JPS6131979A - Photodetector - Google Patents

Abstract

PURPOSE:To simplify the constitution of a detector by placing planely a photodetector group of different exponential weights, and detecting directly an incident position of band-like light as a discrete value, so that the detecting signal can be fetched directly as a digital signal. CONSTITUTION:Sensor groups D1...D4 consisting of D11, D12,...,D21, D22,..., D31,..., and D41,..., respectively are placed planely on a photodetector 11, and each different exponential weight is put onto each group. Also, the incident light is light having a band-like irradiating shape which is orthogonal to an array of the sensor groups and extends over each group. In this state, an incident position of reflected light is determined by a deflection of a film generated in accordance with an acoustic pressure 15, and by photodetecting its reflected light by a specified sensor, a digital signal corresponding to its sensor is fetched directly, and the deflection quantity of the film 14 can be obtained as digitized quantity at a real time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a photodetector that detects the incident position of a light beam.

(Prior Art) As shown in FIG. 5, a conventional photodetector includes a large number of sensors d, d2 . d, . It was configured to detect the light incident position by using a type sensor and dividing the potential by a resistance R□tR2 from the light incident point to the extraction electrode. However, when the signals detected in this way are processed by a microprocessor, a bit conversion circuit 3, a division circuit 4, an A/D converter 5, etc. are required, making the system complicated and expensive. There was a drawback.

(Object of the Invention) The present invention solves the drawbacks of the prior art described above, and provides a photodetector that directly detects the incident position of light as a discrete value and extracts it as an n-bit digital signal. be.

(Structure of the Invention) In order to achieve the above object, first .
Second. Third. . . . The light-receiving element groups are arranged in a plane or in a layered manner, and in the case of a planar arrangement, a band-shaped light is incident so that the irradiation shape of the light spans each light-receiving element group, and in the case of a layered arrangement, The light-transmitting light-receiving element is used so that the incident light is transmitted through all the light-receiving elements in each group located at the incident position. This allows a digital signal to be extracted directly from the photodetector.

Hereinafter, embodiments will be described in detail with reference to the drawings.

(Embodiment) FIG. 1 shows a photodetector 11 according to an embodiment of the present invention, in which a first sensor group Dll, a second sensor group DZT, a third sensor group
A fourth sensor group I'at is arranged in a plane, and each of these groups includes a sensor D1 . ．． D□
3. ..., D2□tozz..., OSl..., D
41..., which are internally connected as shown in Fig. 2.

Each group is given a different exponential weight, for example, the first sensor group D□ is 2°.

The second sensor group D2 is 21. The third sensor group D8 is 22
In the fourth sensor group D4, each digit is given a certain weight, such as 23. Further, the light incident thereon has a band-shaped irradiation shape that is perpendicular to the arrangement of the sensor groups and spans each group. When using this photodetector, each sensor group is connected to the data bus 12 in group units.

FIG. 3 shows an example in which the photodetector 11 of the present invention is applied to a digital microphone.
For example, a light source such as an LED or a laser diode that emits light with good parallelism; 14 is a film that is deflected by the sound pressure 15 and reflects the light emitted from the light source 13; The degree of deflection of this film 14 varies depending on the intensity of sound pressure, and therefore the optical path of light irradiated onto the film changes after reflection. A photodetector is placed at a position to receive this reflected light. 16 is an encoder mask, and the photodetector 11 is arranged under the encoder mask. The reflected light becomes band-shaped light that spreads along the slits of the encoder mask 16, and is always incident on one of the slits.

(In the figure, the spread of reflected light is shown to be extremely wide for ease of understanding.)

As can be seen from this application example, the membrane 1 formed in response to sound pressure
The deflection of the film 14 determines the incident position of the reflected light, and when one or more specific sensors receive the reflected light, a digital signal corresponding to that sensor is directly extracted, and the amount of deflection of the film 14 is measured in real time. It can be obtained as a digitized quantity.

Note that the sensor can be easily formed using amorphous silicon or the like.

FIG. 4 shows a photodetector 18 according to another embodiment of the present invention. In this embodiment, a first sensor group D1, a second sensor group Dll, a third sensor group D31, a fourth sensor The clusters are arranged in layers. Each sensor group is internally connected as shown in FIG. 2, and the glabella is separated. q indicates the light incident position, and the structure is such that the incident light passes through all the sensors directly below it. Even with such a multilayer structure, if amorphous silicon or the like is used, the thickness can be at most about 1 μm, so even if light may be incident obliquely, the difference between the eyebrows will hardly be a problem.

In this embodiment, as in the embodiment shown in FIG. 1, the light incident position can be directly detected as a discrete value and extracted as an n-bit digital signal. Note that the incident light in this case may be a spot.

(Effects of the Invention) As explained above, according to the present invention, the incident position of light can be detected and the detected signal can be directly extracted as a digital signal, so the system configuration can be extremely simplified. This greatly contributes to price reduction.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of a photodetector according to an embodiment of the present invention, FIG. 2 is a diagram showing internal connections of the photodetector, and FIG.
4 is a sectional view showing the configuration of a photodetector according to another embodiment of the present invention, and FIGS. 5 and 6 are configurations of conventional examples, respectively. FIG. 11.18...Photodetector, 12...Data bus,
Dl...first sensor group, D2...second sensor group. D8... Third sensor group, D4... Fourth sensor group, D, 1. D-work 2..., D2□102□..., D
a□..., D4,..., sensor. Patent applicant Tohoku Ricoh Co., Ltd. 50515253 5n

Claims (2)

[Claims] (1) In a detector that receives a light beam and detects the incident position of the beam, the first, second, and third detectors have different exponential weights.
, . . . are arranged in a planar manner, and a band-shaped light is incident such that the light irradiation shape extends over the first, second, third, . . . light-receiving element groups. A photodetector characterized by directly detecting the incident position as a discrete value and extracting it as an n-bit digital signal. (2) In a detector that receives a light beam and detects the incident position of the beam, the first, second, and third detectors have different exponential weights.
A photodetector characterized in that a group of light-transmissive light-receiving elements of , .