shows the 1st structural example of the module package concerning Embodiment 2. FIG. The figure which shows the 2nd structural example of the module package concerning Embodiment 2. FIG.

Hereinafter, an absolute encoder according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to these embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of an absolute encoder according to the first embodiment of the present invention. The absolute encoder 1 is a device that detects a rotation angle of a rotating body that is a measurement object, and includes an optical scale 2, a module package 300, and a control unit 4. The rotation angle detected by the absolute encoder 1 is an absolute rotation angle. In FIG. 1, the upper surface of the module package 300 that is the surface facing the optical scale 2 is illustrated on the lower side, and the bottom surface of the module package 300 is illustrated on the upper side.

The optical scale 2 is connected to a rotating shaft 5 provided in a rotating device such as a motor, and rotates according to the rotation of the rotating shaft 5. The optical scale 2 is configured using a disk-shaped member. The optical scale 2 includes, on the upper surface of a disk-shaped member, a reflective portion 201 that is a line pattern indicating “bright” of light and dark, and a non-reflective portion 202 that is a line pattern indicating “dark”. Are provided with optical patterns 200 arranged alternately.

The reflection portion 201 is a portion that reflects light rays from the light emitting element 31 described later, and the non-reflection portion 202 is a portion that absorbs or scatters light rays from the light emitting element 31. A plurality of reflecting portions 201 are arranged in a direction from the center portion of the disk-shaped member toward the outer peripheral portion. A plurality of non-reflective portions 202 are arranged in a direction from the center portion of the disk-shaped member toward the outer peripheral portion. In other words, the plurality of reflecting portions 201 and the plurality of non-reflecting portions 202 are arranged such that one end of the line shape faces the center of the optical pattern 200 and the other end faces the outside direction of the optical pattern 200.

The non-reflecting part 202 is disposed between the reflecting parts 201, and the reflecting part 201 is disposed between the non-reflecting parts 202. In the optical scale 2, the reflecting portions 201 and the non-reflecting portions 202 are alternately arranged so that the reflecting portions 201 and the non-reflecting portions 202 are arranged in a radial pattern within the annular region of the outer peripheral portion of the disk-shaped member. . The reflection part 201 and the non-reflection part 202 have various dimensional widths. In other words, the reflecting portions 201 are arranged at various intervals, and the non-reflecting portions 202 are arranged at various intervals.

Since the optical pattern 200 is a pattern in which the reflecting portion 201 and the non-reflecting portion 202 are arranged at various intervals, when the rotating optical pattern 200 is irradiated with light, reflection and non-reflection of the light are reflected. It repeats according to the arrangement | positioning space | interval of the part 201 and the non-reflective part 202. FIG. Thereby, the reflection unit 201 and the non-reflection unit 202 function to modulate a light intensity distribution projected on the light receiving element 32 described later.

The optical scale 2 is provided with only one track having the optical pattern 200 composed of the reflecting portion 201 and the non-reflecting portion 202. The reflecting part 201 and the non-reflecting part 202 are arranged at intervals that characterize the rotation angle of the optical scale 2. As described above, the optical scale 2 has the optical pattern 200 unique to the rotation angle. For the arrangement pattern of the reflection unit 201 and the non-reflection unit 202, for example, a pseudo-random code pattern such as an M series is used.

The optical scale 2 is formed from, for example, a metal base material such as stainless steel. When the optical pattern 200 is formed, the non-reflective portion 202 is formed on the surface of the metal substrate by a plating technique or the like, and the reflective portion 201 is formed by mirror-finishing the metal substrate portion. The optical pattern 200 may be formed by any method as long as the reflective portion 201 and the non-reflective portion 202 can be formed.

The module package 300 is a light projecting / receiving module including a light emitting element 31 having a light projecting function and a light receiving element 32 having a light receiving function. The module package 300 is disposed above the optical pattern 200 so as to face the optical pattern 200. The module package 300 detects the light reflected from the optical pattern 200 and incident on the light receiving element 32 out of the light emitted from the light emitting element 31, and outputs a signal corresponding to the detected light to the control unit 4. .

The control unit 4 is connected to the light receiving element 32 on the downstream side of the light receiving element 32. The control unit 4 includes an angle calculation unit 41 and a light emission amount adjustment unit 42. The angle calculation unit 41 calculates the absolute rotation angle of the optical scale 2 based on a signal output from the light receiving element 32 included in the module package 300. The absolute rotation angle calculated by the angle calculation unit 41 corresponds to the rotation position of the rotary shaft 5. Thus, the angle calculation unit 41 calculates the rotational position of the rotary shaft 5 based on the signal corresponding to the encoded optical pattern 200. The angle calculation unit 41 outputs an absolute rotation angle indicating position data of the rotary shaft 5 to the external device as position data. The light emission amount adjustment unit 42 adjusts the light emission amount of the light emitted from the light emitting element 31 based on the signal output from the light receiving element 32.

Thus, in the absolute encoder 1, the angle calculation unit 41 calculates the absolute rotation angle from the signal corresponding to the light beam incident on the light receiving element 32. Note that the control unit 4 may perform rotation control of the measurement object based on the absolute rotation angle. Since the absolute encoder 1 does not need to integrate the pulse signals output from the light receiving element 32, it does not need to return to the origin when the power is turned on, and can be started up quickly.

FIG. 2 is a cross-sectional view illustrating the configuration of the module package according to the first embodiment. FIG. 3 is a top view showing the configuration of the module package according to the first embodiment. 2 and 3 illustrate a configuration of a module package 300A that is an example of the module package 300. FIG.

In FIG. 2, the upper surface of the module package 300A, which is the surface facing the optical pattern 200, is illustrated on the lower side, and the bottom surface of the module package 300A is illustrated on the upper side. Also, in FIGS. 9 to 11 and FIGS. 15 to 18 to be described later, the upper surface of the module package is illustrated on the lower side, and the bottom surface of the module package is illustrated on the upper side. Further, in FIG. 2, the package substrate 30A and the light transmissive resin 33A are not hatched. Also, in FIGS. 9 to 11 and FIGS. 15 to 18 to be described later, hatching of the package substrate and the light transmitting resin is omitted. FIG. 3 is a top view of the module package 300A, but hatching is added to clarify the correspondence with the cross-sectional view of FIG.

The module package 300A includes a package substrate 30A, a light emitting element 31, a light receiving element 32, a light transmissive resin 33A, and a light shielding resin 34A that is a light shielding portion. In the following description, for convenience of explanation, the direction in which the upper surface and the bottom surface of the package substrate 30A are arranged may be referred to as a horizontal direction, and the direction perpendicular to the upper surface and the bottom surface of the package substrate 30A may be referred to as a vertical direction.

The package substrate 30A is a substrate on which the light emitting element 31 and the light receiving element 32 are mounted, and is connected to an encoder substrate (not shown). The encoder board is a board that executes various processes on the rear side of the module package 300A, and the control unit 4 is disposed on the encoder board. Specifically, the encoder board has a processing circuit that executes the processing of the control unit 4. Note that the upper surface of the package substrate 30A has a rectangular shape, and terminals are provided on all of these four sides. Each terminal is connected to the encoder board. For the terminals provided on the package substrate 30A, an end face through hole or a back electrode is applied. By providing the terminals on all four sides of the package substrate 30A, the mounting accuracy of the light emitting element 31 and the light receiving element 32 is improved.

The package substrate 30A has a rectangular upper surface, and the light emitting element 31 and the light receiving element 32 are arranged on the rectangular upper surface. The package substrate 30A is preferably composed of a substrate similar to the encoder substrate. The encoder board is composed of a glass epoxy board, for example. In this case, it is desirable that the package substrate 30A is also formed of a glass epoxy substrate.

The light emitting element 31 is an element that emits light, and irradiates the optical scale 2 with light. For example, a near infrared point light source LED (Light Emitting Diode) is applied to the light emitting element 31. The light emitting element 31 has a light emitting surface 310 disposed on the upper surface thereof, and emits light from the light emitting surface 310. The light emitting element 31 is bonded to the package substrate 30A so that the light emitting surface 310 is in the horizontal direction.

The light receiving element 32 is an element that receives light, and receives reflected light from the optical scale 2. For the light receiving element 32, for example, an imaging device such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor configured by a set of pixels arranged in one dimension is applied. The light receiving element 32 has a light receiving surface 320 disposed on the upper surface thereof, and receives light on the light receiving surface 320. The light receiving element 32 is bonded to the package substrate 30A so that the light receiving surface 320 is in the horizontal direction.

The light receiving element 32 outputs a signal corresponding to the reflected light from the optical scale 2. Specifically, the light receiving element 32 converts light received by the light receiving surface 320 into an analog voltage signal, and further converts the analog voltage signal into an A / D (Analog-to-Digital) conversion built in the light receiving element 32. The signal is converted into a digital signal by the device and output to the control unit 4 at the subsequent stage. Here, the illustration of the A / D converter is omitted. The signal output from the A / D converter to the control unit 4 is a signal corresponding to the light reflected by 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 transmissive resin 33A is formed so as to cover the upper surface of the package substrate 30A. Therefore, the bottom surface and the top surface of the light transmissive resin 33A are rectangular. The light transmissive resin 33 A covers the light emitting element 31 and the light receiving element 32 on the package substrate 30 A in order to protect the light emitting element 31 and the light receiving element 32. The light transmissive resin 33A is made of, for example, an epoxy resin in order to match the linear expansion coefficient with the package substrate 30A.

The light-shielding resin 34A is a member for suppressing the progression of stray light, which is an unnecessary light beam, and is made of an epoxy resin or the like, similar to the light-transmitting resin 33A. The stray light that is an unnecessary light beam is light that is not desired to be incident on the light receiving element 32. An example of unnecessary light is light that is Fresnel-reflected at the interface between the light-transmitting resin 33A and the outside. The light shielding resin 34 A absorbs or scatters light that is not desired to be incident on the light receiving element 32 among the light emitted from the light emitting element 31. Light absorbed or scattered by the light shielding resin 34A is emitted from the light emitting element 31, light emitted from the light emitting element 31 and reflected in the light transmissive resin 33A, and emitted from the light emitting element 31. This is light that has been multiple-reflected between the package substrate 30 A and the optical scale 2.

The light shielding resin 34A has a plate shape, and is disposed between the light emitting element 31 and the light receiving element 32 so that the front surface and the back surface of the plate are in the vertical direction. Specifically, the light shielding resin 34A is disposed so as to divide the region where the light emitting element 31 is disposed from the region where the light receiving element 32 is disposed. That is, as shown in FIGS. 2 and 3, the left side region 420 of the light transmissive resin 33A in which the light emitting element 31 is disposed and the right side region 421 of the light transmissive resin 33A in which the light receiving element 32 is disposed. The light shielding resin 34 A is arranged so that is divided. In this case, a light shielding resin 34A is formed on the package substrate 30A so that the light transmissive resin 33A on the light emitting element 31 side and the light transmissive resin 33A on the light receiving element 32 side are not connected. In FIG. 2, the first horizontal surface of the light shielding resin 34A is in the same plane as the upper surface of the light transmissive resin 33A, and the second horizontal surface of the light shielding resin 34A is the light transmissive resin. The case where it exists in the same surface as the bottom face of 33A is shown. Since the first horizontal surface of the light shielding resin 34A is in the same plane as the upper surface of the light transmissive resin 33A, the light shielding resin 34A is exposed on the upper surface of the module package 300A. In other words, the light shielding resin 34A is exposed from the light transmissive resin 33A on the surface of the light transmissive resin 33A facing the optical scale 2.

It should be noted that a light blocking resin 34 A is arranged so as not to block light rays that are desired to be incident on the light receiving element 32 among light rays emitted from the light emitting element 31 to the optical pattern 200. That is, the light shielding resin 34A is disposed so that the path of the light beam that is desired to enter the light receiving element 32 does not pass through the light shielding resin 34A. In the module package 300A, the light shielding resin 34A is disposed so that the front surface and the back surface of the plate-shaped light shielding resin 34A are perpendicular to the upper surface of the package substrate 30A.

By the way, it is known that a glass epoxy substrate transmits a part of light such as near infrared rays. For this reason, when a glass epoxy substrate is applied to the package substrate 30A, the light emitted from the light emitting element 31 is reflected directly or within the light transmissive resin 33A and is transmitted to the package substrate 30A, and is not necessary for the light receiving element 32. May reach as a light beam. In such a case, a black glass epoxy substrate may be applied to the package substrate 30A. In addition, applying a metal film, black resist, or a combination of these to the surface of the glass-epoxy substrate to prevent unwanted rays from entering the glass-epoxy substrate or preventing the light from propagating in the glass-epoxy substrate. It is effective in preventing. Note that a method using another material may be applied as long as the same effect as the method using these materials can be obtained.

Here, the configuration of the angle calculation unit 41 will be described. FIG. 4 is a block diagram illustrating a configuration of an angle calculation unit included in the absolute encoder according to the first embodiment. The angle calculation unit 41 includes a light amount distribution correction unit 411, an edge detection unit 412, a rough detection unit 413, a high accuracy detection unit 414, and a rotation angle detection unit 415.

The signal output from the light receiving element 32 is sent to the light quantity distribution correction unit 411. Thereby, the light quantity distribution correction unit 411 receives a signal from the light receiving element 32. The waveform of the signal input to the light amount distribution correction unit 411 by the light receiving element 32 is, for example, a waveform as shown in FIG. 5 with the horizontal axis representing the pixel position and the vertical axis representing the signal intensity.

FIG. 5 is a diagram illustrating a waveform example of a signal received from the light receiving element by the angle calculation unit of the absolute encoder according to the first embodiment. The horizontal axis of the graph shown in FIG. 5 is the pixel, and the vertical axis is the signal intensity. In the graphs shown in FIGS. 6 to 8, 12 and 13 to be described later, the horizontal axis is the pixel and the vertical axis is the signal intensity, as in the graph of FIG.

5, the level 1 signal 14 corresponds to the pattern at the reflecting portion 201 of the optical scale 2, and the level 0 signal 15 corresponds to the pattern at the non-reflecting portion 202 of the optical scale 2.

The signal intensity of the level 1 signal 14 and the level 0 signal 15 is non-uniform for each pixel due to the influence of the light amount distribution of the light emitting element 31 itself and the gain variation of each pixel of the light receiving element 32. Therefore, the light amount distribution correction unit 411 corrects the distribution in which the maximum value of the signal intensity is not uniform to the distribution in which the maximum value of the signal intensity is uniform. The light quantity distribution correction unit 411 here corrects the signal intensity shown in FIG. 5 to the signal intensity shown in FIG.

FIG. 6 is a diagram showing the waveform shown in FIG. 5 corrected to a uniform distribution. As shown in FIG. 6, the light quantity distribution correction unit 411 corrects the level 1 signal 14 and the level 0 signal 15 so that the maximum value of the signal intensity for each pixel becomes uniform. In other words, the light amount distribution correction unit 411 corrects the waveform of the signal so that the level 1 signal 14 is the same for each pixel and the level 0 signal 15 is the same for each pixel. In FIG. 6, the corrected waveform is illustrated as a corrected waveform 16.

The correction method by the light amount distribution correction unit 411 may be any method as long as the light amount distribution is uniform. The light quantity distribution correction unit 411 sends the corrected waveform 16 to the edge detection unit 412.

The edge detection unit 412 calculates, for each edge, a pixel value whose signal intensity matches a preset threshold level 17 based on the corrected waveform 16. The edge detection unit 412 sends the calculated pixel value to the rough detection unit 413 as an edge pixel value.

The coarse detection unit 413 decodes a bit pattern projected on the light receiving element 32 in the optical pattern 200 of the optical scale 2 based on the edge pixel value, and calculates a rough absolute rotation angle. Here, the rough absolute rotation angle calculation method will be described with reference to FIG.

FIG. 7 is a diagram for explaining a method of calculating a rough absolute rotation angle from the waveform shown in FIG. In FIG. 7, a bit string corresponding to the corrected waveform 16 is indicated by a bit string 18. The coarse detection unit 413 converts the corrected waveform 16 into a bit string 18 of “1” or “0” as shown in FIG. 7 based on the edge position indicated by the edge pixel value. Further, the coarse detection unit 413 refers to a lookup table 19 stored in advance in a memory (not shown) provided in the control unit 4 and obtains a rough absolute rotation angle 100 from a code that matches the bit string 18. The lookup table 19 is a table that stores a bit string corresponding to the optical pattern 200. The coarse detector 413 sends the coarse absolute rotation angle 100 to the high accuracy detector 414.

The high accuracy detection unit 414 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 100. The coarse absolute rotation angle 100 obtained by the coarse detection unit 413 is the absolute rotation angle 100 in units of bits of the optical scale 2. For this reason, the high-accuracy detection unit 414 calculates a fine absolute rotation angle by detecting the phase shift amount from the reference pixel, which is a reference pixel, to the position of the nearest edge pixel.

FIG. 8 is a diagram for explaining a method of calculating a fine absolute rotation angle from the rough absolute rotation angle described in FIG. As shown in FIG. 8, the high accuracy detection unit 414 detects the phase shift amount 20 from the reference pixel 21 to the edge pixel position 22 that is the position of the edge pixel closest to the reference pixel 21. The reference pixel 21 is a pixel used as a reference when calculating a fine absolute rotation angle, and may be any pixel. The phase shift amount 20 corresponds to the difference between the position of the reference pixel 21 and the edge pixel position 22. The high accuracy detection unit 414 sends the coarse absolute rotation angle 100 and the phase shift amount 20 to the rotation angle detection unit 415.

The rotation angle detection unit 415 calculates an absolute rotation angle finer than the 1-bit unit of the optical scale 2 based on the phase shift amount 20. Specifically, the rotation angle detection unit 415 adds the coarse absolute rotation angle 100 calculated by the coarse detection unit 413 and the phase shift amount 20 calculated by the high accuracy detection unit 414 to obtain a fine absolute rotation angle. calculate. The rotation angle detection unit 415 outputs the calculated fine absolute rotation angle to the external device as position data.

As described above, the absolute encoder 1 receives the light beam reflected by the optical pattern 200 of the optical scale 2 among the light beams emitted from the light emitting element 31, and receives the absolute rotation angle from the light amount distribution pattern of the received light. Is detected. At this time, if stray light, which is an unnecessary light beam, enters the light receiving element 32, the signal quality of the light beam received by the light receiving element 32 deteriorates, and an error is superimposed on the edge pixel position 22 detected by the edge detection unit 412. For this reason, since an error is superimposed on the absolute rotation angle, it is necessary to suppress stray light, which is an unnecessary light beam, in order to detect the absolute rotation angle with high accuracy. This stray light is an unnecessary light beam and causes the absolute rotation angle detection accuracy to deteriorate.

Here, the stray light path that deteriorates the detection accuracy of the absolute rotation angle will be described. Here, of the stray light path, the path of the light beam that has undergone multiple reflection in the module package of the comparative example will be described.

FIG. 9 is a diagram for explaining an example of stray light generated by the module package of the comparative example. Here, the stray light generated in the module package 300X of the comparative example will be described. FIG. 9 shows a cross-sectional view of the module package 300X of the comparative example.

The module package 300X of the comparative example includes a package substrate 30X similar to the package substrate 30A, a light emitting element 31X similar to the light emitting element 31, a light receiving element 32X similar to the light receiving element 32, and light similar to the light transmitting resin 33A. Transparent resin 33X. The light emitting element 31X has a light emitting surface 310X similar to the light emitting surface 310, and the light receiving element 32X has a light receiving surface 320X similar to the light receiving surface 320. Further, the module package 300X of the comparative example does not include the light shielding resin 34A.

FIG. 9 shows an example of a light beam emitted from the light emitting element 31X and reflected into the light receiving element 32X after being reflected in the module package 300X of the comparative example. Since the light emitting element 31X is an isotropic diffusion light source, the light beam is emitted in all directions. Thereby, the light beam emitted from the light emitting element 31X proceeds in various directions. For this reason, when there is no light shielding resin 34A, as shown in FIG. 9, in the module package 300X, there is a light ray incident on the light receiving element 32X after repeating Fresnel reflection at the interface of the light transmitting resin 33X. That is, in the light transmissive resin 33X, the light beam is Fresnel-reflected on the upper surface and the side surface of the light transmissive resin 33X, and a part of the Fresnel-reflected light beam enters the light receiving surface 320X. As a result, stray light other than the desired light is incident on the light receiving surface 320X, and the detection accuracy of the absolute rotation angle is deteriorated.

Therefore, in the first embodiment, as shown in FIG. 2, in the module package 300A, the light shielding resin 34A is divided so that the region 420 where the light emitting element 31 is arranged and the region 421 where the light receiving element 32 is arranged are divided. Is installed.

Thus, since the light shielding resin 34A is arranged in the module package 300A, the light emitted from the light emitting element 31 is changed from the left area 420 on the light emitting element 31 side to the right area on the light receiving element 32 side. Entry to 421 can be prevented. Therefore, stray light that is a part of the light beam reflected by the light transmissive resin 33 A can be prevented from entering the light receiving surface 320.

FIG. 10 is a diagram for explaining the path of light rays in the module package according to the first embodiment. 10 shows a cross-sectional view of a module package 300B that is an example of the module package 300. The module package 300B includes a package substrate 30B, a light emitting element 31, a light receiving element 32, a light transmissive resin 33A, and a light shielding resin 34B as a light shielding part. A groove is provided in the package substrate 30B, and a part of the light shielding resin 34B is inserted. The light shielding resin 34B is formed of the same member as the light shielding resin 34A.

In the module package 300B, the light beam emitted from the light emitting element 31 travels in various directions. In this case, in the light transmitting resin 33A, the light beam is reflected by the upper surface and the side surface of the light transmitting resin 33A in the region 401 on the left side of the region where the light blocking resin 34B is disposed. A region 401 on the left side of the region where the light shielding resin 34B is disposed is a region where the light emitting element 31 is disposed in the light transmitting resin 33A.

Further, the light beam irradiated to the light shielding resin 34B is absorbed or scattered by the light shielding resin 34B. In other words, the light beam emitted from the light emitting element 31 is blocked by the light blocking resin 34B. Accordingly, stray light does not enter the region 402 on the right side of the region where the light blocking resin 34B is disposed in the light transmitting resin 33A. A region 402 on the right side of the region where the light shielding resin 34B is disposed is a region where the light receiving element 32 is disposed in the light transmitting resin 33A.

Thus, since the light shielding resin 34B is arranged in the module package 300B, it is possible to prevent the light emitted from the light emitting element 31 from entering the right region 402 from the left region 401. Therefore, stray light that is a part of the light beam reflected by the light transmissive resin 33 A can be prevented from entering the light receiving surface 320.

It is desirable that the module package 300B is configured such that the light shielding resin 34B enters the package substrate 30B so that no gap is generated between the light shielding resin 34B and the package substrate 30B. Note that a slight gap may be formed between the light-shielding resin 34B and the package substrate 30B. Even in this case, the effect of suppressing unnecessary light hardly changes.

When the module package 300B is manufactured, for example, the light emitting element 31 and the light receiving element 32 are mounted on the package substrate 30B, and the upper surface side of the package substrate 30B is molded with the light transmissive resin 33A. Thereafter, a groove is formed between the light emitting element 31 and the light receiving element 32 by cutting the light transmitting resin 33A and the package substrate 30B. Specifically, a groove is dug in the vertical direction by dicing or the like in a region between the light emitting element 31 and the light receiving element 32 in the light transmitting resin 33A. And this groove | channel is further dug in the perpendicular direction to the middle in the package substrate 30B. After the groove is formed in the light transmitting resin 33A, the light shielding resin 34B can be molded into the module package 300B by embedding the light shielding resin 34B in the groove. As described above, the light-shielding resin 34B is disposed in the region where the package substrate 30B is dug and the region where the light-transmitting resin 33A is dug. Note that the manufacturing method is not limited as long as the module package 300B includes the light-transmitting resin 33A and the light-shielding resin 34B.

By the way, when the module package 300X of the comparative example is applied, there may be a case where light beams that are multiple-reflected between the module package 300X and the optical pattern 200 enter the light receiving element 32X. On the other hand, in the module package 300 B, light beams that are multiple-reflected between the module package 300 B and the optical pattern 200 do not enter the light receiving element 32.

FIG. 11 is a diagram for explaining how the module package according to the first embodiment prevents the multiple reflected light from entering the light receiving element. Here, a light path between the module package 300B and the optical scale 2 will be described. FIG. 11 shows a cross-sectional view of the module package 300B.

A part of the light beam emitted from the light emitting element 31 is reflected by the reflecting portion 201 of the optical pattern 200 provided in the optical scale 2, and then sent to the surface of the light transmissive resin 33A of the module package 300B. The light beam sent to the surface of the light transmissive resin 33A is absorbed or scattered by the light shielding resin 34B. Thereby, in the module package 300B, the light beam sent to the surface of the light transmissive resin 33A does not travel again to the reflecting portion 201 of the optical pattern 200.

In the case of the module package 300X of the comparative example, that is, when there is no light shielding resin 34B, a part of the light beam emitted from the light emitting element 31X is reflected by the reflecting portion 201 of the optical pattern 200 provided in the optical scale 2, and then Reflected by the surface of the light transmissive resin 33X of the module package 300X. Further, the light beam reflected by the surface of the light transmissive resin 33X is reflected by the reflecting portion 201 of the optical pattern 200 and enters the light receiving element 32X. As described above, an unnecessary light path may occur due to multiple reflection between the module package 300X of the comparative example and the optical scale 2.

In FIG. 11, the light ray path indicated by a solid line is a normal light ray path 901 necessary for detecting the absolute rotation angle, and the light ray path indicated by a broken line is an unnecessary light ray path 902. In the case of the module package 300 B, the light beam in the light beam path 901 is incident on the light receiving element 32 after being reflected at the position P 52 of the optical scale 2. On the other hand, in the case of the module package 300X of the comparative example shown in FIG. 9, the light beam in the light path 902 is reflected at the position P51 of the optical scale 2 and then reflected by the light transmissive resin 33X. And is incident on the light receiving element 32X. In this case, the position P52 where the light beam traveling along the normal light beam path 901 is reflected by the optical scale 2 and the positions P51 and P53 where the unnecessary light beam traveling along the light beam path 902 is reflected by the optical scale 2 are optical The position of the radial scale 2 is different. The waveform corresponding to the light beam reflected at the position P52 is an ideal waveform, whereas the waveform corresponding to the light beam reflected at the positions P51 and P53 is deviated from the ideal waveform. . This is because the pattern that has passed through the two positions P51 and P53 having different radial positions is incident on the light receiving element 32X. As a result, an unnecessary light beam depending on the position on the optical scale 2 is generated. . For this reason, when the light receiving element 32X receives the light beam reflected at the positions P51 and P53, the waveform of the signal detected by the light receiving element 32X becomes a distorted waveform with respect to the ideal waveform.

Here, a waveform of a signal when only the light ray of the normal light ray path 901 is received, and a waveform of a signal when both the light ray of the normal light ray path 901 and the light ray of the non-normal light ray path 902 are received, The comparison will be described.

The waveform of the signal when only the light beam of the regular light beam path 901 is received is a light beam signal detected by the light receiving element 32 of the module package 300A or the module package 300B of the first embodiment. On the other hand, the waveform of the signal when receiving both the light beam of the regular light path 901 and the light beam of the non-regular light path 902 is a signal of the light beam detected by the light receiving element 32X of the module package 300X of the comparative example.

FIG. 12 is a diagram illustrating a waveform example of a signal detected by the light receiving element of the module package according to the first embodiment. FIG. 13 is a diagram illustrating a waveform example of a signal detected by the light receiving element of the module package of the comparative example.

The waveform of the signal shown in FIG. 12 is a waveform 71 when the light receiving element 32 of the module package 300A or the module package 300B receives only the light beam of the regular light beam path 901. The waveform of the signal shown in FIG. 13 is a waveform 72 when the light receiving element 32X of the module package 300X receives both of the regular ray path 901 and the irregular ray path 902. The waveform 71 shown in FIG. 12 is an ideal waveform based on the rays of the regular ray path 901, whereas the waveform 72 shown in FIG. 13 is a distorted waveform 71 shown in FIG. As described above, when an unnecessary ray in the ray path 902 is superimposed on the ray in the regular ray path 901, the waveform 71 shown in FIG. 12 becomes a distorted waveform like the waveform 72 shown in FIG.

The signal corresponding to the unnecessary light beam in the light beam path 902 changes according to the reflection position on the optical pattern 200. That is, since the optical pattern 200 has various patterns arranged for each position, a signal corresponding to an unnecessary light beam in the light beam path 902 generates various signals for each light irradiation position on the optical pattern 200. . As described above, the unnecessary light beam reflected by the optical pattern 200 is affected variously for each rotation position of the optical pattern 200. On the other hand, the unnecessary light beam reflected in the light transmissive resin 33 A is always a constant amount regardless of the optical pattern 200. Therefore, the unnecessary light beam reflected by the optical pattern 200 is more difficult to correct than the unnecessary light beam reflected in the light transmissive resin 33A.

As described above, the unnecessary light beam reflected by the optical pattern 200 changes the influence for each reflection position corresponding to the absolute rotation angle. Therefore, it is unnecessary only by correction when the absolute encoder 1 is shipped. The effect of light cannot be removed.

In the case of the module package 300 B, an unnecessary light beam path 902 passes through an intermediate position between the light emitting surface 310 of the light emitting element 31 and the light receiving surface 320 of the light receiving element 32. Therefore, the light shielding resin 34B of the module package 300B is disposed at an intermediate position between the light emitting surface 310 and the light receiving surface 320. As a result, after the light beam in the light path 902 is reflected by the optical scale 2, it is irradiated to the light shielding resin 34B exposed on the upper surface of the light transmissive resin 33A and absorbed or scattered by the light shielding resin 34B. As a result, the light beam in the light beam path 902 is not reflected by the upper surface of the package substrate 30B, so that the light beam in the light beam path 902 is not irradiated onto the optical scale 2. Accordingly, since the light beam in the light beam path 902 is not reflected by the optical scale 2, the light beam in the light beam path 902 is not irradiated on the light receiving surface 320. The light shielding resin 34A of the module package 300A may be disposed at an intermediate position between the light emitting surface 310 and the light receiving surface 320.

Here, the arrangement positions of the

light shielding resins

34A and 34B will be specifically described. FIG. 14 is a diagram for explaining an arrangement position of the light shielding resin provided in the module package according to the first embodiment. The arrangement position of the light shielding resin 34A when the module package 300A is viewed from the upper surface is the same as the arrangement position of the light shielding resin 34B when the module package 300B is viewed from the upper surface. Therefore, here, the arrangement position of the light shielding resin 34B in the module package 300B will be described.

Note that FIG. 14 is a top view of the module package 300B, but is hatched to clarify the correspondence with the cross-sectional view of FIG. As shown in FIG. 14, in the module package 300 B, the light shielding resin 34 B is disposed so as to pass through an intermediate position between the center of the light emitting surface 310 and the center of the light receiving surface 320. Specifically, the light blocking resin 34B is made so that the distance from the center of the light blocking resin 34B to the center of the light emitting surface 310 is the same as the distance from the center of the light blocking resin 34B to the center of the light receiving surface 320. Be placed.

Here, the case where the center of the light-shielding resin 34B is arranged at the intermediate position between the light emitting surface 310 and the light receiving surface 320 has been described, but at the intermediate position between the light emitting surface 310 and the light receiving surface 320, The light-shielding resin 34B only needs to be present. Therefore, the center of the light shielding resin 34 B may be shifted from the intermediate position between the light emitting surface 310 and the light receiving surface 320.

When the module package 300X of the comparative example is applied, the light beam reflected by the optical pattern 200 may be reflected multiple times between the light receiving element 32X and the light transmitting resin 33X and may enter the light receiving element 32X.

FIG. 15 is a diagram for explaining a third example of stray light generated by the module package of the comparative example. Here, a case where the light beam reflected by the optical pattern 200 undergoes multiple reflections between the light receiving element 32X and the light transmissive resin 33X will be described. FIG. 15 shows a cross-sectional view of the module package 300X of the comparative example.

As shown in FIG. 15, when the module package 300X of the comparative example is applied, the light beam emitted from the light emitting element 31X is reflected by the optical scale 2 and then irradiated to the light receiving element 32X. A part of the light beam irradiated to the light receiving element 32X is reflected around the light receiving surface 320X or the light receiving surface 320X itself. The light receiving surface 320X itself reflects the light beam because the light receiving surface 320X is made of a reflective material.

The light beam reflected around the light receiving surface 320X or the light receiving surface 320X itself is reflected by Fresnel reflection on the surface of the light-transmitting resin 33X and travels again toward the light receiving element 32X. The position P52 where the light beam traveling in the normal light beam path 901 is reflected by the optical scale 2 and the position P54 where the unnecessary light beam traveling in the non-normal light beam path 903 is reflected by the optical scale 2 are the optical scale 2 Is shifted in the radial direction of the optical pattern 200 included in the optical pattern 200. That is, the position P54 is shifted from the position P52 in the radial direction of the rotary shaft 5.

Therefore, the optical path length until reaching the light receiving element 32X differs between the light path 901 and the light path 903. Therefore, the magnification rate of the bit pattern of the optical scale 2 when reaching the light receiving element 32X is different between the light path 901 and the light path 903. Accordingly, when the light receiving element 32X receives both the light beam in the light beam path 901 and the light beam in the light beam path 903, the light amount distribution received by the light receiving element 32X is distorted. In other words, when the light receiving element 32X receives the light beam in the light path 903, distortion occurs in the light amount distribution when the light receiving element 32X receives only the light beam in the light path 901. For this reason, when the light receiving element 32X receives the light beam in the light beam path 903, an error occurs in the detection accuracy of the absolute rotation angle.

As the relative distance between the module package 300X and the optical scale 2 increases, the angle of the light incident on the light receiving element 32X becomes closer to the vertical, so that unnecessary light easily enters the light receiving element 32X. Therefore, as the module package 300X is separated from the optical scale 2, multiple reflection between the light receiving element 32X and the light transmissive resin 33X is more likely to occur.

In the first embodiment, by adjusting the dimensional relationship of the components included in the module packages 300A and 300B, unnecessary light rays in the light ray path 903 are prevented from entering the light receiving element 32. Note that the dimensional relationship between the components included in the module package 300A and the dimensional relationship between the components included in the module package 300B are the same. Therefore, here, the dimensional relationship of the components included in the module package 300B will be described.

FIG. 16 is a diagram for explaining a dimensional relationship of components included in the module package according to the first embodiment. Consider a case where the module package 300B and the optical scale 2 are arranged at positions that are separated by an allowable maximum distance. The distance from the upper surface of the module package 300B to the optical scale 2 is a distance L1, and the distance from the center of the light emitting surface 310 to the end surface on the light emitting element 31 side of the light receiving element 32 is a distance L2. In this case, the angle θ1 of the light ray incident on the end face of the light receiving element 32 on the light emitting element 31 side is determined by the distance L1 and the distance L2. In this case, the angle θ1 is calculated after the refractive index n1 of the light-transmitting resin 33A and the refractive index nx of air between the light-transmitting resin 33A and the optical scale 2 are applied to Snell's law. Is done. According to Snell's law, when the angle of the light ray incident on the light transmitting resin 33A from the air side is the angle θx, n1 × sin θ1 = nx × sin θx. Further, when the distance between the light emission point from the light transmitting resin 33A to the air side and the light incident point from the air side to the light transmitting resin 33A is a distance L0, tanθx = L0 / (2 × L1). Thus, the angle θ1 is calculated using the angle θx, and the angle θx is calculated using the distances L1 and L0. When the distance from the light receiving surface 320 in the same plane as the upper surface of the light receiving element 32 to the upper surface of the light transmitting resin 33A is a distance L3, the distance L0 is calculated from the distances L1, L2, and L3. Therefore, the angle θ1 is calculated using the distances L1, L2, and L3.

Further, the distance from the end of the light receiving element 32 on the light emitting element 31 side to the end of the light receiving surface 320 opposite to the light emitting element 31 is defined as a distance L4. The end of the light receiving element 32 on the light emitting element 31 side is a side end surface extending in the vertical direction, and the end of the light receiving surface 320 opposite to the light emitting element 31 is the vertical of the member having the light receiving surface 320. It is a side end surface extending in the direction.

Lx = 2 × tan θ1 × L3, where Lx is the distance between the first incident position on the light emitting element 31 side of the light receiving element 32 in the light beam path 903 and the second incident position.

Here, if Lx> L4, the light incident first on the light emitting element 31 side end of the light receiving element 32 through the light beam path 903 deviates from the light receiving surface 320. Further, the second incidence of the light incident on the right side of the end of the light receiving element 32 on the light emitting element 31 side also deviates from the light receiving surface 320.

for that reason,
2 x tan θ1 x L3> L4 (1)
If this relationship is established, it is possible to prevent light that has been multiple-reflected between the light receiving element 32 and the light transmitting resin 33A from entering the light receiving surface 320. As described above, since the angle θ1 can be calculated using the distances L1, L2, and L3, the relationship (1) described above is
(L2 / L1) × L3> L4 (2)
Can be rewritten.

The module package 300 B is configured to satisfy the formula (1), so that unnecessary light rays can be prevented from entering the light receiving element 32. The distance L1 may be a distance from the upper surface of the module package 300B to the optical pattern 200.

Here, the hardware configuration of the control unit 4 will be described. The control unit 4 can be realized by a control circuit, that is, a processor and a memory. The processor is a CPU (Central Processing Unit) or the like. The memory is RAM (Random Access Memory) or ROM (Read Only Memory).

The control unit 4 is realized by the processor reading and executing a program stored in the memory. This program can be said to cause a computer to execute the procedure or method of the control unit 4. The memory is also used as a temporary memory when the processor executes various processes.

Further, the control unit 4 may be realized by dedicated hardware. Further, part of the functions of the control unit 4 may be realized by dedicated hardware, and part of the functions may be realized by software or firmware.

The light shielding resin 34B described with reference to FIGS. 10 and 16 is not limited to being disposed at an intermediate position between the center of the light emitting surface 310 and the center of the light receiving surface 320, and may be disposed in another region. .

As described above, in the module package 300A of the first embodiment, the entire light emitting element 31 and light receiving element 32 mounted on the package substrate 30A are covered with the light transmissive resin 33A, and light shielding is performed between the light emitting element 31 and the light receiving element 32. 34A is provided. Similarly, in the module package 300B, the entire light emitting element 31 and light receiving element 32 mounted on the package substrate 30B are covered with a light transmissive resin 33A, and a light shielding resin 34B is provided between the light emitting element 31 and the light receiving element 32. Yes. Therefore, the module packages 300A and 300B can remove unnecessary light directly incident on the light receiving element 32 from the light emitting element 31 with the

light shielding resins

34A and 34B, so that the absolute rotation angle can be detected with high accuracy. It becomes.

In the module package 300A, since the light shielding resin 34A is provided at an intermediate position between the center of the light emitting surface 310 of the light emitting element 31 and the center of the light receiving surface 320 of the light receiving element 32, the light transmitting resin 33A and Unnecessary light rays due to multiple reflection with the optical scale 2 can be suppressed. Similarly, in the module package 300B, since the light shielding resin 34B is provided at an intermediate position between the center of the light emitting surface 310 of the light emitting element 31 and the center of the light receiving surface 320 of the light receiving element 32, the light transmitting resin 33A. And unnecessary light rays due to multiple reflection between the optical scale 2 can be suppressed. Therefore, the module packages 300A and 300B can detect the absolute rotation angle with high accuracy.

Further, since the module packages 300A and 300B are configured to satisfy the above-described formula (1), it is possible to suppress unnecessary light rays from entering the light receiving element 32. Therefore, the module packages 300A and 300B can detect the absolute rotation angle with high accuracy.

Further, since the

package substrates

30A and 30B are made of glass epoxy substrates, and the light transmitting resin 33A and the

light shielding resins

34A and 34B are both made of epoxy resin, it is possible to suppress cracks and the like at the time of temperature change. it can. Thereby, the reliability of the module packages 300A and 300B can be improved.

As described above, according to the first embodiment, the module packages 300A and 300B have the light shielding resin 34A at an intermediate position between the center of the light emitting surface 310 included in the light emitting element 31 and the center of the light receiving surface 320 included in the light receiving element 32. , 34B, the absolute rotation angle of the measurement object can be detected with high accuracy.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the light beam reflected by the light transmitting resin is incident on the light receiving surface 320 of the light receiving element 32 by inclining the upper surface of the light transmitting resin with respect to the light receiving surface 320 of the light receiving element 32. Suppress.

FIG. 17 is a diagram illustrating a first configuration example of the module package according to the second embodiment. 17, components that achieve the same functions as those of the module package 300A of the first embodiment shown in FIG. 2 or the module package 300B of the first embodiment shown in FIG. 10 are denoted by the same reference numerals. The overlapping description is omitted.

The module package 300C of the second embodiment includes a package substrate 30B, a light emitting element 31, a light receiving element 32, a light transmissive resin 33C, and a light shielding resin 34C as a light shielding part. As described above, the module package 300C includes the light transmissive resin 33C instead of the light transmissive resin 33A.

The light-shielding resin 34C has a shorter vertical length than the light-shielding

resins

34A and 34B, but the other configurations are the same. The light transmissive resin 33C is formed using the same member as the light transmissive resin 33A, and the shape is different from that of the light transmissive resin 33A. The light transmissive resin 33C covers the entire light emitting element 31 and light receiving element 32 on the package substrate 30B in the same manner as the light transmissive resin 33A.

The light transmissive resin 33C has a region 403 on the left side of the region where the light shielding resin 34C is arranged and a region 404 on the right side of the region where the light shielding resin 34C is arranged. The upper surface of the light transmissive resin 33C in the region 403 is the upper surface 150, and the upper surface of the light transmissive resin 33C in the region 404 is the upper surface 151.

The first horizontal surface of the light shielding resin 34C is in the same plane as the upper surface 150 of the light transmissive resin 33C in the region 403. Further, the second horizontal surface of the light shielding resin 34C is in contact with the package substrate 30B inside the package substrate 30B.

In the first embodiment, the case where the upper surface of the light transmitting resin 33A on the optical scale 2 side has a flat shape has been described. However, in the second embodiment, the gradient is formed on the upper surface 151 of the light transmitting resin 33C. Is provided. In the module package 300C, among the upper surfaces of the light transmissive resin 33C, the upper surface 151 on the light receiving element 32 side is not parallel to the light receiving surface 320 in the same plane as the upper surface of the light receiving element 32 but is inclined. Specifically, the thickness of the light transmissive resin 33C in the region 404 is gradually increased from the end on the light shielding resin 34C side to the end on the opposite side of the light shielding resin 34C. The thickness of the light transmissive resin 33C in the region 404 at the end on the light shielding resin 34C side is the same as the thickness of the light transmissive resin 33C in the region 403. In the module package 300C, the angle formed between the upper surface 150 and the upper surface 151 is the angle θ2. In other words, the gradient angle of the upper surface 151 is the angle θ2.

As described above, the absolute encoder 1 of the second embodiment has the same basic configuration as the absolute encoder 1 of the first embodiment, but the shape of the light-transmitting resin 33C in the region 404 is light-transmitting resin. It is different from the shape in the region 402 of 33A.

As shown in FIG. 15, in the module package 300X of the comparative example, unnecessary light rays from the optical scale 2 are incident on the light receiving element 32X. In this case, the light beam path 903 of the unnecessary light beam and the normal light beam path 901 have substantially the same incident angle to the light receiving element 32X. Specifically, an angle at which an unnecessary light beam is Fresnel-reflected on the upper surface of the light transmitting resin 33X and is incident on the light receiving element 32X is substantially the same as an angle at which a normal light beam is incident on the light receiving element 32X. Therefore, in the second embodiment, the upper surface 151 that reflects unnecessary light as it enters the light is inclined from the horizontal direction. Thus, the upper surface 151 is provided with a gradient so that unnecessary light rays are reflected at a wide reflection angle.

With such a configuration, in the module package 300C, the light beam reflected by the light receiving element 32 is Fresnel-reflected by the upper surface 151 of the light transmissive resin 33C, but the angle of the reflected light beam is the angle θ2 that is the gradient angle of the upper surface 151. Tilt. For this reason, unnecessary light beams reflected by the light receiving element 32 and the upper surface 151 are less likely to enter the light receiving surface 320 of the light receiving element 32. As the angle θ2 that is the gradient angle is larger, unnecessary light rays due to multiple reflection between the light receiving element 32 and the light transmitting resin 33C are less likely to enter the light receiving surface 320. Therefore, the larger the angle θ2, the thinner the light transmissive resin 33C in the region 403 can be made. As described above, in the module package 300C, the thickness of the light transmissive resin 33C can be reduced as compared with the light transmissive resin 33A of the first embodiment.

The module package 300C may include a package substrate 30A instead of the package substrate 30B. In other words, the light transmissive resin 33C may be applied to the module package 300A. In this case, the module package 300A includes a light transmitting resin 33C instead of the light transmitting resin 33A, and includes a light blocking resin 34C instead of the light blocking resin 34A.

In FIG. 17, the case where the upper surface 151 is provided with a gradient has been described, but the upper surface 150 may be provided with the same gradient as the upper surface 151. FIG. 18 is a diagram illustrating a second configuration example of the module package according to the second embodiment. Among the constituent elements in FIG. 18, constituent elements that achieve the same functions as those of the module package 300 C shown in FIG. 17 are denoted by the same reference numerals, and redundant description is omitted.

The module package 300D includes a package substrate 30B, a light emitting element 31, a light receiving element 32, a light transmitting resin 33D, and a light blocking resin 34C as a light blocking portion. As described above, the module package 300D includes the light transmissive resin 33D instead of the light transmissive resin 33C.

The light transmissive resin 33D is formed using the same member as the light transmissive resin 33C, and the shape is different from that of the light transmissive resin 33C. The light transmissive resin 33D covers the entire light emitting element 31 and light receiving element 32 on the package substrate 30B in the same manner as the light transmissive resin 33C.

The light transmitting resin 33D has a region 405 on the left side of the region where the light shielding resin 34C is disposed and a region 406 on the right side of the region where the light shielding resin 34C is disposed. The upper surface of the light transmissive resin 33D in the region 405 is the upper surface 152, and the upper surface of the light transmissive resin 33D in the region 406 is the upper surface 153. A region 406 is a region similar to the region 404, and an upper surface 153 is a surface similar to the upper surface 151.

In the module package 300D, the upper surface 152 of the light transmissive resin 33D is not parallel to the light receiving surface 320 in the same plane as the upper surface of the light receiving element 32, but is inclined. Specifically, the thickness of the light transmissive resin 33D in the region 405 gradually decreases from the end on the light shielding resin 34C side toward the end opposite to the light shielding resin 34C side. .

The thickness of the light transmitting resin 33D at the end of the region 405 on the light shielding resin 34C side is the same as the thickness of the region 406 at the end of the light shielding resin 34C side. In the module package 300D, the angle formed between the bottom surface of the light transmissive resin 33D and the top surface 152 is an angle θ2, and the angle formed between the bottom surface of the light transmissive resin 33D and the top surface 153 is an angle θ2. In other words, the gradient angle of the

upper surfaces

152 and 153 is the angle θ2.

As described above, in the second embodiment, since the slopes are provided on the

upper surfaces

151 and 153 of the

light transmissive resins

33C and 33D on the light receiving element 32 side, the

light transmissive resins

33C and 33D are reflected after the light rays are reflected by the light receiving element 32. When the Fresnel reflection is performed on the

upper surfaces

151 and 153, the light is reflected by being inclined by an angle θ2 that is a gradient angle. For this reason, it is difficult for the unnecessary reflected light beam to enter the light receiving surface 320. As a result, the module packages 300C and 300D can detect the absolute rotation angle with high accuracy. Further, since the thickness of the

light transmissive resins

33C and 33D can be reduced, it is possible to reduce the material cost when manufacturing the module packages 300C and 300D, and to realize the detection of the absolute rotation angle at a low cost. It becomes possible.

The module package 300D may include a package substrate 30A instead of the package substrate 30B. In other words, the light transmissive resin 33D may be applied to the module package 300A. In this case, the module package 300A includes a light-transmitting resin 33D instead of the light-transmitting resin 33A, and includes a light-blocking resin 34C instead of the light-blocking resin 34A.

Further, the light shielding resin 34 C described in FIGS. 17 and 18 is not limited to being disposed at an intermediate position between the center of the light emitting surface 310 and the center of the light receiving surface 320, and may be disposed in another region. .

As described above, according to the second embodiment, since the

upper surfaces

151 and 153 of the

light transmitting resins

33C and 33D are inclined, unnecessary light rays reflected by the

upper surfaces

151 and 153 of the

light transmitting resins

33C and 33D are reflected. It becomes difficult to enter the light receiving surface 320. Therefore, it is possible to accurately detect the absolute rotation angle of the measurement object.

Although the first and second embodiments have described the case where the absolute encoder 1 is a rotary encoder that detects a rotation angle, the absolute encoder 1 can also be applied to a linear encoder that detects a linear movement amount. is there.

The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1 Absolute encoder, 2 Optical scale, 4 Control unit, 5 Rotating shaft, 19 Look-up table, 30A, 30B Package substrate, 31, 31X Light emitting element, 32, 32X Light receiving element, 33A, 33C, 33D, 33X Light transmission Resin, 34A, 34B, 34C light-shielding resin, 41 angle calculation unit, 42 light emission amount adjustment unit, 150-153 top surface, 200 optical pattern, 201 reflection unit, 202 non-reflection unit, 300, 300A, 300B, 300X module package, 310, 310X light emitting surface, 320, 320X light receiving surface, 411 light quantity distribution correction unit, 412 edge detection unit, 413 coarse detection unit, 414 high precision detection unit, 415 rotation angle detection unit, 901-903 ray path.

Claims

An optical scale having an optical pattern;
A light emitting element that emits light to the optical scale and a module package in which a light receiving element that receives reflected light from the optical scale is covered with a light-transmitting resin;
A controller that calculates an absolute rotation angle of the optical scale based on a signal output by the light receiving element according to the reflected light;
With
The module package includes
A light-shielding portion that is exposed on a surface of the light-transmitting resin that faces the optical scale and that passes through an intermediate position between the center of the light-emitting surface of the light-emitting element and the center of the light-receiving surface of the light-receiving element is disposed;
An absolute encoder characterized by this.
The module package further includes a package substrate on which the light emitting element and the light receiving element are mounted.
The light shielding portion is disposed in a region where the package substrate is dug and a region where the light transmitting resin is dug,
The absolute encoder according to claim 1.
The package substrate is a glass epoxy substrate,
The light transmissive resin and the light shielding part are epoxy resins,
The absolute encoder according to claim 2.
An optical scale having an optical pattern;
A light emitting element that emits light to the optical scale and a module package in which a light receiving element that receives reflected light from the optical scale is covered with a light-transmitting resin;
A controller that calculates an absolute rotation angle of the optical scale based on a signal output by the light receiving element according to the reflected light;
With
The module package is
The angle of the light beam applied to the end of the light receiving element on the light emitting element side is θ1, the distance from the light receiving surface of the light receiving element to the upper surface of the light transmitting resin is L3, and the light emitting element of the light receiving element 2 × tan θ1 × L3> L4 is established when the distance from the end on the side to the end of the light receiving surface opposite to the light emitting element side is L4.
An absolute encoder characterized by this.
An optical scale having an optical pattern;
A light emitting element that emits light to the optical scale and a module package in which a light receiving element that receives reflected light from the optical scale is covered with a light-transmitting resin;
A controller that calculates an absolute rotation angle of the optical scale based on a signal output by the light receiving element according to the reflected light;
With
The light transmissive resin has an upper surface that is a surface facing the optical scale inclined with respect to the light receiving surface of the light receiving element.
An absolute encoder characterized by this.