JPH10300418A - Light sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more accurately detect an object using a sensor which detects the position, etc., of a subject for detection by taking in light reflected from the object for detection. SOLUTION: An LED(light emitting diode) 2 illuminating an object for detection and a PD(photodiode) 3 receiving the light reflected therefrom a installed at a predetermined interval to each other in a case 1, and the light reflected from the object for detection is made to impinge on the light receiving part of the PD 3 as a spot of light; the light receiving part is split into two in such a manner that their boundary has a predetermined angle β to the direction in which the spot of light moves according to the position of the object for detection, and the position, etc., of the subject for detection is computed from the outputs of the two light receiving parts 3c, 3d split apart.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light detection sensor for detecting the position (distance) and angle of a detected object by taking in reflected light from the detected object.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a basic configuration of a light detection sensor for measuring a distance to an object. This sensor has the same configuration as that of a distance measuring sensor using a triangulation method.
L as a light emitting element inside the sensor body 1 having a case
An ED (light emitting diode) 2 and PDs (photodiodes) as light receiving elements are arranged at predetermined intervals, and respective condensing (imaging) lenses 4 and 5 are arranged as shown in the figure.

As shown in FIG. 4, the PD 3 is divided into two parts so that the light receiving part has the same light receiving area at 3a and 3b, and outputs (currents) are separately taken out. The light receiving element having the two-segment structure is a PD3
May be replaced by a PSD (position sensitive device).

In the sensor having the above-described structure, light emitted from the LED 2 is condensed by the lens 4 on the light emitting side, and is irregularly reflected on the surface of the detection target (reflective object). A part of the irregularly reflected light becomes a light spot S by the lens 5 on the light receiving side and is collected at a certain position (center x) on the light receiving portion of the PD 3 according to the position of the object.

[0005] That is, PD3 according to the distance to the object
The position X of the center x of the light spot S is determined by the distance D between the lens 4 and the lens 5 and the distance from the lens 4 to the object. Is L, and the distance from the lens 5 to the light receiving surface of the PD 3 is f.
Then, approximately X = (D / L) × f.

Here, in a distance measuring sensor using a light receiving element having a two-part structure as described above, when turning on (ON) and off (OFF) with a certain distance L of an object as a threshold value, each light receiving element X = (D /
L) The position of X determined by xf. In the example of FIG. 4, the boundary between the light receiving units 3a and 3b is set to the position of X determined by the above equation.

Assuming that the photocurrents from the light receiving portions 3a and 3b are Ia and Ib, respectively, when the object is at the threshold distance L, as shown in FIG.
And the area of the light spot S on the light receiving section 3b becomes equal,
(Ia-Ib) = 0.

When the object is farther than the distance L, (Ia-Ib)> 0 by the triangulation method.
When the object is in front of the distance L, the position of the light spot S moves α outward as shown in FIG. 6B, and the area of the light spot S on the light receiving unit 3b is larger than that of the light receiving unit 3a. And (Ia−Ib) <0.

Therefore, if the threshold value is set using a value such that (Ia-Ib) = 0 using a comparator circuit or the like, it can be turned on on the near side of the distance L and off on the far side.

FIG. 6 shows the relationship between the measured distance and the sensor output in the above-described sensor, and shows a case where the threshold value is set to 40 cm.

[0011]

However, in the above-described conventional light detection sensor, the relation between the distance L of the object and the light spot position X is given by X = (D / L) × f. , X change in inverse proportion to L, and the amount of change is small at a distant place, and large at a near point.

For this reason, as shown in FIG. 6, when the distance L changes, the value of the sensor output (Ia-Ib) does not change linearly, and the slope of the output characteristic is small on the far side and large on the near side. However, there is a problem that accurate detection cannot be performed.

When the threshold value is changed by a variable resistor or the like in order to change the position where the sensor output is turned on and off, there is a problem that the adjustment range is narrow because the slope of the output characteristic is large on the near side. Was.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and is capable of performing more accurate detection and capable of widening the adjustment range of the threshold value of the sensor output. It is intended to provide.

[0015]

The light detecting sensor according to the present invention is configured as follows.

(1) A light detection sensor for detecting the position and the like of the detected object by taking in reflected light from the detected object,
The reflected light from the detected object is incident on the light receiving portion of the light receiving element as a light spot, and the light receiving portion of the light receiving element is set in a direction in which the light spot of the reflected light moves according to the position of the detected object. The light receiving unit is divided into a plurality of light receiving units so as to have a boundary line having an angle of?

(2) A light detection sensor for detecting the position and the like of the detected object by taking in reflected light from the detected object,
The reflected light from the object to be detected is incident on the light receiving portion of the light receiving element as a light spot, and the light receiving portion of the light receiving element is divided into a plurality of light receiving portions. The position of the object to be detected and the like are detected from the outputs of the respective light receiving sections so as to change nonlinearly according to the position of the object to be detected.

(3) A light detection sensor for detecting the position and the like of the detected object by taking in reflected light from the detected object,
The reflected light from the detected object is incident on the light receiving unit of the light receiving element as a light spot, and the shape of the light spot of the reflected light is changed according to the position of the detected object. The position of the object to be detected is detected.

(4) A light detection sensor for detecting the position of the detected object by taking in reflected light from the detected object,
The reflected light from the object is incident on the light receiving section of the light receiving element as a light spot, and the setting angle of the light receiving section of the light receiving element is changed according to the position of the object to be detected. The position and the like of the object to be detected are detected.

[0020]

FIG. 1 is a sectional view showing an embodiment of the present invention, showing the structure of a PD 3 provided as a light receiving element. The light receiving section of the PD 3 has a plurality of light receiving sections 3c and 3d.
(Here, divided into two), and a predetermined angle β as shown in the figure with respect to the direction in which the light spot of the reflected light from the object moves according to the position of the object (detected object) to be measured. Are divided obliquely to the distance detection direction so as to have a boundary line

The other configuration is the same as that of FIG.
The LED 2 and the PD 3 are installed in the sensor main body 1, and the condensing lenses 4 and 5 are arranged at predetermined positions.

In the light detecting sensor configured as described above, the distance of the object is measured by taking in the reflected light from the object in the same manner as in the prior art. S is incident.

In order to turn on and off a certain distance L to an object as a threshold value, as shown in FIG.
The boundary between the divided light receiving units 3c and 3d is defined by the above-described expression X = (D
/ L) × f (see FIG. 3).

Then, when the distance L changes to the near side and the light spot S on the light receiving surface moves α from the center to the outside as shown in FIG. Fluctuations in the output value are smaller than in the conventional type. That is, the inclination of the sensor output on the near side becomes small, the adjustment range of the threshold value can be widened, and accurate detection can be performed.

FIG. 2 shows the relationship between the measured distance and the sensor output in the sensor of the present embodiment. The conventional case (NORMAL) in which the boundary of the light receiving section has no inclination is described below.
The tilt angle (45 ° and 30 °) with improved output characteristics of the present embodiment
°) is also shown.

Here, in the present embodiment, a case has been described where the boundary line to be divided with respect to the distance detection range is divided obliquely with an angle β, but the division shape may be changed. That is, the light receiving section of the light receiving element may be divided into a plurality of sections so that the area of the light receiving section of the light spot of the reflected light from the object changes nonlinearly according to the position of the object. .

The shape of the light spot of the reflected light may be changed by a lens according to the position of the object. If the light receiving surface of the light receiving element is sufficiently large with respect to the light spot, the light receiving portion of the light receiving portion may be changed. For example, the setting angle may be changed according to the position of the object.

In the above embodiment, the description has been given of the case of the distance measuring sensor using the triangulation method. However, the present invention relates to a sensor for detecting other distances, a tilt sensor for detecting the inclination of the optical disk, and other applications. Can be applied to the inclination detection sensor or the like.

[0029]

As described above, according to the present invention, since the output characteristics are improved, more accurate detection can be performed, and the adjustment range of the threshold value of the sensor output can be widened. effective.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a measurement distance and a sensor output according to the embodiment.

FIG. 3 is a cross-sectional view showing a basic configuration of a light detection sensor.

FIG. 4 is a plan view showing the structure of a conventional light receiving element.

FIG. 5 is an explanatory diagram showing a change in the position of a light spot on a light receiving portion of the light receiving element in FIG.

FIG. 6 is a diagram showing a relationship between a conventional measurement distance and a sensor output.

[Description of Signs] 1 Sensor main body 2 LED (light emitting element) 3 PD (light receiving element) 3c Light receiving section 3d Light receiving section 4 Lens 5 Lens

Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02B 7/28 G02B 7/11 Z

Claims (4)

[Claims] 1. A light detection sensor for receiving reflected light from a detected object to detect the position of the detected object and the like, wherein the reflected light from the detected object is incident on a light receiving portion of a light receiving element as a light spot. While, the light receiving portion of the light receiving element is divided into a plurality of light receiving portions so as to have a boundary line having a predetermined angle with respect to a direction in which the light spot of the reflected light moves according to the position of the detected object, A light detection sensor for detecting the position and the like of the object to be detected from the outputs of the respective light receiving sections. 2. A light detection sensor which receives reflected light from a detected object to detect a position of the detected object and the like, and the reflected light from the detected object is incident on a light receiving portion of a light receiving element as a light spot. And the light receiving portion of the light receiving element is divided into a plurality of light receiving portions so that the area of the light receiving portion where the light spot of the reflected light is incident varies in a non-linear manner according to the position of the object to be detected. A light detection sensor for detecting the position and the like of the detection target from the output of each light receiving unit. 3. A light detection sensor for receiving reflected light from a detected object to detect the position of the detected object and the like, wherein the reflected light from the detected object is incident on a light receiving portion of a light receiving element as a light spot. A light detection sensor, wherein the shape of the light spot of the reflected light is changed according to the position of the detected object, and the position of the detected object is detected from the output of the light receiving unit. 4. A light detection sensor for receiving reflected light from a detected object to detect a position of the detected object and the like, and the reflected light from the detected object is incident on a light receiving portion of a light receiving element as a light spot. And a setting angle of a light receiving portion of the light receiving element is changed in accordance with a position of the detection target, and a position of the detection target is detected from an output of the light receiving portion. .