JPH0755461A - Distance-measuring device of camera - Google Patents

Abstract

PURPOSE:To use a light-projecting element and a photodetector substantially in a matrix form in order to measure the distance of many points inside a field without making a device large and without a need for a complicated circuit. CONSTITUTION:An IRED 9 has a shape which is oblong in the direction perpendicular to the base line S of a light-projecting lens 3 and a light-receiving lens 4, it is driven by a driver 10, and it emits light to a subject. Reflected signal light from the subject is made incident on PSDs 11a, 11b, 11c via the light- receiving lens 4. The PSDs 11a, 11b, 11c supply their outputs to a CPU 7 via processing circuits 6a, 6b, 6c. The CPU 7 controls the driver 10 and the processing circuits 6a, 6b, 6c, and it controls the focusing of the photographing lens of a camera by a focusing part 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device for a camera, and more particularly to a distance measuring device for a camera which projects a distance measuring light and obtains a distance to the object by a signal light reflected from the object.

[0002]

2. Description of the Related Art Conventionally, various distance measuring devices employing an active AF (autofocus) system have been developed. The conventional AF device can generally measure the distance only in the central portion of the finder screen. Therefore, in a scene in which a person is present near the left or right instead of the center of the screen, the main subject does not exist at the center point in the viewfinder screen, so the person is out of focus. It was

Therefore, for example, a camera (multi-point AF camera) has been put on the market, which is capable of focusing on a person by enabling distance measurement at three points on the screen.
FIG. 18 is a block diagram showing the configuration of such a distance measuring device for a camera.

Infrared light emitting diode (IRED) 1a, 1
b and 1c are sequentially emitted by the drivers 2a, 2b, and 2c, respectively, and are condensed and projected by a light projecting lens 3 onto a subject (not shown). Each IRED1
The reflected signal light from the subject based on a, 1b, and 1c passes through the light receiving lens 4 and the light position detection elements (PSD) 5a and 5a
b and 5c are respectively incident. Here, the projection lens 3
Since the light-receiving lens 4 and the light-receiving lens 4 are arranged apart from each other by a predetermined base line length S, the incident position of the reflected signal light changes according to the subject distance according to the principle of triangulation.

The processing circuits 6a, 6b and 6c are PSDs, respectively.
It is a circuit for detecting the incident position of the reflected signal light from the outputs of 5a, 5b and 5c. An arithmetic control circuit (CPU) composed of a one-chip microcomputer
7 is the driver 2a, 2b, 2c and the processing circuit 6
It controls a, 6b and 6c. And CPU
Reference numeral 7 calculates the distance measurement result of each point from the outputs of the processing circuits 6a, 6b, 6c, and according to the result, the focusing unit 8 controls the focusing of the photographing lens (not shown) of the camera. As the focusing distance, the one with the shortest distance or the like may be selected and adopted from the respective distance measurement results.

Such an apparatus is disclosed in, for example, Japanese Patent Laid-Open No. 62-2.
It is disclosed in Japanese Patent No. 23734. In addition, JP-A-5
No. 9-107332 discloses an AF including a light emitting / receiving element.
An apparatus for rotating a unit to measure a plurality of distance measuring points is disclosed. Furthermore, JP-A-60-60511
In the gazette, IREDs are made to sequentially emit light to generate one PSD.
There is disclosed a distance measuring device which receives light by.

[0007]

However, as shown in FIG.
In the technique as shown in (1), there is a problem that as the number of distance measuring points increases, the number of parts such as the light projecting element and its driver increases.

Further, in the device disclosed in Japanese Patent Laid-Open No. 59-107332, a mechanism system for rotating the AF unit is required, which leads to an increase in size of the device. Further, in the distance measuring device disclosed in Japanese Patent Laid-Open No. 60-60511, it is difficult to perform the processing after the distance measurement, and a complicated circuit is required.

The present invention has been made in view of the above problems, and does not increase the size of the device due to an increase in the number of parts,
An object of the present invention is to provide a distance measuring device for a camera, which is not difficult to process, does not require a complicated circuit, and can measure many points on the screen without increasing the cost.

[0010]

That is, according to the present invention, a light projecting means for sequentially projecting light along a predetermined direction in a photographing screen to change the projecting direction, and the light projecting means for projecting the light, Receiving reflected light reflected from an object in the photographing screen, detecting a receiving position of the reflected light in a direction substantially orthogonal to the predetermined direction, and a plurality of light receiving surfaces divided in the predetermined direction And a calculating means for calculating the distances of a plurality of points along the predetermined direction in the screen by the output of the selected light receiving surface among the plurality of light receiving surfaces of the light receiving means. It is characterized by having.

Further, according to the present invention, light projecting means for sequentially projecting light along a predetermined direction in the photographing screen to change the projection direction, and an object in the photographing screen projected by the light projecting means. Receiving the reflected light reflected from, the light receiving means comprising a plurality of light receiving surfaces divided in a direction substantially orthogonal to the predetermined direction, and in conjunction with the change of the light projecting direction of the light projecting means,
A control means for switching the effective light receiving surface of the light receiving means.

Further, according to the present invention, a plurality of light projecting means for sequentially projecting light in a plurality of directions within the photographing screen to change the projecting direction, and a plurality of light projecting means projecting light respectively,
A plurality of light receiving means for receiving the reflected light reflected from the object in the photographing screen, and a combination of the plurality of light projecting means and the light receiving means for measuring the distance to the object in the photographing screen. And a determination means for performing the determination.

The present invention comprises a light projecting means for projecting light onto an object, and a light receiving means for receiving the reflected light from the object and outputting two current signals depending on the light receiving position.
In a distance measuring device for a camera including a processing circuit for processing the current signal, a light-receiving surface of the light-receiving means and an output electrode corresponding to the light-receiving surface are arranged in a direction substantially perpendicular to the detection direction of the light-receiving position. The present invention is characterized in that output electrodes corresponding to a plurality of light-receiving surfaces that are divided and sandwich at least one light-receiving surface are input to a common processing circuit.

[0014]

In the distance measuring device for a camera according to the present invention, the light projecting means sequentially projects light along a predetermined direction within the photographing screen to change the projection direction. Then, the reflected light projected by the light projecting means and reflected from the object in the photographing screen is received by the light receiving means having a plurality of light receiving surfaces divided in the predetermined direction, and is substantially in the predetermined direction. The light receiving position of the reflected light in the orthogonal direction is detected. The output of the selected light receiving surface of the plurality of light receiving surfaces of the light receiving means causes the calculating means to calculate the distances of the plurality of points along the predetermined direction in the screen.

Further, the light projecting means sequentially projects light along a predetermined direction in the photographing screen to change the projection direction, and a plurality of light receiving surfaces divided in a direction substantially orthogonal to the predetermined direction. The reflected light projected by the light projecting means and reflected from the object in the photographing screen is received by the light receiving means. The effective light-receiving surface of the light-receiving means is switched by the control means in association with the change in the light-projecting direction of the light-projecting means.

Further, according to the present invention, by a plurality of light projecting means,
Light is sequentially projected in a plurality of directions within the shooting screen, the projection direction is changed, and reflected light reflected by an object within the shooting screen is projected by a plurality of light receiving units. Received light. Then, in order to measure the distance to the object in the photographing screen, the combination of the plurality of light projecting means and the light receiving means is determined by the determining means.

In the camera distance measuring device of the present invention,
Light is projected onto the object from the light projecting means, reflected light from the object is received by the light receiving means, two current signals depending on the light receiving position are output, and the current signal is processed by the processing circuit. It The light receiving means divides the light receiving surface and the corresponding output electrode into a direction substantially perpendicular to the detection direction of the light receiving position, and a plurality of light receiving surfaces sandwiching at least one light receiving surface therebetween. The output electrodes corresponding to are input to the common processing circuit.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a block diagram showing the concept of a camera distance measuring apparatus according to a first embodiment of the present invention.
The IRED 9 emits light to a subject (not shown) by the driver 10, and has a shape elongated in a direction orthogonal to the base line length S of the light projecting lens 3 and the light receiving lens 4. The reflected signal light from the subject enters the PSDs 11a, 11b, and 11c via the light receiving lens 4, respectively. The outputs of PSD 11a, 11b, 11c are
It is supplied to the CPU 7 configured by a one-chip microcomputer or the like via the processing circuits 6a, 6b, 6c. The CPU 7 includes the driver 10 and the processing circuits 6a and 6a.
In addition to controlling b and 6c, the focusing unit 8 controls the focusing of the taking lens (not shown) of the camera.

In such a structure, under the control of the CPU 7, a current is made to flow through the driver 10 and the IR
ED9 emits light. Since the IRED 9 has a shape extending in the direction orthogonal to the base line length S as described above, the projection pattern projected onto the subject through the projection lens 3 is as shown in FIG. As shown, it has a rectangular shape extending in the horizontal direction of the screen. Reflected light from the subject having this light projection pattern is transmitted through the light receiving lens 4 to the PSDs 11 a, 1
It is incident on 1b and 11c. Each PSD 11a, 11b,
Areas 13a, 13b, and 13c observed by 11c are the shaded areas 12a, 12b, and
The relationship is as indicated by 12c.

Therefore, the CPU 7 has the PSD 11a,
Processing circuits 6a, 6b, 6c connected to 11b, 11c
From the output of the light projection pattern 12 and the observation areas 13a, 1
Observation points 12a, 12b, 1 overlapping 3b and 13c
It is possible to calculate the distance to the subject existing in the portion 2c. As a result, the distance of the person 15 can be detected by the observation point 12c even in the scene shown in the screen 14 of FIG.

As described above, if the CPU 7 selects the closest distance from the distance measurement results of the observation points 12a, 12b, 12c and controls the focusing unit 8 to focus on that distance, It is possible to take a picture in focus with respect to 15.

If the distance measuring device constructed in this way is used, one driver is needed as compared with the conventional distance measuring device shown in FIG. You can see that you can get it.

FIG. 3 is a block diagram showing the arrangement of a distance measuring device for a camera according to the second embodiment of the present invention. In the above-described first embodiment, since the light of the IRED 9 is divided and used, the amount of signal light incident on each PSD is reduced. In the second embodiment, in consideration of the decrease in the signal light amount, the IRED can be scanned by the motor in the direction orthogonal to the base line length, and most of the signal light is effectively supplied to each of the divided PSDs. The distance measuring light that is incident is projected.

That is, to explain the mechanism for two-dimensionally scanning the IRED, the IRED 16 is driven and controlled by the CPU 7 via the IRED driver 10, and the light projecting lens 13 is arranged in front of it. The IRED 16 is integrally attached to the movable portion 17, and the guide rail 2 is driven by a motor 19 driven by a motor (M) driver 18 and a feed screw 20.
1 slide in the x direction in the figure. Also the contact piece 22
The switch 22 composed of a and 22b is the movable member 1
7, a switch for detecting the initial position of the IRED 16.

Therefore, from this initial position, the motor 19
Is rotated by a predetermined rotation, the IRED 16 slides by a predetermined position, and if the IRED driver 10 is controlled in synchronization, the light can be projected at equal intervals. At this time, the light projection pattern is as shown by 23 in FIG.

In this example, the light projecting pattern 23 includes 23a ...
There are six PSDs 23f, and six PSDs 24a to 24f are provided to receive the light through the light receiving lens 4.
Therefore, the outputs of these PSDs 24a to 24f are supplied to the CPU 7 via the processing circuits 25a to 25f.

When the distance measuring light is projected in the direction of the projection pattern 23a, the PSD2 is processed by using the processing circuit 25a.
By detecting the signal light incident position from the output of 4a, it is possible to detect the subject distance existing in the direction of the light projection pattern 23a.

Next, the operation of the distance measuring device constructed as described above will be described with reference to the flowchart of FIG. The CPU 7 controls this flowchart. First, in step S1, the motor 19 is reversely rotated to move the IRED 16 (movable member 17) to a position where the switch 22 is turned on to initialize the slide position. At this time, it is assumed that the angle formed by the principal points of the IRED 16 and the projection lens 3 and the angle formed by the principal points of the PSD 24a and the light receiving lens 4 are designed to match. Then, in step S2, the IRED 16 emits light. PSD is 24
Since a is used, distance measurement is performed using the output result of the processing circuit 25a.

Next, in step S3, the M driver 18
The motor 19 is energized for a predetermined time through the motor to rotate the motor 19 by a predetermined amount. The rotation of the motor 19 causes the feed screw 20
Is rotated and the movable member 17 slides along the guide rail 21, the light emitting point of the IRED 16 changes in the arrow x direction in the figure. As a result, the relative position between the IRED 16 and the light projecting lens 3 changes, so that the direction in which the distance measuring light is projected changes. In this state, the IRED 16 is caused to emit light in step S4. At this time, the direction of the light beam projected on the IRED 16 is changed by the PSD through the light receiving lens 4.
Since 24b coincides with the gaze direction, PSD24
Distance measurement is performed using b. That is, the processing circuit uses 25b.

Next, in step S5, the light projection pattern is changed, and then in step S6, the IRED 16 emits light.
Distance measurement is performed using the PSD 24c and the processing circuit 25c. In this way, the distance measurement at each point is repeated. In this way, distance measurement of the subject existing at each point of the light projection patterns 23a to 23f is performed according to the flowchart up to step S12.

Then, in step S13, the closest distance is selected from these distance measurement results. Next, in step S14, focusing is performed on the closest distance. As a result, for example, as shown in FIG.
Even when there is no subject in the center of the screen 14, the person 15 can be correctly focused.

FIG. 5 is an external view of a camera equipped with the distance measuring device having such a configuration. In the figure, a photographing lens 27 is arranged in the front surface of the camera body 26 at a substantially central portion. A finder 28, a light projecting lens 3 and a light receiving lens 4 are arranged near the photographing lens 27 as shown. A release button 29 is provided on the upper surface of the camera body 26.

As described above, by arranging the light emitting / receiving lenses 3 and 4 above and below the front surface of the camera body 26, it is possible to increase the number of horizontal distance measuring points of the finder 28. Here, regarding the effect of the distance measuring device shown in FIG.
This will be described with reference to FIGS. 6 to 8.

The laser beam is not used in such a distance measuring device because it has a safety problem for the eyes and is largely restricted as a distance measuring light for a camera, and a light emitting diode (LED) is used as a light source. However, unlike a laser, an LED has a poor spot property of a projected light beam and has a wide intensity distribution. Therefore, as shown in FIG. 6A, the LE emitted by the light projecting lens 3 is projected.
Even if the main light-projected spot 31 by D30 deviates from the person 15, a weak light intensity portion (harmful light) around the spot 31 is projected on the person 15, and this is received by the light-receiving element 24 via the light-receiving lens 4. May be incident.

In such a scene, the person 15 does not exist at the spot 31. Therefore, if such harmful light enters the light receiving element 24 and the distance is measured as it is, C
The PU 7 cannot correctly determine the distance measurement result of each point.

When distance measurement is performed using a wide PSD without finely dividing the PSD as in the same embodiment, FIG.
As shown in, the harmful light spot is incident on the PSD 24. Then, the same distance measurement result as when the correct spot 31 is incident is generated. Such a problem becomes remarkable in the scene as shown in FIG.

In FIG. 7 (a), even if the spot 31a is correctly projected on the person 15, the harmful light 32a existing around the spot 31a returns from the background glass, and
As shown in (b), crosstalk occurs on the PSD 24. That is, the position of the spot 31a is the person 15
Even if the correct distance is shown, the portion 34 of the harmful light 32a reflected by the glass is incident on the portion of the PSD 24 corresponding to the distance irrelevant to the person, so that the correct distance measurement result of the person is obtained. I can't.

On the other hand, regarding whether or not the distance of the background glass can be correctly determined, this time, a part 35 of the harmful light 32b that spreads around the spot 31b impinges on the person 15, which is also erroneous due to crosstalk. It becomes distance measurement. Therefore, the PSD 24 is divided as shown in FIG. 6C, and is switched according to the projected position of the LED 30. Then, the harmful light 32 is transmitted to the selected PSD 24.
Since it does not enter c, it is possible to prevent the influence of crosstalk.

Thus, according to the embodiment, the multi A
It is possible to prevent deterioration of accuracy due to crosstalk during F. Next, with reference to FIG. 8, a description will be given of prevention of variation in distance measuring points.

The accuracy of the switch 22 shown in FIG.
Depending on the stopping accuracy of the
The positions in the inside vary, and the pitch p becomes non-uniform as shown in FIG. This is because the light projecting element is movable, and if the fixed light receiving element side is divided at an equal pitch and used by switching, as shown in FIG. 8B,
Even if there is some variation in the pitch of the projected light, it is possible to obtain a distance measurement result with a uniform pitch.

This device is also effective when a target 14a for spot distance measurement provided in the center of the screen 14 is used, for example. Without such a device, no matter how the photographer tried to shoot the subject inside the target, there was a possibility that the different things would be in focus due to the effects of crosstalk and the like.

Next, a third embodiment of the present invention will be described. FIG. 9 is a block diagram showing the configuration of a distance measuring device for a camera according to the third embodiment of the present invention. As shown in the figure, in this third embodiment, the IRED 16 and its scanning mechanism are similar to those of the second embodiment in FIG. However, the columns of PSDs 24a to 24f are different from those in FIG. 3 in that PSDs 24a and 24d, PSDs 24b and 24e, P
The SDs 24c and 24f are connected to a common processing circuit, respectively, and have a simplified configuration.

This processing circuit is constructed as follows. That is, PSD 24a and 24d, PSD 24b
And 24e and PSDs 24c and 24f are preamplifiers 36a and 37a, 36b and 37b, 36c and 3, respectively.
7c is connected. And these preamplifiers 36
a and 37a, 36b and 37b, 36c and 37c
Buffer 40 via compression diodes 38 and 39.
41 and 41, and NPN transistors 42 and 44 that form a differential operation circuit together with the constant current source 42.

The preamplifiers 36a and 37a are the PSD 24
It is an amplifier that absorbs and amplifies the output currents of a and 24d with a low input impedance, and flows the amplified output currents i ₁ and i ₂ into the compression diodes 38 and 39. The output voltage of each compression diode 38, 39 is supplied to the base of a pair of transistors 43, 44 via a buffer 40, 41.
The emitters of the transistors 43 and 44 are connected to a constant current source 42 which flows a current of I _p . An integrating capacitor 45 is connected between the collector of the transistor 43 and the power source Vcc.

The characteristics of the transistors 43 and 44 and the compression diodes 38 and 39 are the same, and the current I _INT flowing through the integrating capacitor 45 can be expressed by the equation (1).

[0046]

[Equation 1]

On the other hand, this i ₁ / (i ₁ + i ₂ ) is PS
Since it is proportional to the signal light incident position on D, the above formula (1) can be expressed as the formula (2) using the subject distance L.

[0048]

[Equation 2] Here, S is the base line length, and f _J is the focal length of the light receiving lens.

Therefore, prior to the light emission of the IRED 16, the voltage across the integration capacitor 45 is initialized by the switch 46, and then this switch 46 is turned off to turn off the IRED 16.
If the constant current source 42 is turned on for a predetermined time in synchronization with the light emission of
A voltage proportional to the subject distance L is generated in the integrating capacitor 45.

Then, the CPU 7 A / D-converts the voltage signal with the built-in A / D converter and reads the voltage signal, and then the above (2)
The distance L is calculated according to the formula. Next, the distance measuring sequence of the distance measuring device having such a configuration will be described with reference to the time chart of FIG.

The position of the IRED 16 is scanned by the motor 19 and the feed screw 20 as shown in FIG. 9, and each time the movable member 17 changes its position, the position of the IRED 16 is changed.
16 is driven by the IRED driver 10, and the integration operation is performed in synchronization with the time t ₀ shown in FIG. When the integration operation is completed, as described above, the CPU 7
The integration result is read by. Also, IRED1
Prior to the light emission of 6, the switch 46 is repeatedly turned on and off to initialize the integration capacitor 45.

While repeating such operations, IRED
Reference numeral 16 measures distances at points a, b, c, d, e, and f, and the preamplifier is switched each time. As described above, the preamplifiers 36a and 37a are connected to the PSD 24.
Since the electrodes on both ends of a and 24d are commonly connected,
It is selected to amplify the signal during ranging of points a and d. The preamplifiers 36b and 37b are connected to the PSD2.
Since the electrodes on both ends of 4b and 24e are commonly connected,
The preamplifiers 36c and 37c are commonly connected to the electrodes at both ends of the PSDs 24c and 24f, so that the preamplifiers 36c and 37c are selected for the distance measurement of the points c and f.

Further, in the non-selected state, each preamplifier is constructed as shown in FIG. 11 in order to extract the signal light current incident on the light receiving surface of the PSD and not transmit it to the next stage. .

In FIG. 11, the operational amplifier 47 has a PS
The output of D and the base of the amplifying transistor 48 are connected to the negative side input, and the reference voltage Vref is connected to the positive side input. Further, the output of the operational amplifier 47 is connected to the emitter via the buffer 49 so as to control the transistor 48. A buffer 50 is connected between the input terminal of the buffer 49 and the base of the transistor 48, and a switch 51 is connected to the output terminal of the buffer 49. Reference numeral 52 is an inverter.

As a result, when the switch 51 is off, P
The output current from SD is multiplied by h _fe by the transistor 48 and current amplified to i ₁ . This is the state selected during the distance measurement described above. On the other hand, when the switch 51 is turned on, the emitter terminal of the transistor 48 is pulled up, so that the preamplifier has no current amplification function. However, since the buffer 50 is turned on by the selection signal when the switch 51 is turned on, the output current of the PSD is extracted with a low input impedance.

The photocurrent generated on the PSD by using this function is absorbed by the preamplifier even when the preamplifier is not selected, and P
It is configured so as not to cause crosstalk with the output of another light receiving surface on the SD.

Here, the PSD 24c will be described as an example. The main distance measuring light spot 3 described with reference to FIG.
1 is incident on the PSD 24c, FIG.
The harmful light component 32 shown in P is adjacent to the PSD 24c.
It may have been incident on SD 24b or 24d.
However, the PSD 24b has the preamplifiers 36b, 37
b, while the PSD 24d has a preamplifier 36a,
It is connected to 37a. Therefore, the photocurrent due to each harmful light incident on these PSDs is absorbed by each preamplifier without being amplified, as described in FIG.
Therefore, the harmful light and the main signal light spot are
Only the signal photocurrent is amplified and compressed by the selected preamplifiers 36c and 37c without causing crosstalk above, and the calculation result is integrated by the integration capacitor 45. At this time, the PSD 24f is enabled at the same time, but since the PSDs 24 and 24f sandwich the two PSDs between them, harmful light does not reach here.

Thus, according to the third embodiment, as shown in FIG.
As in the second embodiment, the same effect can be obtained with a configuration including three pairs of preamplifiers without having six processing circuits.

As described above, in this embodiment, it is possible to obtain a high-precision multi-point AF camera distance measuring device which is strong in crosstalk and has a simpler structure. Next, a fourth embodiment of the present invention will be described.

FIG. 12 is a block diagram showing the structure of a distance measuring device for a camera according to the fourth embodiment of the present invention.
Also, unlike the distance measuring device of FIG. 9, the scanning mechanism is eliminated. In FIG. 12, the three IREDs 53a, 53b, 53c arranged behind the light projecting lens 3 are
CP via drivers 54a, 54b, 54c respectively
The drive is controlled by U7. The above IRED 53a, 53
b and 53c are, for example, a square-shaped central IRED 53
Rectangular IRED53 extending laterally across b
It has a configuration in which a and 53c are arranged.

On the other hand, on the light receiving side, behind the light receiving lens 4,
Three or more, in this case, some of the seven PSDs 55a to 55g are commonly connected and arranged. And
The outputs of these PSDs 55a to 55g are processed by the processing circuit 56.
It is supplied to the CPU 7 via a, 56b, 56c. The CPU 7 controls the drivers 54a to 54c, the processing circuits 56a to 56c, and the focusing unit 8.

Thus, the configuration having three drivers and three processing circuits is the same as that of the conventional example of FIG. 18, but as shown in FIG. 13B, each driver and each processing circuit are The distance measuring points can be changed by changing the selection method. This principle has already been described in the description of FIG. Accordingly, in the fourth embodiment, as shown in FIGS. 13 (a) and 13 (b), 57
A total of 7 points ranging from a to 57 g can be measured.

If the IREDs 53b and 53d are further divided, the distance can be measured up to 9 points. Here, in consideration of the light amount of the IRED, the IRED in the central portion where 80% or more of the objects are considered to exist is not divided but the light amount is emphasized to improve the accuracy.

When the IRED 53b for distance measurement in the central portion of the screen is selected, the PSDs 55a and 55g other than the PSD 55d are also enabled by the selection of the processing circuit 56a.
However, at a position away from the optical axis of the light receiving lens 4, P
Since SD55a and 55g are arranged, these P
Since the amount of light incident on the SD is small (the cos4 law), it is considered that the adverse effect on the distance measurement of the important central portion of the screen is smaller than that when other PSDs are connected.

Next explained is the fifth embodiment of the invention. FIG. 14 is a block diagram showing the configuration of the fifth embodiment, which is a further development of the idea of emphasizing on the center in the fourth embodiment of FIG. That is, IR for central distance measurement
The ED 53b and the light projecting lens 3a are a completely different light projecting system from the elongated IREDs 53a and 53c and the light projecting lens 3b for distance measurement in the peripheral area. Other configurations are
This is similar to the distance measuring device in FIG. The distance measuring points on the screen 14 according to the fifth embodiment are as shown in FIG.

With this configuration, it is possible to reliably measure the distance in the central portion of the screen where the existence probability of the main subject is high with a sharp spot. Generally, the smaller the projected light spot for distance measurement is, the more advantageous it is for accurate distance measurement. However, when a wide distance measurement light is projected as in the same embodiment, a wider spot is used. Distance systems are preferred. When it is desired to reduce the spot in the center and widen the spot in the periphery to measure a wider range, it is better to use a different projection system for the projection lens as in the same embodiment. It is convenient in design.

FIG. 16A shows a light projecting lens system of a general distance measuring device. In the figure, f _T1 is the focal length of the light projecting lens 3a, and assuming that the light emission diameter of the IRED 53b is d ₁ , the light projecting spot diameter d _{2 at the} distance L.
Can be thought of as in equation (3).

[0068]

[Equation 3] Since the diameter of the projected spot should be as small as possible, d
It is understood that ₁ is small and f _T1 is preferably as long as possible.

However, if f _T1 is unnecessarily lengthened, the F number (FNo) of the lens increases, and the projected light amount decreases. Therefore, it is necessary to increase the diameter of the light projecting lens at the same time, and as a result, the size of the device tends to increase.

FIG. 16B shows the diameter of the light projecting lens for forming a wide light projecting pattern according to the fifth embodiment. Since this light projection pattern is desired to be spread as wide as possible within the screen, the focal length f _T2 of the light projection lens 3b is set to be as small as possible from the formula (4).
It can be seen that it is desired to increase the length W ₂ of the RED light emitting portion as much as possible.

[0071]

[Equation 4] If W ₂ is too large, the element becomes large and the cost increases. Therefore, it is preferable to make f _T2 small, which is the exact opposite of the case shown in FIG. It can be seen that if this f _T2 is made small, FNo can be made small even if the lens diameter is small, which is also advantageous in terms of the amount of signal light. For example, when θ is set to around 6 °, the equation (5) is obtained.

[0072]

[Equation 5] Here, if W ₂ = 0.6 mm, then f _T2 = 6 mm.

On the other hand, the vertical direction of the projection pattern is 1 in 3 m.
Assuming that the distance is 0 cm, using the above formula (3), d ₁ = (6/3000) · 100 = 600/3000 =
It can be seen that 0.2 mm is sufficient.

Therefore, the projection lens 3a shown in FIG.
F _T1 = 16 mm, φ = 12 mm as in the conventional distance measuring device
The light projecting lens 3b needs to have a certain size.
It can be seen that by designing f _T2 = φ = 6 mm, it becomes possible to project a wider width with a brighter FNo. This wide light projection outputs light at three locations with one projection, so the energy of light per PSD is small, but more than 80% of the main subject exists in the center of the screen. Assuming that no other subject exists at such a long distance, the distance measuring device as shown in the embodiment can sufficiently obtain the effect of multipoint AF.

FIG. 17 is a diagram showing a light emitting / receiving system of a distance measuring device for a camera according to a sixth embodiment of the present invention. In the first to fifth embodiments described above, the light emitting / receiving lenses 3 and 4 are
Although the lenses are arranged side by side in the vertical direction of the camera, this sixth embodiment is one in which both lenses are arranged side by side in the lateral direction of the camera.
In FIG. 17A, an IRED 58 extending in an oblique direction is arranged behind the light projecting lens 3. Further, behind the light receiving lens 4, there are provided, for example, three PSD rows 59 arranged in a staircase pattern.

Reflected signal light emitted from the IRED 58 and reflected from a subject not shown in the figure shows PSD5 from a subject at the same distance as shown in FIG. 17 (b).
It is incident on 9a, 59b and 59c. Then, since the portion that overlaps the light receiving surface becomes the distance measuring point, assuming each distance measuring point in the finder 60, FIG.
As shown in. Although the description of the driver, the processing circuit, and the like is omitted here, the configuration thereof is based on FIG. As described above, according to the sixth embodiment, the degree of freedom in the layout of the camera can be obtained without limiting the arrangement of the light projecting / receiving lens to the vertical arrangement.

[0077]

As described above, according to the present invention, the size of the device is not increased due to an increase in the number of parts, the processing is difficult, the complicated circuit is not required, and the cost is increased without increasing the cost. It is possible to provide a distance measuring device for a camera capable of measuring many points.

[Brief description of drawings]

FIG. 1A is a block diagram showing a concept of a distance measuring device for a camera according to a first embodiment of the present invention, and FIG. 1B is a projection diagram of a subject projected from an IRED shown in FIG. It is the figure which showed the light pattern.

FIG. 2 is a diagram showing an example of a scene in which a main subject does not exist at a point in the center of the screen.

3A is a block diagram showing a configuration of a distance measuring device for a camera according to a second embodiment of the present invention, and FIG. 3B is a projection of light emitted from an IRED of FIG. It is the figure which showed the pattern.

FIG. 4 is a flowchart illustrating an operation of a distance measuring device for a camera according to a second embodiment.

5 is an external view of a camera equipped with the distance measuring device having the configuration shown in FIG.

FIG. 6 is a diagram illustrating a relationship between a light projection spot and a harmful light spot.

FIG. 7 is a diagram illustrating a relationship between a light projection spot and a harmful light spot.

FIG. 8 is a diagram illustrating prevention of variation in distance measuring points.

FIG. 9 is a block diagram showing a configuration of a distance measuring device for a camera according to a third embodiment of the present invention.

FIG. 10 is a time chart illustrating a distance measuring sequence of a distance measuring device for a camera according to a third embodiment.

11 is a circuit diagram showing a configuration of each preamplifier shown in FIG.

FIG. 12 is a block diagram showing a configuration of a distance measuring device for a camera according to a fourth embodiment of the present invention.

13A is a diagram showing distance measuring points on a screen 14 according to the fourth embodiment, and FIG. 13B is a diagram showing a relationship between each driver and each processing circuit of FIG. 12 and distance measuring points. Is.

FIG. 14 is a block diagram showing a configuration of a distance measuring device for a camera according to a fifth embodiment of the present invention.

FIG. 15 is a diagram showing distance measuring points on a screen according to the fifth embodiment.

FIG. 16A is a diagram showing a projection lens system of a general distance measuring device, and FIG. 16B is a projection lens diameter for forming a wide projection pattern according to the fifth embodiment. It is the figure which showed.

FIG. 17 is a diagram showing a light emitting / receiving system of a distance measuring device for a camera according to a sixth embodiment of the present invention.

FIG. 18 is a block diagram showing a configuration example of a conventional camera distance measuring device.

[Explanation of symbols]

1a, 1b, 1c, 9, 16 ... Infrared light emitting diode (I
RED) 2a, 2b, 2c, 10 ... IRED driver, 3 ... Emitter lens, 4 ... Light receiving lens, 5a, 5b, 5
c, 11a, 11b, 11c, 24a, 24b, 24
c, 24d, 24e, 24f ... Optical position detection element (PS
D), 6a, 6b, 6c, 25a, 25b, 25c, 2
5d, 25e, 25f ... Processing circuit, 7 ... CPU, 8 ... Focusing section, 17 ... Movable member, 18 ... Motor (M) driver, 19 ... Motor, 20 ... Feed screw, 21 ... Guide rail, 22a, 22b ... Contact piece, 22 ... switch.

Claims (4)

[Claims] 1. A light projecting unit for sequentially projecting light along a predetermined direction in the shooting screen to change the projection direction, and a projecting unit for projecting the light and reflecting from an object in the shooting screen. Receives the reflected light, and detects the receiving position of the reflected light in a direction substantially orthogonal to the predetermined direction,
By the light receiving means having a plurality of light receiving surfaces divided in the predetermined direction, and the output of the selected light receiving surface among the plurality of light receiving surfaces of the light receiving means, the light receiving surface is moved along the predetermined direction in the screen. A distance measuring device for a camera, comprising: a calculating means for calculating distances between a plurality of points. 2. A light projecting means for sequentially projecting light along a predetermined direction in the shooting screen to change the projection direction, and a light projecting means for projecting the light and reflecting it from an object in the shooting screen. The light receiving means for receiving the reflected light, which is composed of a plurality of light receiving surfaces divided in the direction substantially orthogonal to the predetermined direction, and the effective light receiving of the light receiving means in conjunction with the change of the light projecting direction of the light projecting means. A distance measuring device for a camera, comprising: a control means for switching surfaces. 3. A plurality of light projecting means for sequentially projecting light in a plurality of directions within the shooting screen to change the projection direction, and a plurality of light projecting means for projecting light respectively from an object within the shooting screen. It is provided with a plurality of light receiving means for receiving the reflected light reflected and a determining means for determining a combination of the plurality of light emitting means and the light receiving means in order to measure the distance to the object in the photographing screen. A distance measuring device for a camera. 4. A light projecting means for projecting light onto an object, a light receiving means for receiving reflected light from the object and outputting two current signals depending on the light receiving position, and the current signal In a camera distance measuring device including a processing circuit for processing, a light receiving surface of the light receiving means and an output electrode corresponding to the light receiving surface are provided.
A camera characterized by being divided in a direction substantially perpendicular to the detection direction of the light receiving position and inputting output electrodes corresponding to a plurality of light receiving surfaces sandwiching at least one light receiving surface to a common processing circuit. Ranging device.