JPS6326504A - Two-division type semiconductor position detector - Google Patents

Abstract

PURPOSE:To lead out a signal current which has distance information propor tional to the quantity of variation in the distance of a body to be measured by dividing the resistance layer on the surface of a position detector. CONSTITUTION:This position detector is constituted by providing an N<+> layer 23 forming a common terminal on the reverse side of a silicon substrate 22, insulating and separating a rectangular P layer which becomes a photodetection surface of the top side, and arranging signal current lead-out terminals 12 and 13 on the P layers 15 and 16. Then, H(X)+W(X)+I=W and W(X)=ax/(x+b) hold at a position which is X away from the side of the photodetection surface on a light-source side. Wherein, W is the width of the position detector, I the length of the breadthwise separation layer, H(X) the breadthwise length of the photodetection surface on the light-source side, W(X) the breadthwise length of the photodetection surface on the other side, and (a) and (b) constants, which are so defined that a=Lf(W-I)/(Lf-Ln) and b=(f.B)/Lf (where Ln is the short- distance side distance measurement limit, Lf the long-distance side distance measurement limit, B the length of a base line, and (f) image formation length). The position of the body to be measured can be detected from those equations.

Description

[Detailed Description of the Invention] <Industrial Application Fields> The present invention projects light from a light source toward an object to be measured, and uses a semiconductor position detector placed at a certain distance from the light source to receive the reflected light. The present invention relates to an improved two-piece semiconductor position detector used in active distance detection devices that measure the distance to an object by detecting its position.

(Prior Art) FIG. 6 is a schematic diagram showing an optical system of the above-mentioned active type general distance detection device.

The light beam emitted by the light source 1 is focused by the projection lens 2 onto the surface 5 of the object to be measured.

The reflected light from the surface 5 is focused on the semiconductor position detector 4 by the light receiving lens 3 arranged at a constant base line length.

The baseline length is B, the distance to the object to be measured is taken, the distance between the light receiving lens 3 and the photodetecting element 40 (focus (image distance) is f, the light receiving lens 3
When the distance from the optical axis to the focal point on the photodetecting element 4 (the amount of movement of the spot light) is X, the relationship shown in equation (1) holds true.

x=(f-B)/L...(1)
By differentiating both sides of the above equation (1) with respect to the distance, the following equation (2) is obtained.

dx/dL−−f−B/L2 ・−(2) From equation (2), the amount of change in movement of the spot light on the semiconductor position detector 4 (
dx/d'L) is proportional to the square of the reciprocal of the distance to the object to be measured.

In the conventional general distance detection device shown in FIG. 6, the semiconductor position detector 4 is a one-dimensional semiconductor position detector (for example, Hamamatsu Photonics t'!Kiku 32153-02).
is used.

FIG. 7 shows a concave structure of such a semiconductor position detector.

The surface of a high-resistance semiconductor (silicon substrate) is formed by a uniform resistance layer, and a pair of electrodes for signal extraction are provided at both ends of this layer.

The surface layer forms a PN junction and exhibits a photoelectric effect.

In the same figure, the distance between electrode 6 (A) and electrode 7 (B) is 01, the resistance between them is Rc, the distance from electrode 6 (A) to the light incident position is X, and the resistance up to that point is RX.
shall be.

The photogenerated charge generated at the light incident position reaches the P-type resistance layer 8 as a photocurrent proportional to the incident energy of the light, and is divided inversely proportional to the resistance value up to each electrode.
It is taken out from electrodes 6 (A) and 7 (B).

Let the photocurrent generated by the incident light be ro, and the electric current []6
The currents taken out in (A) and 7 (B) are IA and I
When B is set, equation (3) is obtained.

IA=Io・C(Rc-Rx)/Rc).

1 B = r, ) - (Rx/Rc)
-(3) P-type resistance Since the eyebrows are uniform and the length and resistance value are proportional, equation (3) can be rewritten as equation (4).

IA = Io - ((C-x) /C]
.

I B = T o −x/C (4) When the current value of equation (4) is calculated, the following equation (5) is obtained.

(TA-I:)/(IA +IB)=1-2x/C・
(5) From equation (5), it can be understood that the light incident position can be known from the values of IA and 1B, regardless of the intensity of the incident light.

Moreover, when this is graphed, the graph shown in FIG. 8 is obtained.

Movement of the spot light ■For x, the current calculation value (to - IB)/(to IB to T) is the coordinate value (
0, +1), (C/2.O), and (C, -1).

By substituting equation (1) into equation (5>), equation (6) is obtained.

(I A-IB) / (I eighty rB)
=1-(2f-B)/(CL) (6) Also, by differentiating both sides of equation (6) with respect to the distance, equation (7) is obtained.

dC(IA-IB>/(IA+rB)
) /dL=2 r ・B/ (C-L2) -171
From formula (7), current calculation value (I A IB) / CI A + IB
It can be seen that the amount of change in ) is proportional to the square of the reciprocal of the distance, as in equation (2).

(Problems to be Solved by the Invention) As described above, the amount of change in the current calculation value of the conventional semiconductor position detector is proportional to the square of the reciprocal of the distance.

Therefore, in order to use this semiconductor position detector as a distance detection device and obtain an output value proportional to distance, it is necessary to create a linear correction table using a computer or the like and convert the output value.

When using a distance detection device as a visual sensor for an industrial robot, it is essential that its output value be proportional to distance.

The configuration of the distance detection device becomes complicated and expensive, and since software is involved, it becomes impossible to realize a distance detection device with high-speed response.

The object of the present invention 7 is to provide a two-split type semiconductor capable of extracting a signal current having distance information proportional to a change in distance of an object to be measured by dividing a resistance layer on the surface of a semiconductor position detector. The object of the present invention is to provide a high-level FL detector.

(Means for Solving the Problems) In order to achieve the above object, the two-segment type semiconductor position detector according to the present invention uses a triangulation method to detect the incident position τ of the reflected light from the object to be measured of the projected light. In a one-dimensional semiconductor position detector used in a distance detection device, the light-receiving surface of the semiconductor position detector is insulated and separated along a curve, an electrode is provided on each light-receiving surface, and reflected light is transmitted to each of the separated incident on the light receiving surface,
A generated current corresponding to the incident area is taken out from both electrodes, so that a distance ti? proportional to the distance of the object to be measured is obtained. It is configured to extract a signal current having information.

The two-segment semiconductor position detector has an N+ layer forming a common terminal on the back side of the silicon substrate, a rectangular PFi serving as a light-receiving surface is insulated and separated by a separation layer on the front side, and an electrode for signal current extraction is provided on each two layers. In the configuration in which H(x) +W (x) +I=WW (x) is placed at the position X from the light source side of the light receiving surface.
The relationship =a x/(x+b) can be established.

However, W is the width of the semiconductor position detector, ■ is the length of the separation layer in the width direction, H(x) is the length of the light receiving surface on the light source side in the width direction,
W(x) is the widthwise length of the other side light-receiving surface, a, b
is a constant.

Note that the constants a and b can be defined by the following equations.

a = Lf (W - I) / (Lf - Ln)
b = (f-B) /Lf However, Ln is short range! 11 (, I[lJ distance measurement limit, L
f is the far distance III ill [lJ distance limit, B is the baseline length,
f is the distance between the light receiving lens and the detector (imaging distance).

(Example) The present invention will be described in more detail below with reference to the drawings and the like.

FIG. 1 is a plan view showing a first embodiment of a two-part semiconductor position detector according to the present invention.

FIG. 2 is a cross-sectional structural diagram of the two-part semiconductor detector.

Two layers 15 and 16 separated by a separation layer 14 formed on the silicon substrate 22 are light-receiving surfaces and are connected to current extraction electrodes 12 (A) and 13 (B), respectively.

In addition, an N+ layer 23 is formed on the back side, and a common electrode 24 is formed on this.
is connected.

The distance measurement range of the distance detection device is from Ln (short distance II+) to Lf (long distance side).

This semiconductor position detector is combined with the optical system as shown in FIG. 6 described above.

The left electrode 12(A) of the two-part semiconductor position detector is placed on the light source 1 side in FIG.

The spot light position where the reflected light flux from the object to be measured at the distance Lf is focused by the light receiving lens is the spot light position -112 (A) on the left side of the two-segment type semiconductor position detector shown in Fig. 1, and the spot light position Ln. It is set near the right electrode 13(B).

When the base line length of the optical system is B, and the distance from the light receiving lens to the light receiving surface of the two-piece semiconductor position detector for distance measurement is f, the distance F is
The linear spot light position 5X at Ji L x is as follows (
8) It is expressed by the formula.

x=f-B ・((1/Lx)-(1/Lf))...
-(8) Also, the effective length C of the light-receiving surface is expressed by equation (9).

C= f−B ・((1/Ln)−(1/L r))
(9) In FIG. 1, pN! of the two layers separated by the separation layer 14 is caused by the incident light. The photocurrent generated in the portion 5 is extracted from the electrode 12 (A), and the photocurrent from the two layers 16 is extracted from the electrode B (13).

It is assumed that a reflected light beam from a distance Lx is irradiated in the form of a narrow slit light onto the shaded area in the figure.

The total photocurrent generated at this time is the photocurrent extracted from the IO electrode 12 (A) and the electrode 13 (B), respectively.
and 1B, the width of PF#15 in contact with electrode 12 (A) is H(x), and the two layers 16 in contact with electrode 13 (B)
Let the width of W(x) be W(x).

Here, when the width of the slit light is sufficiently small, the photocurrents IA and IB taken out are expressed by the following equations (10) and (11).
It can be approximated by Eq.

IA = H(x) ・Io / CH(x)+W (
x))・・・・・・00) TB mW (x) ・Io / (H(x)+W
(X)) (11) Note that the following relationship holds between H(x) and W(x).

H ('x) + T + W (x) mW where: W is the total width of the semiconductor position detector, ■ is the width of the separation layer 14 in the width direction, and the current calculation value is expressed by equation (12), and the incident light intensity is The irradiation position can be determined regardless.

(IA-IB) / (IA + IB) = (H(x)-W (x)) / (H(x) +w (X)) ・(12) In the same figure, irradiation at distance Lx from the irradiation position at distance Lf Assuming that the distance to the position is It becomes a linear relationship.

W(x) = (L2 f/ (L f-Ln)')・(x
/ (Lf -x+f-B)) ・ (W-1)
...... (13) W(x), which expresses (13) more generally, is W(x
) = a / (x + b).

However, a, b: constant H(x) mW −I −W (x) −(1
4) When the setting condition of the optical system is set to f-B=Lf for the general formula (13), the formula (13) is transformed into the following formula (15).

W(x) = (L f/ (L f - Ln) ) ・ (x/ (x+1)) ・ (W - I) - (15
) Here, by substituting into equations (8) and (14), we get (16
) and (17) are obtained.

W (x) = (W-I,) ・ ((L r-Lx) / (L f-Ln> )...
(16) H(x) - (W -1) ・ ((Lx-Ln)/ (Lf-Ln))... (1
7) By substituting equations (16) and (17) into equation (12), equation (I:) is obtained.

(IA IB) / (T eighty IB) =
1- (2・(Lf-Lx) / (Lf-4,n)
)...(I:) That is, if the widths W(x) and H(x) of the two layers satisfy the conditions of formulas (13) and (14), (1 day)
According to the formula, the current calculation value changes linearly with respect to the distance to be measured Lx between the distance measurement ranges Ln to Lf.

FIG. 3 shows still another embodiment of the two-part semiconductor position detector according to the present invention.

Pff128 and 29 divided by separation layer 27 connect to electrode 25 through contact holes 30 and 31, respectively.
and 26.

In the structure shown in FIG. 1, if the length of the slit light irradiated onto the light receiving surface is shorter than the width W, it cannot be approximated by the conditions of equations (13) and (14).

In this embodiment, by narrowing the width of the basic components and arranging a plurality of them in parallel to form a pattern as shown in Figure 3, it is possible to use the slit light even if the length is shorter than W. It is something.

In the embodiment shown in FIG. 3, the reference measured distance is L ref
This is the pattern when the distance measurement range is set to Lref fo, 5 Lref.

As a result, Lf=1.5Lref, Ln=0.5Lr
ef.

1. Set f−Ln=Lref, and set the optical system setting conditions to f・
When B=Lf=1.5Lref, equations (13) and (14) become equations (19) and (2o).

W (x)= (W-1) ・ (1,5x/ (
x+ 1))...(19) H(x)= (W-1) ・ ((1-0,5x) / (x+ 1))...
(2o) In equations (19) and (20), the variable X may be calculated from 0 to the effective light-receiving surface length C and plotted.

FIG. 4 is a circuit diagram showing an embodiment of an arithmetic circuit for a distance meter using a two-part semiconductor position detector according to the present invention.

In this embodiment, the output of the two-segment type semiconductor position detector 32 is converted into a current voltage by an AC coupling method via a capacitor, and then the output is obtained from a pair of output terminals (electrodes A and B) of the two-segment type semiconductor position sensor 32. The calculation corresponding to the difference (I8−IB) and the sum CIA+IB) of the photocurrents is executed.

The signal sampling circuit (detailed circuit example is shown surrounded by a broken line below) allows the light source 1 shown in FIG. 1 (light source 34 in FIG.
) is on and off with two sample and hold circuits, and an operational amplifier is used to
The difference is output.

This circuit allows extraction of only signal components.

This signal component is calculated by an analog divider 33 and output.

The relationship between this output value and the measured distance Lx is shown in FIG.

In the circuit shown in Fig. 4, the sum of photocurrent values (IA+IB) is constantly monitored, and the light emission intensity of the light source 34 is controlled so that this value remains constant, so that the arithmetic circuit shown in the figure operates in a stable state. can be done.

(Effects of the Invention) As explained in detail above, the two-segment semiconductor position detector according to the present invention is used in a distance detection device for triangulation that detects the incident position of reflected light from an object to be measured of projected light. In the one-dimensional semiconductor device detection device, a resistance layer connected to an electrode on a light source side of the distance detection device of the semiconductor position detector and a resistance layer connected to an electrode on the opposite side from the light source are insulated along a curve. The reflected light is incident on each of the separated resistance layers, and a generated current corresponding to the incident area is extracted from both electrodes, thereby producing a signal having distance information proportional to the amount of change in the distance of the object to be measured. It is configured to extract electric current.

Therefore, it is possible to realize a linear relationship between the current calculation value obtained from the semiconductor position detector and the distance to be measured.

Therefore, it is possible to realize a distance detecting device that is cheaper, smaller, and lighter than a conventional distance detecting device that requires an additional computer to perform linear correction. Furthermore, since the current calculation value can be obtained using only a simple analog calculation circuit, it is possible to realize a distance detection device with a high-speed response that cannot be realized using a computer.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a first embodiment of a two-part semiconductor position detector according to the present invention. FIG. 2 is a cross-sectional structural diagram of the two-part semiconductor position detector. FIG. 3 is a plan view showing a second embodiment of the two-part semiconductor position detector. FIG. 4 is a circuit diagram showing an embodiment of an analog calculation circuit that processes the output of a two-part semiconductor position detector. FIG. 5 is a graph showing the relationship between the distance to be measured and the current calculation value of the two-part semiconductor position detector according to the present invention. FIG. 6 is a graph showing an optical system of a distance detecting device using the conventional three-round side-exit method. FIG. 7 is a cross-sectional structural diagram of a conventional semiconductor T detector. FIG. 8 is a graph of the incident light position and current calculation value by a conventional semiconductor position detector. 1...Light source 2...Emitter lens 3...Receiver lens 4...Semiconductor position T detection Vessel 5...
. . . Target III constant 6 . . . Electrode (A) 7 . . . Electrode (B) 8 . . . P-type resistance layer 9 ......N+ layer 10...Common electrode 11...High resistance layer (1 layer) 12...
...... Electrode (A) 13 ...... Electrode (B) 14 ...... Separation layer 15 ...... Electrode (A) P-employee I met 16.
......Two layers 25 in contact with electrode (B)...
...... Electrode (A) 26 ...... Electrode (B) 27 ...... Separation layer 28 ...... Electrode (A) Connected 2 layers 29
......Two layers 30 connected to electrode (B)...
......Contact hole 31 of electrode (A)...
・・・・・・Contact hole 32 of electric h (B)
...Two-segment type semiconductor position detector 33...
・・・・・・Analog divider patent applicant Hamamatsu Photonics Co., Ltd. Agent Patent attorney Inoro Juko 4Z Ko 5 Shigai 6 diagram

Claims (3)

[Claims] (1) In a one-dimensional semiconductor device detector used in a triangulation distance detection device that detects the incident position of reflected light from a measured object of projected light, the light-receiving surface of the semiconductor device detector is curved. An electrode is provided on each light-receiving surface, and the reflected light is incident on each of the separated light-receiving surfaces, and a generated current corresponding to the incident area is taken out from both electrodes, thereby changing the distance to the object to be measured. A two-part semiconductor device detector characterized in that it is configured to extract a signal current having proportional distance information. (2) The two-segment semiconductor device detector has an N^+ layer forming a common terminal on the back side of the silicon substrate, and a rectangular P layer serving as a light-receiving surface is insulated and separated by a separation layer on the front side.
In a configuration in which signal current extraction electrodes are arranged in the layer,
The two-segment type semiconductor position detector according to claim 1, wherein the following relationship is established at a position x from the light source side of the light receiving surface. H(x)+W(x)+I=W W(x)=ax/(x+b) where W: Width of the semiconductor position detector I: Length of the separation layer in the width direction H(x): Light receiving on the light source side Length in the width direction of the surface W(x): Length in the width direction of the light-receiving surface on the other side a, b: More than a constant (3) The two-segment type semiconductor position detector according to claim 2, wherein the constants a and b are given by the following equations. Note a=Lf(W-I)/(Lf-Ln) b=(f・B)/Lf Ln: Near distance measurement limit Lf: Far distance measurement limit B: Baseline length f: Light receiving lens and detection The distance between the instruments (imaging distance) or more