JPH07286815A - Position detector - Google Patents

Abstract

PURPOSE:To provide a position detector which can be manufactured with high workability and has high resolution. CONSTITUTION:The position detector is provided with a light emitting device which emits a light beam, light receiving means which receives the light beam and on which light incident surfaces (1-18) arranged in one direction are divided into a plurality of groups (1-6, 7-12, and 13-18), group discriminating means (13A-13C) which discriminate the group on which the light beam is made incident by detecting received light signals from each light incident surface of the groups, and incident surface discriminating means (14A-14F) which discriminate the light incident surface on which the light beam is made incident by detecting received light signals from each light incident surface of the groups. The light incident surface discriminating means (14A-14F) are provided with an arithmetic means 16 which finds the cross-sectional center position of the light beam based on the light intensity distribution on the cross section of the light beam including the optical axis of the beam and the output levels of received light signals from at least three light incident surfaces of the groups.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device suitable for use in a device for rotating and irradiating a beam having a Gaussian distribution to measure a level position.

[0002]

2. Description of the Related Art Conventionally, as an example of this type of device, a device having a structure as shown in FIG. 4 has been proposed. In FIG. 4, one end surface of the 16 optical fibers 51 to 66 is
The light receiving surface is formed by linearly arranging, and the other end surfaces of the optical fibers 51 to 66 are provided with 16 optical branching devices 51A to 6A.
6A, and each of the optical branching devices 51A to 66
Optical branching devices 51A, 52A, 53A and 54A are branched from A to the optical path of two optical fibers and are received by the light receiving element A.
One of the optical fibers 51b to 54b branched by the optical path is connected to the light receiving element B by the optical branching devices 55A, 56A,
One optical fiber 55b branched by 57A and 58A
No. 58b are connected to the light receiving elements C and D, optical fibers 59b to 62b are branched by the optical branching devices 59A to 62A, and optical fibers 63b to 66b are branched from the optical branching devices 63A to 66A.
Is connected to the light receiving element E, and an optical branching device 51A,
The other optical fibers 51a, 55a, 59a, 63a branched by 55A, 59A, 63A are connected, and the light receiving element F is provided with optical branching devices 52A, 56A, 60A, 64A.
The other optical fiber 52a, 56a, 60 branched by
a and 64a are connected, and the light branching device 5 is connected to the light receiving element G.
The other optical fibers 53a, 57a, 61a, 65a branched by 3A, 57A, 61A, 65A are connected to the light receiving element H, and optical branching devices 54A, 58A, 62A,
The other optical fibers 54a, 58 branched at 66A
a, 62a, 66a are connected, each of the light receiving elements A to H is connected to the detection circuit 70, and further connected to the CPU 71 and the display 72, so that a beam moving in the arrangement direction of one end face of the optical fiber 51 or 66. Light is an optical fiber 5
When located at an arbitrary position from 1 to 61, the position of the light beam from the optical fibers 51 to 66 can be detected by a small number of light receiving elements by the digital information of two series of light receiving elements A to D and E to H. However, it can be displayed on the display 72.

That is, if the light beam is located at one end face of the optical fiber 53, for example, a signal of receiving the light beam from the light receiving element A is output, but the optical fibers 51 to 54 are connected to the light receiving element A. Therefore, only the output signal of the light receiving element A is used from the optical fibers 51 to 54.
It is impossible to determine which one of the end faces of the beam has the light beam. Therefore, this determination is performed by the output signals of the light receiving elements E to H. That is, the presence of the light beam at the position of the one end face of the optical fiber 53 can be known from the output signals generated from the light receiving element A and the light receiving element G.

[0004]

However, in the above-mentioned conventional techniques, there is a problem in that reading cannot be performed within the array pitch of the optical fibers. Further, since the beam is received by the optical fiber, there is a problem that the arrangement and connection of the optical fibers are complicated and the workability at the time of manufacturing the device is poor.

It is an object of the present invention to provide a high-resolution position detecting device which has good workability in manufacturing the device.

[0006]

To achieve the above object, in the present invention, a light projecting device for emitting a light beam and a plurality of light incident surfaces (1-1) for receiving the light beam and arranged in one direction.
8) to multiple groups (1-6, 7-12, 13-1)
8) divided into light receiving means and the plurality of groups (1 to 1)
6, 7 to 12, 13 to 18) group receiving means (13A to 13C) for detecting a light receiving signal from each light incident surface to determine to which of the plurality of groups the light beam is incident. ) And the light receiving signal from each light incident surface in each group to determine which light incident surface in each group the light beam has entered. 14F), and the incident surface determination means (14A to 14F) includes a light intensity distribution of a cross section including the optical axis of the light beam and a light incident surface in each group. It is a means for solving the problem to have an arithmetic means (16) for obtaining the center position of the cross section of the light beam based on the output levels of at least three light receiving signals (Y1, Y2, Y3).

[0007]

In the present invention, the light beam emitted from the light projecting device is incident on a plurality of light incident surfaces arranged in one direction of the light receiving means of the detecting device. The plurality of light incident surfaces are divided into a plurality of groups. Then, the group determining means detects the light receiving signals from the light incident surfaces of the plurality of groups to determine which of the groups the beam light is incident on, and the incident surface determining means determines the incident light of each light within each group. The light receiving signal from the surface is detected to determine which light incident surface in each group the beam light is incident on. Further, the calculating means of the incident surface determination means is based on the light intensity distribution of the cross section including the optical axis of the beam light and the output level of at least three received light signals of the light incident surface in each group, and the center position of the cross section of the light beam. Therefore, the center position of the cross section of the light beam can be detected with high resolution.

Further, since the light-incident surface has a simple arrangement of the light-receiving elements, the conventional manufacturing difficulties can be eliminated.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the principle configuration of an embodiment of the present invention. In FIG. 1, planar light-receiving elements 1 to 18 whose light-receiving surfaces are rectangular and have the same shape are arranged in two rows in a line in a direction orthogonal to the beam moving direction to form a light-receiving portion. The outputs of the light receiving elements 1 to 6 are connected to the digital circuit 13A, the outputs of the light receiving elements 7 to 12 are connected to the digital circuit 13B, and the outputs of the light receiving elements 13 to 18 are connected to the digital circuit 13C.

The light receiving elements 1, 7 and 13 are also connected to the analog circuit 14A, and the light receiving elements 2, 8 and 1 are also connected.
Reference numeral 4 denotes the analog circuit 14B, light receiving elements 2, 8, 14 for the analog circuit 14B, light receiving elements 3, 9, 15 for the analog circuit 14C, light receiving elements 4, 10, 16 for the analog circuit 14D, light receiving element 5, 11 and 17 are analog circuits 14
E, the light receiving elements 6, 12, and 18 are connected to the analog circuit 14F, respectively. The light receiving elements 1A and 18A respectively arranged at both ends of the light receiving portion are connected to the digital circuit 15.

The digital circuits 13A, 13B, 13C
And 15 have adders and comparators, etc., and are configured to perform digital output when the addition level of the input signal exceeds a predetermined value. The digital circuits 13A, 13B, 13
The respective outputs of C and 15 are input to a CPU (central processing unit) 16. In addition, the analog circuit 14
A to 14F have an adder and a peak hold circuit,
The addition level of the input signal is configured to be held at the peak at the measurement time point in order to correct the time difference caused by the rotary irradiation, and the respective outputs of the analog circuits 14A to 14F are also input to the CPU 16. The data processed by the CPU 16 can be sent to an external personal computer or printer via the interface 17. In addition, the processing data processed by the CPU 16 is displayed on the display unit 1.
It is entered in 8.

Next, the operation of FIG. 1 will be described. The relationship between the diameter R of the beam light having a Gaussian distribution incident on the light receiving portion and each light receiving element is as shown in the detailed operation diagram of FIG. 2 (A). Length L
Is set to about 1/2 of the diameter R of the beam light having a Gaussian distribution, and the predetermined shift amount P in the arrangement direction of the two rows of elements arranged in parallel is set to about 1/4 of the diameter R of the beam. There is.

Considering the beam irradiation as shown in FIGS. 2A and 2B, the outputs of the light receiving elements 1 to 5 are input to the digital circuit 13A shown in FIG. The digital circuit 13A is
It is determined that the added level of the output signals of the light receiving elements 1 to 5 exceeds a predetermined value (threshold level), and the output is set to the H level, for example. This predetermined value is set in order to determine which group of the light receiving elements 1 to 6, the light receiving elements 7 to 12 and the light receiving elements 13 to 18 the beam is incident on. In consideration of the fact that the beam is incident on the beam, it can be distinguished from the case where the beam is not received at all, and the level is set to a low level that is not affected by noise. Since the CPU 16 can roughly determine which group the beam position is in, in the case of FIGS. 2A and 2B, it is determined that the beam exists within the range of the light receiving elements 1 to 6.

The outputs of the light receiving elements 1 to 5 are input to the analog circuits 14A to 14E, respectively. As shown in FIG. 2B again, the light quantity of the beam corresponding to the beam cross-section light quantity distribution strikes the light receiving elements 1 to 5, and is converted into analog electric quantities, respectively. In this case, the maximum value is the light receiving element 3, then the light receiving element 4, the light receiving element 2, the light receiving element 5, and the light receiving element 1 in this order. That is, in terms of analog circuits, analog circuits 14C, 14D, 14B, 14E, 1
The analog quantities are positioned in the order of 4A and input to the CPU 16.

Therefore, in the CPU 16, the analog circuit 14
By detecting the maximum value of the outputs from A to 14F, it is determined which of the light receiving elements 1 to 6 the center position of the light beam is. In the case of FIG. 2A, it can be seen that the light receiving element 3 is located. Further, in order to accurately read where the center position of the light beam is located on the light receiving element 3, the CPU 16 has an analog circuit with the maximum output, an analog circuit with the second largest output, and an analog circuit with the third largest output. Comparing the analog value of.

In FIG. 3, the output of the light receiving element 3 is Y ₁ , the output of the light receiving element 4 is Y ₂ , and the output of the light receiving element 2 is Y.
₃ , Y ₁ , Y ₂ and Y ₃ are values on the Gaussian distribution, that is, the basic formula

[0017]

[Equation 1]

The coordinates on the graph represented by the exponential function of. Since the X-axis center coordinate of this basic equation corresponds to the center of the beam, it is only necessary to obtain the deviation amount δ from the light receiving element 3 (maximum output value). The CPU 16 calculates the shift amount δ and adds it to the group information obtained by the digital circuit 13A to obtain the absolute value H (H shown in FIG. 2) of the center position of the beam. The absolute value H is digitally displayed by the display device 18.

Data is processed by an external processor such as a personal computer through the interface 17. As shown in FIG. 1, the light receiving elements 1A and 18A are
When the light sensor 18 hits the end of the measurement range, the detection result is detected by the digital circuit 15 as CP.
Input to U16. Then, the CPU 16 uses the light receiving element 1
Alternatively, the light beam that has deviated from the light receiving element 18 is used to issue an alarm to an alarm device (not shown) so as not to detect an error.

Therefore, the measurer can know the center position of the light beam only by looking at the display on the display 18. The display on the display 18 does not have the minimum resolution for each pitch of the light receiving elements 1 to 18, but has a value obtained by interpolating the pitch of the light receiving elements, so that the position of the beam can be known with high resolution. The light receiving portion of the above embodiment is shown in FIG.
As described above, the planar light receiving elements having the same light receiving surface having a rectangular shape are arranged side by side in the direction orthogonal to the moving direction of the rotationally irradiated beam, but the shape of the light receiving element may be a triangle or a circle, or may be continuous. Instead of arranging them, they may be arranged discretely at a constant pitch. However, even in this case, the pitch of the light receiving elements is set in consideration of the diameter of the light beam so that three or more analog outputs are always generated. In addition, the equation calculated by the calculation method may use not only Y ₁ , Y ₂ , and Y ₃ but also the fourth largest output value Y ₄ , the fifth largest output value Y _{5, and the} like.

[0021]

As described above, according to the present invention, the center position of the beam having the Gaussian distribution can be obtained by calculation using at least three analog output signals of the arrayed light receiving elements, so that high resolution is achieved. There is an effect that various beam positions can be detected. Further, since the plurality of light receiving elements are arranged at the light receiving portion at a predetermined interval, there is an effect that the structure of the light receiving portion can be simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing a principle configuration of a position detecting device according to the present invention.

2A is an explanatory diagram showing a relationship between a beam having a Gaussian distribution and a light receiving element, and FIG. 2B is a light amount distribution diagram.

FIG. 3 is a diagram illustrating a calculation method.

FIG. 4 is a block diagram illustrating the principle of a conventional device.

[Explanation of symbols]

1-18 .... Light receiving element 1A, 18A ..... Light receiving element 13A, 13B, 13C, 15 ... Digital circuit 14A, 14B, 14C, 14D, 14E, 14F ..・ ・
..Analog circuit 16 ... CPU

Claims (3)

[Claims] 1. A light projecting device for emitting a light beam, a light receiving means for receiving the light beam and dividing a plurality of light incident surfaces arranged in one direction into a plurality of groups, and each of the plurality of groups. Group determination means for detecting a light receiving signal from the light incident surface to determine which of the plurality of groups the light beam has entered, and the light receiving signal from each light incident surface in each group. A position detecting device comprising: an incident surface determining unit that determines which light incident surface in each of the groups the incident light is detected by, and a position detecting device comprising: Calculating means for obtaining the center position of the cross section of the light beam based on the light intensity distribution of the cross section including the optical axis of the light beam and the output levels of at least three light receiving signals on the light incident surface in each group. Position detecting device characterized in that it has. 2. The position detecting device according to claim 1, wherein the light receiving unit has a light receiving element on the light incident surface. 3. The light incident surface has N rows of light receiving element rows in the one direction, and R is a diameter of the light beam,
The length of the light receiving element alone in the one direction is set to R / N, and an arbitrary nth light receiving element row in the Nth row and an n + th light receiving element row
3. The position detecting device according to claim 2, wherein the light receiving elements of the first row and the light receiving elements are arranged so that the pitch between the light receiving elements is shifted by R / N ^{2 in the} one direction.