JPH06112521A - Photoelectric conversion device - Google Patents

Abstract

PURPOSE:To obtain a photoelectric conversion device which can be manufactured by an ordinary IC processing technique and in which a signal processing circuit, etc., can be integrated on the same chip by constituting an optical position detecting element by coupling a plurality of photoelectric conversion elements arranged in a prescribed direction to adjacent ones through resistors. CONSTITUTION:An optical position detecting element is constituted by arranging a plurality of photoelectric conversion elements PD1-PDn in a prescribed direction and coupling the elements PD1-PDn to each other through resistors (r) having nearly the same resistance value and photoelectric current output terminals T1 and T2 are provided to the position detecting element. For example, the elements PD1-PDn arranged on one chip at prescribed pitches are connected to each other by their adjacent anodes through the resistors (r). In addition, the first and second terminals T1 and T2 are respectively provided to the anodes of the first element PD1 and last element PDn. In addition, the cathode of each element PD1-PDn is connected to an input terminal Ta.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device,
For example, it is applied to a device for detecting the position of light such as a distance sensor or a distance measuring photoelectric switch.

[0002]

2. Description of the Related Art The PSD shown in FIG. 1, that is, an optical position detecting element 10 is known as a device for detecting the position of light.
An equivalent circuit of this position detecting element is shown in FIG. That is, the terminal Ta is connected to the N layer serving as a common cathode, and two output terminals T1 and T2 are provided at both ends of the P layer. When light is incident on a certain position of the optical position detecting element 10, the output terminals T1 and T2 of the optical position detecting element 10 are output.
Then, two current outputs I1 and I2 are obtained, and assuming that the effective length of the optical position detecting element 10 is L, the incident position Y of the light of the optical position detecting element 10 is obtained by the following relational expression. I1 / I2 = Z2 / Z1 = (L / 2 + Y) / (L / 2−Y) (1) Therefore, if the current ratio I1 / I2 is known, the incident position Y is Y = (L / 2) × (I1 / I2-1) / (I1 / I2 + 1) (2) As described above, the optical position detection element 10 is widely used because it can electrically determine the incident position Y of light.
As shown in, there is an example applied to a photoelectric switch.

That is, in FIG. 3, the photoelectric switch 1 has a lens system 2, a light projecting section 3, a light receiving section 4 and a signal processing section 5. The light emitted from the light projecting unit 3 forms bright spots on the detected object 6, that is, 6A and 6B, and the light reflected by the detected object 6 passes through the lens system 2 and the light receiving surface of the light receiving unit 4. Form a bright spot image on top. Detected object 6
When the distance X up to (indicated by 6 as a representative of 6A and 6B in FIG. 3) changes, that is, when the detected object 6 reaches the positions shown in 6A and 6B, the position Y of the bright spot image on the light receiving surface changes. Move.
Therefore, by determining the position Y of the bright spot image on the light receiving surface, it is determined whether the bright spot image is due to the detected object 6 or at a position farther from the detected object 6 as seen from the photoelectric switch 1. It can be determined whether it is due to the background 7. Therefore, in order to determine the position Y of the bright spot image, the light position detecting element 10 shown in FIG. 1 is arranged on the light receiving surface of the light receiving unit 4. When the position Y of the bright spot image is larger than a predetermined value, the photoelectric switch emits a detection signal. Compared with the photoelectric switch of the type that detects the amount of light on the light receiving surface, this type of photoelectric switch does not change the detection distance even if the surface reflectance of the detected object 6 changes, and is in front of the background 7 where the reflectance is large. Has an extremely excellent feature such as stable detection of the detected object 6 having a low reflectance, but its optical position detecting element has an extremely shallow structure, for example, a junction of 0.3 [μm]. However, it cannot be manufactured by a normal IC process.
Therefore, the amplifier circuit cannot be integrated on the same chip.

[0004]

The problem to be solved by the present invention is that the optical position detecting element has a structurally extremely shallow junction, which makes it difficult to manufacture by an ordinary IC process.

[0005]

An optical position detecting element is constructed by connecting a plurality of photoelectric conversion elements adjacent to each other arranged in a predetermined direction with a resistor to form an optical position detecting element, and an end of this photoelectric conversion element. A photocurrent output end is provided in the section.

[0006]

The photoelectric conversion element that generates a photocurrent is determined by the position of the incident light, and the photocurrent is shunted by the division ratio of the coupling resistance. Therefore, the light is output from the ratio of the two currents obtained from the photocurrent output end. The incident position is calculated. The optical position detecting element is manufactured by a normal IC process.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. That is, in FIG. 4, a plurality, that is, n
(Where n> 2) photoelectric conversion elements PD1 and PD
, ... PDi, ... PDn are arranged in a predetermined direction and with a predetermined pitch on one chip. Further, the light conversion elements PD1, PD2, ... P
The adjacent anodes of Di, ... PDn are connected by resistors r, r having substantially the same resistance value, as shown in FIG. This constitutes the optical position detecting element 10.
A first photocurrent output terminal T1 is provided at one end of the light position detecting element 10, that is, the anode of the first photoelectric conversion element PD1.
However, the second photocurrent output terminal T2 is provided at the other end of the optical position detecting element 10, that is, at the anode of the last photoelectric conversion element PDn. On the other hand, the cathode of each photoelectric conversion element is connected to the input terminal Ta.

In the above structure, FIG. 5 is equivalently expressed as shown in FIG. Where I1, I2, I3, ...
Ii ... In is the light conversion elements PD1, PD2,
... PDi, ... PDn is a current source. In this circuit, considering that the i-th photoelectric conversion element, that is, PDi is exposed to light, the circuit is simplified to the equivalent circuit of FIG. That is, since the circuit of this figure is substantially the same as the circuit shown in FIG. 3, it is possible to detect the position Y where the light hits by the equation (2) from the current ratio of I1 and I2.

FIG. 8 shows that a portion having a large resistance value is formed between the central portions of the respective photoelectric conversion elements in the arrangement direction of the respective photoelectric conversion elements, which are substantially electrically connected by a resistance r.

Further, FIG. 9 shows that a portion having a large resistance value is formed between the lower portions of the respective photoelectric conversion elements in the arrangement direction of the respective photoelectric conversion elements. Combined with.

Since the present invention is composed of a finite number of photoelectric conversion elements, that is, n photoelectric conversion elements, if the incident light is sufficiently smaller than the pitch of each photoelectric conversion element due to the condensing of a lens or the like, the incident position Y The relationship between the photocurrent outputs I1 and I2 is stepwise as shown in FIG.

However, as shown in FIG. 11, when the pitch of each photoelectric conversion element is sufficiently small as compared with the concentration of incident light, that is, when the incident spot 11 is larger than the pitch of each photoelectric conversion element, It does not show the step-like characteristic but becomes linear as shown in FIG.

[0013]

As described above, according to the present invention, a plurality of photoelectric conversion elements are arranged in a predetermined direction, and adjacent elements are connected to each other by resistors having substantially the same value. It can be manufactured by process technology.

Further, since each photoelectric conversion element and the resistor are integrated on the same chip, there is an advantage that the S / N ratio is improved by this integration.

By integrating the arithmetic circuit and the signal processing circuit together on the same chip, it is possible to reduce the size of the device.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the principle of an optical position detecting element.

FIG. 2 is an equivalent circuit in FIG.

FIG. 3 is a vertical sectional view of a reflective photoelectric switch to which an optical position detecting element is applied.

FIG. 4 is a configuration diagram showing an arrangement state of photoelectric conversion elements of the photoelectric conversion device according to the present invention.

FIG. 5 is a circuit diagram of an optical position detecting element of the photoelectric conversion device according to the present invention.

FIG. 6 is an equivalent circuit diagram in FIG.

FIG. 7 is an equivalent circuit diagram of part of FIG.

FIG. 8 is a configuration diagram showing another arrangement state of photoelectric conversion elements of the photoelectric conversion device according to the present invention.

FIG. 9 is a configuration diagram showing still another arrangement state of photoelectric conversion elements of the photoelectric conversion device according to the present invention.

FIG. 10 is an output characteristic diagram showing the relationship between the incident spot on the optical position detection element of the photoelectric conversion device according to the present invention and the output.

FIG. 11 is a plan view showing the relationship between the light spot on the optical position detection element and the incident spot of the photoelectric conversion device according to the present invention.

12 is an output characteristic diagram of the optical position detecting element in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoelectric switch 2 Lens system 3 Light emitting part 4 Light receiving part 5 Signal processing part 6 Detected object 7 Background 10 Optical position detection element 11 Incident spot PD1, PD2, PD3, ... PDn Photoelectric conversion element r Resistance Ta terminal T1 terminal T2 terminals I1, I2, I3, ... Ii ... In Current source

Claims (2)

[Claims] 1. A plurality of photoelectric conversion elements are arranged in a predetermined direction, and adjacent elements are connected to each other by resistors having substantially equal values to form an optical position detecting element. A photoelectric conversion device provided with a photocurrent output terminal. 2. A plurality of photoelectric conversion elements are arranged in a predetermined direction, and adjacent photoelectric conversion elements are connected by resistors having substantially the same resistance value to form an optical position detection element, and the optical position is detected. A photoelectric conversion device in which a photocurrent output terminal is provided in the detection element, and the photoelectric conversion elements and the resistor are integrated on the same chip.