JPH08320217A - Sensor for two-dimensional inclination - Google Patents

Abstract

PURPOSE: To precisely detect the inclination angle in the x-axis direction and the y-axis direction, respectively, by a two-dimensional inclination sensor which detects the two-dimensional inclination of an object to be measured such as an optical disk having a reflecting mirror face. CONSTITUTION: A light emitting light source 1 and a light receiving element 2 to receive light rays emitted from the light source 1 and reflected by an object to be measured are installed in a sensor main body. The light receiving element 2 is divided into four light receiving parts 2a-2d symmetrically on a straight line (the y-axis) which passes the light source 1 and at the same time a light shielding layer 7 having light receiving holes 7a gradually widened from the sensor origin (0) of the y-axis to the outside is formed in the whole area of the respective light receiving parts 2a-2d. The inclination angles in two-dimensional directions of the object to be measured can be detected by the outputs of the respective light receiving parts 2a-2d by computation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical reflection type two-dimensional tilt sensor for detecting a two-dimensional tilt of an object to be detected such as an optical disk having a reflecting mirror surface.

[0002]

2. Description of the Related Art FIG. 7 is a perspective view showing a schematic structure of a general two-dimensional tilt sensor (two-dimensional skew sensor) for detecting a two-dimensional tilt of an optical disk or the like. This tilt sensor is an optical reflection type sensor, and a light emitting light source 1 such as an LED (light emitting diode) and a four-division light receiving element 2 divided into four light receiving portions 2a to 2d are housed in a main body 3. .
Each of the light receiving portions 2a to 2d of the four-division light receiving element 2 is arranged symmetrically with respect to a straight line (the YY 'axis) passing through the light source 1. A lens portion 4 is provided on the upper portion of the main body 3, and a lead terminal 5 is connected to the lower portion of the main body 3.

8A and 8B are views showing the positional relationship between the light emitting source 1 and the light receiving element 2. FIG. 8A shows an equivalent circuit, and FIG. 8B shows an arrangement position viewed from the Z-axis direction. Further, reference numeral 6 in the figure denotes an object to be detected such as a CD (compact disc) having a reflecting mirror surface above the lens unit 4.

The tilt sensor having the above-described structure is provided with the Z of the lens unit 4.
The two-dimensional tilt of the object 6 arranged above the axis can be detected. That is, the light emitted from the light source 1 passes through the lens portion 4, is reflected by the mirror surface of the object 6, passes through the lens portion 4 again, and is incident on each of the light receiving portions 2a to 2d of the four-division light receiving element 2. Then, the tilt angles of the object 6 with respect to the XX 'axis and the YY' axis can be detected from the outputs of the light receiving units 2a to 2d.

For example, as shown in FIG.
Is tilted by Δθy about an axis parallel to the YY ′ axis, and the outputs of the respective light receiving portions 2a to 2d of the four-division light receiving element 2 are respectively a, b, c, d, then (a + c) − (B +
The tilt angle can be detected by performing the calculation of d), and therefore, as shown in FIG.
The inclination angle θy of the object 6 with respect to the XX ′ axis can be detected from the detection signal of (c) − (b + d).

Further, as shown in FIG.
Is inclined by Δθx about an axis parallel to the XX ′ axis, as shown in (b) of the figure, (a + b) − (c + d)
The inclination angle θx can be detected by performing the calculation of

[0007]

However, in the conventional two-dimensional tilt sensor as described above, the light receiving element 2 is used.
Since each of the light receiving portions 2a to 2d is not symmetrical with respect to the XX 'axis, there is a problem that the tilt angle of the detected object 6 cannot be accurately detected.

That is, when the object 6 to be detected is tilted about an axis parallel to the YY 'axis, the difference output of (a + c)-(b + d) changes depending on the tilt angle θy, and the difference between the -direction and the + direction is obtained. The absolute value of the output is symmetrical. However, the detected object 6 is X
When tilted around an axis parallel to the -X 'axis, (a + b)
The output of-(c + d) changes depending on the tilt angle θx,
The absolute value of the output is not symmetrical between the-direction and the + direction.

As the detected object 6 tilts, the light reflected by the detected object 6 cannot enter the lens portion 4 again, and the decentered aberration caused by the tilt of the detected object 6 causes light reception. The image on the element 2 is distorted, which affects the detection output.

When the object 6 to be detected is tilted about an axis parallel to the Y-Y 'axis, the detection output is symmetric with respect to the-direction and the + direction because the light sources 1 and 4 in the main body 3 are divided. Light receiving element 2
Is symmetric with respect to the Y-Y 'axis, and the influence of the above-mentioned distortion similarly occurs in the-direction and the + direction.

When the object 6 to be detected is tilted about an axis parallel to the XX 'axis, the light source 1 and the four-division light receiving element 2 in the main body 3 are not symmetrical with respect to the XX' axis. The influence of the above distortion is different depending on whether the detected object 6 is tilted in the − direction or tilted in the + direction. In particular, as the detected object 6 tilts in the + direction, the light reflected by the detected object 6 cannot enter the lens unit 4, and the outputs a, b, c, d become smaller.

The present invention has been made by paying attention to the above-mentioned problems, and it is possible to give good symmetry to the two-dimensional output of the light receiving element in each ± direction, and An object of the present invention is to provide a two-dimensional tilt sensor capable of accurately detecting the tilt angle in the dimensional direction.

[0013]

A two-dimensional tilt sensor according to the present invention is a tilt sensor for detecting a two-dimensional tilt of an object to be detected. The light sensor is a light emitting source and the light is emitted from the light source and reflected by the object to be measured. The light receiving element includes a light receiving element that receives light, the light receiving element has a plurality of light receiving portions that are symmetrically divided with respect to a straight line that passes through the light source, and the light transmittance is continuous from the light source side of the straight line. A light shielding layer having an increasing density gradient is provided over each of the light receiving portions, and the inclination of the object to be measured is detected from the output of each light receiving portion of the light receiving element.

In the two-dimensional tilt sensor having the above structure, the light-shielding layer of the light-receiving element has a light-receiving hole whose size is smaller or larger than that on the light source side, or is larger or smaller than that on the light source side. Those having a light-shielding portion, or those having a linear light-shielding portion whose interval is smaller to larger than the light source side,
Alternatively, it is formed by having a light-shielding portion in the shape of an inverted triangle whose width is larger or smaller than that on the light source side.

[0015]

According to the present invention, the light receiving element is divided into a plurality of light receiving portions symmetrically with respect to a straight line passing through the light source, and the entire light receiving portion has a light-transmitting layer whose light transmittance is continuously increased from the light source side. Is provided, the detection output of the light receiving element is symmetrical in ± directions with respect to each inclination of the detected object in the two-dimensional direction.

[0016]

1 is a plan view showing an essential part of an optical reflection type two-dimensional tilt sensor according to a first embodiment of the present invention.
The same reference numerals denote the same components.

In FIG. 1, reference numeral 1 denotes a light-emitting light source including a light-emitting element such as an LED, and 2 denotes a four-division for receiving light emitted from the light source 1 and reflected by a reflecting mirror surface (not shown) of an object to be detected such as an optical disk. In the light receiving element, a straight line (Y-Y '
It has a plurality of (four in this case) light receiving portions 2a to 2d which are symmetrically divided with respect to the axis.

Reference numeral 7 is a light-shielding layer having a density gradient in which the light transmittance is continuously increased from the light source side of the straight line passing through the light source 1, and is provided over the entire light receiving portions 2a to 2d of the light receiving element 2. ing. In this embodiment, the light shielding layer 7 has a circular light receiving hole 7a whose size is smaller to larger than that on the light source side, as shown in the figure. Each light receiving portion 2a in the figure
Circular hatched portions in 2d are output terminal portions, and surrounding shaded portions are light shielding portions.

The other structure is the same as that shown in FIG.
The light receiving element 2 having the light source 1 and the light shielding layer 7 is housed in the main body 3, the lens portion 4 is provided on the upper portion thereof, and the detected object is located above the lens portion 4. Further, the inclination of the object to be detected is detected from the outputs of the light receiving portions 2a to 2d of the lead terminal 6.

In the two-dimensional tilt sensor constructed as described above, when the upper object to be detected is tilted about the axis parallel to the YY 'axis, the light receiving element 2 changes its tilt angle θy. Difference output (a + c) − of each light receiving unit 2a to 2d
In (b + d), the absolute values of the outputs are symmetric in the − direction and the + direction, so that the accurate tilt angle θy can be detected.

When the object to be detected is tilted about an axis parallel to the XX 'axis, the difference output (a + b)-in the conventional configuration.
Although the absolute values of (c + d) are not symmetric in the − direction and the + direction, in this embodiment, since the light shielding layer 7 having the sensitivity gradient calculated by calculating backward from the characteristic is provided, the detection output is in the − direction and the + direction. It is corrected so that it becomes symmetric.

That is, on the four light receiving portions 2a to 2d of the four-divided light receiving element 2, a continuous pattern is formed along the Y-Y 'axis from the sensor origin (O) direction toward the outer peripheral direction so as to become denser to coarser. A light-shielding layer 7 having a high density gradient
It has a continuous sensitivity gradient along the axis. Therefore, as shown in FIG. 2, the inclination characteristic with respect to the XX ′ axis, that is, the difference output (a + b) − (c + d) is also symmetrical in the − direction and the + direction, and the inclination angle θx can be accurately detected. .

FIG. 3 is a plan view showing a second embodiment of the present invention, and the same reference numerals as those in FIG. 1 indicate the same constituent elements. In this embodiment, Y- is formed on each of the light receiving portions 2a to 2d of the light receiving element 2.
A light-shielding layer 7 having a circular light-shielding portion 7b whose size is larger or smaller in the outer peripheral direction than the sensor origin (O) direction is provided along the Y ′ axis.

Even with such a configuration, the inclination characteristic with respect to the XX 'axis is corrected as in the above-described embodiment. Therefore, the two-dimensional output of the light receiving element 2 in each ± direction can be provided with good symmetry, and the two-dimensional tilt angles θx and θy of the detected object can be accurately detected.

4 and 5 are plan views showing the third and fourth embodiments of the present invention. The embodiment shown in FIG. 4 has four divisions having linear light-shielding portions 7c whose intervals are small to large along the Y-Y 'axis from the sensor origin (O) direction toward the outer peripheral direction. The example in which the light-receiving element 2 is provided, that is, the embodiment shown in FIG. 5, also has an inverted triangular light-shielding portion 7d whose width is larger or smaller than the sensor origin (O) direction along the YY 'axis. This is an example in which the divided light receiving element 2 is provided.

Even with such a configuration, the same operational effects as those of the above-described respective embodiments can be obtained, and by providing the light receiving element 2 with a sensitivity gradient, favorable ± directions in the X and Y directions can be obtained. The symmetry can be obtained, and the accurate tilt angle can be detected.

Here, the structure of the four-division light receiving element 2 is as follows.
The light receiving portions 2A to 2D are not limited to those shown in FIGS. 1 and 3 to 5, and may be divided into triangular portions as shown in FIG. 6A, for example. In this case,
As shown in (b) of FIG.
Assuming B, C and D, the difference output in the θy direction is (AB),
The difference output in the θx direction is (CD).

The structure of the light shielding layer 7 is not limited to those shown in FIGS. 1 and 3 to 5, and for example, the light receiving hole 7 shown in FIG.
The shape of a and the light-shielding portion 7b of FIG. 3 may be a quadrangle or another shape.

1 and 3 to 5, in order to make the structure of the light shielding layer 7 easy to understand, the light receiving hole 7a and the light shielding portion 7 are shown.
Although the shapes of b, 7c and 7d are drawn to be relatively large compared to the size of the light receiving element 2, in reality, the light receiving hole 7a and the light shielding portions 7b, 7c and 7d have a considerably fine shape. is there.

[0030]

As described above, according to the present invention, the light receiving element for receiving the reflected light from the object to be detected is divided into a plurality of light receiving portions symmetrically with respect to the straight line passing through the light source, and each light receiving element is received. Since a light-shielding layer that continuously increases the light transmittance from the light source side is provided over the entire part, it is possible to provide good symmetry in the two-dimensional ± direction output of the light receiving element, and There is an effect that the tilt angle in the dimensional direction can be accurately detected.

[Brief description of drawings]

FIG. 1 is a plan view showing a main part of a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a detection signal in the first embodiment.

FIG. 3 is a plan view showing a main part of a second embodiment of the present invention.

FIG. 4 is a plan view showing an essential part of a third embodiment of the present invention.

FIG. 5 is a plan view showing an essential part of a fourth embodiment of the present invention.

FIG. 6 is an explanatory view showing another structural example of a four-division light receiving element.

FIG. 7 is a perspective view showing a schematic configuration of an optical reflection type tilt sensor.

FIG. 8 is an explanatory diagram showing a positional relationship between a light emitting source and a light receiving element.

FIG. 9 is an explanatory diagram showing a state of conventional tilt angle detection.

FIG. 10 is an explanatory diagram showing a state of conventional tilt angle detection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light emitting light source 2 4 split light receiving element 2a light receiving section 2b light receiving section 2c light receiving section 2d light receiving section 3 main body 4 lens section 6 object to be detected 7 light blocking layer 7a light receiving hole 7b light blocking section 7c light blocking section 7d light blocking section

Claims (5)

[Claims] 1. An inclination sensor for detecting a two-dimensional inclination of an object to be detected, comprising: a light emitting light source; and a light receiving element for receiving light emitted from the light source and reflected by the object to be measured, the light receiving element comprising: A light-shielding layer having a plurality of light receiving portions that are symmetrically divided with respect to a straight line passing through the light source, and having a density gradient in which the light transmittance continuously increases from the light source side of the straight line is the entire light receiving portion. A two-dimensional tilt sensor which is provided over the entire length of the light receiving element and detects the tilt of the object to be measured from the output of each light receiving portion of the light receiving element. 2. The two-dimensional tilt sensor according to claim 1, wherein the light shielding layer has a light receiving hole whose size is smaller than that of the light source side. 3. The two-dimensional tilt sensor according to claim 1, wherein the light-shielding layer has a light-shielding portion whose size is larger or smaller than that on the light source side. 4. The two-dimensional tilt sensor according to claim 1, wherein the light-shielding layer has a linear light-shielding portion having a small to large distance from the light source side. 5. The two-dimensional tilt sensor according to claim 1, wherein the light-shielding layer has an inverted triangular light-shielding portion whose width is larger or smaller than that on the light source side.