JPH0518072B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention forms an optical image of an object to be detected at an end face by dividing the light-receiving surface into four areas by two dividing lines substantially orthogonal to each other, and forming four light-receiving parts. An image is formed on the light-receiving surface of the formed light-receiving element, an edge detection signal is generated by adding and subtracting each output from each light-receiving part, and the edge surface of the object to be detected is detected based on the edge detection signal. This invention relates to an improvement of an end face detection device. (Prior Art) Conventionally, as shown in FIG. 1, an end face detection device has been equipped with a method in which an object 3 to be detected for an end face is moved so as to cross a parallel beam optical path 2 of an optical system 1 for end face detection. A device is known in which an optical image is formed on the light-receiving surface 6 of the light-receiving element 5 (Japanese Unexamined Patent Application Publication No. 1986-
(See Publication No. 173408). The light receiving surface 6 of this light receiving element 5
is defined into four areas by two dividing lines 7 and 8 that are substantially perpendicular to each other as shown in
Light receiving sections 9, 10, 11, and 12 are formed. Each of the light receiving sections 9, 10, 11, 12 is connected to an edge detection signal generation circuit 13, and the edge detection signal generation circuit 13 is connected to each of the light receiving sections 9, 10, 1.
Subtractors 14, 15, 16 each output from 1, 12
By performing addition/subtraction calculations, end face detection signals as shown in FIG. 3 (a) and (b) are generated. In addition, in FIG. 1, 17 and 18 are illumination light sources;
9 and 20 are condensing lenses, 21 is a half mirror, 2
2 is an imaging lens. (Problems to be Solved by the Invention) By the way, in this conventional end face detection device, the second
As shown in the figure, the optical image 23 corresponds to arrows A ₁ , B ₁ , C ₁ ,
When the light approaches the light receiving surface 6 from the _D1 direction, the output of the end face detection signal becomes small, and the light receiving element 5 has a problem that there is a dead zone in which the end face cannot be detected. For example, when the optical image 23 advances toward the light receiving surface 6 from the direction of arrow _A1 , the light receiving portions 9 and 11 are first blocked by approximately the same area, and then the light receiving portion 1
0 and 12 are shielded from light by approximately the same area. Therefore, if the outputs of the light receiving sections 9 to 12 are P, Q, R, and X,
The outputs P and R of the light receiving sections 9 and 11 decrease approximately equally,
Next, the outputs Q and X of the light receiving sections 10 and 12 decrease equally. The outputs P and Q are input to a subtracter 14, and the subtracter 14 outputs the difference P-Q, and the outputs R and X are input to the subtracter 15, and the subtracter 15 outputs the difference R-X. is output, the outputs P-Q and R-X are input to the subtracter 16, and the subtracter 16 outputs (P-Q)-(R-X), but the outputs P, If R is substantially the same and the outputs Q and X are substantially the same, the amplitude of the end face detection signal output from the subtracter 16 will be small, resulting in a problem that it is virtually impossible to obtain the end face detection signal. This is also the case when the optical image 23 advances to the light receiving surface 6 from the directions of arrows B ₁ , C ₁ , and D ₁ . There is a dead zone in which end face detection cannot be performed depending on the approach angle of the object 3. Therefore, as shown in FIG. 4, an end face detection device is known in which the end face 3a of the end face detection object 3 is detected by a sensor 29 having five light receiving elements 24 to 28. (See Publication No. 30866). A sensor using this sensor 29 has the advantage of not having a dead zone compared to the above-mentioned sensor, but has the following disadvantages compared to the above-mentioned sensor. The light-receiving performance of a light-receiving element is proportional to its light-receiving area, so when making a comparison, the light-receiving area Y of each of the light-receiving elements 24 to 28 of the sensor 29 and the light-receiving area Z of the light-receiving parts 9 to 12 of the light-receiving element 5 are Suppose that they are equal. At that time, if the diameter of the light receiving element 5 is Φ (see FIG. 5) and the diameter of each of the light receiving elements 24 to 28 of the sensor 29 is φ, the total area S of the light receiving element 5 is S=πΦ ² /4, each The area Z of the light receiving sections 9 to 12 is Z=πΦ ² /16, and the area Y of each light receiving element 24 to 28 is Y=πφ ² /
It is 4. In the case of the sensor 29, if the outer edges of the light-receiving elements 24 to 28 are not geometrically arranged so as to be in contact with each tangent line as shown in FIG. 4, the accuracy of end face detection will deteriorate. Assuming that, the center-to-center distance l ₁ from the center O ₁ of the central light-receiving element 24 to the center O ₂ of the light-receiving elements disposed beside it is l ₁ =√2φ by geometric calculation. So, from center O ₁ to center line
The distance l between m ₁ and tangent m ₂ to the intersection O ₃ is: l=√2φ+φ/2. Therefore, the maximum spacing 2l between the light receiving elements arranged on both sides of the central light receiving element 24 is 2l=2√2φ+φ. Since φ=φ/2, approximately 2l=1.96φ, and the detection width m ₃ of the end face detection object 3 is m ₃ =φ as shown in FIG. 5, at least in the case of the light receiving element 5.
This is approximately twice as large as that of . In addition, the minimum detection length m (see Fig. 5) of the end face detection target object 3 is:
In the case of the light receiving element 5, m = 0.5Φ, which is the resolution, but in the case of the sensor 29, m
= l = 0.96Φ, and as shown in Fig. 6, the length and width of the whole are approximately 4 in the case of sensor 29.
The end face detection target 3 is twice as large and smaller than that.
The accuracy of end face detection will deteriorate. (Object of the Invention) Therefore, an object of the present invention is to provide an end face detection device that can accurately detect an end face using a four-segment light receiving element even if it has a dead zone. (Means for Solving the Problems) The configuration of the present invention is such that the light receiving surface that receives the optical image of the end face detection target is divided into four regions by two dividing lines that are substantially perpendicular to each other. a first light-receiving element having a light-receiving portion formed in each region; and a first light-receiving element having a first optical axis passing through the intersection of the dividing lines and forming an optical image of the end face detection target on the light-receiving surface of the first light-receiving element. 1 optical system; and a first edge detection signal generation circuit that receives outputs from each light receiving section of the first light receiving element and generates an edge detection signal by adding and subtracting each output. In this step, a light-receiving surface that receives the optical image of the end face detection object is divided into four regions by two dividing lines substantially perpendicular to each other, and each region is divided into four regions by a light-receiving portion of the first light-receiving element. A second light-receiving section formed with a corresponding one, respectively.
A light receiving element is provided, and each light receiving part of the second light receiving element is optically rotated by a predetermined angle about the intersection of the dividing line of the first light receiving element with respect to each light receiving part of the corresponding first light receiving element. a second optical axis passing through the intersection of the dividing lines of the second light receiving element and having a part of the first optical axis in common; a second optical system that forms an optical image; and a second end face detection signal generation circuit that receives outputs from each light receiving portion of the second light receiving element and performs addition/subtraction operations on each output to generate an end face detection signal. , determining whether either the first end face detection signal generation circuit or the second end face detection signal generation circuit is in a state in which it is unable to generate a detection signal, based on the output of each light receiving portion of the first and second light receiving elements; and a discrimination circuit for outputting an edge detection signal from one of the first edge detection signal generation circuit and the second edge detection signal generation circuit which is in a state capable of generating an edge detection signal based on the discrimination result. It is in. (Function) According to this, when either one of the first and second light receiving elements is in the dead zone area with respect to the optical image, the other one of the first and second light receiving elements is not in the dead zone area. Even when a split type light receiving element is used, end face detection can be performed accurately. (Example) Examples of the end face detection device according to the present invention will be described below with reference to the drawings. FIG. 7 shows an optical system 30 of the end face detection device according to the present invention.
32 is an illumination light source, 33 and 34 are condensing lenses, and 35
3 is an imaging lens, 36 is a half mirror, and 37 is a beam splitter.
7 is a pair of light receiving elements 39 (first light receiving element) and 40 (second light receiving element) for transmitting an optical image of the end face detection target 38.
It has the function of distributing and forming images. The illumination light source 32 and the half mirror 36
This is provided when the surface of the reticle 8 is slightly illuminated to make it easier to see the overlapping state with the black reticle line using a finder (not shown). It is not necessarily necessary. This pair of light receiving elements 39, 40 is the eighth
As shown in FIG.
is defined into four areas, and each light receiving element 39, 40
Four light receiving sections 45 to 48 and 49 to 52 are formed in each region. The pair of light receiving elements 39 to 40 are arranged such that the relative positional relationship with respect to the optical image 53 of the end face detection object 38 is rotated by 45 degrees about the intersection 54 of the dividing line.
This angle does not necessarily have to be 45 degrees. Here, the optical system 30 has an optical axis (first optical axis) l ₂ passing through the intersection 54 of the dividing line of the light receiving element 39, and displays an optical image of the end face detection target 38 on the light receiving surface 43 of the light receiving element 39. An optical axis (second optical axis) passing through the intersection 54 of the first optical system that forms 53 and the dividing line of the light receiving element 40
l ₃ and forms an optical image 53 of the end face detection object 38 on the light receiving surface 44 of the light receiving element 40. That is, a part of the optical axis of the first optical system is common to the optical axis of the second optical system. As shown in FIGS. 8 and 9, the light receiving section 45 is connected to a subtracter 55 and a subtracter 57, and the output is A. The light receiving section 46 includes a subtracter 55 and a subtracter 5.
8, and its output is designated as B. Light receiving part 4
7 is connected to a subtracter 56 and a subtracter 57, and its output is designated as C. The light receiving section 48 is connected to a subtracter 56 and a subtracter 58, and its output is designated as D.
The subtracter 55 has a function of outputting an output A-B, the subtracter 56 outputs an output CD, the subtracter 57 outputs an output A-C, and the subtracter 58 has a function of outputting an output B-D. . The output A-B of the subtracter 55 is
9 and an adder 60. The output CD of the subtracter 56 is input to a subtracter 59 and an adder 60, and the outputs A-C and BD of the subtracters 57 and 58 are input to an adder 61. The subtracter 59 calculates the difference (A-B)-(C-
It has a function of outputting D) to a determination circuit 62 and a later-described pointer control circuit, and its output is denoted by α. The determination circuit 62, together with the subtractor 59, roughly constitutes a first end face signal generation circuit 63 which receives the outputs of the light receiving sections 45 to 48 of the light receiving element 39, adds and subtracts the respective outputs, and generates an end face detection signal. . The adder 60 calculates the sum (A-
B)+(C-D) to the determination circuit 64, and the adder 61 outputs the output A-C and the output B.
The circuit 65 determines the sum (A-C) + (B-D) with -C.
It has the function of outputting to the destination. Note that the functions of the determination circuits 62, 64, and 65 will be described later. The outputs of the determination circuits 64 and 65 are input to an AND circuit 66, and the output of the AND circuit 66 is input to an AND circuit 67 and an inverter circuit 68, as well as to a pointer control circuit. do. Adder 60, adder 61, determination circuits 64, 6
5. The AND circuits 66 and 67 have a function of inhibiting the output of the first edge detection signal generation circuit 63 when the edge cannot be detected, and cooperate with the inverter circuit 68 to generate a second edge detection signal, which will be described later. It has the function of outputting an edge detection signal from the circuit. The light receiving section 49 is connected to a subtracter 70 and a subtracter 72, and its output is designated as A. The light receiving section 50 is connected to a subtracter 69 and a subtracter 72, and the output thereof is designated as B. The light receiving section 51 is connected to a subtracter 70 and a subtracter 71, and the output thereof is designated as C. The light receiving section 52 is connected to a subtracter 69 and a subtracter 71, and the output thereof is designated as D. The subtracter 72 has a function of outputting an output A-B, the subtracter 71 outputs an output CD, the subtracter 70 outputs an output A-C, and the subtracter 69 has a function of outputting an output B-D. . The output A-B of the subtracter 72 is input to a subtracter 73 and an adder 74. The output CD of the subtracter 71 is output from the subtracter 73 and the adder 7.
4, and the output A- of the subtracters 70 and 69
C and output B-D are input to an adder 75.
The subtracter 73 has a function of outputting the difference (A-B)-(CD) between the output A-B and the output CD to the determination circuit 76 and a pointer control circuit to be described later.
Let the output be β. The determination circuit 76 includes a subtracter 7
3 as well as the outputs of the light receiving sections 49 to 52 of the light receiving element 40 are input, and the second end face signal generating circuit 77 is configured to add and subtract the respective outputs and generate an end face detection signal. The adder 74 has an output A-B and an output C-
The adder 75 has a function of outputting the sum (A-B)+(C-D) of the output A-C and the output B-D to the determination circuit 78. +(B-D)
It has a function of outputting to the determination circuit 79. The outputs of the determination circuits 78 and 79 are sent to the AND circuit 8.
0, and the output of the AND circuit 80 is input to the AND circuit 81 together with the output of the inverter circuit 68. The output of the AND circuit 81 is
6 is input to the AND circuit 82, and outputs an output δ to the pointer control circuit.
The adders 74 and 75, the determination circuits 78 and 79, and the AND circuits 80 and 81 are the second end face detection signal generation circuit 77.
It has a function of inhibiting the output together with the AND circuit 82 when the end face cannot be detected. The optical image 53 is arranged as shown in FIG.
A If the light-receiving elements 39 and 40 are traveling from _one direction, each light-receiving part 45 of the light-receiving element 39
The waveforms of the outputs A to D of ~48 are as shown in FIG.
The waveforms of outputs A to D of 52 are as shown in FIG. First, in the light receiving element 39, the edge 5 of the optical image 53
3a approaches the light receiving parts 45 and 47, and the light receiving part 4
The outputs A and C of 5 and 47 begin to decrease [time t ₁ ].
The way the outputs A and C decrease is determined by the light receiving portions 45 and 4.
7 are symmetrically shielded, they are almost the same, but if the attitude of the optical image 53 with respect to the light receiving element 39 is somewhat tilted, either of these outputs A or C will begin to decrease first. Become. Next, when the edge 53a touches the intersection 54, the light receiving parts 45, 47
The outputs A and C become zero (time t ₂ ). After that, the edge 53a approaches the light receiving sections 46, 48, so the outputs B, D of the light receiving sections 46, 48 begin to decrease, and the light receiving sections 46, 48 are completely covered by the optical image 53. and its outputs B and D become zero (time t ₃ ). The manner in which the outputs B and D of the light receiving sections 46 and 48 are reduced is also approximately the same since the light receiving sections 46 and 48 are symmetrically shielded from light. On the other hand, in the light receiving element 40, the edge 53a of the optical image 53 first hits the light receiving section 51, and the output C of the light receiving section 51 begins to decrease (time _t1 ). after that,
After a while, the light receiving sections 49 and 52 begin to be blocked by the optical image 43. Therefore, after the output C of the light receiving section 51 begins to decrease and before the output C becomes zero, the outputs A and D of the light receiving sections 49 and 52 begin to decrease. When the edge 53a of the optical image 53 reaches the intersection 54, the output C of the light receiving section 51 becomes zero (time _t2 ).
At this time, approximately half of the light receiving sections 49 and 52 are blocked, so the outputs A and D thereof become approximately half of the initial values. Thereafter, the light receiving section 50 begins to be shielded and its output B begins to decrease, and before its output B reaches zero, the light receiving sections 49 and 52 are completely shielded and their outputs A and D become zero (at time t ₃ ). In addition,
Since the light receiving sections 49 and 52 are symmetrically shielded from light, their outputs A and D are reduced in approximately the same manner. The outputs of the subtractors 55-58 are as shown in FIG. 11, and the outputs of the subtracters 69-72 are as shown in FIG.
The result will be as shown in the figure. That is, in the light-receiving element 39, the outputs A and C decrease approximately equally, and the outputs B and D decrease approximately equally; therefore, the subtracters 57 and 5
The output of subtractor 8 becomes approximately zero, and the outputs AB and CD of subtracters 55 and 56 have approximately the same waveform with constant amplitude. Therefore, the output (A-B)- of the subtracter 59 that subtracts and outputs the outputs A-B and CD is
The waveform (CD) becomes approximately zero as shown in FIG. Further, the waveform of the output (A-C)+(B-D) of the adder 61 which adds and outputs the outputs A-C and BD also becomes approximately zero. On the other hand, the output (A-B) + (C-D) of the adder 60 which adds and outputs the output A-B and the output CD
It becomes a negative waveform with an amplitude approximately twice that of . The determination circuits 64 and 65 determine whether the outputs of the adders 60 and 61 exceed the reference amplitude value _K1 , and become H if they exceed the reference amplitude value _K1 . Since the output of the adder 60 exceeds the reference amplitude value _K1 , the output M of the determination circuit 64 becomes H as shown in FIG. does not exceed the reference amplitude value _K1 , so it becomes L. The output F of the determination circuit 62 becomes H when the amplitude of the output of the subtracter 59 is less than or equal to the reference amplitude value _K2 .
Here, since the output of the subtracter 59 is near zero, the output maintains H. AND circuit 66
Since the output of the determination circuit 64 is H and the output of the determination circuit 65 is L, the output becomes L. Therefore, the output of the AND circuit 67 becomes L, and the end face detection signal is not output from the end face detection signal generation circuit 63, and output is prohibited. Note that the magnitudes of the reference amplitude value K ₁ and the reference amplitude value K ₂ can be adjusted. The waveforms of the outputs of the subtracters 69-72 are as shown in FIG. That is, the output of the subtracter 69 becomes the output D before the output B starts to decrease.
As shown in Figure 15, the time decreases rapidly.
The waveform has a positive amplitude on the _t3 side, and the subtracter 70
Since the output C becomes zero when the output A decreases by about half, the output of the subtracter 71 becomes a symmetrical positive waveform with time _t2 as the boundary, and the output of the subtracter 71 becomes the same as that of the subtracter 70. It becomes a negative waveform that is symmetrical to the output waveform. Since the output A of the subtracter 72 decreases to approximately half of its initial value before the output B begins to decrease, the output of the subtracter 72 becomes a waveform having a negative amplitude at time _t3 .
This is symmetrical to the output of the subtractor 69. Because it is,
Output (A-C) + (B-) output from adder 74
D) becomes a positive waveform exceeding the reference amplitude value _K1 as shown in FIG. 16, and the output (A-B)+(C-D) output from the adder 75 becomes becomes a negative waveform exceeding the reference amplitude value K ₁ ,
Output (A-B)-(C-) output from the subtracter 73
D) becomes a pseudo sine wave having a portion exceeding the reference amplitude value K ₂ as shown in FIG. Judgment circuit 7
The outputs M and N of the circuits 8 and 79 become H as shown in FIG. 17, and the output F of the determination circuit 76 becomes
Along with this, the signal changes from H to L, becomes H near time _t2 , becomes L again, and then becomes H. The AND circuit 80 becomes H when the determination circuits 78 and 79 are H, and the AND circuit 81 outputs the inverter circuit 68.
Since the output H is input through the circuit, the second end face detection signal generation circuit 77 outputs the end face detection signal ε near time _t2 . This end face detection signal ε is input to the pointer control circuit. The optical image 53 is shown as an arrow in a posture as shown in FIG.
A If the light-receiving elements 39 and 40 are traveling from _one direction, each light-receiving part 45 of the light-receiving element 39
The waveforms of outputs A to D of ~48 are as shown in FIG.
The waveforms of outputs A to D of 52 are as shown in FIG. First, in the light receiving element 40, the edge 5 of the optical image 53
3a approaches the light receiving parts 49 and 51, and the light receiving part 4
The outputs A and C of 9 and 51 begin to decrease (time t ₁ ).
The manner in which the outputs A and C decrease is determined by
1 is symmetrically shielded, they are almost the same, but if the attitude of the optical image 53 with respect to the light receiving element 40 is somewhat tilted, either of these outputs A or C will begin to decrease first. Become. Next, when the edge 53a touches the intersection 54, the light receiving parts 49, 51
The outputs A and C become zero (time t ₂ ). After that, the edge 53a approaches the light receiving sections 50, 52, so the outputs B, D of the light receiving sections 50, 52 begin to decrease, and the light receiving sections 50, 52 are completely covered by the optical image 53. and its outputs B and D become zero (time t ₃ ). The manner in which the outputs B and D of the light receiving sections 50 and 52 are reduced is also approximately the same since the light receiving sections 50 and 52 are symmetrically shielded from light. On the other hand, in the light receiving element 39, the edge 53a of the optical image 53 first hits the light receiving section 45, and the output A of the light receiving section 45 begins to decrease (time _t1 ). after that,
After a while, the light receiving sections 46 and 47 begin to be shielded from light by the optical image 53. Therefore, after the output A of the light receiving section 45 begins to decrease and before the output A becomes zero, the outputs B and C of the light receiving sections 46 and 47 begin to decrease. When the edge 53a of the optical image 53 reaches the intersection 54, the output A of the light receiving section 45 becomes zero (time _t2 ).
At that time, approximately half of the light receiving sections 46 and 47 will be blocked, so the outputs B and C will be approximately half of the initial values. Thereafter, the light receiving section 48 begins to be shielded and its output D begins to decrease, and before the output D becomes zero, the light receiving sections 46 and 47 are completely shielded and their outputs B and C become zero (at time t ₃ ). In addition,
Since the light receiving sections 46 and 47 are symmetrically shielded from light, the manner in which their outputs B and C are reduced is also approximately the same. The outputs of the subtractors 55 to 58 are as shown in FIG. 19, and the outputs of the subtractors 69 to 72 are as shown in FIG.
The result will be as shown in the figure. That is, in the light-receiving element 40, the outputs A and C decrease to approximately the same amount, and the outputs B and D decrease to approximately the same amount, so the subtracters 69 and 7
The outputs A-C and B-D of 0 are approximately zero, and the subtracter 7
The outputs A-B and CD of Nos. 1 and 72 have substantially the same negative waveforms with constant amplitude. Therefore, the subtracter 73 subtracts and outputs the outputs A-B and C-D.
The waveform of the output (A-B)-(C-D) becomes approximately zero as shown in FIG. Also, outputs A-C, B
-D is added and output from the adder 75 (A-
The waveform of C)+(B−D) also becomes approximately zero. On the other hand, the output (A-B) + (C-D) of the adder 74 which adds and outputs the output A-B and the output CD is approximately 2 of the outputs A-B and CD. A negative waveform with twice the amplitude will be output. The determination circuits 78 and 79 determine whether the outputs of the adders 74 and 75 exceed the reference amplitude value _K1 , and become H if they exceed the reference amplitude value _K1 . Since the output of the adder 74 exceeds the reference amplitude value _K1 , the output M of the determination circuit 78 is
As shown in FIG. 25, it becomes H, but the determination circuit 79
The output of the adder 75 is L because the output of the adder 75 does not exceed the reference amplitude value _K1 . The output of the determination circuit 76 becomes H when the amplitude of the output of the subtracter 73 is less than or equal to the reference amplitude value _K2 .
Here, since the output of the subtracter 73 is near zero, its output F maintains H. AND circuit 80
Since the output of the determination circuit 78 is H and the output of the determination circuit 79 is L, the output becomes L. Therefore, the output of the AND circuit 81 becomes L, the output of the AND circuit 82 becomes L, and the end face detection signal is not output from the end face detection signal generation circuit 77, so that output is prohibited. The waveforms of the outputs of the subtracters 55 to 58 are as shown in FIG. That is, the output of the subtracter 55 becomes a waveform having a negative amplitude on the time _t3 side as shown in FIG. 19 because the output A becomes zero when the output B decreases by approximately half. Since the output D starts to decrease when the output C decreases by about half, the output of the subtracter 56 becomes a waveform with a negative amplitude on the time _t1 side, and the output of the subtracter 57 becomes the same as that of the subtracter 55. It becomes a negative waveform that is almost the same as the output. The output of the subtracter 58 has a negative waveform that is substantially the same as the output of the subtractor 56, since the output D starts to decrease when the output B starts to decrease by about half. Therefore, the output output from the adder 61 (A-C) + (B-
D) becomes a negative waveform exceeding the reference amplitude value K ₁ as shown in FIG. becomes a negative waveform exceeding the reference amplitude value K ₁ ,
Output (A-B)-(C-) output from the subtracter 59
D) becomes a pseudo sine wave having a portion exceeding the reference amplitude value K ₂ as shown in FIG. Judgment circuit 6
The outputs M and N of the circuits 4 and 65 become H as shown in FIG. 21, and the output F of the determination circuit 62 is
Along with this, the signal changes from H to L, becomes H near time _t2 , becomes L again, and then becomes H. The AND circuit 66 becomes H when the determination circuits 64 and 65 are H, and the output H of the AND circuit 66 is inverted and inputted via the inverter circuit 68, so the output of the AND circuit 81 is prohibited, and the AND circuit Since the output H of the AND circuit 66 is input to 67, the AND circuit 67 inputs the H output near time _t2 .
, and the first end face detection signal generation circuit 63 outputs an end face detection signal ε. Note that the four-division shape of the light receiving elements 39 and 40 is not limited to a four-circle shape, but also a square shape divided into small squares as shown in FIG. 26, and a square shape divided into small squares as shown in FIG. The light-receiving elements 39 and 40 may be divided into four isosceles triangles, or any other shape having an arbitrary outer shape may be divided into four equal parts. Moreover, this end face detection device is shown in FIGS. 28 to 30.
As shown in the figure, a projection device 83, a tool microscope 84,
It can be applied to the belt conveyor type conveyance device 85 and other arbitrary devices. Next, regarding the pointer control circuit, see Figures 31 to 35.
This will be explained with reference to the figures. In this FIG. 31, 86 is a pointer control circuit. This pointer control circuit 86 includes a meter 87,
Red indicator light 89, green indicator light 88, and relay 9
0, 91, 93, and an OR circuit 92. The red indicator light 89 and the green indicator light 88 are connected to the pointer 8.
The reason why it is provided at a location other than 7a is as follows. When the pointer control circuit 86 detects the end face 38a of the end face detection target 38, the pointer 87a
Although the pointer 87a is configured to display "0", the pointer 87a is in a state where the optical image 53 is located only at the light receiving section 51 and completely covers the light receiving sections 49 to 52 (see FIG. 32). When the edge 53a of the optical image 53 is between and, it swings slightly as shown in C of FIG. 33, and when it is between and, it shows "0". As shown, there is a large shake, and the edge 53 of the optical image 53
As a progresses towards empty, the 34th
As shown in the figure, the pointer oscillates toward the vicinity of "0", and when passing the intersection 54 of the light receiving element 40, the oscillation of the pointer becomes "0". Then, as the edge 53a of the optical image 53 advances toward the position,
The pointer 87a swings slightly to the opposite side as shown in E of FIG. The deflection of the pointer 87a gradually decreases as the pointer 87a moves toward the position , as shown in FIG. Therefore, when the end face is detected and when the end face is slightly approaching the light receiving element, the pointer 87a points near “0”, making it difficult to confirm when the end face is detected. A red indicator light 89 and a green indicator light 88 are provided. The relay 90 is composed of fixed contacts 94 and 95 and a movable contact 96, and the relay 91 is composed of fixed contacts 94 and 95 and a movable contact 96.
7, 98 and a movable contact 99, the relay 93 includes fixed contacts 100, 101 and a movable contact 10.
It is composed of 2. The fixed contact 94 is connected to the subtracter 55, and the movable contact 96 is connected to the AND circuit 6.
When the output γ of No. 6 is H, the circuit is closed. The fixed contact 97 is connected to the subtracter 72, and the movable contact 99 is closed when the output δ of the AND circuit 81 is H. The fixed contact 100 is connected to an OR circuit 92, the OR circuit 92 is connected to AND circuits 66, 81, and the movable contact 102 is closed when the output ε of the AND circuits 67, 82 is H. The fixed contacts 100 and 101 are connected via a resistor 103, the red indicator light 89 is connected to the fixed contact 101 and the resistor 103, and the green indicator light 88 is connected to the OR circuit 92 via an inverter circuit 104. . Next, the operation of this pointer control circuit will be explained. Here, for the optical image 53, the light receiving element 39,
The case where 40 has a relative relationship as shown in FIG. 8 will be explained. When the edge 53a of the optical image 53 is in front of the position shown in FIG.
(A-B), the output β (A-B) of the subtractor 72 is zero as shown in FIGS. 11 and 15 (at time t ₁
). At that time, the output γ of the AND circuit 66 and the output δ of the AND circuit 81 are both L, so the output of the OR circuit 92 is L, and the output of the inverter circuit 104 is H, so the red indicator light 89 is lit. Similarly, when the optical image 53 is in the position shown in FIG. 32, that is, when the light receiving surface 44 is completely covered, the red indicator light 89 is turned on.
is lit (after time t ₃ ). AND circuit 66
The output γ remains zero even when the optical image 53 covers the light-receiving surface 43, but the output δ of the AND circuit 81 becomes H when the outputs M and N of the determination circuits 78 and 79 are H (the 32). Further, when the output δ of the AND circuit 81 becomes H, the movable contact 99 of the relay 91 is closed and the pointer 87a begins to swing. The deflection of the pointer 87a is approximately at its maximum at the position shown in FIG. At the same time, when the output δ of the AND circuit 81 becomes H, the green indicator light 88 lights up weakly via the resistor 103 (
). Then, near time _t2 , the movable contact 102 of the relay 93 is closed by the output ε, and the green indicator lamp 88 is illuminated strongly. From now on, since the lighting and extinguishing will be repeated in the reverse order, a detailed explanation will be omitted and a table will be used to summarize.

[Table] According to this device, the green indicator light 88 lights up strongly at the position shown in Fig. 33 when detecting an edge, so that edge detection can be easily distinguished from the case where the edge is slightly overlapping the light-receiving element. This has the effect of allowing confirmation. (Effect of the invention) As explained above, the present invention provides the first and second
The configuration is such that when one of the light receiving elements is in a dead zone with respect to the optical image, the other of the first and second light receiving elements is not in the dead zone with respect to the optical image. Even if the light receiving element has a dead zone, the end face can be detected accurately. Further, even if the length and width of the object to be detected is small, it can be detected, and the detection accuracy is higher than that of a device having five light-receiving elements.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the optical system of a conventional edge detection device, Figure 2 is a configuration diagram of an edge detection signal generation circuit, Figure 3 is a waveform diagram of the edge detection signal, and Figures 4 to 6.
The figure is an explanatory diagram for explaining the problems of the conventional edge detection device, FIG. 7 is an optical system diagram of the edge detection device according to the present invention, FIGS. 8 and 9 are configuration diagrams of the edge detection signal generation circuit, 10 to 25 are explanatory waveform diagrams of the edge detection signal of the edge detection signal generation circuit,
26 and 27 are diagrams showing other examples of light receiving elements used in the end face detection device, and FIGS. 28 to 30
The figure is a diagram for explaining an application example of the end face detection device according to the present invention, FIG. 31 is a diagram of a pointer control circuit according to the present invention, and FIGS. 32 to 35 are diagrams for explaining the pointer control circuit, It is. 30...Optical system, 38...End face detection target, 3
8a... end face, 39, 40... light receiving element, 45~
52...Light receiving section, _l1 , _l2 ...Optical axis, 53...Optical image, 53a...Edge, 55-59...Subtractor, 6
2, 64, 65...determination circuit, 63...first end face detection signal generation circuit, 69-73...subtractor, 7
6, 78, 79...determination circuit, 77...second end face detection signal generation circuit.

Claims (1)

[Scope of Claims] 1. A light-receiving surface that receives an optical image of an end face detection object is divided into four regions by two dividing lines substantially orthogonal to each other, and a light-receiving portion is formed in each region. 1 light receiving element; a first optical system having a first optical axis passing through the intersection of the dividing lines and forming an optical image of the end face detection target on the light receiving surface of the first light receiving element; An end face detection device comprising: a first end face detection signal generation circuit which receives outputs from each light receiving portion of the element and generates an end face detection signal by adding and subtracting each output; A light-receiving surface for receiving an image is defined into four regions by two dividing lines substantially orthogonal to each other, and each region has a light-receiving portion corresponding to the light-receiving portion of the first light-receiving element. 2
A light receiving element is provided, and each light receiving part of the second light receiving element is optically rotated by a predetermined angle about the intersection of the dividing line of the first light receiving element with respect to each light receiving part of the corresponding first light receiving element. a second optical axis passing through the intersection of the dividing lines of the second light receiving element and having a part of the first optical axis in common; a second optical system that forms an optical image; and a second end face detection signal generation circuit that receives outputs from each light receiving portion of the second light receiving element and performs addition/subtraction operations on each output to generate an end face detection signal. , determining whether either the first end face detection signal generation circuit or the second end face detection signal generation circuit is in a state in which it is unable to generate a detection signal, based on the output of each light receiving portion of the first and second light receiving elements; and a discrimination circuit for outputting an edge detection signal from one of the first edge detection signal generation circuit and the second edge detection signal generation circuit which is in a state capable of generating an edge detection signal based on the discrimination result. An edge detection device featuring: