Optical ranging sensor and warm water wash toilet seat

Abstract

A light receiving device 12 that receives reflected light condensed by a light receiving condenser means 14 has two first and second electrodes 15, 16 provided on a light receiving surface at prescribed intervals along a baseline that connects a light emitting device 11 with the light receiving device and a resistive region 21 provided between the two electrodes. An electric charge generated at the incident position of light incident on the light receiving surface of the light receiving device 12 becomes a photo current and outputted from the first and second electrodes 15, 16 via the resistive region 21. The resistance value of the resistive region 21 of the light receiving device 12 is distributed so as to be roughly inversely proportional to a distance from the optical axis of the light receiving condenser means 14 to the incident position of a light spot on the light receiving surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not intended to limit the present invention, and wherein:

FIG. 1 is a view showing the structure of an optical ranging sensor according to a first embodiment of the present invention;

FIG. 2 is a view showing the pattern configuration of the resistive region (p− layer) of a PSD used as a light receiving device of the optical ranging sensor;

FIG. 3 is a view showing the pattern configuration of the resistive region (p− layer) of a PSD used as a light receiving device of an optical ranging sensor according to a second embodiment of the present invention;

FIG. 4 is a view showing the pattern configuration of the resistive region (p− layer) of a PSD used as a light receiving device of an optical ranging sensor according to a third embodiment of the present invention;

FIG. 5 is a view showing the pattern configuration of the resistive region (p− layer) of a PSD used as a light receiving device of an optical ranging sensor according to a fourth embodiment of the present invention;

FIG. 6 is a view showing the pattern configuration of the resistive region (p− layer) of a PSD used as a light receiving device of an optical ranging sensor according to a fifth embodiment of the present invention;

FIG. 7 is a sectional view showing the structure of the PSD used for the optical ranging sensor of the first embodiment;

FIG. 8 is a graph showing the resistivity distribution of the resistive region of the PSD used for the optical ranging sensor of the first embodiment;

FIG. 9 is a graph showing a relation between the distance and the output signal of the optical ranging sensor of the present invention;

FIG. 10A is a front view of an optical ranging sensor according to one embodiment of the present invention;

FIG. 10B is a sectional view of the optical ranging sensor viewed from the line IB-IB of FIG. 10A;

FIG. 11A is a view showing the structure of the optical ranging sensor;

FIG. 11B is a plan view of the light receiving portion of a position detecting light receiving device used for the optical ranging sensor;

FIG. 12A is a graph for explaining the ratio of a total resistance at a distance from the left end of the light receiving surface of the position detecting light receiving device;

FIG. 12B is a graph showing the output characteristic of the position detecting light receiving device;

FIG. 13A is a front view and a sectional view showing a movable structure of a light receiving condenser portion of the optical ranging sensor;

FIG. 13B is a schematic view of a cross section viewed from the line IVB-IVB of FIG. 13A;

FIG. 14 is a view showing the structure of a conventional optical ranging sensor;

FIG. 15 is a graph showing the resistivity distribution of the resistive region of the conventional PSD;

FIG. 16 is a view showing the pattern configuration of the resistive region (p− layer) of the conventional PSD;

FIG. 17 is a graph showing a relation between the distance and the output signal of the conventional optical ranging sensor;

FIG. 18 is a view showing the structure of a conventional optical ranging sensor having a plurality of light emitting devices;

FIG. 19 is a graph showing the resistivity distribution of the resistive region of the conventional PSD; and

FIG. 20 is a view showing the pattern configuration of the resistive region (p− layer) of the conventional PSD.

Claims

1. An optical ranging sensor of an optical trigonometrical ranging system comprising: a light emitting device for emitting light;a light projecting condenser means for condensing the light emitted from the light emitting device and projecting the light onto an object to be ranged;a light receiving condenser means for condensing reflected light from the object to be ranged; anda light receiving device, which is arranged so that the light receiving surface thereof is perpendicular to an optical axis of the light emitted from the light emitting device and receives the reflected light condensed by the light receiving condenser means, whereinthe light receiving device has two electrodes provided at prescribed intervals on the light receiving surface along a baseline that connects the light emitting device with the light receiving device and a resistive region provided between the two electrodes,an electric charge generated at an incident position of light on the light receiving surface of the light receiving device becomes a photo current and is outputted from the two electrodes via the resistive region, anda resistance value of the resistive region of the light receiving device is distributed so as to be roughly inversely proportional to a distance from an optical axis of the light receiving condenser means to an incident position of a light spot on the light receiving surface.

2. The optical ranging sensor as claimed in claim 1, wherein the resistive region has a zigzag bent line whose line width and return pitch interval are roughly identical, and the resistance value of the resistive region is distributed so as to be roughly inversely proportional to the distance from the optical axis of the light receiving condenser means to the incident position of the light spot on the light receiving surface by changing a stroke length of the bent line configuration from one electrode toward the other electrode of the two electrodes.

3. The optical ranging sensor as claimed in claim 1, wherein the resistive region has a zigzag bent line whose stroke length and line width are roughly identical, and the resistance value of the resistive region is distributed so as to be roughly inversely proportional to the distance from the optical axis of the light receiving condenser means to the incident position of the light spot on the light receiving surface by changing a return pitch interval of the bent line configuration from one electrode toward the other electrode of the two electrodes.

4. The optical ranging sensor as claimed in claim 1, wherein the resistive region has a zigzag bent line whose stroke length and return pitch interval are roughly identical, and the resistance value of the resistive region is distributed so as to be roughly inversely proportional to the distance from the optical axis of the light receiving condenser means to the incident position of the light spot on the light receiving surface by changing a line width of the bent line configuration from one electrode toward the other electrode of the two electrodes.

5. The optical ranging sensor as claimed in claim 1, wherein the resistive region is a semiconductor layer having a zigzag bent line whose line width and return pitch interval are roughly identical, and the resistance value of the resistive region is distributed so as to be roughly inversely proportional to the distance from the optical axis of the light receiving condenser means to the incident position of the light spot on the light receiving surface by changing an impurity concentration of the semiconductor layer of the bent line configuration from one electrode toward the other electrode of the two electrodes.

6. An optical ranging sensor for detecting a distance to an object to be ranged by a trigonometrical ranging system comprising: a light emitting device;a light projecting condenser portion for condensing the light emitted from the light emitting device and projecting the light onto an object to be ranged;a light receiving condenser portion for condensing reflected light from the object to be ranged;a position detecting light receiving device, which is arranged so that a plane including the light receiving surface thereof is perpendicular to an optical axis of the light emitted from the light emitting device and receives the reflected light condensed by the light receiving condenser portion; andan integrated circuit for carrying out processing of a signal outputted from the position detecting light receiving device and driving the light emitting device in accordance with a prescribed timing, whereinthe light receiving portion of the position detecting light receiving device is divided into a plurality of light receiving regions arranged along a baseline that connects the light emitting device with the position detecting light receiving device, andthe plurality of divided light receiving regions of the light receiving portion have mutually different resistance values.

7. The optical ranging sensor as claimed in claim 6, wherein a number of divisions of the light receiving portion of the position detecting light receiving device and the resistance values of the plurality of light receiving regions are set so that the output of the position detecting light receiving device is roughly proportional to the distance of the object to be ranged.

8. The optical ranging sensor as claimed in claim 7, wherein the number of divisions of the light receiving portion of the position detecting light receiving device is five, areas of the plurality of divided light receiving regions are equalized, and ratios of the resistance values of the plurality of light receiving regions are 80:10:5:3:2 in order from the light emitting device side.

9. The optical ranging sensor as claimed in claim 6, wherein the light receiving condenser portion is movable along a direction in which a light condensing position on the position detecting light receiving device moves in accordance with the distance to the object to be ranged, andthe light condensing position on the position detecting light receiving device can be changed by moving the light receiving condenser portion.

10. A warm water wash toilet seat comprising the optical ranging sensor claimed in claim 6.