JPH09210620A - Surface position detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface position detection device which has a wide positioning response range and can accurately detect even a transparent object to be inspected with reverse side reflection and an object to be inspected with a narrow surface width to be detected. SOLUTION: A device has a light projection part for projecting the light of a light source to the surface of an object to be inspected and a light reception part for outputting a signal corresponding to the above position by detecting the position of the above reflection light which is displaced on a sensor surface according to the change in distance between the above object to be inspected and a focus position detection device. In this case, a light reception element 26 is constituted of at least four regions (SA-SD) which are linearly arranged and has a signal processing part for generating a detection signal S for detecting that a surface position is located at a specific position according to a signal from two adjacent regions SB and SC and for generating a deviation direction signal Z indicating the deviation direction of the surface position according to signals from at least one region which continue over the above two regions and its both sides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface position detecting device, and more particularly to a non-contact type surface position detecting device used for auto-focusing of optical equipment or measuring the height of an object surface.

[0002]

2. Description of the Related Art As a non-contact type surface position detecting device, a triangulation type device is known. FIG. 7 is an explanatory diagram of the principle of the conventional device, and FIG. 8 is an explanatory diagram of sensors and signal waveforms of the device of FIG. In this device 9, for example, light from a light source 1 such as a laser diode is projected as a light spot 4 on a surface 3 to be inspected by a projection lens 2, and light reflected by the surface 3 to be inspected is collected by a condenser lens 5. Light is emitted to form a light spot image 7 on the two-divided sensor 6. As shown in FIG. 8, the two-divided sensor 6 has two areas SA 'adjacent to each other with a narrow gap.
And SB ′ are photodiode two-divided sensors.

When the distance K between the object surface 3 and the device 9 changes, the position of the light spot 7 on the sensor 6 changes, and photoelectric conversion from the two areas SA 'and SB' of the two-divided sensor 6 is performed. The signals (A 'and B', respectively) change. Explaining the signal A ′, in (a), since the light spot 7 is outside the area SA ′, the output is 0. The output gradually increases when the light spot 7 approaches the area SA ′, and reaches the maximum output when the light spot 7 is included in the area SA ′ (b). Then, the light spot 7 is the area SA.
The output gradually decreases (c) when leaving from ′, and becomes 0 after leaving. The signal SB 'follows the opposite course.

The surface 3 to be inspected is separated from the device 9 by a predetermined distance K0.
The device 9 is adjusted so that the light spot 7 is located at the center of the areas SA ′ and SB ′ (state (C)) when the position (7) is reached.
Therefore, when the object surface 3 comes to the position of the predetermined distance K0 from the device 9, the difference (A′−B ′) between the two signals becomes zero. The device 9 processes the signals of the driving device 8 that changes the distance K, the position reading device 10 that detects the amount of change in the distance K, and the sensor 6, and obtains a difference signal (A′−B ′),
A'-B '= 0 and A' + B '>T' (where 0 <T '<
And a signal processing device 50 that outputs a detection signal S ′ when it reaches the maximum value of A ′ + B ′). Therefore, the distance K is changed before and after a predetermined value K0, the value of the position reading device 10 is read by a computer by the detection signal S ', and the surface position is obtained. This is used, for example, to measure the height of the surface with respect to the reference surface, and the test object is replaced or the test object is moved to change the measurement position as necessary.

A target is a predetermined position (for example, a position where K in FIG. 7 has a predetermined value) determined based on the obtained surface position (the value of the position reading device 10 read by the detection signal S '). It is also possible to provide a control device for driving the drive device 8 as a position to position the device to which the device 9 is attached at a predetermined position. When this is used for automatic focusing of the optical device, it is sufficient to position the optical device with accuracy close to the depth of focus of the optical device. This method is less likely to be affected by the ambient light during the positioning operation, as compared with the positioning in which the drive device 8 is driven by the difference signal described later.

However, in such a conventional device,
When the test object is a transparent body such as a plate glass, a light spot due to the reflected light from the front surface of the test object and a light point due to the reflected light from the back surface of the transparent body are formed on the two-divided sensor 6,
The detection signal is affected by that, and the detection position shifts. (The position of the center of gravity weighted by the light quantity ratio of the two light spots is detected.) Furthermore, in the case of an object in which the width of the surface to be detected is narrow, the light of the portion protruding from the surface to be detected of the light spot 4 is However, there is a drawback in that the light is reflected by a surface other than the detection surface and is condensed on the two-divided sensor 6, and the detection position is displaced due to the influence thereof.

In order to improve such a defect, there is an apparatus disclosed in Japanese Patent Laid-Open No. 3-291512. FIG.
This device shown in FIG. 0 irradiates the laser light from the laser diode 12 to the measurement target, receives the reflected light from the measurement target in a direction different from the irradiation direction, and forms an image of the irradiation point on the measurement target as the light receiving element 17. A displacement gauge which is formed on the light receiving element 17 and detects the position of the object to be measured from the movement of the image of the irradiation point on the light receiving element 17, and which is provided with means 18 and 19 for partially limiting light reception on the light receiving surface of the light receiving element 17. Of the light incident on the light-receiving surface, the light reflected by the back surface is blocked. However, in this device, the detectable range of the surface position becomes extremely narrow, which conflicts with the desire to expand the response range.

As another usage, the difference signal (A'-B ')
It is possible to drive the driving device 8 at a driving speed proportional to, and position the device 9 at a predetermined distance (K = K0) from the surface. In this case, in order to obtain the difference signal used for positioning in the widest possible range (expand the response range), the two-divided sensor 6 has a size larger than the size of the light spot. This method is used for the purpose of positioning a device provided with the device 9 in a predetermined position from a surface, for example, automatic focusing of optical equipment. This method has advantages in that the signal processing device 50 can be simply configured, a computer is not required, and the like, as compared with the method of positioning the device 9 at a predetermined position determined based on the detected surface position.

Of course, in any of the above cases, the position of the test object surface 3 may be changed by providing the driving device 8 on the device side for holding the test object. However, in this case, while the light spot 7 is included in the area SA '(SB'), the signal A '(B
Since ') is a constant value, the difference signal (A'-B') is a positive or negative constant value (see FIG. 7) except near the predetermined position.
Therefore, the displacement direction can be known, but the size of the displacement cannot be known. Therefore, the maximum drive speed is determined in consideration of deceleration and stop at a predetermined position. As a result, even if the position of the surface is largely deviated from the predetermined position, the driving speed cannot be increased, and it takes a long time for positioning.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a surface position detecting device having a wide positioning response range and capable of accurately detecting even a transparent body or an object having a narrow width, and positioning time is short. It is an object to provide a surface position detecting device and to propose a method for easily adjusting each of the above devices to the best condition.

[0011]

According to a first aspect of the invention, a light projecting section (1, 2) for projecting light from a light source onto the surface of an object to be inspected.
And a position of the reflected light which receives the reflected light of the projected light from the surface of the test object and displaces on the light receiving element (26) according to a change in the distance between the test object and the surface position detection device. Is detected and outputs a signal corresponding to the position (5,
26), the light receiving element (26) includes at least four regions (SA to SD) linearly arranged, and includes the outermost portion of the light receiving element (26). Not two adjacent areas (SB, S
A signal from (C) is used to generate a detection signal (S) for detecting that the surface position is at a predetermined position, and at least one of each of the two adjacent regions (SB, SC) and the outside thereof is continuous. The signal processing unit (100) that generates the displacement direction signal (Z) that represents the displacement direction of the surface position by the signal from the area (SB, SC) is provided.

According to a second aspect of the present invention, a light projecting portion (1, 2) for projecting light from a light source onto the surface of the object to be inspected and light reflected by the surface of the object to be inspected of the projected light are received. , The light receiving element (2
6) In a surface position detecting device including a light receiving section (5, 26) for detecting a position of the reflected light displaced above and outputting a signal according to the position, the light receiving element (26),
At least four areas (SA to S) arranged linearly
D), signals from two adjacent regions (SB, SC) not including the outermost part of the light receiving element (26),
And one or more areas (SA, continuous to the outside of the area)
The signal from SD) indicates the direction of displacement of the surface position,
A signal processing unit (100) that generates a displacement direction signal (Z) is provided, and each region (SA to S) is provided in the signal processing unit (100).
The amplifiers (32a to 32d) for amplifying the signal from D) and outputting to the subsequent stage of the signal processing unit (100) are provided, and the amplification factor of each of the amplifiers (32a to 32d) from the two adjacent regions. The gain is adjusted so as to increase as the distance increases, and the deviation direction signal (Z) changes according to the magnitude of the deviation of the surface position from the reference position.

As described in claim 3, in any one of claims 1 and 2, the light receiving element (26) is arranged such that the two adjacent elements are substantially equal in size to the light spot on the light receiving element. It is preferable to include a region to be formed and a region that is longer in the arrangement direction of the regions. In the invention according to claim 4, adjacent two
A light spot having a light receiving element composed of two photoelectric conversion regions (SB, SC), processing a signal from the light receiving element, and detecting that the light spot formed on the light receiving element is at a predetermined position. In the position detecting device, one or more photoelectric conversion regions (S) are provided adjacent to both outer sides of the region of the light receiving element.
A, SD) are provided, and adjustment is performed including the following steps.

By moving the light receiving element or the light spot in the array direction of the areas, the difference between the signals from two adjacent areas not including the outermost area of the light receiving element is "0".
The process of making. Moving the light receiving elements or the light spots in a direction perpendicular to the arrangement direction to maximize the sum of signals from the two adjacent regions.

The two adjoining regions including two regions adjoining both outer sides of the two adjoining regions by moving the light receiving element in the optical axis direction or adjusting the size of the light spot. The process of "minimizing" the sum of signals from other sources.

[0016]

1 to 4 are explanatory views of one embodiment of the present invention, FIG. 2 is an explanatory view of the entire configuration, FIG. 1 is a block diagram showing an outline of signal processing, and FIG. 3 is a signal. Waveform diagram, Figure 4
[Fig. 4] is a waveform diagram when there is back surface reflection. In FIG.
The same members as those of the conventional device of FIG. 5 are designated by the same reference numerals. The light emitted from the light source 1 is condensed by the light projecting optical system 2 and obliquely projected onto the surface 3 of the object to be examined to form a light spot 4. The light reflected by the surface 3 to be inspected is condensed by the light receiving optical system 5. As shown in FIG. 1, the sensor 26 is composed of four areas SA, SB, SC, and SD arranged in a straight line, and the light spot image 7 having substantially the same size as the combined size of the areas SB and SC. To form. Object surface 3 and surface position detection device 2
As the distance K from the sensor 2 changes, the position of the light spot 7
6 changes in the arrangement direction of each region.

The signal from the sensor 26 is sent to the signal processor 100.
Is input to The signal processing unit 100 detects the detection signal S when the distance K between the object surface 3 and the device 9 reaches a predetermined value K0.
At other times, the surface 3 of the object to be inspected is on the larger side (K> K0) with respect to the predetermined distance K0 and on the smaller side (K> K0).
A deviation direction signal Z for identifying the case of <K0) is output.

Next, details of the signal processing unit 100 will be described with reference to FIG. The sensor 26 is composed of four areas of SA, SB, SC and SD. Signals a, b from each area
c and d are current-voltage conversion amplifiers 32a and 32, respectively.
b, 32c, and 32d are amplified, and signals A, B, and
It becomes C and D. Here, the conversion constants (gain constants) of the amplifiers 32a to 32d are set to be equal. Adder 3
Signals A and B are input to 3 and a sum signal (A + B) is output. The signals B and C are input to the subtractor 34, and the difference signal (BC) is output. The signals B and C are input to the adder 35, and the sum signal (B + C) is output. Adder 36
The signals C and D are input to and the sum signal (C + D) is output. The outputs of the adders 33 and 36 are input to the subtractor 37, and the difference signal ((A + B)-(C + D)) is output.
This difference signal ((A + B)-(C + D)) is the above-mentioned shift direction signal Z.

38 is a reference voltage generator for outputting 0 V, 3
9 is a predetermined voltage TV lower than the maximum value of the sum signal (B + C)
Is a reference voltage generator that outputs Reference numeral 40 denotes a voltage comparator, which receives an output (BC) of the subtractor 34 (hereinafter referred to as a difference signal) and an output (0V) of the reference voltage generator 38, and both are equal, that is, BC = 0. The signal is output at. 41 is a voltage comparator, which is the output (B + C) of the adder 35.
(Hereinafter, referred to as sum signal) and the output (TV) of the reference voltage generator 39 are input, and a signal is output when B + C> T. The trigger signal generator 43 includes two voltage comparators 40,
The output of 41 is input, and the AND signal of both signals is output. That is, the trigger signal is output when B−C = 0 and B + C> T. This trigger signal is the above-mentioned detection signal S. The detection signal S is input to the counter 44 of the position reading device 40 that detects the amount of change in the distance K between the object surface 3 and the device 29, and the value of the counter 44 at the moment when the detection signal S is input is not shown. Read by computer. . If you do this for multiple surfaces with different heights,
The interval of each surface can be known from the value of the counter 44 for each surface.

FIG. 3 shows the waveforms of the signals A, B, C, D and the difference signal and the sum signal due to the change in the position of the light spot 7 on the sensor 26 with the change in the distance K. The light spot 7 is shown in FIG.
When approaching the area SA from above, the signal A gradually increases and reaches the maximum output while the light spot 7 is included in the area SA (b). As the light spot 7 leaves the area SA, the signal A gradually decreases (b), and when it leaves, the output becomes 0 (c) to (e). On the other hand, the light spot 7 enters the area SB as it leaves the area SA, and the signal B gradually increases (B). That is, the decrease of the signal from one side and the increase of the signal from the other side of the adjacent areas SA to SD simultaneously proceed. The device 29 is adjusted so that the light spot 7 is located at the center of the areas SB and SC (state (C)) when the surface 3 to be inspected is located at a predetermined distance K0 from the device 29. Therefore, when the object surface 3 comes to the position of the predetermined distance K0 from the device 29, B = C.

The difference signal has an output of 0 when the light spot 7 is in the area SA. When the light spot 7 approaches the area SB, the output gradually increases to the positive side, and when the light spot 7 approaches the area SC, the output starts to decrease (B). Then, the light spot 7 is the area SB and the area S.
When it reaches the center of C, the output crosses 0 (C). After that, the output increases to the negative side, and when the light spot 7 leaves the area SB, the output starts to decrease (d). When the light spot 7 reaches the area SD, the output becomes 0 (e).

On the other hand, the sum signal has an output of 0 when the light spot 7 is in the area SA. When the light spot 7 approaches the area SB, the output gradually increases to the positive side, and the light spot 7 becomes the area SB and the area SC.
When it comes to the center of, the output becomes maximum. After that, the output starts to decrease, and when the light spot 7 reaches the area SD, the output becomes 0. The output T of the reference voltage generator 39 is shown in the waveform diagram of the sum signal. The level of the output T can be changed by adjusting the reference voltage generator 39, and is set to a level higher than the noise level included in the sum signal and lower than the maximum value of the sum signal. B when the light spot 7 comes to the center of the area SB and the area SC
-C = 0, and the detection signal S is output from the trigger signal generator 43 (see the waveform diagrams of the difference signal and the sum signal). At this time, the device 9 is located at a predetermined distance from the surface 3 to be inspected.

Next, the case of an object having a back surface reflection will be described. FIG. 4 shows the signals B and C, the difference signal, and the sum signal in such a case. Reference numeral 7 denotes a light spot on the sensor 26 due to the reflected light on the surface 3 of the test object, and 11 denotes a light spot formed on the sensor 26 by the reflected light from the back surface of the test object.
Since the size of the light spot 7 is made substantially equal to the combined size of the areas SB and SC, the light spot 11 due to the back surface reflection also has the area S.
It is almost equal to the combined size of B and SC. Therefore, when the light spot 7 is in the center of the areas SB and SC, the light spot 11 due to the back surface reflection is in the other area of the sensor 26. When the light spot 11 due to back surface reflection is in the center of the areas SB and SC, the light spot 7 is in the other area of the sensor 26.

The signals B and C are obtained by superimposing the waveform of the light spot 11 due to the back surface reflected light on the waveform of FIG. 3 (see FIG. 4). Since the light spot 11 is deviated from the light spot 7, the position of the peak of the waveform due to the back surface reflection deviates from that of the waveform of FIG. Further, since the back surface reflected light is generally weaker than the front surface reflected light, the peak of the waveform due to it is smaller than the peak of the waveform due to the front surface reflection. Drive the driving device 8 and
When the distance between the surface 3 to be inspected and the device 9 is set to a predetermined distance or more and then the two are brought close to each other, and the difference signal first turns from positive to negative (passes 0) (a in FIG. 4). The front surface 3 of the object to be inspected comes to a predetermined position, and the second time it turns from positive to negative (passes 0) (B in FIG. 4) is the time to bring the back surface of the object to come to a predetermined position.

Therefore, in order to detect the position of the transparent surface of the object, the counter 44 of the position reading device 40 is operated by the first detection signal S output from the trigger signal generator 43.
Is read by a computer (not shown), and then the drive device 8 decelerates and stops. After the output of the first detection signal S, when the change amount of the distance between the object surface 3 and the device 9 before the stop is larger than the thickness of the transparent object, the back surface of the object is detected and the second detection is performed. A signal is output from the trigger signal generator 43. The value of the counter 44 read by the computer by the second detection signal is rejected as an invalid value. Thus, the position of the transparent front surface of the test object can be obtained with high accuracy without being affected by the back surface reflection.

If the data processing method by the computer is changed so that the value of the counter 44 read by the first detection signal is rejected and the value of the counter 44 read by the second detection signal is made effective, the transparent object is transparent. The position is required on the back of the specimen. In order to obtain highly accurate measurement values,
The speed at which the surface 3 of the object to be inspected and the device 9 are brought close to each other is a constant speed (there is no speed fluctuation), and a predetermined distance when the two are once separated is necessary for obtaining the constant speed. The minimum distance (including the acceleration region from the stopped state) is preferable.

If the reference voltage generator 39 is adjusted so that its output T is higher than the peak due to the back surface reflection of the sum signal and lower than the peak due to the front surface reflection, the detection signal S corresponding to the back surface reflection is obtained. Only the detection signal S due to surface reflection is detected without being output. This is because the width of the surface to be detected is narrow, and the light of the portion of the light spot 4 protruding from the surface to be detected is reflected by a surface other than the detection surface and is condensed on the sensor 26 to generate a disturbance signal. It is particularly effective when it is unknown whether the disturbance signal comes before or after the true signal.

Next, the positioning using the shift direction signal Z will be described. In FIG. 2, a surface position detecting device 29 including a light source 1, a light projecting optical system 2, a light receiving optical system 5, and a sensor 26 includes a drive device 8 for changing a distance K between the device 29 and the surface 3 of the object to be inspected, and a distance. A position reading device 10 for detecting the amount of change in K is provided. The displacement direction signal Z is input to the drive circuit 42 of the drive device 8 to drive the drive device 8 to move the device 29 from the object surface 3 at a predetermined distance (K = K).
It can be positioned at the position 0).

Referring to FIG. 3, the output ((A
+ B)-(C + D)), that is, the waveform of the displacement direction signal Z is
When the light spot 7 is in the area SA, the output is positive (a),
The output does not change even when the light spot 7 approaches the area SB (b). Then, when the light spot 7 approaches the area SC, the output decreases, and when the light spot 7 comes to the center of the areas SB and SC, the output passes 0 (c). After that, the output increases to the negative side until the light spot 7 leaves the area SB (d), and then becomes a constant negative value (e).

Therefore, according to the displacement direction signal Z, the surface 3 of the object to be inspected is on the far side (K> K0) or the near side (K <K0) with respect to the predetermined position (K = K0). Can be identified. Then, this signal is input to the drive circuit 42 of the drive device 8 that changes the distance K, and the drive device 8 is driven at a speed proportional to the magnitude of the displacement direction signal Z to position the object surface 3 at a predetermined position. It can be positioned at (K = K0). Since the signals from the areas SA and SD outside the areas SB and SC used to generate the detection signal S are also used, the shift direction signal can be obtained in a wider range than in the conventional device, and the response range is widened.

As shown in FIG. 5, the sensor 26 has a plurality of regions outside the regions SB and SC, and the sum signal of signals from the regions continuous outside the region SB is output to the amplifier 32a in FIG. , A wider response range can be obtained by inputting the sum signal of the signals continuous from the area SC to the amplifier 32d in FIG. The signal processing method may be various other methods. This device can also be used for purposes other than surface positioning, for example, by connecting signals from respective areas to different display devices and displaying a standard deviation of the position of the surface. Area SB and SC
It is necessary that the area outside the area be a continuous area in order to prevent a dead zone. Further, the area SA of the sensor 26
And SD are long in the moving direction of the light spot 7 according to the change in the distance K between the object surface 3 and the device 9, a wide response range can be obtained even if the number of regions forming the sensor is small. Moreover, since the number of signals to be processed is small, the signal processing circuit can be simplified.

FIG. 6 shows conversion constants (gain constants) na, nb, nc and nd by the amplifiers 32a to 32d of FIG.
3 schematically shows signals a to d, signals A to D, and displacement direction signal Z when na = nd, nb = nc, and na> nb. Signals A and D are larger than signals B and C,
As a result, the deviation direction signal Z = ((na × a + nb × b)
-(Nc * c + nd * d)) becomes a larger signal as the deviation of the surface from the predetermined position is larger. As a result, the drive device 8 is driven at a higher speed as the deviation of the surface of the object to be measured from the predetermined position is larger. When a plurality of regions are provided outside the regions SB and SC used to generate the detection signal S, amplifiers connected to the respective regions are provided, and the larger the distance from the regions SB and SC is, the more amplifiers are connected. When the conversion constant is set to a large value, the device 29 is driven at a higher speed as the distance between the device 29 and the surface 3 of the object to be measured is farther from the predetermined distance. As a result, the positioning time of the device 29 is reduced.

Next, a method of adjusting this device will be described with reference to FIG. Output A of each area SA, SB, SC, SD,
B, C and D are input to a measuring instrument (not shown), (BC),
Observe (B + C) and (A + D). And the light spot 7
Is preliminarily adjusted so as to come to the central portions of the areas SB and SC of the light receiving element 6, and then adjusted by the following steps. The light receiving element 6 is moved in the array direction (x direction) of the areas SA to SD to set (BC) to "0". By this adjustment, the light spot 7 is located at the center of the areas SB and SC in the arrangement direction (x direction) of the areas SA to SD (FIG. 9).
(A)).

The light-receiving element 6 is moved in the direction (y direction) perpendicular to the array direction of the areas SA to SD to make (B + C) "maximum". By this adjustment, the light spot 7 becomes the area SA.
It is located at the center of the width of the regions SB and SC in the direction (y direction) perpendicular to the array direction of SD (FIG. 9B). By moving the light receiving element in the optical axis direction (z direction), (A
+ D) to "minimum". Here, "minimum" means not being "0" but being as small as possible, or (A +
D) is adjusted so that (A + D) becomes "0". By this adjustment, the light spot 7 has almost the same size as the combined size of the areas SB and SC (FIG. 9C).

The above adjusting method is not limited to the apparatus shown in FIG. 2, and a light receiving element having one or more photoelectric conversion regions provided on both outsides of two adjacent photoelectric conversion regions is used.
For example, it can be applied to all devices that detect the position of a light spot, such as a laser spot position detection device.

[0036]

According to the first aspect of the present invention, the positioning response range can be widened, and the back surface reflection and the detection can be performed even on the transparent object having the back surface reflection or the object having the narrow width of the surface to be detected. The surface position can be accurately detected without being affected by the reflected light from other than the surface to be processed. According to the invention described in claim 2, the apparatus is driven at a speed according to the magnitude of the surface deviation, so that the positioning time can be shortened.

According to the third aspect of the present invention, further, it is possible to obtain a wide response range with a sensor that is less susceptible to the back surface reflected light and has a small number of regions. as a result,
The sensor is easy to manufacture, and the signal processing circuit is simple and inexpensive. According to the method of the present invention described in claim 4, the device can be easily adjusted to a state in which the position of the light spot can be detected with the highest sensitivity.

[Brief description of drawings]

1 is a block diagram of signal processing of the apparatus of FIG.

FIG. 2 is an explanatory view of the principle of one embodiment of the present invention.

3 is an explanatory diagram of signal waveforms of the apparatus of FIG.

FIG. 4 is an explanatory diagram of a signal waveform when there is back reflection.

FIG. 5 is an explanatory diagram of a sensor used in a modified example of the present invention.

FIG. 6 is an explanatory diagram of a signal waveform when the conversion constant of the amplifier is weighted.

FIG. 7 is an explanatory diagram of the principle of a conventional device.

FIG. 8 is an explanatory diagram of a sensor of the apparatus of FIG.

FIG. 9 is an explanatory view of a method for adjusting the device of the present invention.

FIG. 10 is a partially cutaway perspective view of another conventional device.

[Explanation of symbols]

 1 ………… light source 3 ………… the surface of the object to be inspected 4 ………… the light spot projected on the object to be inspected 7 ………… the image of the light spot 8 ………… the drive 10 ……… position Reading device 11 ... Light spot image due to back surface reflection 26 ... Sensor (light receiving element) 29 ... Surface position detection device 32a to 32d ... Amplifier (amplifier) 100 ... Signal processing device SA, SB, SC, SD: Area forming the sensor 26

Claims (4)

[Claims] 1. A distance between a test object and a surface position detecting device, which receives a light projecting section for projecting light from a light source onto the test object surface and reflected light of the projected light from the test object surface. In a surface position detection device including a light receiving unit that detects a position of the reflected light that is displaced on the surface of the light receiving unit of the light receiving unit according to a change, and outputs a signal according to the position, the light receiving unit is A detection signal for detecting that the surface position is at a predetermined position is formed by signals from two adjacent regions which are linearly arranged and include at least four regions and which do not include the outermost region of the light receiving element. In addition to the generation, the displacement direction signal that represents the displacement direction of the surface position with respect to the reference position is generated by the signals from the two adjacent regions and the signals continuous from the two adjacent regions from each one or more regions. Having a signal processor Surface position detecting apparatus according to symptoms. 2. A distance between a test object and a surface position detecting device, which receives a light projecting portion for projecting light from a light source onto the surface of the test object and light reflected by the surface of the test object of the projected light. In a surface position detection device including a light receiving unit that detects a position of the reflected light that is displaced on the surface of the light receiving unit of the light receiving unit according to a change, and outputs a signal according to the position, the light receiving unit is Signals from two adjacent regions, which are linearly arranged and include at least four regions and do not include the outermost region of the light-receiving element, and one or more regions each continuous to the outside thereof. And the signal of
A signal processing unit that generates a displacement direction signal that represents a displacement direction of the surface position with respect to the reference position is provided, and the signal processing unit is provided with an amplifier that amplifies the signal from each of the regions and outputs the signal to the subsequent stage of the signal processing unit. At the same time, the amplification factor of each of the amplifiers is adjusted so that the amplification factor increases as the distance from the two adjacent regions increases, and the displacement direction signal changes in accordance with the displacement amount of the surface position with respect to the reference position. A surface position detection device characterized by what is done. 3. The device according to claim 1, wherein the light receiving element has two adjacent areas that are substantially equal to the size of a light spot on the light receiving element. A surface position detecting device including a region having a longitudinal direction in the arrangement direction. 4. A light-receiving element having two adjacent photoelectric conversion regions, wherein a signal from the light-receiving element is processed to detect that a light spot formed on the light-receiving element is at a predetermined position. In the light spot position detecting device, one or more photoelectric conversion regions are provided adjacent to both outer sides of the region of the light receiving element, and the light spot position is adjusted by the following steps. Adjustment method of detection device. The light receiving element or the light spot is moved in the array direction of the area, and the outermost area of the light receiving element is not included.
The step of setting the difference between signals from two adjacent areas to "0". Moving the light receiving elements or the light spots in a direction perpendicular to the arrangement direction to maximize the sum of signals from the two adjacent regions. The light receiving element is moved in the optical axis direction or the size of the light spot is adjusted to include two regions adjacent to both outer sides of the two adjacent regions. The process of "minimizing" the sum of signals.