JPH04318415A - Position detecting apparatus - Google Patents

Abstract

PURPOSE:To miniaturize a photodetector having a position detecting function and a peripheral circuit for electrically processing outputs of the photodetector in a position detecting apparatus which measures the distance to an object. CONSTITUTION:A PSD 12 as a position detecting apparatus, a PNP transistor 13, an NPN transistor 14, and a resistance 15 which constitute a peripheral circuit of the apparatus are positioned on the same chip thereby to form an integrated circuit. A light shielding aluminum plate 6 is formed on the surface of the integrated circuit except for a photodetecting surface 5 of the PSD 12, thereby to prevent the erroneous operation of the peripheral circuit.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detection device that generates a position detection signal according to the distance to an object to be inspected.

0002

2. Description of the Related Art Conventionally, a position detection device (PSD) for measuring the distance to an object to be inspected has been known. FIG. 4 is a block diagram for explaining the measurement principle of such a position detection device, in which light from a light source 10 such as a laser or LED is irradiated onto an object 11 to be inspected, and the reflected light is reflected by a condensing lens 13.
The light is focused and projected onto the PSD 12 equipped with a light receiving element. Currents I1 and I2 are obtained from both ends of the PSD 12, which vary depending on the receiving position of the reflected light. By converting this current to voltage and calculating the ratio, PSD
The incident position of the reflected light on 12 is measured. That is, when the distance to the inspection object changes, the incident position of the reflected light on the PSD 12 changes, so the calculation output becomes a position detection signal corresponding to the distance to the inspection object.

FIG. 5 is a block diagram showing the configuration of an example of an arithmetic circuit, in which the current I1 appearing across the PSD 12
, I2 is a current-voltage conversion circuit (IV conversion circuit) 1a
, 1b, respectively, resulting in voltages V1 and V2. These voltages are appropriately amplified by amplifiers 2a and 2b and supplied to arithmetic circuit 3. For example, the arithmetic circuit 3 (V
1 −V2 )/(V1 +V2). The position detection signal calculated by the calculation circuit 3 is supplied to a signal processing circuit 4 which performs appropriate signal processing. Signal processing circuit 4
For example, it is configured by a combination of an appropriate window comparator, etc., for outputting distance information as three types of signals: small, medium, and large depending on the polarity and level of the position detection signal, but it is not limited to this. do not have.

0004

[Problem to be solved by the invention] As mentioned above, PSD
Reference numeral 12 denotes an individual device, and if this is to be used, a peripheral electric circuit as shown in FIG. 5 is required. However, since the PSD and the peripheral electric circuit are separate devices, there are disadvantages in that the number of parts is large and the mounting area is large. Furthermore, there are various drawbacks such as an increase in the number of man-hours for wiring, variations in the characteristics of each circuit cannot be avoided, and disturbance performance is also deteriorated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a small and stable position detection device in order to overcome the drawbacks of the conventional techniques.

[0006]

[Means for Solving the Problems] The position detection device of the present invention is characterized in that a light receiving element having a position detection function and a peripheral circuit for electrically processing the output of the light receiving element are formed on the same chip. do.

[0007]

[Operation] According to the position detection device having the above configuration, a light receiving element having a position detecting function and a peripheral circuit for electrically processing the output of the light receiving element are arranged on the same chip. ).

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the position detection device of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a plan view and a sectional view of an IC in which a light receiving element having a position detection function and peripheral circuits are integrated.

In FIG. 1b, a PSD 12 having a light receiving surface 5 and a position detection function, and a PSD 12 forming a peripheral circuit are shown.
An NP transistor 13, an NPN transistor 14, and a resistor 15 are arranged on the same chip. Note that the configuration of the peripheral circuit is not limited to these combinations.

[0011] In these IC structures, a PSD 12 is formed by forming a PN junction of a high resistance layer and providing a light receiving surface in the wafer manufacturing process of the conventional IC manufacturing process. Further, an aluminum electrode 7 is connected to each element, and an insulating film 8 electrically insulates each element. Further, the aluminum electrodes are electrically connected by a pattern surface (not shown).

Further, the surfaces other than the light-receiving surface 5 are covered with an aluminum plate 6 as a light-shielding plate to prevent malfunction of each circuit.

[0013] If the one-chip component thus formed is sealed in a package such as a transparent resin whose light-receiving surface can receive light, an IC integrating a PSD and peripheral circuits is formed. A plan view of this is shown in FIG. In addition, in Figure 3, I
Pads 8 for connecting gold wires connected to transmit and receive signals from the IC are appropriately provided at necessary locations on the periphery of the IC.

[0014]

[Effects of the Invention] As described above, according to the position detection device of the present invention, since the PSD and the peripheral circuit are formed as an integrated IC, the number of parts can be reduced and the mounting area can be reduced. At the same time, variations in each element can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the configuration of an embodiment of a position detection device of the present invention.

FIG. 2 is a sectional view showing the configuration of an embodiment of the position detection device of the present invention.

[Fig. 3] A plan view of the position detection device of the present invention integrated into an IC.

[Figure 4] Block diagram for explaining the principle of PSD

[Figure 5] Block diagram showing the configuration of one embodiment of PSD and peripheral circuits

[Explanation of symbols]

1a, 1b Current-voltage conversion circuit 3 Arithmetic circuit 5 Light receiving surface 6 Aluminum plate 12 PSD

Claims (1)

[Claims] 1. A position detection device characterized in that a light receiving element having a position detection function and a peripheral circuit for electrically processing the output of the light receiving element are formed on the same chip.