JP3268918B2 - Optical position detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical position detecting device, and is mainly used for an active type distance measuring device which projects distance measuring light to a subject and receives the reflected light to measure a distance. The present invention relates to an optical position detecting device.

[0002]

2. Description of the Related Art Conventionally, a PSD as shown in FIG.
(Position Sensitive Device) is used. This PSD is configured such that electrodes 41 and 42 are provided opposite to a light receiving surface 40 and a resistance layer 43 is provided therebetween.
Then, the reflected light of the distance measuring light is transmitted to the light receiving surface 40 via the distance measuring device.
When the light is condensed on the top, the light spot 45 causes the electrodes 41, 42
Currents I ₁ , I ₁ divided by the magnitude of the resistance
₂ is output through each of the electrodes 41 and 42. And
The position of the light spot 45 is known from the magnitudes of the currents I ₁ and I ₂ . In the example of FIG. 3, the position of the light spot 45 moves in the direction of the arrow b as the distance from the lens to the subject becomes shorter, and moves in the direction of the arrow a as it becomes farther.

On the other hand, active AF (automatic focusing)
In most cameras that use, when the distance from the lens to the subject is too short, a "short distance warning" is issued by blinking an LED or the like in the viewfinder to inform the photographer that proper shooting cannot be performed. .

[0004]

For this reason, it is desirable to make the short distance warning range 46 as wide as possible. However, if this warning range is widened, the following inconvenience will occur. 46 is set narrow.

In FIG. 3, as an example, the photographing distance is 0.6
m, a short distance warning range 46 is set, and a "short distance warning" is issued when the shooting distance is 0.6 m or less. Therefore, in order to increase the short distance warning range 46, as shown in FIG. 4, the area of the light receiving surface 40 is enlarged in the direction of the arrow b and the resistance layer 43 is also extended, so that the light receiving region 40 for the short distance warning is formed. Just extend it. However, if the bias is constant, the 100% level of the current I ₂ is constant,
Under these conditions, the resistance layer 43 becomes longer. Therefore, as compared with the case of FIG. 3, the level of the current I ₂ corresponding to the distance 0.6m is lowered. Therefore, in this example, there is a disadvantage that the distance measurement accuracy of 0.6 m to 5 m is reduced.

Further, since the distance measurement is of the active type, the received light contains a constant white noise 47 (see FIG. 4), and the level of the current I ₂ is reduced, so that the distance measurement accuracy is improved. It will be even lower.

For such a reason, the short distance warning range 46 is usually set to be narrow. However, as a result, when the lens and the object are close to each other beyond the range of the distance measurement, the light spot 45 is set.
Is converged on the left side (arrow b side) beyond the left end 1 of the light receiving surface 40, and the position of the light spot 45 becomes undetectable. In this case, the subject is 5
Most of the cameras have functions that are internally determined and processed as being located on the TELE side farther than m.
When shooting is performed, a so-called out-of-focus photograph is completed.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a light position detecting device capable of securing a sufficient short distance warning range while maintaining the conventional distance measuring accuracy. Is to provide.

[0009]

SUMMARY OF THE INVENTION Therefore, an optical position detecting device according to the present invention comprises a first light-receiving surface provided opposite to a light-receiving surface.
And a second electrode and a second electrode on the light receiving surface from the first electrode.
A resistance layer extending toward the second electrode and terminating shortly before reaching the second electrode, and a terminal portion of the resistance layer and a second electrode electrically insulated from the light receiving surface. And a connection wiring member for electrically connecting the first and second electrodes to each other. The first electrode is arranged on the far side and the second electrode is arranged on the near side.

[0010]

The resistive layer has one end electrically connected to the first electrode, and the other end electrically connected to the second electrode via a connection wiring. Therefore, the first electrode and the second electrode
In the region where the resistive layer is formed between the electrodes, a normal PSD is formed.

Further, since the resistance layer is terminated shortly before reaching the second electrode, a region where the resistance layer does not exist is formed near the second electrode on the short distance side. It functions as a normal photodiode that detects only

With such a configuration, a PSD for detecting the position of a light spot is formed in a normal distance measurement area, and a photodiode is formed on a short distance side required for a short distance warning. Becomes It is not necessary to measure a specific distance in order to detect the "short distance warning range", but it is sufficient if a signal notifying the photographer that the distance is short can be output, and a photodiode is provided in this area. , Only the presence or absence of light reception is detected.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an optical position detecting apparatus according to this embodiment. The light position detection device 10 is a light receiving element used for active type distance measurement, receives reflected light of distance measurement light projected on a subject, and a light spot (light spot) where the reflected light is collected. Is an element that outputs a current corresponding to the position of.

The optical position detecting device 10 has a P layer (P),
It has a PIN substrate in which an I layer (I) and an N layer (N) are sequentially laminated, and the surface of the uppermost P layer (P) serving as the light receiving surface 20 has output electrodes 11 at opposite positions. 12 are provided. A resistance layer 13 extends from the output electrode 11 toward the output electrode 12.
It terminates shortly before reaching the output electrode 12. This resistance layer 1
3 is connected to the electrode section 14, and the electrode section 14 is electrically connected to the output electrode 12 via the wire 15. The I layer (I) is biased to a predetermined voltage _VEE via the electrode layer 25.

As described above, the light receiving surface 2 of the optical position detecting device 10
0, the region 20a where the resistance layer 13 exists and the resistance layer 1
A region 20b where no 3 exists is formed.

In one area 20a, when the light spot 30 of the reflected light by the distance measurement is condensed in this area, an electric charge proportional to the light energy is generated at the light receiving position, and becomes a photocurrent to become a resistive layer. Go through 13. The photocurrent is divided and taken out in inverse proportion to the distance to both ends of the resistance layer 13 with reference to the light receiving position of the light spot 30. One of the output currents is taken out via the output electrode 11 and the other is the wire 1
5 is taken out from the output electrode 12. Therefore, this region 20a is divided into currents I ₁ and I ₁ divided according to the length (the magnitude of the resistance) from the light spot 30 to both ends of the resistance layer 4.
₂ is output from each of the output electrodes 11 and 12, so that the normal P
This constitutes the SD.

In the other area 20b, when the light spot 30 of the reflected light by the distance measurement is condensed in this area, an electric charge proportional to the light energy is generated, and most of the electric charge is output from the output electrode 12. Is done. Therefore, this region 20
b, the output electrode 12 and the electrode layer 25 form the region 20
This constitutes a PIN photodiode having b as a light receiving surface.

When the light position detecting device 10 is used as a light receiving element for distance measurement, an output electrode is provided on the side (in the direction of the arrow a) where the light spot 30 moves as the distance to the subject increases. 11 and the light spot 30
The output electrode 12 is arranged on the side (the direction of the arrow b) in which is moved.

The operation of such an arrangement will be described with reference to FIG. In FIG. 2, the current output from the output electrode 11 is denoted by I ₁ , and the current output from the output electrode 12 is denoted by I ₂ . Further, the resistance layer 1 shown in FIG.
3 has the same length as the resistance layer 4 shown in FIG. 3, and the bias is also set to the same value.

When the distance from the lens to the object is about 5 m, the position of the condensed light spot 30 becomes the position closest to the output electrode 11 side, and the current I _{2 with} respect to the total output current (I ₁ + I ₂ ) Is 0% (at this time, I ₁ is 1
00%). Then, as the distance between the lens and the subject approaches, the position of the light spot 30 moves in the direction of arrow b.
At this time, although also increases the proportion of current I ₂ to be outputted, since the length of the resistive layer 13 is set to the same as that of FIG. 3 described above, the proportion of this increase is also equal.

When the distance from the lens to the object is 0.6 m, a "short distance warning" is issued by blinking an LED or the like in the viewfinder to notify the photographer that proper photographing cannot be performed. The value of the current I ₂ when the distance is 0.6m also the same value as that of Figure 3 described above.

Further, when the distance between the lens and the object is short, the position of the light spot 30 is closest to the vicinity of the end of the resistance layer 13 and the current I _{2 with} respect to the total output current (I ₁ + I ₂ ). Is 100%.

When the distance between the lens and the subject is further reduced, the position of the light spot 30 moves into the area 20b. In the case of FIG. 3 described above, the light receiving surface no longer exists at this position, and the measurement became impossible, so that a short-range warning could not be issued. In the case of the present embodiment, a PIN photodiode is formed at this position, and an electric charge proportional to the light energy is generated at the light receiving position. In this case, since the distance to the subject is short, the amount of reflected light is large. However, this charge does not flow to the resistance layer 13, but directly or via the electrode portion 14 and the wire 15.
2 and output as current I ₂ . Thus, when the light spot 30 is focused in the region 20b from the terminal end of the resistor layer 13, the ratio of the current I ₂ is becomes always 100%, within the range to point 30 issues a short distance warning Positioning can be reliably detected. The size of this region 20b (length along the moving direction of the light spot 30) is in some cases increased by the desired current I ₂ in the case where the light spot 30 in the region 20b is focused always 100%. For this reason, the range in which a short distance warning can be issued can be expanded as long as necessary.

In this embodiment, an example is shown in which the optical position detecting device is formed on a PIN substrate. However, the present invention is not limited to this configuration, and any device structure capable of forming a PSD can be applied. . The output electrode 12 and the electrode section 14
Is connected using the wires 15, but the present invention is not limited to this configuration.
It is only necessary to be able to electrically connect

[0026]

As described above, the optical position detecting device according to the present invention terminates the resistive layer extending from the first electrode to the second electrode shortly before reaching the second electrode. Accordingly, a region functioning as a PSD and a region functioning as a photodiode can be formed on one light receiving surface. By arranging the region constituting the photodiode on the short distance side required for the short distance warning, the short distance warning region can be expanded without changing the length of the resistance layer constituting the PSD. can do. As a result, it is possible to maintain a sufficient distance measurement range while maintaining the conventional distance measurement accuracy.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an optical position detecting device according to an embodiment.

[Figure 2] with showing the light receiving surface of the optical position detecting device shown in FIG. 1 is a diagram illustrating a light spot position and relationship between the current I ₂ of the light-receiving surface.

FIG. 3 shows a light receiving surface of a conventional optical position detecting device,
It is a diagram illustrating a light spot position and relationship between the current I ₂ of the light-receiving surface.

FIG. 4 is a diagram showing a light receiving surface when a short distance warning area is enlarged in the optical position detecting device of FIG. 3, and showing a relationship between a light spot position on the light receiving surface and a current I ₂ .

[Explanation of symbols]

10: Optical position detecting device, 11: Output electrode (first electrode), 12: Output electrode (second electrode), 13: Resistive layer,
14 ... electrode part, 15 ... wire (connection wiring member), 20 ...
Light receiving surface, 20a area, 20b area, 30 light spot.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B 11/00-11/30 102 G01C 3/00-3/32 G02B 7/11

Claims (1)

(57) [Claims] 1. A light position detecting device for receiving distance measuring light reflected by a subject on a light receiving surface and outputting a current signal depending on a position of a light spot condensed on the light receiving surface, wherein: First and second electrodes provided facing each other, and extending from the first electrode toward the second electrode on the light receiving surface and before reaching the second electrode. And a connection wiring member that electrically connects a terminal portion of the resistance layer and the second electrode while being electrically insulated from the light receiving surface. An optical position detecting device, wherein one electrode is arranged on a long distance side, and the second electrode is arranged on a short distance side.