JP2007324365A - Detecting sensor, detection apparatus, sensor head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detecting sensor etc. which is capable of detecting both the existence and the protruding of a tabular member, and capable of fitting an apparatus in a minimum size. <P>SOLUTION: A detecting sensor 30 is composed of a sensor head 40, a sensor amplifier 70, and optical fibers F1-F4. In the sensor head 40, two optical axes of a detection optical axis L1 and a detection optical axis L2 are established. The detection optical axis L1 is arranged so as to cross the end of a wafer W in a normal storage position from side to side in Figure 4. In contrast to that, the detection optical axis L2 is in a position that the optical axis L is moved to the output port 12 in parallel therewith so as to avoid the wafer W in the normal storage position. In other words, the detection optical axis L2 does not cross this when the wafer W is in a regular holding state, and when the wafer W changes into a state that it protrudes toward the output port 12 side from the normal storage position, detection optical axis is set so as to cross the end of the wafer W from side to side. Consequently, a common use can be attained in the sensor head 40 about the both optical detection axes L1, L2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sensor head for detecting plate-like members accommodated in multiple stages, and a detection sensor and a detection device using the sensor head.

In a semiconductor manufacturing process, a plurality of silicon wafers and the like may be handled in a multistage manner in a box-shaped cassette whose one side surface opens as a take-out port. This is because the heat treatment, the diffusion treatment, etc. are performed collectively in a state of being accommodated in the cassette. However, since the silicon wafer is taken out by a dedicated device following the above-described processing, the silicon wafer can be taken in and out of the cassette. It has become. That is, since the wafer is not fixed with respect to the cassette, for example, the wafer may jump out of the cassette while moving between the processes. In some cases, the wafer is not stored in the original position because the cassette is forgotten to be stored.
In view of the above points, prior to taking out a wafer that has already been subjected to heat treatment or diffusion treatment from the cassette, it is possible to detect the state of accommodation of the wafer in the cassette, that is, the presence or absence of the wafer and the pop-out from the cassette, Various techniques of this type have been proposed (Patent Document 1 and Patent Document 2 below).

In Patent Document 1, a first arm and a second arm are arranged to face each other with a wafer interposed therebetween. Each arm is provided with a light emitting element and a light receiving element, respectively, so that light is projected and received between them. And the presence or absence of a wafer is detected based on the output information of a light receiving element (refer FIG. 3 in patent document 1). On the other hand, in Patent Document 2, a light projecting head and a light receiving head are arranged with the optical axis directed up and down at the opening portion of the cassette to detect the protrusion of the wafer (see FIG. 1 in Patent Document 2). ).
Japanese Patent No. 2868645 JP2003-17548

As described above, dedicated apparatuses for detecting the presence / absence of a wafer and pop-out have already been proposed. Recently, however, there is a demand for detecting these by a single apparatus.
However, in Patent Document 1, the detection is performed by applying light from the side to the peripheral surface of the wafer, whereas in Patent Document 2, detection is performed by applying light perpendicularly to the plate surface of the wafer. Cannot be integrated into one device. Even if they can be integrated, the two optical axes that are orthogonal to each other are required as the detection optical axis, so that the apparatus becomes large, and it is necessary to individually hold each light projecting element and light receiving element. There is also a problem of increasing.
The present invention has been completed based on the above-described circumstances, and can detect both the presence or absence of a plate-like member and the protrusion, and can keep the apparatus in a minimum size. An object of the present invention is to provide a simple detection sensor.

  As a means for achieving the above object, the invention of claim 1 is a detection sensor for detecting a plate-like member that is accommodated in a container having one surface opened as an outlet with a gap therebetween. And a light emitting portion that is lateral to the plate-like member and is capable of emitting detection light in a direction substantially perpendicular to the overlapping direction of the plate-like member, and forms a detection optical axis in a pair with the light emitting portion. And a sensor head having a light detection means, and a determination means for determining the plate-like member based on the amount of light received by the light reception part of the sensor head. And a sensor amplifier that performs detection while moving the sensor head in the stacking direction of the plate-like member in the vicinity of the outlet. One detection optical axis Two light detection means, a first light detection means for forming and a second light detection means for forming a second detection optical axis, are provided, and the first detection optical axis of the first light detection means is While the plate-like member is housed in the containing body, it is set so as to cross the plate-like member from its end surface direction, whereas the second detection by the second light detection means The optical axis does not cross the plate-like member when the plate-like member is in the accommodated state, and when the plate-like member is in a protruding state where the plate-like member jumps out to the outlet side, The determination means of the sensor amplifier is configured to receive the detection light level obtained by receiving the detection light of the first detection optical axis, and the light reception obtained by receiving the detection light of the second detection optical axis. Based on the signal level, the presence or absence of each plate-like member and the pop-out are detected. - having the features in place

  According to a second aspect of the present invention, in the first aspect, the sensor head includes a pair of detection heads disposed opposite to both sides of the plate-like member in the end face direction of the plate-like member. One of the detection heads is provided with a light emitting part, and the other detection head, which is the other side, is provided with a light receiving part, and the light emitted from the light emitting part is received by the light receiving part. It is characterized in that each of the detection optical axes is formed by being received by the unit.

  According to a third aspect of the present invention, the sensor head comprises a pair of detection heads disposed opposite to both sides of the plate-like member in the end face direction of the plate-like member. The light emitting unit and the light receiving unit are both installed in the detection head on one side, and a reflector is installed on the detection head on the other side which is the counterpart, and the light emitted from the light emitting unit is It is characterized in that each of the detection optical axes is formed by being reflected by the reflector to the emission side and receiving this light by a light receiving portion.

  Invention of Claim 4 is the thing of Claim 2 or Claim 3, When the opposing space | interval of the plate-shaped members accommodated by the said accommodating body with a clearance gap is defined as D, A diaphragm means for restricting detection light emitted from the detection head is provided inside the detection head, and the light beam d when the detection light reaches the vicinity of the center of the plate-like member by the diaphragm means, It is characterized in that the light is squeezed and emitted in the detection head so as to be narrower than at least the facing interval Z between the plate-like members adjacent to the plate-like member to be detected.

  According to a fifth aspect of the present invention, in the sensor amplifier according to any one of the second to fourth aspects, the sensor amplifier includes a light projecting element for projecting detection light and a light receiving element for receiving the detection light. The detection head on the light projecting side is provided with an emission window serving as the light emitting unit, while the detection head on the light receiving side is provided with a light receiving window serving as the light receiving unit. The sensor amplifier and the detection head on the light emitting side are connected by a light projecting optical fiber, and the sensor amplifier and the detection head on the light receiving side are connected by a light receiving optical fiber, and the sensor amplifier After the light projected by the light projecting element is transmitted through the light projecting optical fiber, the light is emitted from the emission window of the detection head on the light projection side, and the emitted detection light becomes the light receiving side. Provided in the detection head Wherein is through the light receiving window guided to the light-receiving optical fiber that, after being transmitted through the same optical fiber, characterized by where it is received by the light receiving element.

  According to a sixth aspect of the present invention, in the method according to any one of the first to fifth aspects, the second detection optical axis is a front side in the moving direction of the sensor head with respect to the first detection optical axis. Then, the second detection optical axis passes through the plate member at a timing earlier than the first detection optical axis.

  According to a seventh aspect of the present invention, in the head according to the sixth aspect, the tip of the detection head arranged toward the plate-like member is cut into a stepped portion corresponding to the second detection optical axis. It is characterized in that it is notched and the notched portion is a relief for the plate-like member.

  According to an eighth aspect of the present invention, in the apparatus according to the sixth or seventh aspect, the sensor amplifier is provided with a signal input unit for inputting an external timing signal in accordance with the movement of the sensor head. On the side, the light receiving element for the first detection optical axis and the light receiving element for the second detection optical axis are shared by a single light receiving element, and the determination means is based on the timing signal, By receiving the light reception signal of the shared light receiving element, the light reception signal when the first detection optical axis passes through the plate member and the second detection optical axis pass through the plate member. It is characterized in that it discriminates the received light signal at the time.

  According to a ninth aspect of the present invention, in the method according to any one of the first to fifth aspects, the first detection optical axis and the second detection optical axis have the same height in the movement direction of the sensor head. In this position, when the sensor head is moved, both detection optical axes pass through the plate-like member almost simultaneously, and the light receiving elements for both detection optical axes are shared by a single light receiving element. The sensor amplifier has a first reference level corresponding to a state in which both of the detection optical axes are not shielded with respect to a light reception signal output from a single shared light receiving element, and both detections. A second reference level corresponding to a state in which both of the optical axes are shielded from light is preset, and the determination means determines the preset first and second reference levels and the signal level of the received light signal. The process of comparing the size of It is, having the features the presence of the plate members, where the detected jumping out as well.

  The invention of claim 10 is characterized in that, in the invention of claim 8 or claim 9, there is provided a light branching means for branching the detection light emitted from one light projecting element as two detection lights. Have

  According to an eleventh aspect of the present invention, in the tenth aspect of the present invention, there are two light projecting optical fibers corresponding to the two detection optical axes between the detection head on the light projecting side and the sensor amplifier. And the sensor amplifier is provided with the light branching means, and the two detection lights branched by the light branching means are respectively guided to the light projecting optical fibers. Have

  As means for achieving the above object, a twelfth aspect of the invention provides the detection sensor according to any one of the first to eleventh aspects and a sensor head constituting the detection sensor in the vicinity of the outlet. A moving unit that moves the plate-shaped member in the overlapping direction; and a control unit that controls movement of the sensor head by the moving unit.

  According to a thirteenth aspect of the invention, in the twelfth aspect of the invention, the determination means of the sensor amplifier takes in the received light signal every time the sensor head passes a position corresponding to one plate-like member. It is configured to determine the housing status of the plate-like member as needed, and when a jump-out of the plate-like member is detected by the same determination, an error is output to the control means to stop the movement of the sensor head. Has characteristics.

  As means for achieving the above object, the invention of claim 14 is directed to the detection sensor according to claim 7 and the sensor head constituting the detection sensor in the stacking direction of the plate-like members in the vicinity of the outlet. Moving means, and a control means for controlling movement of the sensor head by the moving means, wherein the sensor amplifier determination means each time the sensor head passes through a position corresponding to one plate-like member. The light receiving signal is taken in to determine the housing status of the plate-like member at any time, and when the jump-out of the plate-like member is detected by the same determination, an error is output to the control means, It is characterized in that the movement of the sensor head is stopped.

  As a means for achieving the above object, the invention according to claim 15 is directed to detecting a plate-like member accommodated in a container, one surface of which is opened as an outlet, with a gap therebetween, and the outlet of the outlet. A sensor head that is supported in the vicinity so as to be movable in the stacking direction of the plate-like members, and can detect light in a direction that is lateral to the plate-like members and substantially perpendicular to the stacking direction of the plate-like members. A first light detecting means comprising a first light receiving portion which forms a first detection optical axis in a pair with the first light emitting portion, and the plate-like shape A second light receiving portion that forms a second detection optical axis in a pair with the second light emitting portion and a second light emitting portion capable of emitting detection light in a direction substantially perpendicular to the overlapping direction of the members; A second light detection means comprising: a first detection optical axis of the first light detection means; The second detection optical axis of the second light detection means is set to cross the plate-like member from the end surface direction when the plate-like member is housed. The plate-like member is not traversed when the plate-like member is in the accommodated state, and the plate-like member is traversed from the end surface direction when the plate-like member is in a projecting state where the plate-like member is projected to the outlet side. Further, the second detection optical axis is on the front side in the moving direction of the sensor head with respect to the first detection optical axis, and the second detection optical axis is the first detection optical axis. It is characterized in that it passes through the plate-like member at an earlier timing.

  According to a sixteenth aspect of the present invention, in the head according to the fifteenth aspect, the tip of the detection head arranged toward the plate-like member is cut into a stepped portion corresponding to the second detection optical axis. It is characterized in that it is notched and the notched portion is a relief for the plate-like member.

<Invention of Claims 1 and 12>
According to invention of Claim 1 and Claim 11, when the said plate-shaped member is accommodated in the said container, the 1st detection optical axis which crosses the same plate-shaped member, and plate shape When the member is in the accommodated state, the plate-like member is not traversed, and when the plate-like member is in the projecting state of projecting to the outlet side, two axes of the second detection optical axis are set across the plate-like member. With such a configuration, as seen in the prior art, it is possible to detect the presence or absence of protrusion with light from the end face direction without irradiating the plate member with light perpendicular to the plate surface. That is, according to the present invention, although two optical axes of the first detection optical axis and the second detection optical axis are required, the presence or absence of the plate-like member and the detection of the protrusion are detected for the plate-like member. This can be realized by a detection format in which light is emitted from the end face direction. With such a configuration, it is not necessary to separately provide the sensor head for the first detection optical axis and the sensor head for the second detection optical axis, so that the apparatus can be easily downsized.

<Invention of Claim 2>
Photoelectric detection sensors include so-called reflection type sensors and transmission type sensors. In the reflection type, light reflected by the detection target is received, and the presence or absence of the detection target is determined based on the amount of the reflected light. In the present invention, since light is emitted from the side with respect to the plate-like member, when a reflective photoelectric sensor is used, reflected light reflected by the peripheral surface of the plate-like member is received. The peripheral surface of the plate-like member is often rough, and irregular reflection generally occurs there. Therefore, the reflection direction of light is not determined, and it is expected that the amount of received light is very small even if the plate-like member is in the detection region. That is, the level of the received light signal hardly changes depending on whether the plate member is present or not, and the detection accuracy cannot be increased.

  In this regard, according to the second aspect of the present invention, the light emitting portion and the light receiving portion are arranged to face each other with the detection region interposed therebetween to form the detection optical axis. Thereby, when there is no plate-shaped member in the detection region, the emitted light is received as it is on the other side. On the other hand, if a light-shielding object (plate member) is located in the detection region, light is shielded there, and as a result, the amount of light reaching the other side is greatly reduced. With this, light-shielding of the detection optical axis is detected ( So-called transmission type). In this way, in the case of a transmission type that uses light blocking of the detection optical axis, the change in the level of the received light signal inevitably appears with and without the plate-like member, so the detection accuracy is high. Can be high.

<Invention of Claim 3>
According to the third aspect of the present invention, the light emitting part and the light receiving part are both arranged on one side of the detection head, and the other side detection head which is the other side is constituted by the reflector. In this way, if one of the detection heads is made of a reflector, it is possible to emit light from the light emitting unit even if there is a relative misalignment between the two detection heads by using a reflector having a large reflective surface. The reflected light can be reflected to the emission side by the reflector. After that, it is only necessary to receive the reflected light at the light receiving portion, and therefore, a severe alignment work between the two detection heads is not necessary.

<Invention of Claim 4>
According to the invention of claim 4, when the diaphragm means is provided and the light beam d when reaching the vicinity of the center of the plate-like member, at least the facing interval Z between the plate-like members adjacent to the plate-like member to be detected. I made it narrower. With such a configuration, the light reflected by the other plate-like member adjacent to the plate-like member to be detected does not form an image at the light receiving portion, thereby causing the reflected light. Measurement error can be suppressed.

<Invention of Claim 5>
According to the invention of claim 5, the light projecting element and the light receiving element are built in the sensor amplifier, and are not installed on the detection head side. With such a configuration, the detection head is suitable for further downsizing, and can be used without problems even in situations where there is a risk of fire.

<Inventions of Claims 6 and 15>
According to the invention of claim 6 and the invention of claim 15, the second detection optical axis, that is, the optical axis for detecting the protrusion of the plate-like member, detects the presence of the first detection optical axis, ie, the plate-like member. The plate member is passed before the optical axis. With such a configuration, it is possible to detect the protrusion of the plate-like member prior to the presence or absence of the plate-like member. Depending on the protruding state of the plate-like member, it may interfere with surrounding devices, so that such interference can be avoided at an early stage by detecting the protruding first.

<Invention of Claims 7 and 16>
According to the seventh and sixteenth aspects, the tip of the detection head has a stepped shape, and the portion corresponding to the second detection optical axis is escaped. The part corresponding to the second detection optical axis of the detection head approaches the plate-shaped member first, but by providing a relief here, even if the plate-shaped member is in a state of protruding, it Interference can be avoided.
When the entire detection head is moved as it is, the portion corresponding to the first detection optical axis of the detection head is popped out next to the portion corresponding to the second detection optical axis of the detection head. As it approaches the plate-like member, it will eventually interfere, but it can detect the pop-out of the plate-like member by the second detection optical axis, so it corresponds to the first detection optical axis of the detection head If the movement of the detection head itself is stopped before the portion to be interfered with the plate-like member, such interference can be avoided in advance.

<Invention of Claim 8>
According to the eighth aspect of the invention, the first light projecting element for the detection optical axis and the second light projecting element for the detection optical axis are provided exclusively, and these are alternately time-divisionally projected. The configuration. With such a configuration, even if the light receiving element is shared, by detecting the light receiving signal in synchronization with the light projection timing, the signals output from the common light receiving element are separated from the detected optical axis, that is, the first It can be discriminated whether the light reception signal having received the light of one detection optical axis is the light reception signal having received the light of the second detection optical axis.

<Invention of Claim 9>
According to the ninth aspect of the present invention, both the optical axis of one detection optical axis and the second detection optical axis are arranged at the same height position in the moving direction of the sensor head, and the presence or absence of the plate-like member and the protrusion Were detected at the same time. Such a configuration is suitable for speeding up detection. Further, when simultaneous detection is performed, if there is no plate-shaped member, both optical axes are simultaneously transmitted, whereas if the plate-shaped member is projected, both optical axes are simultaneously shielded from light. The Therefore, if a reference value (first reference level) corresponding to two optical axis transmission and a reference value (second reference value level) corresponding to two optical axis light shielding are set in advance, the shared light reception By comparing the output signal of the element with these, it is possible to know the presence or absence of the plate-like member and the protrusion.

<Invention of Claims 10 and 11>
According to the tenth aspect of the present invention, the optical branching unit is provided to split the detection light. Thereby, since a light projection element can be shared between both detection optical axes, it contributes to cost reduction. According to the invention of claim 11, the light branching means is built in the sensor amplifier.

<Inventions of Claims 13 and 14>
According to the thirteenth aspect of the present invention, when the jump-out of the plate-like member is detected, an error is output to the control means to stop the movement of the sensor head. As a result, the protruding plate-like member can be returned to the normal state at an early stage, and interference with the peripheral device including the sensor head can be avoided.

  According to the fourteenth aspect of the present invention, the tip of the detection head has a stepped shape, and the portion corresponding to the second detection optical axis is escaped. The part corresponding to the second detection optical axis of the detection head approaches the plate-shaped member first, but by providing a relief here, even if the plate-shaped member is in a state of protruding, it Interference can be avoided (effective in preventing breakage of the plate-like member).

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a cassette 10 that houses a silicon wafer W (corresponding to a plate-like member of the present invention, hereinafter referred to as a wafer W). The cassette 10 has a box shape, and the front surface is open. On the left and right inner walls of the cassette 10, a plurality of support grooves 11 for supporting the wafer W are formed in the vertical direction.
In the following description, the front-rear direction is defined as follows. That is, for the cassette 10, the side on which the attachment opening 12 is provided is the front side, and the back wall side facing this is the rear side. On the other hand, for the sensor head 40 to be described later, the side inserted into the mounting opening 12 of the cassette 10 is the front side, and the opposite side (the side from which the optical fibers F1 to F4 are led out) is the rear side.

  Each support groove 11 extends horizontally in the depth direction of the cassette 10. By inserting the wafer W from the front surface of the cassette 10 between the left and right support grooves 11, the wafer W is maintained in a horizontal posture in the cassette 10. Can be accommodated in multiple stages.

The front surface of the cassette 10 is an outlet 12 from which the wafers W accommodated in multiple stages are taken in and out one by one by a robot arm (not shown).
In the present invention, the “stacking direction of the plate-shaped members” is the vertical direction (height direction) in FIG. 5, and the “direction perpendicular to the stacking direction of the plate-thickness members” in the present invention is The horizontal direction in FIG. 5 (horizontal direction).

Next, the wafer detection apparatus 20 will be described.
As shown in FIG. 2, the wafer detection device 20 is roughly composed of a detection sensor 30, an elevating device 80, and a control device 90. The wafer detection device 20 detects the accommodation status of the wafers W accommodated in the cassette 10 described above, that is, the presence / absence of the wafers W and the jumping-out of the wafers W for each stage. The lifting device 80 corresponds to the moving means of the present invention, and the control hand device 90 corresponds to the control means of the present invention.

  The detection sensor 30 includes a sensor head 40, a sensor amplifier 70, and optical fibers F1 to F4. The sensor amplifier 70 incorporates a control board (not shown) on which a CPU 77 (corresponding to the determination means of the present invention) 77 to be described later is mounted, and has a function of processing a signal and determining a detection result. The sensor amplifier 70 incorporates light projecting elements 71 and 72 and light receiving elements 73 and 74 (see FIG. 6).

  The light projecting elements 71 and 72 and the light receiving elements 73 and 74 built in the sensor amplifier 70 are for forming a detection optical axis L for detecting the wafer W. In the present embodiment, Two light projecting elements 71 and 72 and two light receiving elements 73 and 74 are provided to form two optical axes of one detection optical axis L1 and the second detection optical axis L2. In the following description, the first detection optical axis L1 is referred to as a detection optical axis L1, and the second detection optical axis L2 is referred to as a detection optical axis L2.

  FIG. 3 is an enlarged view of the sensor head 40. The sensor head 40 includes a light projecting head (corresponding to the detection head of the present invention) 41 and a light receiving head (corresponding to the detection head of the present invention) 51. The light projecting head 41 has a long block shape in one direction. Grooves are formed in the light projecting head 41 so as to penetrate the longitudinal direction back and forth. In FIG. 3, the rear half is slightly wider in FIG. 3, whereas the front half is slightly narrow.

  The widened portion is a sleeve holding groove 45 in which sleeves 61 and 62 described later are held. On the other hand, the narrowed portion is a fiber insertion groove 46 through which optical fibers F1 and F2 connected to the sleeves 61 and 62 are inserted. In the light projecting head 41, the sleeve holding groove 45 and the fiber insertion groove 46 described above are formed on the upper surface side and the lower surface side, respectively.

  The light receiving head 51 has the same configuration as that of the light projecting head 41 and has a long block shape in one direction. A sleeve holding groove 55 and a fiber insertion groove 56 are formed on the upper and lower surfaces of the light receiving head 51, respectively.

  The light projecting head 41 and the light receiving head 51 are positioned so as to face each other, and their ends are fixed by a connecting block B.

  The optical fibers F1 to F4 are for transmitting detection light between the sensor head 40 and the sensor amplifier 70, and correspond to the two light projecting elements 71 and 72, and the two light projecting optical fibers F1. F2 and two light receiving optical fibers F3 and F4 corresponding to the two light receiving elements 73 and 74 are provided.

  Cylindrical sleeves 61 to 64 are respectively attached to one ends of the optical fibers F1 to F4. At the tip of each of the sleeves 61 to 64, the emission windows 61A and 62A are provided for the light emitting sleeves 61 and 62, respectively, and for the light receiving sleeves 63 and 64, the light receiving windows 63A and 64A are provided. Each is provided.

  As shown in FIG. 3, the sleeves 61 to 64 are fitted and fixed to sleeve holding grooves 45 and 55 provided in the sensor head 40, respectively, but the sleeves 61 and 64 mounted on the upper surface side of the sensor head 40 are fixed to each other. In addition, the sleeves 62 and 63 attached to the lower surface side of the sensor head 40 are paired to constitute the detection optical axes L1 and L2.

  Specifically, on the upper surface side of the sensor head 40, as shown in FIG. 3, the sweeps 61 and 64 are fixed with the emission window 61A and the light receiving window 64A facing inward. The emission window 61A and the light receiving window 64A are aligned so as to face each other when the sleeve is mounted. The fiber insertion grooves 46 and 56 accommodate optical fibers F1 and F4 connected to the respective sweeps 61 and 64, and the optical fibers F1 and F4 are drawn from the rear end face of the sensor head 40, respectively.

  The other ends of the optical fibers F1 and F4 drawn out from the sensor head 40 are drawn into the sensor amplifier 70, and the end of the optical fiber F1 on the light projecting side faces the light projecting surface of the light projecting element 71. The end of the optical fiber F4 on the light receiving side faces the light receiving surface of the light receiving element 74 (see FIG. 6).

Thus, when the detection light is emitted from the light projecting element 71, the light is guided to the light projecting head 41 through the light projecting optical fiber F1. Then, the detection light is emitted horizontally (horizontal in FIG. 5) from the emission window 61 </ b> A of the sweep 61 toward the light receiving head 51. The emitted detection light reaches the light receiving head 51, is guided into the sleeve 64 through the light receiving window 64A, and then is guided to the light receiving surface of the light receiving element 74 through the light receiving optical fiber F4. As described above, the detection optical axis L1 is formed by the pair of sleeves 61 and 64, and the light of the detection optical axis L1 is received by the light receiving element 74.
Incidentally, the sleeve 61 and the sleeve 64 constitute the first detection means in the present invention.

On the other hand, the sleeves 62 and 63 are both mounted on the lower surface side of the sensor head 40, and these also form a pair of detection optical axes L2 in the same manner as the above-described configuration. That is, when the detection light is emitted from the light projecting element 72, the light is guided to the light projecting head 41 through the light projecting optical fiber F2. Then, the detection light is emitted horizontally (horizontal in FIG. 5) from the emission window 62 </ b> A of the sweep 62 toward the light receiving head 51. The emitted detection light reaches the light receiving head 51 and is guided into the sleeve 63 through the light receiving window 63A. Thereafter, the light passing through the light receiving optical fiber F <b> 3 is guided to the light receiving surface of the light receiving element 73 and is received by the light receiving element 73.
Note that the sleeve 62 and the sleeve 63 constitute second detection means in the present invention.

  As shown in FIG. 2, the above-described sensor head 40 lays the heads 41 and 51 horizontally in the vicinity of the outlet 12 of the cassette 10, and the tip at which the detection optical axis L 1 is formed in the cassette 10. It is installed in the inserted posture. That is, while the light projecting head 41 is located near the left inner wall of the cassette 10, the light receiving head 51 is located near the right inner wall of the cassette 10, and both heads 41, 51 hold the wafer W accommodated in the cassette 10. It is installed so as to be sandwiched between.

  FIG. 4 is a diagram showing a relative positional relationship between the wafer W and each of the detection optical axes L1 and L2 in a state where the head is installed. In FIG. 4, the regular accommodation state in which the wafer W is correctly accommodated in the cassette 10 is indicated by a solid line, and the jumping state in which the wafer W jumps out from the regular accommodation state to the outlet 12 side (lower side in FIG. 4). It is indicated by a one-dot chain line.

  As shown in FIG. 4, the positions of the two detection optical axes L <b> 1 and L <b> 2 are different from each other in the depth direction of the cassette 10 (the vertical direction shown in FIG. 4). That is, the detection optical axis L1 is arranged so as to cross the end of the wafer W in the normal accommodation state to the left and right in FIG. The optical axis L is in a position translated to the outlet 12 side so as to avoid it. In other words, the detection optical axis L2 does not cross when the wafer W is in the normal accommodation state, and the end portion of the wafer W when the wafer W protrudes from the normal accommodation state to the outlet 12 side. Is set to cross the left and right.

According to the above configuration, the first detection optical axis of the first light detection means of the present invention is the same as the plate-like member when the plate-like member is housed in the container. Whereas the second detection optical axis of the second light detecting means is set so as to cross from the end face direction, the plate-like member does not cross the plate-like member when the plate-like member is in the accommodated state, and the plate When the plate-like member is in the protruding state where it protrudes to the outlet side, the plate-like member is set to cross from the end surface direction ”.
Further, in the present invention, “crossing the plate-like member from the end surface direction” means that the wafer W is crossed substantially horizontally from the side of the wafer W in the present embodiment.

  As a result, when light is projected and received while the entire sensor head 40 is moved along the height direction of the cassette 10 by an elevating device 80 described later, the respective detection optical axes L1 and L2 are moved to the respective wafers. When passing through a height position corresponding to W, light is shielded or not shielded depending on the accommodation state of the wafer W. Therefore, by determining whether or not the detection optical axes L1 and L2 are shielded, it is possible to detect the presence or absence of the wafer W and the protrusion of the wafer W at each stage.

  Specifically, if the wafer W is stored in a certain stage in the cassette 10, the detection optical axis L1 crosses the wafer W horizontally from the end face direction when passing through a height position corresponding to that stage. Therefore, the detection optical axis 1 is shielded from light. On the contrary, if there is no wafer W, the detection optical axis L1 passes through without being shielded. Therefore, the presence / absence of the wafer W can be known by determining the presence / absence of light shielding of the detection optical axis 1.

  Further, if the wafer W accommodated in a certain stage in the cassette 10 is in the normal accommodation state, the detection optical axis L2 passes through the height position corresponding to that stage. On the other hand, when the wafer W has jumped out of the normal accommodation state, the detection optical axis L2 crosses the projected wafer W almost horizontally from the end surface direction, so that the detection optical axis L2 is shielded. Therefore, the protrusion of the wafer W can be detected by determining the presence or absence of light shielding with respect to the detection optical axis L2.

  FIG. 5 shows the positional relationship between the detection optical axes L1 and L20 in the vertical direction. As shown in the figure, the detection optical axis L2 is arranged below the detection optical axis L1 in the vertical direction in FIG. This takes into account the direction of movement of the sensor head 40 when performing detection.

  In the present embodiment, as shown in FIG. 5, in the cassette 10, the sensor head 40 is installed above the wafers W <b> 1 to W <b> 5 that are stacked one above the other, and the sensor head 40 is lowered to perform detection. I try to do it. As described above, if the detection optical axis L2 is arranged at a position below the detection optical axis L1, the detection optical axis L2 passes through each stage at an earlier timing than the detection optical axis L1. Thereby, it is possible to detect the protrusion of the wafers W1 to W5 prior to the detection of the presence or absence of the wafers W1 to W5.

  Further, as shown in FIG. 5, the tip shape of the light projecting heads 41 and 51 constituting the sensor head 40 is notched on the lower side where the detection optical axis L2 is mounted, thereby forming a stepped shape. In other words, the tip lower portions 43 and 53 corresponding to the detection optical axis L2 have a shape retracted in the right direction in FIG. 5 (outside as viewed from the cassette 10) with respect to the tip upper portions 42 and 52 with respect to the detection optical axis L1. . This considers the following points.

  As shown in FIG. 4, the cassette 10 is not sized so as to have a margin with respect to the outer shape of the wafer W, and the space for arranging the sensor head 40 is limited in the cassette 10. For this reason, when the wafer W is in a state of protruding like a one-dot chain line shown in FIG. 4, the tips of the heads 41 and 51 may interfere with the end of the wafer W (A portion in FIG. 4).

  Therefore, by making the tips of the heads 41 and 51 stepped as described above, it is possible to avoid interference with the protruding wafer W. Since the escape from the wafer W is provided only on the lower side of the heads 41 and 51, the upper part of the heads 41 and 51 interferes with the wafer W if it jumps out. However, when the protrusion of the wafer W is detected by the detection optical axis L2, the control device 90 described later stops the movement of the sensor head 40. As a result, the movement of the entire sensor head 40 is stopped before the tip top portions 42 and 52 of the heads 41 and 51 interfere with the protruding wafer W, so that the interference is avoided in advance.

  In this embodiment, the E dimension (the difference in height between the detection optical axis L1 and the detection optical axis L2) shown in FIG. 5 is smaller than the D dimension (opposite distance between adjacent wafers) shown in FIG. It is set.

  The lifting device 80 may be any device that can move the sensor head 40 up and down. As an example, for example, a slider 82 is movably fitted to a base 81 extending up and down. The structure which raises / lowers with the motor M for a drive etc. is mentioned. In the embodiment, as shown in FIG. 2, the left outer surface of the light projecting head 41 is fixed to the slider 82. Therefore, when the slider 82 moves up and down along the base 81 by driving the motor M, the entire sensor head 40 moves up and down integrally therewith.

  The control device 90 has a function of transmitting and receiving various control signals Sa to Sd between the lifting device 80 and the sensor amplifier 70 to control and control the entire wafer detection device 20. More specifically, the signal Sc output from the control device 90 to the lifting device 80 is a motor control signal Sc. The motor control signal Sc is a signal for controlling driving / stopping of the motor M and the like.

  On the other hand, the signal Sd output from the lifting device 80 to the control device 90 is a position signal Sd. The position signal Sd is a pulse signal that is output in accordance with the amount of movement of the slider 82 that is moved by driving the motor M. For example, each time the slider 82 moves 1 mm, the elevating device 80 outputs one pulse.

  In the control device 90, processing for detecting the timing at which each of the detection optical axes L1 and L2 passes through the height corresponding to the wafer W accommodated in each stage is performed based on the input position signal Sd. That is, by counting the number of pulses of the position signal Sd with a counter or the like, it is possible to calculate the amount of movement of the slider 82 and thus the sensor head 40. On the other hand, the control device 90 stores in advance information such as the facing distance D of the wafers W stacked in multiple stages, the thickness C of the wafers W, the number of accommodation stages of the wafers W, and the like.

  Therefore, based on this information and the movement distance of the sensor head 40, it is possible to know the timing at which each of the detection optical axes L1 and L2 passes through the height position corresponding to the wafer W at each stage. Note that the height positions (hereinafter also referred to as detection positions) corresponding to the wafers W at each stage are Y1 to Y5 in FIG.

The signal Sa output from the control device 90 to the sensor amplifier 70 is a synchronization detection signal Sa. The synchronization detection signal Sa is output in accordance with the timing at which the detection optical axes L1 and L2 described above pass through the detection positions Y1 to Y4.
Reference symbol P in FIG. 6 is an input port (corresponding to a signal input unit of the present invention), to which the synchronization detection signal Sa is input. When the synchronization detection signal Sa is input to the input port P, the CPU 77 takes in the light reception signals S3 and S4 from the respective light receiving elements 73 and 74 in synchronization therewith.
The synchronization detection signal Sa corresponds to the timing signal of the present invention, and the input port P provided in the CPU 77 corresponds to the signal input unit of the present invention.

  When the CPU 77 takes in the light reception signals S3 and S4, the CPU 77 performs processing for comparison with a predetermined threshold value, and detects the presence or absence of a light shielding state for the detection optical axes L1 and L2. That is, when the levels of the light reception signals S3 and S4 are higher than the threshold value, it is determined that “the detection optical axis L is not shielded”, and on the contrary, the levels of the light reception signals S3 and S4 are lower than the threshold value. If it is, it is determined that “the detection optical axis L is shielded”.

  An error signal Sb is output from the CPU 77 to the control device 90. The error signal Sb is output when light shielding is detected for the detection optical axis L2.

  Next, a series of detection operations for the wafer detection apparatus 20 configured as described above will be briefly described. As shown in FIG. 5, the sensor head 40 is set above the wafer W accommodated in an overlapping manner. When detection is started, first, both the light projecting elements 71 and 72 of the sensor amplifier 70 are turned on simultaneously. Accordingly, the detection light is guided to the sensor head 40 through the optical fibers F1 and F2, and both the detection optical axes L1 and L2 are turned on. At substantially the same timing as this, the control device 90 gives a motor control signal Sc to the lifting device 80.

  Thus, the motor M is driven, and the slider 82 starts to descend along the base 81 in response to the driving force. Thus, the sensor head 40 is lowered while both the detection optical axes L1 and L2 are turned on.

  Eventually, when the detection optical axis L2 reaches the detection position Y1 shown in FIG. 5, the synchronization detection signal Sa is output from the control device 90 to the CPU 77. In response to this, the CPU 77 performs processing for taking in the light reception signal S4 output from the light receiving element 74 in accordance with the input timing of the synchronization detection signal Sa.

  Thereby, the light reception signal S4 when the detection optical axis L2 just passes the detection position Y1 is obtained. When the CPU 77 takes in the light reception signal S4, it compares it with a threshold value and determines whether or not there is light shielding for the detection optical axis L2. In the example of FIG. 5, since the detection optical axis L2 passes through the side of the wafer 1 without being blocked by the wafer W1, a light receiving signal S4 having a high level is detected from the light receiving element 74, and the light receiving signal S4 The level is above the threshold. From the above, the CPU 77 determines that the detection optical axis L2 is not shielded, that is, the wafer W1 is in the normal accommodation state.

  Subsequently, as a result of further lowering of the sensor head 40, the detection optical axis L1 now reaches the detection position Y1 shown in FIG. Then, the synchronization detection signal Sa is output again from the control device 90 to the CPU 77. As a result, the CPU 77 performs a process of fetching the light reception signal S3 from the light receiving element 73.

  Thus, the light reception signal S3 when the detection optical axis L1 just passes the detection position Y1 is obtained. When the CPU 77 takes in the light reception signal S3, it compares it with a threshold value and determines the presence or absence of light shielding for the detection optical axis L1. In the example of FIG. 5, since the detection optical axis L1 is blocked by the wafer W1, the signal level of the light reception signal S3 becomes small and falls below the threshold value. From the above, it is determined by the CPU 77 that the detection optical axis L1 is shielded, that is, the wafer W1 is stored in the first stage of the cassette 10.

  Thus, for the first stage, the detection of the jumping out of the wafer W from the normal accommodation state and the detection of the presence or absence of the wafer W itself are completed.

  Thereafter, as the sensor head 40 is lowered, the detection optical axes L1 and L2 sequentially pass through the detection positions Y2 to Y5 corresponding to the wafers W at each stage. Then, when the detection optical axes L1 and L2 reach the detection positions Y, the synchronization detection signal Sa is output from the control device 90 to the CPU 77 in the manner described above.

  In response to this, the CPU 77 performs processing for taking in the light reception signal S4 from the light receiving element 74 in synchronization with the synchronization detection signal Sa, and the wafer from the normal accommodation state for the second stage based on the obtained light reception signal S4. W jump-out detection is performed. Subsequently, a process of taking in the light reception signal S3 from the light receiving element 73 in synchronization with the synchronization detection signal Sa input next is performed, and the presence or absence of the wafer W itself is detected based on the obtained light reception signal S3. Thereby, the detection of the second stage is completed.

  Thereafter, detection is performed in the same order as described above in the order of the third and fourth stages.

  As a result of the detection, if at least the jumping out of the wafer W is not detected for each stage, the sensor head 40 moves down while performing the detection operation without stopping the movement, and eventually the detection is completed for all the stages. Then, it reaches the bottom surface of the cassette 10 and stops (a series of detections are completed).

  At this time, the wafer W may not be accommodated in any of the stages, but at that time, a display to that effect is given to a display means (not shown) by a command from the CPU 77.

  On the other hand, if the wafer W jumps out at any stage, the lowering operation of the sensor head 40 is stopped there. In the example of FIG. 5, when passing through the fourth stage wafer W4, the detection optical axis L2 is blocked by the end of the wafer W4, and the level of the received light signal S4 that has exceeded the threshold until then reaches the threshold. Below. As a result, the jump out of the wafer W4 is detected by the CPU 77.

  When the protrusion of the wafer W is detected, the CPU 77 performs a process of outputting an error signal Sb to the control device 90 (corresponding to an error output of the present invention). Accordingly, the control device 90 that has received the error signal Sb outputs the motor control signal Sc to the lifting device 80, and the driving of the motor M is immediately stopped. As a result, the lowering operation of the slider 82 and thus the sensor head 40 is stopped on the spot.

  If the sensor head 40 is further lowered even though the jumping out of the wafer W4 is detected, as described above, a part of the sensor head 40 is formed at the end of the wafer W that has jumped out. This is because there is a possibility of damaging the wafer W due to interference (see part A in FIG. 4).

  According to the present embodiment, the two detection optical axes L1 and L2 are used to detect the presence / absence of the wafer W and the protrusion of the wafer W. However, these are the arrangement of the optical axes in the depth direction of the cassette 10. Although the optical axes are substantially horizontal, the extending directions of the axes coincide with each other.

  With such a configuration, if the light projecting head 41 and the light receiving head 51 are made long in the depth direction of the cassette 10, the sleeves 61 and 62 for the detection optical axes L1 and L2 are both on the light projecting side. The sleeves 63 and 64 for the detection optical axes L1 and L2 can be attached to the single light receiving head 51 on the light receiving side. That is, it is not necessary to provide a dedicated sensor head for each of the detection optical axes L1 and L2, and the sensor head 40 can be shared, so that the number of parts can be reduced and the apparatus can be easily downsized. Can be done.

  In this embodiment, a photoelectric sensor is used, and there are a so-called reflective type and a transmissive type. The reflective type emits light to the detection target and receives the light reflected by the detection target. In the present embodiment, light is emitted horizontally from the side with respect to the wafer W. Therefore, when a reflective photoelectric sensor is used, reflected light reflected by the outer peripheral surface of the wafer W is received. The outer peripheral surface of the wafer W is often rough, and irregular reflection generally occurs there.

For this reason, the light reflection direction is not determined, and the amount of received light is expected to be very small. That is, the level of the received light signal hardly changes between the state where the optical axis crosses the wafer W and the state where it does not cross the wafer W, and the detection accuracy cannot be increased.
In this regard, the transmissive type is used in this embodiment. In the case of the transmission type, when the optical axis does not cross the wafer, the emitted light is received as it is on the other side. If the wafer W is positioned in the detection area, the amount of light reaching the other side is greatly reduced as a result of the light being blocked there. In this way, in the case of the transmission type, the change in the level of the received light signal appears remarkably, so that the detection accuracy can be increased.

  Further, according to the present embodiment, the light projecting elements 71 and 72 and the light receiving elements 73 and 74 are built in the sensor amplifier 70 and are not installed on the sensor head 40 side. Such a configuration is a preferable configuration for further downsizing the head as compared with a configuration in which the photoelectric element is built in the sensor head 40. It can also be used without problems even in situations where there is a risk of fire.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIGS.
In the second embodiment, the light receiving element is shared with respect to the configuration of the first embodiment. That is, in the first embodiment, the light receiving elements 73 and 74 are provided exclusively for the respective detection optical axes L1 and L2, but in this embodiment, both the light receiving elements 73 and 74 are shared by the light receiving element 75. Yes. In this case, the light of both detection optical axes L1 and L2 enters the light receiving surface of the light receiving element 75 at the same time, and a signal of a level corresponding to the received light reception signal is output accordingly. .

  Therefore, also in this embodiment, similarly to the case of the first embodiment, the light reception signal is extracted in synchronization with the timing at which each of the detection optical axes L1 and L2 passes through each of the detection positions Y1 to Y4. That is, in accordance with the input timing of the synchronization detection signal Sa output from the control device 90, the CPU 77 performs a process of taking in the light reception signal Se output from the light receiving element 74.

  With this configuration, the light reception signal Se when the detection optical axis L1 passes through the detection positions Y1 to Y4 and the light reception signal Se when the detection optical axis L2 passes through the detection positions Y1 to Y4. Can be discriminated by the CPU 77.

Therefore, based on the light reception signal Se when the detection optical axis L1 passes through each of the detection positions Y1 to Y4, it is possible to know whether or not the detection optical axis L1 is shielded, and the detection optical axis L2 detects each of the detection positions Y1 to Y4. Based on the light reception signal Se when passing, it is possible to know whether or not the detection optical axis L2 is shielded.
Specifically, the light of the detection optical axes L1 and L2 enters the light receiving element 75. However, for example, taking the detection optical axis L2 as an example, when the detection optical axis L2 passes through each of the detection positions Y1 to Y4, the detection optical axis L1 has not yet reached the detection position, and is always transmitted. It becomes a state. Therefore, the level of the light receiving signal Se output from the common light receiving element 75 eventually changes according to the light shielding state of the detection optical axis L2, and based on this, the presence or absence of light shielding can be known.

  Note that, according to the above-described configuration, the “determination means (here, the CPU) of the present invention is configured so that the shared light-receiving element (here, the light-receiving element) is based on the timing signal (here, the synchronization detection signal). 75), the light reception signal when the first detection optical axis passes through the plate member and the light reception signal when the second detection optical axis passes through the plate member. Is discriminated. ”Is realized.

  As a modification of this embodiment, the light projecting elements 71 and 72 may be lit in a time division manner. That is, in the above description, during the detection, the light projection timing is not particularly controlled, and both the light projecting elements 71 and 72 are always lit. In contrast, if each of the light projecting elements 71 and 72 is turned on in a time-sharing manner in accordance with the timing at which each of the detection optical axes L1 and L2 passes through each of the detection positions Y1 to Y4, the light is received in synchronization with the light projection timing. By extracting the signal Se, it is possible to separately extract the light reception signals Se of the detection optical axes L1 and L2 from the common light receiving element 75.

<Embodiment 3>
Next, Embodiment 3 of the present invention will be described with reference to FIGS.
FIG. 9 is a block diagram showing an electrical / optical configuration of the wafer detection apparatus applied to the third embodiment. In this embodiment, a light branching section (corresponding to the light branching means of the present invention) 110 is provided in the sensor amplifier 70 so that the light emitted from the light projecting element 76 is branched. The configuration of the light branching unit 110 is as shown in FIG. 10, and includes a half mirror 111 disposed on the front side (left side in FIG. 10) of the light projecting direction of the light projecting element 76, and a reflection mirror 113. . The light emitted from the light projecting element 76 is branched by the half mirror 111.

  That is, part of the light passes through the half mirror 111 and travels toward the light projecting optical fiber F1. A part of the light is reflected downward by the half mirror 111 in the figure. A reflection mirror 113 is disposed on the front side in the reflection direction, and the light reflected by the half mirror 111 is reflected to the left in the figure by the reflection mirror 113 and travels toward the light projecting optical fiber F2.

  11 and 12 are a perspective view of the wafer detection apparatus applied to the third embodiment and a perspective view of the sensor head 120. FIG. In this embodiment as well, light is transmitted to the sensor head 120 by the projecting optical fibers F1 and F2, and two detection optical axes L1 and L2 are formed. Further, as shown in FIG. 4, both the detection optical axes L <b> 1 and L <b> 2 are displaced in the front-rear direction in the depth direction of the cassette 10, and this point is the same as the configuration of the first embodiment. It is.

  FIG. 13 shows the relationship between the two detection optical axes L1 and L2 in the height direction. In the third embodiment, both detection optical axes L1 and L2 are installed at the same height in the vertical direction. This point is different from the first embodiment. Accordingly, in the third embodiment, both detection optical axes L1 and L2 pass through the detection positions Y1 to Y5 at the same timing.

In FIG. 14, the accommodation state of the wafer W is divided into three states, and the detection optical axes L1 and L2 are either blocked or transmitted.
The first state is a state where the wafer W is not accommodated. At this time, when detection is performed, both detection optical axes L1 and L2 are in a transmission state.
The second state is a state where the wafer W is correctly accommodated. At this time, when detection is performed, the detection optical axis L1 is shielded from light, and the detection optical axis L2 is in a transmission state.
The third state is a state where the wafer W protrudes. At this time, when detection is performed, both the detection optical axes L1 and L2 are shielded from light.

  On the other hand, in this embodiment, as shown in FIG. 9, the light receiving element 75 is shared for both detection optical axes L 1 and L 2, and the detection light of both detection optical axes L 1 and L 2 is transmitted to the light receiving element 75. It is simultaneously incident. As a result, the level of the light receiving signal Sr output from the common light receiving element 75 is as shown in the lower part of FIG. That is, in the first state, since both the two optical axes L1 and L2 are transmitted, the level of the light receiving element Sr becomes very high (large). On the other hand, in the second state, since only the detection optical axis L1 is shielded, the level of the light receiving element Sr is slightly lowered (middle). In the third state, since both the two detection optical axes L1 and L2 are shielded from light, the level of the light reception signal Sr becomes very small (small).

  Considering the above points, in this embodiment, two reference values H and L are set. The first reference value H is used to discriminate between the first state and the second state. The magnitude of the first reference value H is the level of the received light signal Sr detected in the first state and the second state. It is set to an intermediate value of the level of the detected light reception signal Sr. The first reference value H corresponds to the first reference level of the present invention, and the second reference value L corresponds to the second reference level of the present invention.

  The second reference value L is used to discriminate between the second state and the third state. The magnitude of the second reference value L depends on the level of the light reception signal Sr detected in the second state and the third state. It is set to an intermediate value of the level of the light reception signal Sr detected in the state.

  With this configuration, the CPU 77 performs a process of comparing the level of the light receiving signal Sr output from the common light receiving element 75 with both reference values H and L, whereby the accommodation state of the wafer W can be determined. FIG. 15 shows an example of the transition of the light reception signal Sr output from the light receiving element 75.

  The transition of the light reception signal Sr shown in FIG. 15 corresponds to FIG. 13, and the time t1 in FIG. 15 corresponds to the passage of the detection position Y1 in FIG. Further, time t2 corresponds to the time of passage of detection position Y2 in FIG. 13, time t3 corresponds to the time of passage of detection position Y3 in FIG. 13, and time t4 corresponds to the time of passage of detection position Y4 in FIG. ing.

  As apparent from FIG. 15, at the time t1, the level of the light reception signal Sr is lower than the second reference value L, whereby both the detection optical axes L1 and L2 are shielded, that is, the wafer W is It can be determined that it is in a protruding state.

  On the other hand, at times t2 to t4, the level of the light reception signal Sr is between the first reference value H and the second reference value L. Thereby, it can be determined that one of the detection optical axes L1 and L2 is shielded, that is, the wafer W is in the normal accommodation state.

  As described above, in this embodiment, although two optical axes L1 and L2 are required as detection optical axes, this is realized by one detection element 75, 76 on both the light projecting side and the light receiving side. This configuration is suitable for reducing the cost of the apparatus. In addition, both optical axes of the detection optical axes L1 and L2 are arranged at the same height position so that the presence / absence of the wafer W and the jumping-out are simultaneously detected. Such a configuration is suitable for speeding up detection.

<Embodiment 4>
A fourth embodiment will be described with reference to FIG.
In the fourth embodiment, as in the third embodiment, the light of both detection optical axes L1 and L2 is received by one light receiving element 75. Thus, if the light receiving element 75 is used in common for both optical axes L1 and L2, the following signal is output from the common light receiving element 75 when the light projecting side is turned on simultaneously. That is, the signal component obtained by receiving the light of the detection optical axis L1 and the signal component received by the light of the detection optical axis L2 are mixed.

  In this regard, in the fourth embodiment, focusing on the wavelength of the light, the wavelength of the light of the detection optical axis L1 and the wavelength of the light of the detection optical axis L2 are differentiated in advance, so that the light is output from the common light receiving element 75. This signal is divided into a signal component after receiving the light of the detection optical axis L1 and a signal component receiving the light of the detection optical axis L2.

  Specifically, the signal processing circuit 140 is provided between the output stage of the light receiving element 75 and the input stage of the CPU 77 in order to decompose the signal component of the light receiving signal Sr output from the common light receiving element 75 for each predetermined wavelength. Is provided. The signal processing circuit 140 includes an amplifier 141 for signal amplification, a first filter 142, and a second filter 143.

  According to the applicant's knowledge, if the wavelength of the light is different in advance, the wavelength of the light reception signal that is received and output is also different. Therefore, if two types of filters 142 and 143 corresponding to the wavelengths of light forming the detection optical axes L1 and L2 are provided, only a signal having a desired wavelength can be extracted from the received light signal Sr.

  With such a configuration, even if the lights of both detection optical axes L1 and L2 are incident on the light receiving element 75 at the same time, the output light reception signal Sr is subsequently converted into the components of the detection optical axes L1 and L2. Can be divided into Accordingly, since the light shielding state of each of the detection optical axes L1 and L2 can be determined based on the level of the signal after passing through the filter, it is possible to detect the presence or absence of the wafer and the protrusion of the wafer.

In the present embodiment, the light projecting element is also shared on the light projecting side. In this case, it is necessary to make the wavelength of light different between the detection optical axis L1 and the detection optical axis L2, and this is realized by installing the optical filters 151 and 152.
The optical filters 151 and 152 have a function of allowing only light of a specific wavelength to pass. However, the filters 151 and 152 have different wavelengths to pass. As a result, the light emitted from the light projecting element 76 (light including various wavelengths) is branched by the light branching unit 110, and then becomes light having different wavelengths as it passes through the filters 151 and 152. . That is, the detection optical axis L1 and the detection optical axis L2 are configured by light having different wavelengths.

<Embodiment 5>
Next, Embodiment 5 of the present invention will be described with reference to FIGS.
In the first embodiment, light is emitted from one side of the sensor head 40 and received on the opposite side. More specifically, for example, in the case of the detection optical axis L1, light is emitted from the emission window 61A of the sleeve 61 installed in the light projecting head 41, and this is installed in the light receiving head 51 on the counterpart side. 64 is received by a light receiving window 64 </ b> A provided in 64.

  On the other hand, in the fifth embodiment, both the light projecting sleeve 171 and the light receiving sleeve 181 are installed on one side 170 of the pair of heads 170, 190. The configuration is such that the reflector 191 is installed at a position facing the detection light exit window 175. The reflector 191 has a corner cube structure in the reflecting surface 192, and performs a function of inverting the light emitted toward the reflecting surface 192 and returning it to the emitting side (so-called recursive reflection).

  With the above configuration, when the wafer W is not present in the detection region, the light emitted from the emission window 175 of the head 170 reaches the opposite head 190 without being interrupted, and is reflected there. Reflected by the body 191. Thereafter, the retroreflected light travels toward the head 170 and is received by the light receiving window 185 formed in the head 170. Thus, since the emitted light is received without loss, a light receiving signal having a high level is output from the light receiving element.

  On the other hand, if the wafer W is present in the detection region, the light emitted from the head 170 is blocked halfway and is irregularly reflected there. Therefore, the head 170 receives only a part of the irregularly reflected light, and the level of the received light signal is lowered.

  Even in the above-described configuration, as in the case of the transmission type of the first embodiment, when a wafer is present in the detection region, the light is blocked and the level of the received light signal is reduced. It is possible to detect the presence / absence of a wafer and pop-out by the same method as in FIG. Moreover, the following effects are acquired by setting it as such a structure. That is, if the reflector 191 is installed on the head 190 on one side, it is emitted even if there is a relative positional shift between the heads 170 and 190 by making the reflecting surface 192 large. Light can be reflected by the reflecting surface 192 to the emission side. After that, it is only necessary to receive the reflected light by the light receiving window 185. Therefore, a severe alignment operation between the heads 170 and 190 is not necessary.

  In this embodiment, lenses 172 and 182 are accommodated in sleeves 171 and 181, respectively. The lens 172 squeezes the light that has passed through the optical fiber F1 (reduces the light beam), and the lens 182 squeezes the light toward the optical fiber F2 (reduces the light beam). With such a configuration, light having a narrow light beam can be emitted as the detection light from the emission window 175, and the light traveling toward the optical fiber F4 through the light receiving window 185 can be effectively transmitted. Can lead in. The lens 172 corresponds to the diaphragm means of the present invention.

  The advantage of emitting light (detection light) having a narrow beam d is as follows. In this embodiment, the wafers W stacked one above the other are objects to be detected, and light is emitted from the side with respect to the wafers W as shown in FIG. Since the emitted detection light has a certain extent as shown in FIG. 18, if the light beam d is wide from the beginning, the spread of the light is increased accordingly.

  For this reason, the light may be reflected by the plate surfaces of the wafer W adjacent vertically, and this causes a detection error when entering the light receiving window 185. In this respect, in the present embodiment, the detection light is narrowed so that the d dimension shown in FIG. 18 is smaller than the Z dimension shown in FIG. The Z dimension shown in FIG. 18 is the distance between the wafers W positioned above and below the central wafer W to be detected, and the d dimension shown in FIG. The diameter of the light beam.

  With such a configuration, even if light is reflected by the plate surfaces of wafers W adjacent vertically, the reflected light does not form an image at the light receiving window 185, thereby suppressing the influence of the reflected light. I can do it. In FIG. 18, in order to make the effect easy to understand, the light emitting side sleeve 171 and the light receiving side sleeve 181 are shown facing each other, and the directions are also changed.

  In FIG. 17, only the structure related to the detection optical axis L1 is shown, and the structure related to the detection optical axis L2 is omitted. In addition, the transmission type detection format using regression reflection in the fifth embodiment can be applied to those in the second to fourth embodiments.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.

  (1) In all of the first to fifth embodiments, a so-called transmission type detection method is adopted in which the presence or absence of a wafer is determined by detecting the light shielding of the detection optical axis L. It is not limited to this, and a so-called reflective type may be used. Here, the reflection type means a type that detects the presence or absence of a wafer by receiving reflected light reflected by the wafer.

  (2) In the third embodiment, the configuration using the half mirror 111 and the reflection mirror 113 is described as the light branching section. However, the light branching section only needs to be able to branch the light emitted from the light projecting element 76 into two. For example, it may be branched by a bifurcated optical fiber.

The perspective view which shows the state which accommodated the wafer in the cassette in Embodiment 1. FIG. The perspective view which shows the whole structure of a wafer detection apparatus Perspective view of sensor head Diagram showing the positional relationship between both detection optical axes and the wafer The figure which shows the positional relationship of the up-down direction of both detection optical axes Block diagram showing electrical configuration of wafer detection apparatus The block diagram which shows the electric constitution of the wafer detection apparatus in Embodiment 2. The figure which shows the light projection timing of both light projection elements The block diagram which shows the electrical constitution of the wafer detection apparatus in Embodiment 3. Diagram showing the configuration of the optical branching unit The perspective view which shows the whole structure of a wafer detection apparatus Perspective view of sensor head The figure which shows the positional relationship regarding the up-down direction of both detection optical axes A diagram that summarizes the shading and transmission on both detection optical axes. The figure which shows transition of received light signal Sr FIG. 9 is a block diagram showing an electrical configuration of a wafer detection apparatus in the fourth embodiment. FIG. 9 is a diagram illustrating a configuration of a sensor head in the fifth embodiment. A diagram showing a phenomenon in which a part of detection light is reflected by the plate surface of an adjacent wafer

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Wafer detection apparatus 30 ... Sensor head 40 ... Light projection head 50 ... Light reception head 70 ... Sensor amplifier 80 ... Lifting device 90 ... Control apparatus F1-F4 ... Optical fiber L1 ... Detection optical axis L2 ... Detection optical axis

Claims (16)

It is a detection sensor whose detection target is a plate-like member that is accommodated with a gap opened in a container that opens as an outlet on one side,
A light emitting portion that is lateral to the plate-like member and is capable of emitting detection light in a direction substantially perpendicular to the overlapping direction of the plate-like member, and light that forms a detection optical axis in a pair with the light emitting portion A sensor head having a light detection means comprising: a receiving portion;
A sensor amplifier connected to the sensor head and provided with a determination means for determining the plate-like member based on the amount of light received by the light receiving portion of the sensor head, and the sensor head in the vicinity of the outlet And detecting while moving in the overlapping direction of the plate-like member,
In the sensor head, as the light detection means,
Two light detection means, a first light detection means for forming a first detection optical axis and a second light detection means for forming a second detection optical axis, are provided,
The first detection optical axis of the first light detection means is set so as to cross the plate-like member from the end surface direction when the plate-like member is housed in the container. Whereas
The second detection optical axis of the second light detection means does not cross the plate-like member when the plate-like member is in the accommodated state, and is in a protruding state in which the plate-like member has jumped to the outlet side. In addition, it is set to cross the same plate-shaped member from its end face direction,
The determination means of the sensor amplifier is based on a level of a light reception signal obtained by receiving the detection light of the first detection optical axis and a level of a light reception signal obtained by receiving the detection light of the second detection optical axis. And detecting the presence or absence of each of the plate-like members and popping-out. The sensor head is composed of a pair of detection heads arranged opposite to both sides of the plate member in the end face direction of the plate member,
Among the detection heads, a light emitting part is set on one detection head,
The light receiving unit is installed on the detection head on the other side, which is the counterpart,
2. The detection sensor according to claim 1, wherein each of the detection optical axes is formed by receiving light emitted from the light emitting unit at the light receiving unit. The sensor head is composed of a pair of detection heads arranged opposite to both sides of the plate member in the end face direction of the plate member,
Among the detection heads, the light emitting unit and the light receiving unit are installed together on one side of the detection head,
A reflector is installed on the detection head on the other side, which is the counterpart,
2. The detection according to claim 1, wherein each of the detection optical axes is formed by reflecting the light emitted from the light emitting part to the emitting side by the reflector and receiving the light by the light receiving part. Sensor. When the opposing distance between the plate-like members accommodated in a stack with a gap is defined as D,
Inside the detection head is provided with a diaphragm means for reducing the detection light emitted from the detection head,
When the detection light reaches the vicinity of the center of the plate-like member by the diaphragm means, the light beam d is at least narrower than the facing interval Z between the plate-like members adjacent to the plate-like member to be detected. The detection sensor according to claim 2, wherein the detection sensor is squeezed and emitted in the detection head. The sensor amplifier includes a light projecting element for projecting detection light and a light receiving element for receiving the detection light.
The detection head on the light projecting side is provided with an emission window serving as the light emitting unit, while the detection head on the light receiving side is provided with a light receiving window serving as the light receiving unit,
Between the sensor amplifier and the detection head on the light projecting side is connected by a light projecting optical fiber,
Between the sensor amplifier and the detection head on the light receiving side is connected by a light receiving optical fiber,
After the light projected by the light projecting element in the sensor amplifier is transmitted through the projecting optical fiber, it is emitted from the exit window of the detection head on the projecting side,
The emitted detection light is guided to the light receiving optical fiber through the light receiving window provided in the detection head on the light receiving side, transmitted through the optical fiber, and then received by the light receiving element. The detection sensor according to any one of claims 2 to 4. The second detection optical axis is on the front side in the movement direction of the sensor head with respect to the first detection optical axis, and the second detection optical axis is earlier than the first detection optical axis. The detection sensor according to claim 1, wherein the detection sensor passes through the plate-like member. The tip of the detection head that is arranged toward the plate-like member has a step corresponding to the second detection optical axis cut out in a step shape, and the cut-out portion is escaped from the plate-like member. The detection sensor according to claim 6, wherein: The sensor amplifier is provided with a signal input unit for inputting a timing signal from the outside according to the movement of the sensor head,
On the light receiving side, the light receiving element for the first detection optical axis and the light receiving element for the second detection optical axis are shared by a single light receiving element,
Based on the timing signal, the determination means captures a light reception signal of the shared light receiving element,
A light reception signal when the first detection optical axis passes through the plate member;
8. The detection sensor according to claim 6, wherein the detection sensor determines a received light signal when the second detection optical axis passes through the plate-like member. 9. The first detection optical axis and the second detection optical axis are at the same height in the movement direction of the sensor head, and when the sensor head is moved, both detection optical axes are the plate-like members. And pass through almost simultaneously,
The light receiving elements for both detection optical axes are shared by a single light receiving element,
The sensor amplifier has a first reference level corresponding to a state in which both of the detection optical axes are not shielded with respect to a light reception signal output from a single shared light receiving element, and both of the detection optical axes. A second reference level corresponding to a state in which both are shielded from light is preset,
The determination means detects the presence / absence of each plate-like member and the protrusion by performing a process of comparing the first and second reference levels set in advance with the signal level of the light reception signal. The detection sensor according to claim 1, wherein: 10. The detection sensor according to claim 8, further comprising a light branching unit that branches the detection light emitted from one light projecting element as two detection lights. Between the detection head on the light projecting side and the sensor amplifier, two light projecting optical fibers are provided corresponding to the two detection optical axes,
11. The sensor amplifier is provided with the light branching unit, and two detection lights branched by the light branching unit are guided to the light projecting optical fibers, respectively. The detection sensor described in 1. A detection sensor according to any one of claims 1 to 11,
A moving means for moving a sensor head constituting the detection sensor in the overlapping direction of the plate-like members in the vicinity of the outlet;
Control means for controlling movement of the sensor head by the moving means. The determination means of the sensor amplifier is configured to take in the received light signal every time the sensor head passes through a position corresponding to one plate-like member, and to determine the accommodation status of the plate-like member as needed, and 13. The detection device according to claim 12, wherein when the jump-out of the plate-like member is detected by the same determination, an error is output to the control means to stop the movement of the sensor head. 8. The detection sensor according to claim 7, a moving means for moving the sensor head constituting the detection sensor in the stacking direction of the plate-like member in the vicinity of the outlet, and movement of the sensor head by the moving means is controlled. Control means,
The determination means of the sensor amplifier is configured to take in the received light signal every time the sensor head passes through a position corresponding to one plate-like member, and to determine the accommodation status of the plate-like member as needed, and An error output is output to the control means to stop the movement of the sensor head when a jump-out of a plate-like member is detected by the same determination. A sensor head that is supported by a plate-like member that is accommodated in a container having one surface opened as an outlet with a gap therebetween and is movable in the stacking direction of the plate-like member in the vicinity of the outlet. Because
A first light emitting portion that is on the side of the plate-like member and can emit detection light in a direction substantially perpendicular to the overlapping direction of the plate-like member and the first light emitting portion are paired with each other. A first light receiving portion that forms a detection optical axis of the first light detection means,
A second light receiving unit that forms a second detection optical axis by forming a pair with the second light emitting unit capable of emitting detection light in a direction substantially perpendicular to the overlapping direction of the plate-like members. And a second light detection means comprising:
The first detection optical axis of the first light detection means is set so as to cross the plate-like member from the end surface direction when the plate-like member is housed in the container. Whereas
The second detection optical axis of the second light detection means does not cross the plate-like member when the plate-like member is in the accommodated state, and is in a protruding state in which the plate-like member has jumped to the outlet side. In addition, it is set to cross the same plate-shaped member from its end face direction,
Further, the second detection optical axis is on the front side in the movement direction of the sensor head with respect to the first detection optical axis, and the second detection optical axis is more than the first detection optical axis. A sensor head characterized by passing through the plate-like member at an early timing. The tip of the detection head that is arranged toward the plate-like member has a step corresponding to the second detection optical axis cut out in a step shape, and the cut-out portion is escaped from the plate-like member. The sensor head according to claim 15, wherein:

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