Workpiece detection device and transfer robot

Abstract

To provide a workpiece detection device capable of detecting translucent workpieces with a relatively simple configuration. [Solution] The detection device A10 comprises a reference surface 311, a reference axis N, a light-emitting unit 411, and a light-receiving unit 511. The light-emitting unit 411 and the light-receiving unit 511 are located on opposite sides of each other with the reference surface 311 in between, and are also located on opposite sides of each other with the reference axis N in between in a virtual cross-section S that includes the reference axis N in its plane. When a translucent workpiece 80 is on the reference surface 311, the light emitted from the light-emitting unit 411 enters from a first region 831 of the end face 83 of the workpiece 80, undergoes total internal reflection at the interface between the workpiece 80 and the outside air, and then exits from a second region 832 of the end face 83 of the workpiece 80 without reaching the light-receiving unit 511. When the workpiece 80 is not on the reference surface 311, the light emitted from the light-emitting unit 411 reaches the light-receiving unit 511.

Description

Technical Field

[0001] The present invention relates to a workpiece detection device that detects the presence or absence of a workpiece, and a transfer robot including the workpiece detection device.

Background Art

[0002] Patent Document 1 discloses an example of a workpiece detection device for detecting the presence or absence of a workpiece disposed in a transfer robot or the like. The workpiece is, for example, a semiconductor wafer. In the workpiece detection device, light emitted from a light projecting unit reaches a light receiving unit. When a workpiece is present, the light emitted from the light projecting unit is blocked by the workpiece. Therefore, in the workpiece detection device, when the light emitted from the light projecting unit does not reach the light receiving unit, it is determined that a workpiece is present. On the other hand, when the light emitted from the light projecting unit reaches the light receiving unit, it is determined that no workpiece is present.

[0003] However, depending on the material of the workpiece, there are those having translucency. In this case, since the light emitted from the light projecting unit passes through the workpiece, the light reaches the light receiving unit. Therefore, with the configuration of the workpiece detection device disclosed in Patent Document 1, it is difficult to detect the workpiece.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of the above circumstances, an object of the present invention is to provide a workpiece detection device capable of detecting a translucent workpiece with a relatively simple configuration.

Means for Solving the Problems

[0006] A workpiece detection device provided by a first aspect of the present invention comprises a reference surface facing a first direction and exposed to the outside air, a reference axis extending in the first direction and passing through the reference surface, a light-emitting unit located on one side of the reference surface in the first direction, and a light-receiving unit located on the opposite side of the reference surface from the light-emitting unit and receiving light emitted from the light-emitting unit. In a virtual cross-section including the reference axis in the plane, the light-emitting unit and the light-receiving unit are located on opposite sides of the reference axis in a second direction perpendicular to the first direction. When a translucent workpiece is present on the reference surface, light emitted from the light-emitting unit enters from the end face of the workpiece facing the second direction, undergoes total internal reflection at the interface between the workpiece and the outside air, and exits from the end face without reaching the light-receiving unit. When the workpiece is not present on the reference surface, light emitted from the light-emitting unit reaches the light-receiving unit. In the virtual cross-section, the end face includes a first region and a second region located on opposite sides of the reference axis. When the workpiece is on the reference surface, the light emitted from the light-emitting unit enters the first region and exits the second region.

[0007] Preferably in the implementation of the present invention, the workpiece is made of a material including glass.

[0008] A transport robot provided by a second aspect of the present invention comprises a workpiece detection device provided by a first aspect of the present invention, a hand, and an arm supporting the hand on one side of the hand in the second direction. The hand includes the reference plane. The workpiece detection device is provided on the hand.

[0009] Preferably in the implementation of the present invention, the light-emitting portion is located on the side opposite to the side facing the reference plane in the first direction.

[0010] Preferably in the implementation of the present invention, the light-emitting portion is located on the side facing the reference plane in the first direction. The hand has an opening that penetrates in the first direction z. When the workpiece is on the reference plane, the workpiece and the light-receiving portion each overlap the opening when viewed in the first direction. [Effects of the Invention]

[0011] In the configuration of the workpiece detection device according to the present invention, it is possible to detect translucent workpieces with a relatively simple configuration.

[0012] Other features and advantages of the present invention will become more apparent from the detailed description below, based on the accompanying drawings. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view showing an overview of a transport robot according to the first embodiment of the present invention. [Figure 2] This is a plan view of a transport robot according to the first embodiment of the present invention. [Figure 3] Figure 2 is a magnified plan view of one of the two hands of the transport robot shown. [Figure 4] Figure 2 is a partially enlarged bottom view of one of the two hands of the transport robot shown. [Figure 5] This is a cross-sectional view along the VV line in Figure 3. [Figure 6] This is a cross-sectional view showing the configuration of one of the two workpiece detection devices equipped in the transport robot shown in Figure 2. [Figure 7] This is a partially enlarged plan view of one of the two hands comprising a transport robot according to a second embodiment of the present invention. [Figure 8] This is a cross-sectional view along the line VIII-VIII in Figure 7. [Figure 9] This is a cross-sectional view showing the configuration of one of the two workpiece detection devices equipped in the transport robot shown in Figure 7.

Best Mode for Carrying Out the Invention

[0014] A mode for carrying out the present invention will be described based on the accompanying drawings.

[0015] 〔First Embodiment〕 Based on FIGS. 1 to 6, a work detection device and a transfer robot B10 according to a first embodiment of the present invention will be described. The transfer robot B10 includes a main body 10, two arms 20, two hands 30, and two work detection devices (hereinafter referred to as "two detection devices A10" in the description of the first embodiment).

[0016] The transfer robot B10 transfers the work 80 shown in FIG. 3 to a predetermined position. The work 80 is, for example, a substrate used in the manufacture of semiconductor devices. Here, for the sake of convenience of explanation, the direction in which the reference plane 311 described later faces is referred to as the "first direction z". The first direction z generally corresponds to the vertical direction. A direction orthogonal to the first direction z is referred to as the "second direction x". A direction orthogonal to each of the first direction z and the second direction x is referred to as the "third direction y".

[0017] As shown in FIGS. 1 and 2, the main body 10 supports two arms 20. The main body 10 has a seat portion 11 and a movable portion 12. The seat portion 11 is fixed to the floor of the work place where the work 80 is transferred. The seat portion 11 houses a motor for operating the transfer robot B10 and an electronic circuit for controlling the motor. The movable portion 12 is supported by the seat portion 11. At least a part of the movable portion 12 is housed in the seat portion 11. The movable portion 12 is movable in the first direction z with respect to the seat portion 11 and is rotatable about the first direction z with respect to the seat portion 11.

[0018] As shown in FIGS. 1 and 2, the two arms 20 are supported on one side of the movable part 12 of the main body 10 in the first direction z. The two arms 20 are separated from each other in the third direction y. Each of the two arms 20 has a first arm 21 and a second arm 22. One end of the first arm 21 is supported by the movable part 12 so as to be rotatable around the first direction z with respect to the movable part 12. The second arm 22 is located on the side opposite to the movable part 12 with respect to the first arm 21 in the first direction z. One end of the second arm 22 is supported by the other end of the first arm 21 so as to be rotatable around the first direction z with respect to the first arm 21.

[0019] As shown in FIGS. 1 and 2, the two hands 30 are individually supported by the second arms 22 of each of the two arms 20. Each of the two hands 30 is rotatable around the first direction z with respect to the second arm 22 of any one of the two arms 20. Two detection devices A10 are individually provided on the two hands 30. As shown in FIGS. 2 and 3, each of the two hands 30 has a main part 31, a bracket 32, a plurality of regulating pieces 33, an opening 34, a groove 35 and a base 36.

[0020] As shown in FIG. 3, the main part 31 extends in the second direction x. The main part 31 has a reference surface 311 and a back surface 312 facing opposite sides in the first direction z. The reference surface 311 is exposed to the outside air. When using the transfer robot B10, the workpiece 80 is placed on the reference surface 311.

[0021] As shown in FIG. 2, the bracket 32 is located on one side of the main part 31 in the first direction z. The main part 31 is supported by the bracket 32. In this case, the main part 31 is fixed to the bracket 32. The bracket 32 is located on the side opposite to the first arm 21 of any one of the two arms 20 with respect to the second arm 22 of any one of the two arms 20 in the first direction z. The bracket 32 is supported by any one of the second arms 22 of the two arms 20. The bracket 32 is rotatable around the first direction z with respect to the second arm 22.

[0022] As shown in Figures 3 and 5, the multiple restricting pieces 33 are positioned on the reference surface 311 of the main portion 31. Each of the multiple restricting pieces 33 protrudes from the reference surface 311 in a first direction z. Viewed in the first direction z, the multiple restricting pieces 33 surround the workpiece 80. The movement of the workpiece 80 in a direction perpendicular to the first direction z is restricted by contact between the workpiece 80, positioned on the reference surface 311, and at least one of the multiple restricting pieces 33.

[0023] As shown in Figures 3 to 5, the opening 34 penetrates the main portion 31 in the first direction z. The opening 34 extends in the second direction x. In the second direction x, the opening 34 is located on the opposite side of the base 36 with respect to the multiple restricting pieces 33.

[0024] As shown in Figures 3 to 5, the groove 35 is recessed from the back surface 312 of the main portion 31 and extends in a predetermined direction. When viewed in the first direction z, the entire opening 34 overlaps with the groove 35.

[0025] As shown in Figures 3 and 5, the base 36 is fixed to the reference surface 311 of the main part 31. The material of the base 36 is preferably light-absorbing.

[0026] As shown in Figures 3 and 5, each of the two detection devices A10 includes a reference surface 311, a reference axis N, a light-emitting means 40, and a light-receiving means 50 on either the main portion 31 of each of the two hands 30. Here, the reference axis N extends in a first direction z and passes through the reference surface 311 and the workpiece 80. The reference axis N corresponds to the normal to the reference surface 311.

[0027] As shown in Figures 3 to 5, the light-emitting means 40 is housed in a groove 35 of one of the two hands 30. The light-emitting means 40 has a first light guide 41. The first light guide 41 is, for example, an optical fiber. A light-emitting section 411 is provided at one end of the first light guide 41. When light emitted from a light-emitting element such as an LED is incident on the other end of the first light guide 41, the light is emitted from the light-emitting section 411. This light is visible light, including infrared light. The light-emitting element that causes light to be incident on the other end of the first light guide 41 is, for example, located in a bracket 32 ​​of one of the two hands 30. The light-emitting section 411 is located on the side opposite to the side facing the reference plane 311 in the first direction z. Viewed in the first direction z, the light-emitting section 411 overlaps with the opening 34 of one of the two hands 30.

[0028] As shown in Figures 3 and 5, the light-receiving means 50 is located on the base 36 of one of the two hands 30. The light-receiving means 50 has a second light guide 51 and a support 52. The second light guide 51 is, for example, an optical fiber. A light-receiving section 511 is provided at one end of the second light guide 51. The light-receiving section 511 receives light emitted from the light-emitting section 411 of the light-emitting means 40. When the light emitted from the light-emitting section 411 reaches the light-receiving section 511, the light is emitted from the other end of the second light guide 51. The light emitted from the other end of the second light guide 51 is detected by a light-receiving element such as a phototransistor. The light-receiving element is located, for example, on the bracket 32 ​​of one of the two hands 30. The light-receiving section 511 is located on the side facing the reference plane 311 in the first direction z. Therefore, the light-receiving unit 511 is located on the opposite side from the light-emitting unit 411, with the reference surface 311 in between.

[0029] As shown in Figures 3 and 5, the support 52 is fixed to the base 36 of either of the two hands 30. In the first direction z, the support 52 is positioned between the base 36 and the second light guide 51. The second light guide 51 is supported by the support 52.

[0030] As shown in Figure 6, in a virtual cross-section S that includes the reference axis N in its plane, the light-emitting part 411 of the light-emitting means 40 and the light-receiving part 511 of the light-receiving means 50 are located on opposite sides of the reference axis N. Here, the in-plane directions of the virtual cross-section S are the first direction z and the second direction x.

[0031] Next, the operation of each of the two detection devices A10 will be explained based on Figure 6.

[0032] Each of the two detection devices A10 targets a workpiece 80 that is translucent. The workpiece 80 is made of a material that includes glass.

[0033] As shown in Figure 6, the workpiece 80 has a first surface 81, a second surface 82, and an end surface 83. The first surface 81 faces the same side as the reference surface 311 in the first direction z. The second surface 82 faces the opposite side of the first surface 81 in the first direction z. Therefore, the second surface 82 faces the reference surface 311. The end surface 83 faces the second direction x. In a virtual cross section S, the end surface 83 includes a first region 831 and a second region 832 that face opposite each other with the reference axis N in between. The first region 831 is located closer to the light-emitting section 411 of the light-emitting means 40 than the second region 832.

[0034] When the workpiece 80 is on the reference plane 311, the light emitted from the light-emitting section 411 of the light-emitting means 40 passes through the aperture 34 of one of the two hands 30 and then enters the first region 831 of the end face 83 of the workpiece 80. This light is refracted in the first region 831 according to Snell's law. The light entering from the first region 831 undergoes total internal reflection at the interface between the workpiece 80 and the outside air, and then exits from the second region 832 of the end face 83 of the workpiece 80 after being refracted according to Snell's law, without reaching the light-receiving section 511 of the light-receiving means 50. The light exiting from the second region 832 reaches the base 36 of one of the two hands 30. Viewed in the second direction x, the second region 832 overlaps with the base 36. The path of light when the workpiece 80 is on the reference plane 311 is shown as the first optical path L1 in Figure 6. The refractive index of the workpiece 80 is greater than the refractive index of the outside air. For example, the refractive index of workpiece 80, which is made of a material containing glass, is approximately 1.5.

[0035] When the workpiece 80 is not present on the reference surface 311, the light emitted from the light-emitting section 411 of the light-emitting means 40 passes through the aperture 34 of either of the two hands 30 before reaching the light-receiving section 511 of the light-receiving means 50. The path of the light when the workpiece 80 is not present on the reference surface 311 is shown as the second optical path L2 in Figure 6.

[0036] In each of the two detection devices A10, when light emitted from the light-emitting section 411 of the light-emitting means 40 reaches the light-receiving section 511 of the light-receiving means 50, it is determined that the workpiece 80 is not present on the reference surface 311. On the other hand, if the light emitted from the light-emitting section 411 does not reach the light-receiving section 511, it is determined that the workpiece 80 is present on the reference surface 311. In the virtual cross-section S, the first optical path L1 and the second optical path L2 emitted from the light-emitting section 411 are each inclined with respect to the second direction x.

[0037] Next, we will explain the operation and effects of detection device A10.

[0038] The detection device A10 comprises a reference surface 311, a reference axis N, a light-emitting unit 411, and a light-receiving unit 511. The light-emitting unit 411 and the light-receiving unit 511 are located on opposite sides of each other with the reference surface 311 in between, and are also located on opposite sides of each other with the reference axis N in between in a virtual cross-section S that includes the reference axis N in its plane. When a translucent workpiece 80 is present on the reference surface 311, the light emitted from the light-emitting unit 411 enters from a first region 831 of the end face 83 of the workpiece 80, undergoes total internal reflection at the interface between the workpiece 80 and the outside air, and exits from a second region 832 of the end face 83 of the workpiece 80 without reaching the light-receiving unit 511. When the workpiece 80 is not present on the reference surface 311, the light emitted from the light-emitting unit 411 reaches the light-receiving unit 511. By adopting this configuration, the presence or absence of a translucent workpiece 80 can be determined using the conventional configuration of the light-emitting unit 411 and light-receiving unit 511. Therefore, the configuration of the detection device A10 makes it possible to detect the translucent workpiece 80 with a relatively simple configuration.

[0039] In the detection device A10, when a translucent workpiece 80 is on the reference surface 311, light emitted from the second region 832 of the end face 83 of the workpiece 80 reaches the base 36 of the hand 30. Here, by having the property of absorbing light, it is possible to prevent the light from being diffusely reflected from the base 36.

[0040] [Second Embodiment] Based on Figures 7 to 9, a workpiece detection device and a transport robot B20 according to the second embodiment of the present invention will be described. In these figures, elements that are the same as or similar to those of the transport robot B10 and the two detection devices A10 described above are denoted by the same reference numerals, and redundant explanations are omitted. The transport robot B20 comprises a main body 10, two arms 20, two hands 30, and two workpiece detection devices (hereinafter referred to as "two detection devices A20" in the description of the second embodiment).

[0041] In the transport robot B20, the configuration of the two hands 30 and the two detection devices A20 differs from the configuration of the transport robot B10 described above.

[0042] As shown in Figures 7 and 8, in view in the first direction z, each opening 34 of the two hands 30 overlaps the workpiece 80. Thus, in view in the first direction z, the opening 34 is surrounded by multiple restricting pieces 33 of either of the two hands 30.

[0043] As shown in Figures 7 and 8, the light-emitting means 40 is positioned on the base 36 of one of the two hands 30. The light-emitting means 40 has a first light guide 41 and a support 42. The light-emitting portion 411 of the first light guide 41 is located on the side facing the reference plane 311 in a first direction z. The support 42 is fixed to the base 36 of one of the two hands 30. In the first direction z, the support 42 is located between the base 36 and the first light guide 41. The first light guide 41 is supported by the support 42.

[0044] As shown in Figures 7 and 8, the light-receiving means 50 is housed in a groove 35 of either of the two hands 30. The light-receiving portion 511 of the light-receiving means 50 is located on the side opposite to the side facing the reference plane 311 in the first direction z. Viewed in the first direction z, the light-receiving portion 511 overlaps with the opening 34 of either of the two hands 30.

[0045] Next, the operation of each of the two detection devices A20 will be explained based on Figure 9.

[0046] The workpieces 80 targeted by each of the two detection devices A20 are also translucent, just as in the case of the two detection devices A10.

[0047] When the workpiece 80 is located on the reference surface 311, the light emitted from the light-emitting section 411 of the light-emitting means 40 enters a first region 831 on the end face 83 of the workpiece 80. The light entering from the first region 831 undergoes total internal reflection at the interface between the workpiece 80 and the outside air, and then exits outwards from a second region 832 on the end face 83 of the workpiece 80 toward the transport robot B10 without reaching the light-receiving section 511 of the light-receiving means 50. In this case, viewed in the first direction z, the workpiece 80 is aligned with the opening 34 of one of the two hands 30.

[0048] When no workpiece 80 is present on the reference surface 311, the light emitted from the light-emitting section 411 of the light-emitting means 40 passes through the aperture 34 of either of the two hands 30 before reaching the light-receiving section 511 of the light-receiving means 50.

[0049] In each of the two detection devices A20, when light emitted from the light-emitting section 411 of the light-emitting means 40 reaches the light-receiving section 511 of the light-receiving means 50, it is determined that the workpiece 80 is not present on the reference surface 311. On the other hand, if the light emitted from the light-emitting section 411 does not reach the light-receiving section 511, it is determined that the workpiece 80 is present on the reference surface 311. In the virtual cross-section S, the first optical path L1 and the second optical path L2 emitted from the light-emitting section 411 are each inclined with respect to the second direction x.

[0050] Next, we will explain the operation and effects of detection device A20.

[0051] The detection device A20 comprises a reference surface 311, a reference axis N, a light-emitting unit 411, and a light-receiving unit 511. The light-emitting unit 411 and the light-receiving unit 511 are located on opposite sides of each other with the reference surface 311 in between, and are also located on opposite sides of each other with the reference axis N in between in a virtual cross-section S that includes the reference axis N in its plane. When a translucent workpiece 80 is on the reference surface 311, the light emitted from the light-emitting unit 411 enters from a first region 831 of the end face 83 of the workpiece 80, undergoes total internal reflection at the interface between the workpiece 80 and the outside air, and exits from a second region 832 of the end face 83 of the workpiece 80 without reaching the light-receiving unit 511. When the workpiece 80 is not on the reference surface 311, the light emitted from the light-emitting unit 411 reaches the light-receiving unit 511. Therefore, even with the configuration of the detection device A20, it is possible to detect a translucent workpiece 80 with a relatively simple configuration.

[0052] In the transport robot B20, the light-emitting unit 411 is located on the side facing the reference surface 311 in the first direction z. The hand 30 has an opening 34 that penetrates in the first direction z. When the workpiece 80 is on the reference surface 311, the workpiece 80 and the light-receiving unit 511 each overlap the opening 34 when viewed in the first direction z. By adopting this configuration, the dimension of the main part 31 of the hand 30 in the second direction x can be reduced compared to the case of the transport robot B10.

[0053] The present invention is not limited to the embodiments described above. The specific configuration of each part of the present invention can be modified in various ways. Each of the detection devices A10 and A20 is applicable not only to the transport robots B10 and B20, but also to various devices that require the detection of a translucent workpiece 80. [Explanation of Symbols]

[0054] A10, A20: Detection device, B10, B20: Transport robot, 10: Main body, 11: Seat, 12: Movable part, 20: Arm, 21: First arm, 22: Second arm, 30: Hand, 31: Main part, 311: Reference surface, 312: Back surface, 32: Bracket, 33: Regulating piece, 34: Opening, 35: Groove, 36: Base, 40: Light projection means, 41: 1: Light guide, 411: Light emitter, 42: Support, 50: Light receiving means, 51: Second light guide, 511: Light receiving part, 52: Support, 80: Workpiece, 81: First surface, 82: Second surface, 83: End face, 831: First region, 832: Second region, N: Reference axis, S: Virtual cross-section, L1: First optical path, L2: Second optical path, z: First direction, x: Second direction, y: Third direction

Claims

1. It faces the first direction, and the reference surface is exposed to the outside air, A reference axis extending in the first direction and passing through the reference plane, A light-emitting unit located on one side of the reference surface in the first direction, The device comprises a light-receiving unit located on the opposite side of the light-emitting unit, with the aforementioned reference surface in between, and which receives light emitted from the light-emitting unit. In a virtual cross-section that includes the reference axis in the plane, the light-emitting unit and the light-receiving unit are located on opposite sides of each other with the reference axis in between in a second direction perpendicular to the first direction. When a translucent workpiece is located on the reference surface, the light emitted from the light-emitting unit enters from the end face of the workpiece facing the second direction, undergoes total internal reflection at the interface between the workpiece and the outside air, and then exits from the end face without reaching the light-receiving unit. When the workpiece is not on the reference surface, the light emitted from the light-emitting unit reaches the light-receiving unit. In the virtual cross-section, the end face includes a first region and a second region located on opposite sides of the reference axis, A workpiece detection device wherein, when the workpiece is located on the reference surface, light emitted from the light-emitting unit enters the first region and exits from the second region.

2. The workpiece detection device according to claim 1, wherein the workpiece is made of a material including glass.

3. A workpiece detection device according to claim 1 or 2, Hand and, The hand comprises an arm that supports the hand on one of the two aforementioned directions, The hand includes the reference surface, The workpiece detection device is a transport robot provided on the hand.

4. The transport robot according to claim 3, wherein the light-emitting unit is located on the side opposite to the side facing the reference surface in the first direction.

5. The light-emitting unit is located on the side facing the reference plane in the first direction, The hand has an opening that penetrates in the first direction z, The transport robot according to claim 3, wherein when the workpiece is located on the reference surface, when viewed in the first direction, the workpiece and the light-receiving unit each overlap the opening.

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