JP3362910B2 - Camera ranging device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention projects an infrared signal,
The present invention relates to a distance measuring device for a camera that obtains a distance by receiving the light.

[0002]

2. Description of the Related Art Conventionally, many distance measuring devices for cameras have been capable of measuring distance only at a central point on the screen. However, with this method, when a subject is not located at the center of the screen, a phenomenon called "blankhole" may occur. There were many. This is a phenomenon in which the main subject is out of focus because the background is in focus, and several proposals have been made to prevent this, and it is installed in many cameras.

Japanese Unexamined Patent Publication No. 59-107332 is the simplest one and rotates the entire distance measuring unit. Further, in Japanese Patent Laid-Open No. 60-60511, a plurality of light projecting elements are prepared, and by sequentially projecting them, it is possible to measure the distance in an area other than the center of the screen.

[0004]

However, the method disclosed in Japanese Patent Laid-Open No. 59-107332 has a drawback that the speed is slowed because the whole unit is scanned. Further, the method disclosed in Japanese Patent Application Laid-Open No. 60-60511 has the drawbacks that the number of light-projecting elements and the drivers are the same as the number of distance measuring points in the screen, so that the cost is high and the configuration is complicated.

For example, in the case of a distance measuring device for measuring three points on the screen, in the simplest case, as shown in FIG. 3, the three light projecting elements 3a to 3c and the light projecting circuits 2a to 2c are associated with each other. Light receiving elements 4a to 4c and light receiving circuits 7a to 7
c, the arithmetic circuits 8a to 8c, and the integrating circuits 9a to 9c may be used. Then, the arithmetic control circuit (CPU) 1 controls these and determines the focusing distance from the outputs of the light receiving circuits 7a to 7c.

However, this method is
Since the cost required to configure a circuit and a circuit becomes enormous, many conventional cameras have only the light emitting / receiving elements as many as the distance measuring points as shown in FIG. 2, and the circuit is used as commonly as possible. It was aimed at simplification and cost reduction.

The operation of the circuit shown in FIG. 2 will be described below. Reference numeral 2 denotes a selective light projecting circuit for selectively projecting three infrared distance measuring light projecting elements (IREDs) 3a, 3b, 3c in accordance with the output of the CPU 1, and 5 designates this light for projecting light to a subject. It is a projection lens for illuminating.

This distance measuring light is reflected by the subject and then is received by the light receiving lens 6 by the light receiving elements 4a, 4b, 4c.
Is focused on. In addition to the distance measuring light, the light receiving elements 4a to 4c also receive a background light component such as sunlight or light of an electric light that constantly illuminates the subject, and thus the light receiving circuit 7 receives the background light component. Remove and amplify only the signal. The operation of removing the background light varies depending on the size of the background light, but the preliminary operation generally takes time.

Next, the signal output amplified by the light receiving circuit 7 is operated by the operation circuit 8 to be a distance-dependent signal, which is integrated in the integrating circuit 9 and then A / D.
It is converted and input to the CPU 1.

The light receiving circuit 7 will be described in more detail with reference to FIG. As the light receiving element 4, a semiconductor element (PSD) having a light position detecting function is assumed here. Figure 5
In (a), the PSD 4 outputs the following two current signals i ₁ and i ₂ to the light incident position x.

[0011]

[Equation 1]

Here, t is the length of the PSD, and a is the length from the PSD end to the reference point. The i ₁ and i ₂ are amplified by the preamplifiers 11 and 12, but the background light component is flowed to the GND by the transistors 13 and 14 and removed. The background light removing circuits 17 and 18 are circuits that determine the base potentials of the transistors 13 and 14 according to the magnitude of the background light. This circuit stops the background light monitor and the base potential determination operation by the HOLD signal synchronized with the light emission of the IREDs 3a to 3c.
Held by, so background light is removed,
Only the signal will be amplified by the preamplifiers 11 and 12.

[0013] i ₁ which is amplified, i ₂ is compressed diodes are amplified in the amplification factor β times as shown in Figure - is crowded flowed de 19,20. This potential is connected via the buffers 21 and 22 to the bases of the transistors 23 and 24 whose emitters are commonly connected. The emitters of these transistors are connected to a constant current source 25 having a switching function, and one collector of these transistors is connected to an integrating capacitor 26. Therefore, the current i flowing in the integrating capacitor
_c is the current source 25 in synchronization with the light emission of the IREDs 3a to 3c.
When turning on

[0014]

[Equation 2] Becomes Here, I ₀ is the current value of the constant current source 25.

Therefore, it is understood that the arithmetic circuit block 8 performs the arithmetic operation represented by the equation (1) in an analog manner. This integrating capacitor 26 is an operational amplifier 28
, And the + side input of the operational amplifier 28 is connected to the reference voltage V _ref . Therefore, when the negative feedback switch 29 is turned on by the Reset signal, the potential V _INT of the integrating capacitor 26 becomes V Fixed to _ref level.

When the switch 29 is turned off, the operational amplifier 28 works as a comparator. The integration capacitor 26 synchronizes with the light emission of the IREDs 3a to 3c (2)
It is charged by the current as shown in the equation, but the second (2n
d) When the current source 27 is turned on by the integration signal, the constant current i
Discharged with _g .

The operation of the circuit thus constructed is shown in FIG.
The time chart (b) will be described in more detail. First, the Reset signal is output from the CPU 1 to reset the output voltage V _INT of the integrating capacitor 26, and the CHARGE signal for rapidly charging the background light removing capacitors 15 and 16 is simultaneously output. Since the holding capacitors 15 and 16 use a large capacitor of 1 μF order in order to fix the base potentials of the transistors 13 and 14, it takes time to charge to a predetermined voltage. This is the preliminary operation for removing the background light described above.

When this preliminary operation is completed, IRED 3a
~ 3c emits light a predetermined number of times. At the same time, the HOLD signal causes the background light hold by the capacitors 15 and 16, but the first (1st) integrated signal turns on the current source 25 synchronously, so that both ends of the integrating capacitor 26 are as shown in the figure. (2), that is, the integrated voltage that depends on the subject distance is output.

When light emission of a predetermined number of times is completed in order to average and improve accuracy, the second integration signal is output and the integration voltage V _INT is discharged at a constant current. Double integral type A /
Due to the principle of D conversion, when V _INT returns to the original potential V _ref , the output COMP of the comparator 28 is inverted and 2n
The pulse width between the d integration signal and COMP, DATA becomes the distance measurement signal.

As described above, if the CPU 1 counts this pulse width at a predetermined clock, it can be read after A / D conversion is performed. With the configuration shown in FIG. 2, distance measurement at three points is possible. When performing, it is necessary to perform charge, light emission, and DATA reading three times in series.

On the other hand, in the configuration of FIG. 3 described above, since the circuit is not shared, the charge and the IRED3
Since the light emission of a to 3c can be performed at the same time, the CPU of DATA
Except reading to 1, it is possible to measure the distance within almost the same time as the distance measurement for one point. However, in this case, the configuration is complicated and the cost is high, as described above.

The camera distance measuring device of the present invention has been made in view of such a problem, and its object is to have a simple structure and to accurately detect a plurality of points on the screen at high speed. An object of the present invention is to provide a distance measuring device for a camera capable of measuring distance.

[0023]

In order to achieve the above object, the distance measuring device for a camera according to the first aspect of the present invention comprises:
In a distance measuring device for a camera capable of measuring a plurality of points on a screen, a light projecting unit that sequentially projects distance measuring light toward the plurality of points, and the above-mentioned measuring from a subject located at the plurality of points. A single light receiving means for sequentially receiving the reflected light of the distance light, an integrating means for integrating the light receiving signal of the light receiving means, and a single converting means for converting the integration result of the integrating means into digital data and reading the digital data. , And the integration means includes first and second integration circuits and switching means for alternately switching the first and second integration circuits each time the distance measuring operation is performed. Is performing the integration operation of the received light signal, the integration result of the other integration circuit is converted into digital data by the conversion means and read out.

The distance measuring device for a camera according to the second aspect of the invention includes a light projecting means for sequentially projecting the distance measuring light toward a plurality of distance measuring points on the screen, and each of the plurality of distance measuring points. ,
A plurality of light receiving means for receiving the reflected light of the distance measuring light from the object to be measured and outputting a light receiving signal, and a plurality of light receiving means, each of which is connected to the plurality of light receiving means, and outputs the light receiving signal for each of the distance measuring points. A plurality of integrating means for integrating, a background light removing means for removing the background light that illuminates the subject constantly, and a single converting means for converting the integrated output of the integrating means into digital data and reading the digital data. Control means for controlling the background light removal operation for one of the plurality of distance measuring points to be performed simultaneously with the data reading operation for the other distance measuring points.

[0025]

[0026]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of a first embodiment of the present invention. In the figure, a CPU 1, a selective light projecting circuit 2, projecting elements (IRED) 3a to 3c, and projecting / receiving lenses 5 and 6 are shown.
Is the same as in FIG.

However, since the number of light receiving elements is fixed to one, it is considered that the background light does not change during the entire distance measurement period, so the time-consuming preliminary operation for background light removal described above is only once. Mu. Further, the light receiving circuit 7 and the arithmetic circuit 8 are circuits similar to those described in FIG. 5, and the output of the arithmetic circuit 8 is connected to the two integrating circuits 9 and 10.

The CPU 1 sequentially emits light from the IREDs 3a, 3b and 3c and alternately switches the integrating circuits 9 and 10 to perform distance measurement. The timing is shown in FIG.
It is (c). 4A shows the operation of the circuit of FIG. 3, and FIG. 4B is a time chart showing the operation of the circuit of FIG.

As described above, the preliminary operation for removing the background light, that is, the rapid charge operation of the hold capacitor is performed by the IR.
It may be performed only once before the ED emission. Next, the integration is performed in synchronization with the light emission from the IRED by the double integration formula. However, when one integration circuit performs the second integration (DATA reading), another integration circuit performs integration so that another integration circuit performs integration. 9, 1
Since 0 is operated, three-point distance measurement is completed in a shorter time than in FIG. 4 (b).

The distance measuring operation is roughly divided into three operations of a background light removing preliminary operation, an integrating operation, and an A / D converting operation. In this embodiment, the A / D converting operation has a simplified structure. High-speed distance measurement is performed by overlapping other operations and combining the background light removal preliminary operation into one operation.

FIG. 6 is a diagram showing the configuration of the second embodiment of the present invention. The difference from the first embodiment of FIG. 1 is that, in order to project the distance measuring light in different directions, a plurality of elements are not sequentially projected, but the light from one element is scanned by a mirror. It is in.

This system does not require as many light projecting elements as the number of distance measuring points as in Japanese Patent Laid-Open No. 60-60511, and the entire unit as in Japanese Patent Laid-Open No. 59-107332. This enables faster control than the scan type. Therefore, for example, when performing distance measurement of 10 points or more on the screen, an inexpensive and high-speed distance measuring device can be provided.

The light of the IRED 3 emitted through the driver 2 as the selective light projecting circuit is condensed by the lens 5 and reflected and projected by the mirror 30. Mira-3
0 is driven by an electromagnetic actuator 31 via an EM driver (electromagnetic driver) 32, and its angle is monitored by an angle detection circuit 33.

The distance measuring light is reflected on the subject and enters the PSD 4. The background light component of the light incident on the PSD 4 is removed by the background light removing circuit 36, and only the signal light is input to the circuits 34 and 35 including a preamplifier and a compression diode. This circuit corresponds to 11, 12, 19, 20 in FIG.

The compressed voltage output from the circuits 34 and 35 is
Transistor pairs 41, 42 and 44 whose emitters are commonly connected by the buffers 37, 38, 39 and 40,
It is input to 45 bases. Constant-current sources 43 and 44 are connected to the emitters of these transistor pairs, and one of the collectors of the pair has integration capacitors 47 and 48 and constant-current sources 49 and 50, the amplifier 28 of FIG.
The reset & comparator circuits 51 and 52 corresponding to 9 are connected.

Therefore, the CPU 1 causes the 1st integration 1, 1st integration 2, 2nd integration 1, 2 via the timing circuit 53.
By controlling each signal of the nd integration 2, the signal corresponding to the position of the light incident on the PSD 4, that is, the subject distance is selectively integrated into the condenser 47 or 48.

Optical scanning for distance measurement by the mirror 30 will be described with reference to FIG. The light emitted from IRED3
The light is condensed by the light projecting lens 5 and reflected and projected by the mirror 30.

FIG. 7 (a) is a diagram in which the mirror is tilted by 45 ° and is projected onto the front of the camera, and FIG. 7 (b) is the mirror tilted by ψ and θ.
It is a figure at the time of projecting light only in the inclined direction. As is clear from the figure, in order to project light with an inclination of θ, the mirror inclination ψ must be in the relationship of θ = 90 ° −2ψ (3).

When ψ = 45 °, θ becomes 0, and ψ = 40
If it is °, θ = 40 °. When the light projecting lens 5 shown in FIG. 6 is arranged above and below the camera, the distance measuring light 61 moves laterally in the finder screen 60 by the scanning of the mirror 30 as shown in FIG. FIG. 9 shows the structure of the electromagnetic actuator 31 shown in FIG.
A moving magnet type moving along the direction of the arrow is shown. In the figure, a coil 67 is wound around the bobbin 66, and is integrated with the shaft 66 to form a protrusion 6.
9, magnets 63, 64 and yokes 62, 65 are coils 67
It receives a force and moves according to the current flowing through it.

FIG. 10 shows such an electromagnetic actuator 3.
1 illustrates an angle control method of the mirror 30 according to the first embodiment. In the figure, the mirror 30 is a mold member whose both surfaces are mirror coated, and is rotated about a shaft 75 by a spring 76 and an electromagnetic actuator 31. When the LED 71 emits light via the driver 70, the light of the LED 71 is condensed by the lens 72, reflected by the back surface of the mirror 30, and incident on the position detection element (PSD) 73. The output current of the PSD 73 is calculated by the position detection circuit 74, and the position signal is input to the CPU 1. This position detection circuit 74 is shown in FIG.
This can be achieved with the same configuration as the arithmetic circuit 8 of.

The angle of the mirror 30, that is, the IRE for distance measurement
With such a configuration, the projection angle of D3 to the subject is
It is monitored by CPU1, and from this result CPU1
The electromagnetic actuator 3 via the EM driver 32.
1 is controlled to control the projection angle.

As shown in FIGS. 11 (a) and 11 (b), the mirror
The angle ψ of 30 has the following relationship with the light spot position x _M on the PSD 73 of the LED 71. x _M = d × tan (90 ° −2ψ) (4) Here, d is the distance between the mirror 30 and the PSD 73.

In this way, the light projecting point is changed by the mirror scan, but the light receiving side also has to deal with the change of the light projecting angle θ. FIG. 12A shows the relationship between the light receiving lens 6 and the PSD 4, and the maximum value of θ is 12 °,
When the focal length f _J of the light receiving lens 6 is 20 mm, the width W of the PSD 4 is W = f _J · tan θ + α = 4.75 mm (5) with the margin α of 0.5 mm. On the other hand, the length t of the PSD 4 in the light detection direction is as shown in FIG. 13B when the distance (baseline length) S between the light projecting and receiving lenses is 36 mm and the shortest distance l _min is 0.6 m.

[0044]

[Equation 3] And it is sufficient.

The operation of the distance measuring device having such a structure is shown in FIG.
This will be explained using the flowchart of No. 3. In the figure,
The mirror position initialization in S1, the background light removal in S2, and the integration capacitor reset in S3 are simultaneously performed. Of these, the CPU
It is only necessary for S.1 to perform feedback control or monitoring strictly at the mirror position initialization of S1, and for each step of S2 and S3, the CPU 1 instructs only the start time, and then the timing circuit 53 determines the predetermined time. Since only time control is required, parallel control becomes possible.

When these operations are judged to be completed in S4, the number of distance measuring points n is reset in S5, and then S
6, the IRED 3 emits light a predetermined number of times, and the integrating capacitor 47
A synchronous integration is performed on.

Next, in S7, the mirror scan is performed by a predetermined amount according to the outputs of the electromagnetic actuator 31 and the angle detection circuit 33 as described with reference to FIG. In S8, n is incremented, and in S9, the number of distance measuring points n is an odd number,
It is determined whether it is an even number. If it is an odd number, the process branches to S14 and S15, and if it is an even number, the process branches to S10 and S11. S14, S15 and S
10 and S11 are the light emission and integration of IRED3, and D
This is a step of performing ATA reading.

Also at this time, the CPU 1 needs to strictly monitor only the DATA reading, and controls only the start point of the light emission of the IRED 3 and the integration operation by controlling the current sources 43 and 46, and then the timing circuit. It may be controlled by 53. In S9, the capacitor for synchronous integration and the capacitors 47, 48 for DATA reading are switched depending on whether n is an odd number or an even number. This is the same as the method described with reference to FIG.

When the data reading is completed in S11 and S15, each integrating capacitor is initialized in S12 and S16. When it is determined in S13 and S17 that these steps are completed, it is determined in S18 whether the number of distance measuring points n has reached the predetermined number of points n ₀ (odd number). If n has not reached n ₀ , the process returns to S7 and the subsequent steps are repeated. When the flow branches to Y in S18, the distance measurement data of the last distance measurement point is finally read in S19.

As described above, the distance measuring data of n ₀ points are input to the CPU 1. The CPU 1 determines the main subject distance from these data and focuses the camera on the main subject distance via the focusing circuit 54. The control completion determination in S4, S13, and S17 may be performed by measuring time with a counter inside the CPU 1.

FIG. 14 shows a third embodiment of the present invention. As described above, the PSD 4 in FIG. 6 has a 4.8 mm ×
It has an area of 1.7 mm, which is five times the area of the PSD of the conventional range finder. This is a disadvantage in terms of S / N, because the background light noise becomes 5 times.

Therefore, in this embodiment, the background light noise is reduced by dividing the PSD 4 in the W direction as shown in FIG. 12C. If all the subjects are at the same distance, the beam for distance measurement will be
It moves on the sensor as shown in (b).

The PSD 4b at the center of the screen has a longer detection area so that it can handle a short-distance subject,
The distances D4a and 4c are shortened and the distance measuring range is reduced in consideration of the influence of the background light noise. However, since there is a high probability that the main subject is present in the center of the screen in a short-distance shooting scene called macro photography, there is little effect on the focusing rate.

The light projecting section for scanning the light of the IRED 3 with the mirror 30 is the same as that shown in FIG. As described above, in the light receiving unit, the sensor is divided into 4a, 4b, and 4c, but the electrodes of 4a and 4c are common, and the amplification compression circuit 80 is used.
And the background light removing circuit 86 via the selection circuit 85.

The central distance measuring PSD 4b is also connected to the background light removing circuit 86 via the selecting circuit 85.
Only the signal current is input to the amplification compression circuit 81.

The amplifying / compressing circuits 80 and 81 are selectively input to the integrating circuit 82 by the CPU 1. The integrating circuit 82, like 55 of FIG. The signal is selectively integrated into the integration capacitors 83 and 84.

The operation of the third embodiment having such a configuration will be described below with reference to the timing chart of FIG. In this embodiment, the PSD 4 is divided and the background light removing circuit 8
6 is shared, a preliminary operation CHARGE for background light removal is required every time the PSD 4 being used is switched.

Similar to FIG. 13, during the first background light removal preparatory operation, the mirror positions are reset, and when they are completed,
The IRED3 is driven by the mirror every time the light emission is started a predetermined number of times and the integration is completed.

Then, at the same time as the next light emission and the integration by another integration capacitor, the result of the previous integration is read out. In this way, when the mirror 30 is set to a predetermined angle and the distance measurement is performed at the center of the screen, the CPU 1 switches to the selection circuit 85 and selects 81 as the amplification compression circuit, and the timing circuit 53 makes the PSD 4b incident. The background light component to be removed is removed and the IRED3 emits light. At this time, at the same time, the result of integration performed before that is read.

Since there is a high probability that the main subject exists in the central portion of the screen, the number of light projections and integrations is increased from other points to try to improve the accuracy by averaging calculation.
In this embodiment, as described above, the background light removing operation,
The time lag is shortened by simultaneously performing the DATA read operation. When the DATA reading is not finished even after the background light removing operation is finished, the next integration is performed on the integration capacitor different from the integration capacitor reading the output, as in the embodiment of FIG. .

Next, a fourth embodiment of the present invention will be described with reference to FIG. As shown in FIG. 12D, the area of the PSD 4 can reduce the background light noise depending on the direction in which the distance measuring range is reduced. Therefore, if it is left as it is, the camera will not be able to photograph a subject at a short distance.

Therefore, in the fourth embodiment, the second light receiving lens 91 and the PSD 90 are provided close to the light projecting portion as shown in FIG. 16 (a). According to the equation (6), when t and α are constant, the shortest distance l _min that can be measured is reduced by S.
It is clear that f _J should be small. Therefore,
If S is 20 mm, f _J is 10 mm, and t = 2 mm,
From equation (6)

[0063]

[Equation 4] Therefore, it becomes possible to measure the distance to a very short distance.

FIG. 17 is an external view of a camera provided with such a second light receiving system. When 92 is a camera body and 94 is a photographing lens, the light projecting window 93, the mirror 30 for scan distance measurement, the light receiving lens 6 and the PSD 4 are arranged as shown in the figure. Further, the second light receiving lens 91 and the PSD 90 are
A camera body 92 and an IRED3 as shown in FIG.
16B, the mirror 30 projects the distance measuring light in a direction coinciding with the optical axis of the photographing lens, as shown in FIG. The subject distance is calculated from the incident position x.

FIG. 18 shows a circuit block diagram of such a distance measuring device. The mirror-scan type light-projecting unit and the light-receiving circuit unit having a wide PSD 4 for scan distance measurement have the same configuration as in FIG.

As described with reference to FIG. 17, the second light receiving lens and the PSD 90 are arranged.
Similarly, the background light removing circuit 96 is connected to the AF circuit 95 including a signal light current amplification amplifier ratio calculating circuit and an integrating circuit. Reference numeral 97 is an integrating capacitor.

FIG. 19 is a timing chart showing the operation of this embodiment. As shown in FIG. 18, since two PSDs are provided with different background light removing circuits, the background light removing preliminary operation is performed at the beginning of the distance measuring sequence. Further, since there are three integrating capacitors 83, 84, and 97, if these outputs are V _INT1 , V _INT2 , and V _INT3 , V _INT1 and V _INT2 are alternately integrated as shown in the figure, and one of the DATs is repeated.
During the reading of A, the integration timing of the other overlaps to shorten the distance measuring time.

V _INT3 is used as the distance measuring data on the short distance side by performing integration based on the PSD 90 signal when the mirror angle reaches the center distance measuring on the screen. V _INT1 and V during central distance measurement
_{Although INT3} is the simultaneous integration, the CPU 1 reads these data in a time division manner. Of course, V _INT2 is simultaneously measuring and integrating the next point at that time.

FIG. 16C is a diagram showing the configuration of the fifth embodiment of the present invention. In this embodiment, the tilting of the projection beam is used to determine the subject distance 1 from the projection angle θ. At this time, the subject distance 1 is calculated from the baseline length S and the projection angle θ by

[0070]

[Equation 5] Is required as.

Θ is obtained from the mirror angle detector, and the light receiving element here may be not a PSD but a photodiode for simply determining whether or not light is incident. That is, θ can be changed by the mirror scan, and the distance can be obtained from the angle at which the signal light incident on the PSD 90 becomes a peak by using the equation (7).

FIG. 21 shows a sixth embodiment of the present invention in which a PSD having a short position detection direction as shown in FIG. 12D can be used to measure a short distance. The principle of short-distance measurement according to this embodiment will be described with reference to FIG. If the light emitting and receiving lenses are 5, 6 and the light emitting and receiving elements are 3, 4, then IRED3
The closest distance measurement distance l _{1 according to}

[0073]

[Equation 6] IRED101, P from IRED3
When it is arranged at a position on the side Δx far from SD4, the minimum distance l ₂ that can be measured by this IRED3 is when the focal lengths of the projecting / receiving lenses 5 and 6 are equal.

[0074]

[Equation 7] Therefore, it can be seen that it is advantageous for short distance measurement. This Δ
If x is S · f _J / l ₁ , then from equation (8)

[0075]

[Equation 8] Becomes Based on the numerical value used in the equation (6), l ₁ = 1.2
Assuming that m and l ₂ = 0.6 m, the length t of the PSD 4 is

[0076]

[Equation 9] Therefore, it is possible to reduce the influence of noise by reducing the area by 35% with respect to 1.7 mm in the expression (6).

FIG. 21 shows a block diagram of a distance measuring device based on such a principle. For the circuit of FIG. 6, as described above, P
IRED for short distance measurement, except that the SD area is reduced
101 and a dedicated driver 102 are added.

FIG. 22 shows a time chart of this embodiment. Short distance IRED1 for all distance measuring points
If 01 is used, it is disadvantageous in terms of time lag.
As described in the above embodiment, the short distance IRED is used only at the time of distance measurement at the center. It is the same as in the previous embodiment that two integrators are used and the integration operation is alternately performed for each distance measurement.

According to the present embodiment, it is possible to provide a distance measuring device that is resistant to background light noise and has a wide distance measuring range only by adding an IRED and a driver. In each of the above examples,
The explanation has been made on the premise that the mirror is rotated by the electromagnetic actuator. In this mirror scan method, if there is backlash in the axial portion, a deviation occurs perpendicularly to the scanning direction of the distance measuring light. If this shifts by Δφ in the base length direction as shown in FIG. 25, a distance measurement error of Δl occurs as shown in the figure.

Therefore, in the case of performing distance measurement with higher accuracy, a device for detecting the tilt amount Δφ of the mirror which causes the angle error is required. As shown in FIG. 24 (a), the IRED1 for monitoring is used to detect the tilt of the mirror 30.
11 and PSD 113 are arranged. 112 is a condenser lens. PSD of IRED111 when mirror does not fall
Based on the light spot position on 113, the light spot position Δg when there is a mirror tilt Δφ is given by the following relational expression.

Δg = m · tan Δφ (10) m is the distance between the mirror and the PSD, and the relationship between the tilt Δφ of the mirror and the deviation angle Δψ of the projection direction is Δψ = −, as in the equation (3). Since 2Δφ (11),

[0082]

[Equation 10] As a result, Δψ is obtained from Δg. The relationship between Δψ and Δl is

[0083]

[Equation 11] Becomes

Therefore, the light spot position Δg is detected from the output of the PSD 113, and the CPU 1 performs the correction calculation according to the equation (13), whereby the distance measurement error due to the backlash in the tilt direction of the mirror can be corrected.

FIG. 23 shows, as a seventh embodiment, an embodiment with such a mirror tilt amount monitor mechanism. The light receiving circuit including the light projecting section by the mirror scan, the light receiving lens 6, the light receiving element 4 and the like is the same as that of the previous embodiment. However, the projection lens 5 and the mirror tilt monitor lens are integrally formed, and the monitor IRED 111 and PSD 113 are arranged as shown in the figure. The position detection circuit 114 may be the same as the position detection circuit 74 of FIG.

According to this embodiment, the error in the tilt direction of the mirror is also corrected, so that a distance measuring device with higher accuracy can be provided. If a two-dimensional PSD is used as the PSD 113, the angle sensor 33 can be used as a substitute and the configuration can be further simplified.

In FIG. 26, the scanning mirror 30 is provided with a cutting portion 114, and the IRED condensed by the projection lens 5 is used.
This is an embodiment in which the light of No. 3 is a mirror that guides the light in a direction different from the original projection direction. Here, the two-dimensional PSD 113 receives the light and detects the rotation angle of the mirror 30 and the backlash.

With such a configuration, the monitor IRE
IRED3 can also be used as D111, and the cost can be reduced. The distance measuring light has a cutout 114 at the center.
However, since most of the light is used for distance measurement, the S / N deterioration can be ignored.

[0089]

As described above, according to the distance measuring device for a camera of the present invention, it is possible to provide a distance measuring device which can measure a plurality of points on the screen with high precision and high speed with a simple structure.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a conventional distance measuring device.

FIG. 3 is a diagram showing another configuration of a conventional distance measuring device.

FIG. 4 is a time chart showing the operation of the first embodiment of the present invention.

5 is a diagram showing a detailed configuration of the light receiving circuit of FIG.

FIG. 6 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 7 is a diagram for explaining a method of optical scanning for distance measurement.

FIG. 8 is a diagram showing that the distance measuring light is moved laterally by scanning with a mirror.

9 is a diagram showing a configuration of an electromagnetic actuator in FIG.

FIG. 10 is a configuration diagram for realizing angle control of a mirror by an electromagnetic actuator.

FIG. 11 is a diagram showing a relationship between a mirror angle ψ and a light spot position x _{M of} an LED on a PSD.

FIG. 12A is a diagram showing the relationship between the light receiving lens and the light receiving element, and FIG. 12B is the length t in the light detection direction of the PSD, the distance (baseline length) S between the light emitting and receiving lenses, and the closest distance. is a diagram showing the relationship between the distance l _min, (c) is a diagram showing a configuration of a third embodiment, (d) is a diagram showing a configuration of a fourth embodiment.

FIG. 13 is a flowchart showing the operation of the second embodiment.

FIG. 14 is a diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 15 is a timing chart showing the operation of the third embodiment.

16 (a) and 16 (b) are diagrams showing the configuration of the fourth embodiment, and FIG. 16 (c) is a diagram showing the configuration of the fifth embodiment.

FIG. 17 is an external view of a camera provided with a second light receiving system.

FIG. 18 is a diagram showing an overall configuration of a fourth embodiment of the present invention.

FIG. 19 is a timing chart showing the operation of the fourth embodiment.

FIG. 20 is a diagram for explaining the principle of short-distance measurement according to the fifth embodiment.

FIG. 21 is a diagram showing a configuration of a sixth exemplary embodiment of the present invention.

FIG. 22 is a timing chart showing the operation of the sixth embodiment.

FIG. 23 is a diagram showing a configuration of a seventh exemplary embodiment of the present invention.

FIG. 24: I for monitoring when detecting the fall of the mirror
It is a figure which shows arrangement | positioning of RED and PSD.

FIG. 25 shows Δl when the angle is shifted by Δψ in the base length direction.
FIG. 6 is a diagram showing how the distance measurement error occurs.

FIG. 26 is a view showing a modified example of the scanning mirror.

[Explanation of symbols]

1 ... CPU, 2 ... Selective light projecting circuit, 3a to 3c ... IRE
D, 4 ... PSD, 5 ... Emitter lens, 6 ... Light receiving lens, 7
... light receiving circuit, 8 ... arithmetic circuit, 9 ... integrating circuit 1, 10 ... integrating circuit 2.

Claims (2)

(57) [Claims] 1. A distance measuring device for a camera capable of measuring a plurality of points within a screen, wherein a distance measuring light is projected sequentially toward said plurality of points.
Light means and for the distance measurement from the subject located at the plurality of points
A single light receiving means for sequentially receiving the reflected light of light, an integrating means for integrating the light receiving signal of the light receiving means, and a single converting means for converting the integration result of the integrating means into digital data and reading the digital data. The integrating means includes first and second integrating circuits and switching means for alternately switching the first and second integrating circuits each time the distance measuring operation is performed. A distance measuring device for a camera, wherein an integration result of the other integrating circuit is converted into digital data and read out by the converting means during the integration operation of the received light signal. 2. A light projecting means for sequentially projecting distance-measuring light toward a plurality of distance-measuring points in a screen, and a plurality of distance-measuring points, from which the distance-measuring light is emitted from an object to be measured. A plurality of light receiving means for receiving the reflected light and outputting a light receiving signal, a plurality of integrating means connected to each of the plurality of light receiving means for integrating the light receiving signal at each of the distance measuring points, and Background light removing means for removing the background light illuminating, a single converting means for converting the integrated output of the integrating means into digital data and reading the digital data, and one of the plurality of distance measuring points. A distance measuring device for a camera, comprising: a control unit that controls a background light removing operation for a point to be performed simultaneously with a data reading operation for another distance measuring point.