JPS5827111A - Automatic focusing device - Google Patents

Abstract

PURPOSE:To perform automatic focusing of a lens for forming a light spot to be disposed in front of a semiconductor optical position detecting element or a lens to be used in common with said lens by making the former lens movable in the optical axis direction. CONSTITUTION:A lens L1 is supported by a supporting member 13, and is moved in the optical axis direction by the revolution of the output shaft 12a of a motor 12. The detecting electrode of a semiconductor optical position detecting element 10 provided behind said lens is connected to the 1st arithmetic circuit I, by which the signal Ep corresponding to the ratio b/a between an image side distance (b) and the distance (a) from the lens L1 to an object is operated and outputted. On the other hand, in the 2nd arithmetic circuit II, the actual position information (b) of the lens L1 is detected, and the signal Vp corresponding to the ratio b/a' to the object side distance a' determined by the focal length (f) of the lens L1 is operated and outputted. The signal (g) for the difference between the signals Ep and Vp is outputted from a driving circuit III, by which the motor 13 is driven in the direction where the differential signal (g) is made to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic focusing device using a semiconductor device detection element.

2. Description of the Related Art Semiconductor device detection elements that can output the position of an incident light beam are known. First, the structure of a semiconductor device detection element will be explained with reference to FIG. This device 0 has a semiconductor substrate 1 having a relatively large surface, and a semiconductor layer 2 of a conductivity type different from that of the substrate is formed on one surface of the semiconductor substrate. A resistive layer 3 is formed on the semiconductor layer 2, and two detection electrodes 4a are provided at both ends of the resistive layer 3.

4b is provided, and the substrate 3 is provided with a common electrode 5, b
Ru.

When a point-like beam of light is incident between the poles 4a and 4b, a current flows from the point of incidence to the electrode 4a through the resistance layer 3 and the electrode 4b.
A current I2 flows to. In addition, electric current 3 flows to the IT electrode. The following relationship holds between them.

Is -'L+ +T2 If the resistance of the resistance layer 3 is made uniform, the distance between the point of incidence of the light beam and the electrode 4a is Ll-, and if the distance between the point of incidence of the light beam and the electrode 4b is 2, then Ll- The relationship Tl-β2·I2 holds true. By calculating based on this relationship, the incident point of the incident light beam on the semiconductor device detection element 10 can be obtained by the following equation.

p=(Il-I2)/Ia p is the incident point of the luminous flux with the coordinates having the midpoint between the electrodes 4a and 4b as the origin and the electrode 4a as the positive direction. When the point of incidence has an area, such as a circle, p indicates its center.

The main object of the present invention is to make the lens for forming a light spot disposed in front of the semiconductor device detection element described above movable in the optical axis direction, and by this lens or a lens cooperating with this lens, an object image can be substantially changed to the semiconductor device. An object of the present invention is to provide an automatic focus adjustment device that performs automatic focus adjustment by automatically controlling the processing so that an image is formed on a desired imaging plane that is on the same plane as a detection device.

A second object of the present invention is to provide an automatic focus adjustment device in which the lens is used as a measurement lens, and a photographing lens having the same focal length is coupled and moved integrally with the measurement lens.

A third object of the present invention is to provide an automatic focus adjustment device in which the photographic lens optical system can also be used as a measurement light beam projection system.

In order to achieve the above objects, an automatic focusing device according to the present invention includes a semiconductor device detection element that generates a position signal corresponding to the position of a light spot projected onto a surface, and a focal length (0).
, and the image side distance between the lens and the detection element (
b); a light source device that emits a light beam parallel to the optical axis of the lens and separated by a certain base line length (A)'; ) and the distance (a) from the lens to the target object b
a first arithmetic circuit that calculates and outputs a signal (Ep) corresponding to a second arithmetic circuit that outputs a signal (Vl)) corresponding to the ratio b/a/ of the ratio b/a/'), and a signal (g) of the difference between the above (Ep) and (Vp);
and a drive circuit that outputs the (
g) a motor that drives the support member in a direction in which the angle becomes zero.

The configuration and principle of the automatic focus adjustment device according to the present invention will be briefly described below with reference to FIG. Figure 2 (a).

(b) and (c) are the first
゜Second. It is a schematic diagram showing a third configuration.

In each figure, ob indicates a target object, and ]0 indicates the aforementioned semiconductor device detection element. A lens Ll having a focal length f is supported in front of the semiconductor device detection element 10 and is movable in the optical axis direction. In each figure, when the lens Ll is at an arbitrary position, the distance between the lens L1 and ob is sL+, and the distance between the semiconductor device detection element 10 is b. However, this a,
b is not necessarily the formula for lens imaging in relation to f.
/f = 1/a + 1z6, but is controlled as described later to satisfy the above equation. Furthermore, if the relative position between the automatic focus adjustment device and the target object Ob is constant, then a and b are a-1-b-c(c
is a constant).

The explanation will start from the first configuration shown in FIG. 2(A). [Light source device] A light beam is emitted from 1 to the front parallel to the optical axis of Ll and separated by a base line length A. The obO image of the object irradiated by this beam creates the center (L) of the semiconductor device detection element 10.
Suppose that a light spot is formed at a point p apart from the optical axis of 1, the relationship shown in the following equation (1) holds between them.

'/a = p71; ・・・・・・・・・・・・
・・・・・・・・・・・・・・・(1) As mentioned above, the output current of the detection electrode of the semiconductor device detection element 1o is
, , I2 If the output of the common electrode is I3, the relationship (Il-Iz)/Ia=kp (k is a constant) holds between them. The first arithmetic circuit (■) is (It-I
z)/Ia and outputs the voltage Ep.

In this case, only half of the surface of the semiconductor device detection element 10 is used for detecting the incident point. (II By adding an appropriate value to I23/I3, the reference point can be moved from the center. In particular, if the reference point is set near the electrode on the light source device 11 side, the semiconductor device detection element can be used to detect the incident point. ] 0 can be used.gp becomes a voltage proportional to b//1 as shown in the following equation (2).

I+ −I2 Ab bEp =−■
−−kp = lcτ−E〒・・・・・・・・・・・・
(2) However, B=kA, the second calculation circuit ■ is the lens L
1 is obtained, and vp shown in the following equation (3) is calculated and output in relation to the known f.

-fb vp-E-T--Ebian 7 ・・・・・・・・・・・・・・・
...(3) However, a' is the distance on the object side that should correspond to the current position of the lens, and is usually a'! It is 5a. The output voltage Ep of the first arithmetic circuit I and the output Vp of the second arithmetic circuit I are connected to the drive circuit 1]1.

This drive circuit (■) is a subtracter (El) as described later.
and VpO difference g is output, and the motor 12 is driven by this g. The motor 12 drives Ll in the direction where g becomes zero. The output g of the drive circuit (2) is given by equation (4).

b g=Ep-Vp=jEi(=--)=Edanyufudana
a' af When g=o holds true in formula (4), the above-mentioned lens image formation formula 1/f=1/+1/b holds true, and the lens L
This is because l is brought to a position where the KObO image is formed on the semiconductor device detection element 10.

a) If b, then g is b as clear from equation (4)
changes monotonically with respect to changes in a, so the overall control system is a
It is stable with only one b for .

FIG. 3 shows an embodiment corresponding to the configuration shown in FIG. 2(A). The lens Ll is supported by a support member 13 guided in the optical axis direction, and the support member 13 is connected to the motor 1.
The lens L1 is moved forward and backward in the optical axis direction by rotation of the second output shaft 12a. The detection electrodes of the semiconductor device detection element 10 are respectively connected to the input terminals of the subtracter 150 of the first arithmetic circuit I, and the above-mentioned 1l-I2 is calculated here. The common electrode of the semiconductor device detection element 10 is connected to the divider 1 of the first arithmetic circuit
It is connected to the division input terminal of 5.

The output l3=(Il+I2) of the common electrode is the output (
Il-I2), Ep=(I1-I2)/I3
Output. The second arithmetic circuit (2) is constituted by a potentiometer consisting of a power source E and a resistor R. The output terminal of the potentiometer is moved in accordance with the movement of the lens Ll, and outputs the voltage Vp shown in equation (3) above, where vp indicates the position of the lens Ll and is a function of the focal length f. If b=f, Vp=O, a'=ω,
When b=2f, Vp=g, and a'=2f. Output Ep of the first and second arithmetic circuits.

Vp is connected to the input terminals of a subtracter 15 constituting the drive circuit 12, respectively, and a drive signal g for the motor 12 is obtained.

The second configuration shown in Figure 2 ←) is
A photographic lens L2 having the same focal length f is provided integrally with the lens L+ in the configuration described with reference to the drawings, and the imaging plane S is made to correspond to this lens L2.

Other configurations remain the same as described above. Lens L1
Accordingly, when a light spot image of Ob is formed on the plane of the semiconductor device detection element 10, the lens L2 is adjusted to a position where ob is imaged with respect to S.

In the third configuration, as shown in FIGS. 2(c) and 4, the photographing lens L2 is movable together with the lens Ll, and the lens L2 is used as a part of the light source device. . The lenses Ll and L2 are integrally provided on the support member 14.

The distance A between the optical axes of the lens Ll and the lens L2 becomes the base line length. lla is a reflecting mirror that directs the light from the light source to the lens L.
It is reflected in the direction of the optical axis of 2. This light is focused by the lens L2, converted into a parallel beam, and emitted in the Ob force direction. Reflector 11
a can be retracted from the optical axis, and an imaging surface S is provided corresponding to the lens L2. The other configurations are the same as those described with reference to FIG. 3 and the like. Lenses L1 and L2 are driven together and are automatically focused at the same time.

As described in detail above, in the present invention, the lens Ll is made movable, so that the arithmetic circuit can be extremely simplified.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a semiconductor device detection device used in the device according to the present invention, and FIG. 2 is a diagram showing the configuration of a semiconductor device detection device used in the device according to the present invention.
Second. Schematic diagrams showing the third configuration, FIG. 3 is a diagram showing an embodiment corresponding to the first configuration, and FIG. 4 is a schematic diagram showing the third configuration.
FIG. 2 is a diagram showing an example corresponding to the configuration of FIG. ■...First arithmetic circuit ■...Second arithmetic circuit■
...Drive circuit S...Image plane Ll, L2.
...Lens 10...Semiconductor device detection element 11...Light source device 12...Motor 13.14
...Supporting member 15.17...Subtractor】6...
Divider patent applicant Hamamatsu Television Co., Ltd. agent Patent attorney Hisashi Inoro

Claims (3)

[Claims] (1) A semiconductor device detection element that generates a position signal corresponding to the position of a light spot projected onto the surface, a lens at focal point jH1(f), and an image-side distance (b) between the lens and the detection element.
The image side distance (
b) and the distance from the lens to the target object (a) b/
a first arithmetic circuit that calculates and outputs a signal (Ep) corresponding to a second arithmetic circuit that outputs a signal ffp) corresponding to 4t compared to 4t; a drive circuit that outputs a signal (g) of the difference between the (Ep) and (Vp); and the drive circuit. According to the output (g
) for driving the supporting member in a direction in which the angle becomes zero. (2) A semiconductor device detection element that generates a position signal corresponding to the position of a light spot projected onto the surface, a measuring lens of focal length (f), and an image-side distance (
1)) a support member that makes the adjustment possible; a photographic lens having substantially the same focal length as the lens and supported integrally with the lens; and an imaging plane provided corresponding to the photographic lens. , a constant base line length (
A light source device that emits a light beam at a distance of A") and a position signal of the detection element produce a signal ( A first calculation circuit that calculates and outputs Bp ), detects the image side distance (b), and calculates (b) and (
a second arithmetic circuit that outputs a signal (vp) corresponding to the ratio b/a・ to the object side distance (a′) determined by ), and a motor that drives the support member in a direction in which (g) becomes zero by the output of the drive circuit, and is configured to automatically adjust the distance between the photographic lens and the imaging plane. Automatic focus adjustment device. (3) A semiconductor device detection element that generates a position signal corresponding to the position of a light spot projected onto the surface, a measuring lens having a focal length (f), and an image-side distance (b) between the lens and the detection element.
); a photographic lens having substantially the same focal length as the lens and integrally supported with a base length (A) apart from the lens; A light beam that coincides with the optical axis of the imaging plane can be emitted forward from between the imaging plane, the imaging lens, and the imaging lens through the imaging lens. A signal (Ep) corresponding to the ratio between the image side distance (b) and the distance (a) from the photographic lens to the target object is determined by the retractable light source device and the position signal of the detection element.
), and a first calculation circuit that calculates and outputs the image side distance (b
) and outputs a signal (Vp'l) corresponding to the ratio b/al of the object side distance (a') determined by (b) and (f) with respect to (b); , said (En
) and (v[)), and a motor that drives the support member in the direction in which (g) reaches zero by the output of the drive circuit. An automatic focusing bag (1) to (f) configured to project a light beam forward through the lens, automatically adjust the distance between the photographing lens and the imaging plane, and then retract the light source device.