JPH05273457A - Camera with active type range finding device - Google Patents

Abstract

PURPOSE:To obtain the camera with the active type range finding device which prevents range finding precision to a high-brightness subject from decreasing and does not increase shutter release lag. CONSTITUTION:This device is equipped with a deciding means 3 which decides whether or not an object of range finding is the subject with high brightness, a stationary light component storage means 6 for storing a stationary light component, a sequence altering means which alters the sequence of the camera by varying the stable time of the stationary light component storage means 6 according to the output of the deciding means 3, and a control means 5 which executes the sequence of the camera according to the output of the sequence altering means 4.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to cameras, and in particular
The present invention relates to a camera having an active distance measuring device.

[0002]

2. Description of the Related Art There are roughly two types of distance measuring devices applied to cameras. One is a passive type that uses the brightness distribution information of the subject, and the other is an active type that projects light toward the subject and detects the distance by the reflected light. The active type is popular because of its simple structure and low cost. A conventional active distance measuring device will be described below.

FIG. 17 shows an optical system of an active distance measuring device,
It is a figure which shows arrangement | positioning of a light receiving element. In the figure, IR
The infrared light projected from the ED 10 through the light projecting lens 11 is reflected by the subject 12 and is incident on the PSD 14 through the light receiving lens 13. Here, the distance between the light projecting lens 11 and the light receiving lens 13 is S, and the light projecting lens 11 and the subject 1 are
2 is 1, the distance between the light receiving lens 13 and the PSD 14 is f, and the incident position of the infrared light is x, as shown in the figure, the intersection of the optical axis of the light receiving lens 13 and the PSD 14 is the origin, and x = S. f / l (1)

The following relationship is established. In principle, the PSD 14 generates a signal photocurrent I _p and outputs a signal depending on the incident position x from two output ends. P on the IRED10 side
Letting a be the distance from the SD end to the origin, i _a = {(a + x) / t} × I _p (2) Here, t represents the length of the PSD 14. Further, from I ₀ + i _b = I _p (3), the relationship i _a / (i _a + i _b ) = (a + S · f / l) × 1 / t (4) holds. Therefore, the subject distance 1 can be obtained by performing the ratio calculation based on the equation (4).

FIG. 18 is a diagram showing a circuit configuration of the active type distance measuring device of FIG. Output current I from PSD14
_Since the circuits that process _a and I _b have the same configuration, only the circuit that processes I _a will be described below. FIG. 17
The output current I _a from the PSD 14 is amplified by the preamplifier 32A and the amplification transistor 33A via the input terminal 31A. This amplification transistor 33A has a current source 3
4A, 35A, compression diode 36A and buffer 43
A is connected. The amplification transistor 33A is provided at the inverting input end of the amplifier 37A, the compression diode 38A and the current source 39A are provided at the non-inverting input end, and the hold transistor 40A and the hold resistor 41A are provided at the output end.
And the hold capacitor 42A is connected as shown. In addition, the compression diode 3 is connected to the transistors 44A and 45A that form the ratio calculation circuit 47A together with the current source 46A.
The output of 6A is connected via the buffer 43A.

Next, the operation of such a circuit will be described. The output current i _a from the PSD 14 is amplified by the preamplifier 32A and the amplification transistor 33A via the input terminal 31A, but since the stationary photocurrent I _p is also input, the hold amplifier 37A operates to remove it. ing. Here, the compression diodes 36A and 38A have the same characteristics, and also the current sources 34A and 35A.
A is set to the same current value.

The hold amplifier 37A is the output voltage of the compression diodes 36A and 38A, that is, the hold amplifier 3
The output voltage is determined so that the input voltage of the inverting input terminal of 7A becomes equal to the input voltage of the non-inverting input terminal. Stationary photocurrent I _p
Is amplified by the preamplifier 32A, the compression diode 36
A lowers the output voltage due to the current, and the hold amplifier 3
The potential at the inverting input terminal of 7A also drops. Then, the output voltage of the hold amplifier 37A rises, the base potential of the hold transistor 40A rises, and the stationary photocurrent I _p flows to the ground via the hold resistor 41A as a collector current. That is, the stationary photocurrent I _p is not amplified and always flows to the ground by such a feedback action. The bias current of the amplification transistor 33A is supplied by the current source 34A.
When no light is emitted, current does not flow to the point A in the figure.

Next, when the IRED 10 emits light, the hold signal T _H causes the hold amplifier 37A to stop its function. Here, since the hold capacitor 42A holds the electric charge for removing the stationary light, the stationary photocurrent I _p is removed, but the signal currents i _a and i _b are amplified by the preamplifier 32A and the amplification transistor 33A to be compressed diode. A signal current flows through 36A. When the IRED 10 emits light, the current source 35A is turned off by the hold signal T _H. Therefore, the output voltage V _a of the compression diode 36A
Occurs at _{V a = V T ln {(} K · i a) / I S} (5) V T ... thermal voltage I _S ... reverse saturation current and the power supply (Vcc) reference.

As described above, the output current of the PSD 14 becomes a voltage compressed by the compression diode. Hereinafter, a circuit for obtaining the above ratio i _a / (I _a + i _b ) using this compressed signal will be described. I _OUT in FIG, I _Z is I _OUT + I _Z = I ₀ becomes a relationship of (6), also _{V a -V b = V T ln} (i a / I S) -V T ln (i b / I S ) = V _T ln (I _OUT / I _S ) −V _T ln (I _Z / I _S ) (7) Therefore, i _a / i _b = I _OUT / I _Z. Here, from the _{I Z = I 0 -I OUT,} i a / i b = I OUT / (I 0 -I OUT), i b · I OUT = i a (I 0 -I OUT) becomes, therefore, I _{OUT = {i a / (i} a + i b)} × 0 becomes (8). By substituting the equation (4) into this, I _OUT = (a + S · f / l) × 1 / t (9), and thus an output depending on the subject distance 1 can be obtained.

A graph obtained by excluding a / t from the equation (9) is as shown in FIG. The straight line indicated by X in the figure is a theoretical line based on the equation (9), but in reality, since the signal light diffuses and the signal light amount decreases on the far distance side, S /
The accuracy on N deteriorates and the error tends to increase as the distance increases, as indicated by Y in the figure. Further, when the brightness F is high, that is, when the stationary photocurrent I _p is relatively large, a large disturbance occurs as shown by Z in the figure, and it is impossible to distinguish between a subject at a long distance l _{c and} a subject at a short distance l _d. There will be cases.

As described above, in FIG. 18, IRED1
When 0 emits light, the hold signal T _H causes the hold amplifier 37A to stop its function and the hold capacitor 42A.
The stationary photocurrent I _p is removed as the collector current of the transistor 40A, which is h _FE times the base current, by discharging the electric charge stored in the transistor 40A as the base current of the transistor 40A. Hold capacitor 42A voltage V _H
Is

V _H = I _p · R _H + V _T ln (I _p /
I _S ), ( _RH : resistance value of the hold resistor), and the larger the steady-state photocurrent I _P, that is, the larger the value under high brightness.

By the way, the capacitor 207 (see FIG. 20)
20A is generally represented by an equivalent circuit shown in FIG. 20B, in which parasitic elements such as a resistor 202 and a capacitor 201, a resistor 204 and a capacitor 203, and a resistor 206 and a capacitor 205 are connected in parallel to the capacitor 200. Has been done. Therefore, a constant current source I _X
If is connected for a time t, both ends of the capacitor

The voltage V _{C at} which V _C = I _x · t / C is temporarily charged, but the V _C decreases with time, and the behavior becomes stable eventually (FIG. 20 (c)). That is, a part of the electric charge initially charged in the capacitor 200 is passed through the resistors 202, 204 and 206 to the capacitor 20.
It is a phenomenon that occurs when it moves to 1, 203, 205 and is called dielectric absorption.

If such dielectric absorption occurs with respect to the hold capacitor 42A of FIG. 18, if the dielectric absorption causes a change of I _p → I _p −Δi _p , the above ratio calculation result is

[0016] The _{I OUT = (i a + Δi} p) / (i a + Δi p + i b + Δi p) = (i a + Δi p) / (i a + i b +2 · Δi p) (10) , and the hold capacitor 42A The influence of the error current Δi _p due to the dielectric absorption appears in the ratio calculation result.

The value of the error current Δi _p is higher as the voltage V _H across the hold capacitor 42A is higher, that is, the steady photocurrent I _p.
Because the larger value in a high large luminance, the subject is a long distance signal photocurrent i _a, i _b decreases the ratio calculation result _{I OUT = Δi p / (2} · Δi p) = 1/2 As the result approaches (11), the distance measuring characteristic deteriorates as indicated by Z in FIG.

Therefore, the applicant of the present invention, by increasing the stabilization time for storing the stationary light component in the hold capacitor under high brightness, the capacitors 201, 2
03, ... 205 is sufficiently charged to prevent the above-mentioned deterioration of the distance measurement accuracy.
No. 64 is doing it.

[0019]

However, if the stabilization time for stationary optical storage is lengthened in this way, the following problems occur. That is, the time lag from pressing the release button as the camera to performing the shutter operation becomes long. Such an increase in the release time lag causes a risk of missing a photo opportunity, which is a great drawback.

The camera having the active type distance measuring device of the present invention is made by paying attention to such problems.
An object of the invention is to provide a camera having an active distance measuring device which prevents deterioration of distance measuring accuracy for a high-luminance subject and does not increase the release time lag.

[0021]

In order to achieve the above object, a camera having an active distance measuring device of the present invention projects light toward an object to be measured, and the light is projected from the object to be measured. Distance measuring means for receiving the reflected light of the object and detecting the distance to the object based on the received light, light measuring means for detecting the brightness of the distance measuring object, and the distance measuring object based on the output of the light measuring means. Determination means for determining whether or not the object is a high-luminance subject, stationary light component storage means for storing the stationary light component in order to remove the stationary light component in the distance measuring means, and the determination means It comprises sequence changing means for changing the stabilization time of the stationary light storage means based on the output and changing the camera sequence, and control means for executing the camera sequence based on the output of the sequence changing means.

[0022]

That is, in the camera having the active distance measuring device of the present invention, it is determined whether or not the object to be measured is a high-luminance object, and the stationary light component is stored based on the result of the determination. The sequence of the camera is changed by changing the settling time of the stationary light component storage means.

[0023]

First, the concept of an embodiment of the present invention will be described with reference to FIG.

In the figure, the distance measuring means 1 projects light toward an object to be measured, receives the reflected light of the light projected from the object to be measured, and detects the distance to the object based on the received light. To do. The photometric means 2 detects the brightness of the object to be measured. Based on the output of the photometry unit 2, the determination unit 3 determines whether or not the object to be measured is a high-luminance subject that causes erroneous distance measurement. The stationary light component storage means 6 stores the stationary light component in order to remove the stationary light in the distance measuring means 1. The sequence changing means 4 changes the stabilization time of the stationary light storage means 6 based on the output of the judging means 3, and also changes the sequence of the camera. The control means 5 executes the camera sequence based on the output of the sequence changing means 4.

That is, first, the control means 5 causes the photometric means 2 to perform photometry to detect the subject brightness. Next, the determination unit 3 determines whether the subject is a high-luminance subject that causes erroneous distance measurement based on the output of the photometry unit 2. Based on the output of the judging means 3, the sequence changing means 4 gives a signal for increasing the stabilization time of the stationary light component storage means 6 for a high-luminance subject, and also gives an instruction for changing the sequence of the camera. The signal is output to the control means 5. Control means 5
Causes the distance measuring means 1 to perform distance measurement based on the output of the sequence changing means 4.

The sequence changing means 4 is the distance measuring means 1
The operation time is increased, and the sequence is changed so as to execute other operations in parallel with the operation time so that the total operation time is not increased and the release time lag is prevented from increasing.
FIG. 2 is a schematic configuration diagram showing a configuration of an electric circuit when the active distance measuring apparatus according to the above-described embodiment is applied to a camera.

In FIG. 2, the CPU 15 sequentially and sequentially controls each constituent element in the camera based on a program stored in a ROM provided therein, thereby controlling peripheral elements. Also, this CP
U15 has a built-in AD conversion circuit and converts the analog voltage to A
It is possible to perform D conversion and arithmetic processing.

The distance measuring unit 1 measures the distance to the subject by the infrared light active method, and the obtained subject distance information is stored in the CPU.
Output to 15. The distance measuring unit 1 is capable of measuring the distance in the center of the shooting screen. The photometric unit 2 measures the brightness of the subject. As will be described later, the photometric unit 2 measures the central portion and the peripheral portion of the photographing screen, and the obtained subject luminance information is stored in the CPU.
Output to 15.

The motor drive unit 16 is a zoom motor (M _Z ).
17, the lens drive and the lens motor shutter driving motor (M _L) 18, and a film feeding hoist motor (M _W) 19, the motor selection signals of a CPU 15, forward, reverse, brake, stop Drive each according to the signal.

Zoom motor 17 and lens motor 1
8. The rotational position of the hoisting motor 19 is detected by the zoom encoder 20, the lens position encoder 21, and the hoisting encoder 22, and is supplied to the CPU 15.

E ² The PROM 23 is a non-luminous storage element, and stores adjustment data for correcting an error generated at the time of production, which error occurs due to a mechanical variation of the lens position when converting the distance data into the lens position data.

The strobe 24 starts its charging in response to a control signal from the CPU 15. And the charging voltage is CP
It is monitored by U15, and when the predetermined charging voltage is reached, the CPU 15 outputs a charging stop signal to the strobe 24. The strobe 24 also emits light in response to a light emission timing signal from the CPU 15.

The DX contacts 25, 26, 27 are contacts for reading the DX code of the film cartridge, and the film sensitivity is read by the CPU 15 via these contacts. The finder display section 83 displays the inside of the finder under the control of the CPU 15. The liquid crystal display unit 28 is the CPU 1
Based on the control signal of No. 5, various displays such as mode display and film frame number display are performed.

First release switch (hereinafter R1S
Reference numeral 29 is an abbreviated W) switch which operates when the release button is half-pushed. When the R1SW 29 is turned on, distance measurement and photometry are performed, and the distance measurement value and photometry value are stored in the CPU 15. A second release switch (hereinafter abbreviated as R2SW) 30 is a switch that operates when the release button is fully pressed. When the R2SW 30 is turned on, the taking lens is extended and exposed based on the distance measurement value and the light measurement value. Be done. FIG. 3 is a configuration diagram showing a configuration of an electric circuit of the photometric unit 2 shown in FIG. Further, FIG. 4 is a diagram showing a photometric area in the photographing screen.

In FIG. 3, a light receiving element 51 is a photodiode for spot photometry for measuring the central area 67 of FIG. 4, and a light receiving element 52 is an average photometric photo for measuring the peripheral area 68 of FIG. It is a diode. The cathodes of the photodiodes 51 and 52 are connected to the reference voltage V _r1, and the anode of the photodiode 51 is the collector and base of the transistor 53 forming a current mirror, the base of the transistor 54, and a switching transistor for turning on / off the current mirror. It is connected to the collector of 55. Here, the emitter area of the transistor 54 is set to 16 times the emitter area of the transistor 53, and the collector current of the transistor 54 is the collector current of the transistor 53, that is, the photodiode 5.
It is amplified to 16 times the photocurrent I _SP of 1. Similarly, the anode of the photodiode 52 is connected to the collector and the base of the transistor 56 that forms the current mirror, the base of the transistor 57, and the collector of the switching transistor 58 that turns on and off the current mirror. Here, the emitter areas of the transistors 56 and 57 are the same, and the collector current of the transistor 57 has a current value equal to the collector current of the transistor 56, that is, the photocurrent I _{AP of the} photodiode 52. The transistors 55 and 58 are connected to the CPU 1 via the base terminals 69 and 70.
The photodiode 5 is controlled by the control signal from the photodiode 5.
The photocurrent I _{SP of} 1 and the photocurrent I _AP of the photodiode 52 are independently processed by the subsequent processing circuit.

The diodes 60 and 61 have the reverse saturation current I
It is a diode for removing _S , and the cathode of the diode 61 and the diode 6 are connected to the reference voltage V _r2 proportional to the absolute temperature.
The cathode of the diode 60 is connected to the anode of 1, and the constant current source 59 is connected to the anode of the diode 60. The constant current I ₀ of the constant current source 59 flows into the reference voltage V _r2 via the diodes 60 and 61 and generates the following voltage obtained by logarithmically compressing the constant current I ₀ . V ₁ = 2 · V _{T In} (I ₀ / I _S ) + V _r2 (12)

The base of the transistor 62 is connected to the connection point of the constant current source 59 and the anode of the diode 60, the emitter of the transistor 62 is the anode of the diode 63, and the cathode of the diode 63 is the output of the current mirror. 54 and transistor 5
It is connected to 7 collectors. Photodiode 5
The photocurrent outputs of 1 and 52 flow through the diode 63 and the emitter of the transistor 62 via the current mirror, so that they are logarithmically compressed by the transistor 62 and the diode 63. Therefore, the following equation is established. V ₂ = V ₁ −2 · V _T ln (I _p / I ₀ ) (13) The cathode output of the diode 63 is input to the non-inverting amplifier circuit including the operational amplifier 64 and the resistors 65 and 66, and the output of the output terminal 71. The voltage V _BV is V _BV = V ₂ · (1 + R ₁ / R ₂ ) (14). From the equations (14) and (12) and (13),

V _BV = (1 + R ₁ / R ₂ )  {2V _T ln (I ₀ / I _S ) + V _r2 } (15) holds, and the photometric output V that does not depend on the reverse saturation current I _S
You can get _BV . This photometric output voltage V _BV is the CPU
It is input to the AD conversion circuit built in 15, converted into a digital signal, and stored as a spot photometric value and an average photometric value, respectively.

By the way, the photometric unit 2 has the characteristic that the response becomes slower as the luminance becomes lower. This is because the photocurrents of the photodiodes 51 and 52 are extremely small at low luminance, so that the photodiodes 51 and 52 shown in FIG.
This is because it takes time to charge and discharge the capacitance components such as the junction capacitances 72 and 73 of 52, the compression diode 63, and the junction capacitances 74 and 75 of the compression transistor 62.

FIG. 5 is a diagram showing the response of the photometric output V _BV . It takes a very long time to stabilize at low luminance b as compared to at high luminance a. Therefore, conventionally, a waiting time of t _D is provided from the start of photometry to the photometry, that is, from the A / D conversion by the CPU 15 to the reading.

FIGS. 6A and 6B are views showing the configuration of the electric circuit of the distance measuring unit 1. The same components as those in FIG. 18 are designated by the same reference numerals, and only different portions from FIG. 18 will be described.

The timing generation circuit 81 (FIG. 6B) is supplied with a clock from the CPU 15 and operates by using this as a basic clock to generate the light emission timing signal T of the IRED.
_I , ON signal T _C of current source 46, hold amplifier 32,
Outputs an ON signal T _H of the current source 35, the operation of the distance measuring unit 1. The integrating capacitor 80 is connected to the ratio calculation circuit 47, and when the current source 46 is turned on by the timing signal T _C in synchronization with the light emission of IRED, the integrating capacitor 80 is integrated by the integrated current I _OUT shown in the equation (8). The integrated voltage V _INT of the integrating capacitor 80 is expressed by the following equation and is output to the CPU 15. Capacity of _{V INT = {i a / (} i a + i b)} × I 0 × n × (τ / C) (16) where n ... IRED number of emissions tau ... 1 times integration time C ... integrating capacitor 80 value

Prior to the integration operation, the reset circuit 82 initializes the potential of the integration capacitor 80 to set the integration voltage V _INT = 0. When the IRED emission and the integration operation are completed a predetermined number of times, the CPU 15 AD-converts the integration voltage V _INT of the integration capacitor 80 and reads the distance measurement data.

The operation of one embodiment of the present invention will be described below. First, the operation of the conventional camera and its drawbacks will be described with reference to FIGS. Note that, here, the release button related to the present invention is pressed halfway, and R1SW2
Only the operation after 9 is turned on will be described.

FIG. 21 shows a release sequence routine R1.
It is a flowchart of. First, when the release button is half pressed and the R1SW 29 is turned on, photometry and distance measurement are performed in "AFRD". Next, in "AFCNV", distance calculation is performed from the distance measurement data to calculate the subject distance. If "ZMRCV" indicates that the zoom is not in the shooting area, the zoom is moved to the shooting area. "SCHGC
In "K", the strobe charging voltage is checked to determine whether strobe emission is possible. Then, in "CALSV", the DX code is read from the film cartridge and stored, and "B" is read.
VCNV "performs the photometric calculation together with the photometric data.

Next, in "AECAL", an exposure calculation for driving the shutter is performed based on the photometric calculation result. In “AFCAL”, the extension position of the photographing lens is calculated based on the subject distance. Then, the process shifts to a loop waiting for the second release (R2SW30 on), the in-finder display "FINDD" is executed, and the in-finder display LED 83 is turned on or blinked. Next, if the R2SW30 is turned on, the process advances to "LDRIV" to extend the taking lens, and then "SHUT".
At "R", the shutter is driven to perform exposure. Then, at "OWIND", the film is wound up one frame, and "LENR".
The photographing lens extended in is reset to the initial position. This completes the operation of the release sequence routine R1.

Next, the release sequence routine R1
A subroutine "AFRD" for performing distance measurement and photometry operations will be described with reference to the flowchart shown in FIG. 24 and the timing charts shown in FIGS. First, in order to determine whether or not the subject is a high-brightness subject that causes erroneous distance measurement in normal distance measurement, pre-spot photometry is performed at the center of the shooting screen. The CPU 15 sets the terminals 69 and 70 to the photometric unit 2 at the L level and the H level ((a) and (b) of FIGS. 22 and 23), and at the same time, starts the internal timer 1 (S1 of FIG. 24) and outputs the photometric output. The stable time T _S ′ of is counted. Here, since it is only determined whether or not the brightness is high, the stable time T _S ′ is set to a very short time. When the output of the timer 1 reaches the stable time T _S ′ (S2 of FIG. 24), the CPU 15 AD-converts the photometric output voltage V _BV of the output terminal 71 of the photometric unit 2 and reads the spot photometric data (FIGS. 22 and 23). (A) of FIG.
S3). The CPU 15 compares preset data with the spot photometric data to determine whether or not the result of the spot photometry is high brightness (S4 in FIG. 24).

As a result, when the brightness is not high, the process proceeds to S5 of FIG. 24, and the normal distance measuring and photometric operations are performed. Here, as described above, when the brightness is low, it takes time for the photometric output voltage V _BV of the photometric unit 2 to stabilize. Therefore, the necessary stabilization time for the minimum brightness is set as a waiting time, and for spot and average photometry, respectively. T _S is set to about 100 ms and T _A is set to 50 ms. Further, in order to reduce the release time lag, the distance measuring unit 1 performs distance measurement during the waiting time T _S for spot light measurement.

Therefore, the CPU 15 supplies a clock ((i) in FIG. 23) to the timing generation circuit 81 of the distance measuring section 1,
The preamplifier 32 is turned on ((d) of FIG. 23). Also C
Start the timer 1 inside the PU 15 (see S in FIG. 24).
5) Count the stable time T _S for spot photometry. On the other hand, in the distance measuring unit 1, when the stable light component is stored as the clock starts to be input and the stable time T _C elapses, the timing generator 81 causes the IRED to emit light,
In synchronization with this, the current source 46 is turned on and the integration operation is performed ((e), (f), (g) in FIG. 23, S in FIG. 24).
6). After the IRED emits light a predetermined number of times, the AD conversion of the integration voltage V _INT of the integration capacitor 80 is performed by the CPU 15.
Done by. In the CPU 15, the integrating capacitor 80 is inversely integrated by a constant current source (not shown) ((g) in FIG. 23), and the distance measurement data is obtained by counting the inverse integration time ((i) in FIG. 23). Stop the supply and finish the distance measurement.

Next, the timer 1 sets the spot metering stable time T _S.
24 (S7 in FIG. 24), the CPU 15 performs AD conversion of the photometric output voltage V _BV which is the output of the photometric unit 2 to obtain spot photometric data ((c) in FIG. 23, S in FIG. 24).
8). The distance measuring operation described above is performed by the spot metering stable time T _S.
It is set to finish in a shorter time (about 50 ms) than (about 100 ms).

Next, the CPU 15 sets the terminals 69 and 70 to the "H" level and the "L" level, respectively, and selects the average photometry ((a) and (b) in FIG. 23). At the same time, the timer 1 is started to start the average. The photometric stabilization time T _A (about 50 ms) is counted (S9 in FIG. 24). When timer 1 reaches T _A , C
The PU 15 performs AD conversion of the photometric output voltage V _BV of the photometric unit 2 to obtain average photometric data ((c) of FIG. 23, S11 of FIG. 24). This is the end of the subroutine "AFRD" for performing distance measurement and photometry operations.

Next, returning to S4 of FIG. 24, if it is determined that the brightness is high, the process proceeds to S12 of FIG. 24, and in order to prevent the deterioration of the ranging accuracy at the time of high brightness, the stability for steady light storage is maintained. After taking a longer time, the distance measuring operation is performed. Under high brightness such as outdoors on a sunny day, the stable time T _C ′ is required to be about 200 ms in order to obtain sufficient distance measuring accuracy.

In S12 of FIG. 24, the timer 1 and the timer 2 inside the CPU 15 are started. Below, timer 1
Is used for counting the average spot photometry stabilization time, and the timer 2 is used for time management of the distance measuring operation.

In the photometry unit 2, the terminals 69 and 70 are held at the L level and the H level, and the spot photometry stabilization time T _S is counted ((a) and (b) in FIG. 22). On the other hand, in the distance measuring unit 1, the stationary optical storage operation is performed by the clock from the CPU 15, but the CPU 15 stops the clock supply at the predetermined count of the timer 2 in order to extend the stable time ((i) in FIG. 22). ). In this state, the distance measuring unit 1 continues the stationary light storage operation.

When the timer 1 reaches T _S , the CPU 15 performs AD conversion of the spot photometric data (S in FIG. 24).
13 and 14), terminals 69 and 70 are set to H and L, and the timer 1 is restarted to count the average photometry stabilization time T _A. When the timer 1 reaches T _A , the CPU 15 AD-converts the average photometric data and ends the photometric operation (FIG. 24).
S16, 17). In this way, the distance measuring unit 1 performs the photometric operation while the steady light storage operation is being performed to reduce the time lag.

Next, when the output of the timer 2 reaches the required stable time T _C ′ for the stationary light storage (S18 in FIG. 24), C
The PU 15 restarts supplying the clock to the distance measuring unit 1 ((i) in FIG. 22). Then, in the distance measuring unit 1, the timing generation circuit 81 emits light from the IRED and the current source 46 is turned on in synchronization with this, and the integration operation is started ((e), (f), (g in FIG. 22). )). After the IRED emits light a predetermined number of times, the CPU 15 performs AD conversion of the integration voltage V _INT of the integration capacitor 80 ((g) of FIG. 22) and obtains distance measurement data ((h) of FIG. 22, FIG. 24).
S19). As described above, it is possible to sufficiently extend the stabilization time for stationary light storage, and to obtain distance measurement data without deterioration in accuracy under high brightness. However, in the conventional example described above, the difference ΔT between the release time lags under high brightness and otherwise is ΔT = (T _C ′ + T _l ) − (T _S + T _A ) (where T
_l ... IRED emission of the distance measuring unit 1, integration, and AD conversion), and when a numerical value is actually entered, ΔT = (200 ms + 50 ms) − (100 ms + 50 ms) =
It becomes 100ms. As described above, in the conventional example, there is a large release time lag when the brightness is high compared to when the brightness is not high.

Next, a first embodiment of the present invention will be described with reference to the flowchart of FIG. 7 and the timing chart of FIG. The configuration of the present embodiment is the same as the schematic configuration diagram shown in FIG. 2, and the photometry unit and the distance measurement unit are also the same as those shown in FIGS. Therefore, the main part of this embodiment is expanded by the CPU 15 in FIG. 2 executing a predetermined program.

FIG. 7 is a flowchart of a subroutine "AFRD" for performing photometry and distance measurement operations corresponding to FIG. 24 described above as a conventional example. FIG. 8 is a timing chart of distance measurement and photometry at high brightness. First, the CPU 15 clears the flag F indicating the result of high brightness determination by pre-spot photometry (S50 in FIG. 7).

Next, the CPU 15 causes the terminal 69 of the photometric unit 2 to
70 is set to L level and H level ((a) of FIG. 8,
(B)), at the same time, the timer 1 is started to count the pre-spot photometry stabilization time T _S ′ (S2 in FIG. 7).
1). When the timer 1 reaches T _S ′ (S22 in FIG. 7),
The CPU 15 AD-converts the output voltage V _BV of the photometric unit 2 to obtain pre-spot photometric data (S23 in FIG. 7, (c) in FIG. 8). Next, the pre-spot photometric data is compared with prestored data to determine whether or not the subject has high brightness (S24 in FIG. 7). When it is determined that the subject has high brightness, the flag F is set to "1" (S5 in FIG. 7).
1).

Next, proceeding to S32 in FIG. 7, the CPU 15 starts the timer 1 and the timer 2 and simultaneously sets the terminals 69 and 70 of the photometric unit 2 to H level and L level to set average photometry ((a) in FIG. 8). , (B)). Further, supply of a clock to the distance measuring unit 1 is started. Next, at the predetermined count of the timer 2, the CPU 15 stops the supply of the clock,
The state where the distance measuring unit 1 is performing the stationary light storage operation is held. On the other hand, when the timer 1 reaches the average photometry time T _A , C
The PU 15 AD-converts the output voltage V _BV of the photometric unit 2 and reads the average photometric data (S33 and S34 in FIG. 7, (c) in FIG. 8). When the subject has a high luminance, spot photometry has a sufficiently fast response, and thus pre-spot photometry data can be used as a substitute. Therefore, the spot photometry is not performed again, the time lag is reduced, and the photometry is completed.

The part to be described below is the point of the present embodiment. In the above-mentioned conventional example, as shown in S8 of the flowchart of FIG. 24, the CPU 15 keeps the steady light storage stable time by the timer 2 from the end of the average photometry to the restart of the supply of the clock to the distance measuring unit 1. T
I was just counting _C '. On the other hand, as shown in the flow chart of FIG. 7, in the present embodiment, the photometry calculation is performed by the subroutine "CALSV" (S35 in FIG. 7) for reading the film sensitivity by the DX code of the film cartridge, the spot, the average photometric data and the film sensitivity data. Subroutine "BVCNV" (S36 in FIG. 7),
A subroutine "AECAL" for performing exposure calculation for driving the shutter based on the photometric calculation result (S in FIG. 7).
37) is being executed. Therefore, as will be described later, in the release sequence routine, "CALSV", "B
Since it is not necessary to perform VCNV "and" AECAL ", the time lag for the above processing can be shortened.
In "AECAL", the calculation for controlling the flash emission amount is performed based on the subject distance, but since the brightness is high, it is not necessary to emit the flash. Therefore, the above calculation is omitted.

After that, the timer 2 sets the stationary light storage stabilization time T
_When reaching _C ', the CPU 15 supplies the clock again to the distance measuring unit 1 (S38 in FIG. 7, (i) in FIG. 8). Then, in the distance measuring unit 1, the timing generation circuit 81 causes the I
The light emission of the RED and the turning on of the current source 46 are performed in synchronization with each other,
The integration operation is performed ((e), (f) in FIG.
(G)). After the IRED emits light a predetermined number of times, C
PU15 is the AD of the integration voltage V _INT of the integration capacitor 80.
Conversion is performed to obtain distance measurement data ((h) of FIG. 8 and S39 of FIG. 7).

In this way, the stable time T for stationary optical memory is
_{Since C} ′ is set sufficiently long, it is possible to obtain distance measurement data without deterioration in accuracy even under high brightness. If the result of pre-spot photometry is not high brightness (S in FIG.
24), the same contents as the conventional example (S25 to S31 in FIG. 7)
Therefore, the description is omitted.

Next, the flow chart of the release sequence routine "R1" of this embodiment shown in FIG. 9 will be described. Description of the same parts as in the flowchart of FIG. 21, which is a conventional example, is omitted, and only different parts will be described.
The details of the “AFRD” (S41 in FIG. 9) have been described above. “AFCNV” to “ZMRCV” in FIG. 9 (S42 to
43) is the same as the conventional example.

Next, the CPU 15 determines whether or not the result of the pre-spot photometry in "AFRD" is high brightness, by a flag F.
Is checked to determine (S44 in FIG. 9). as a result,
If the brightness is not high, the same process as the conventional example is performed after "SCHCK". On the other hand, when the brightness is high, it is not necessary to use strobe light, so "SCHCK" is omitted and "CAL" is omitted.
SV ”,“ BVCNV ”,“ AECAL ”(S4 in FIG. 9
Since the processes 6 to 48) have already been performed in "AFRD", the process proceeds to "AFCAL" (S49 in FIG. 9) and the same processes as in the conventional example are performed thereafter.

As described above, in the release sequence "R1" excluding "AFRD", "SCHCK", "CALSV",
Since the processes of "BVCNV" and "AECAL" are reduced, the time lag can be shortened accordingly. In the embodiment described above, the difference ΔT ′ between the release time lags under high brightness and otherwise is ΔT ′ = (T _S ′ + T _C ′) − (T _S ′ + T _S + T _A +
The _{T SC + T CA + T BV} + T AE) = T C '-T S -T A -T SC -T CA -T BV -T AE. Here, the processing time of T _SC ... "SCHCK" T _CA ... the processing time of "CALSV" T _BV ... the processing time of "BVCNV" T _AE ... the processing time of "AECAL" When the actual numerical value is entered, T _SC = 10 ms, T _CA = 10 ms, T _BV = 10 ms, T _AE = 2
0 ms, ΔT '= 200 ms-100 ms-50 ms-10 ms-10 ms
-10ms-20ms = 0

It becomes In this way, the conventional large release time lag under high brightness can be greatly reduced from 100 ms to 0 ms, and it is also possible to avoid deterioration of distance measurement accuracy under high brightness.

[0068] Note that in the embodiment between the high stationary light storage stabilization time when luminance _{T C '"CALSV","}BVCNV",
Although the processing of "AECAL" is performed, the processing content is not limited to this, and there is no problem even if it is other processing.

Next, a multi-AF camera having a plurality of distance measuring points will be described as a second embodiment. Figure 10
FIG. 3 is a diagram showing a configuration of an electric circuit of the distance measuring unit 1. FIG. 6
The same components as those in FIG. 6 are designated by the same reference numerals, and different parts from FIG. 6 will be described.

IRED89 and IRE shown in FIG. 11 (b)
D90, IRED91 and PSD92, PSD9 of FIG.
3 and PSD94 are paired with each other, as shown in FIG.
Distance measuring points 101 and 10 in the photographing screen shown in FIG.
Distance measurement is performed on Nos. 2 and 103. Preamplifier 111A
Is the preamplifier 32A and the amplification transistor 33 of FIG.
A and the current source 34A are collectively described, and similarly, the preamplifier 111B is the collective description of the preamplifier 32B, the amplification transistor 33B, and the current source 34B shown in FIG. Also, the preamplifiers 110A, 110B, 112A, 1
The same circuit is also used for 12B. These preamplifiers can be selectively operated by the timing signals T ₅ , T ₆ , and T ₇ from the timing generation circuit 120. The amplifier 95A is the amplifier 37 shown in FIG.
A and the current sources 35A and 39A are collectively described. Similarly, the amplifier 95B is also the amplifier 37B in the figure, the current sources 35B and 3A.
9B is collectively described.

At the output terminal of the amplifier 95A, in addition to the hold capacitor 42A, hold transistors 113A to 11A are provided.
5A and hold resistors 116A to 118A are connected as shown. Hold transistors 113A to 115
The collectors of A are analog switches 96A to 98, respectively.
Through A is connected to the output of the PSD, the analog switch 96A~98A is selectively turned on in synchronism with each preamplifier by the timing signal T ₅ through T ₇ of the timing generation circuit 120. From the compression diode 36A to the ratio calculation circuit 4
The configuration up to 7 is the same as that in FIG. Integrating capacitor 80
Is connected to the output of the ratio calculation circuit 47, and when the current source 46 is turned on in synchronization with the light emission of IRED, the integrated current I _OUT shown in the equation (8) is integrated, and the integrated voltage V _{INT is set} to the CPU 15
Output to. Integration voltage V _INT, as indicated at _{(16), V INT = {i a /} (i a + i b)} × I 0 × n × (τ /
C). Here, n ... IRED emission frequency τ ... Single integration time C ... Integral capacitor 80 capacitance value. The reset circuit 82 sets the potential of the integrating capacitor 80 to the initial state before the light emission of the IRED, and the integrated voltage V
_{Set INT} = 0.

The timing generator circuit 120 includes the CPU 15
A clock is supplied from the CPU, and operation is performed using this as a basic clock.
A selection signal for selecting SD, that is, at which of the plurality of distance measuring points 101 to 103 in the photographing screen shown in FIG. 91 light emission timing signal T ₁
Timing signals T _{1 to} T ₈ such as T ₃ are generated and output to each section. The CPU 15 A / D-converts the integrated voltage V _INT based on the equation (16) and processes it as distance measurement data. In this way, the CPU 15 can selectively perform distance measurement at a plurality of distance measurement points and obtain each distance measurement data.

In a camera having a plurality of distance measuring points, the central distance measuring point is usually emphasized. Therefore, in this embodiment, the left and right distance measuring points IRED shown in FIG. 11B are used.
IRED of the projected light amount of 89 and 91 at the central distance measuring point
The distance is lower than 90, and the distance that can be measured is reduced.

Since the photometric unit 2 is exactly the same as that of the first embodiment, its explanation is omitted. The other electric circuits in the camera are the same as those of the first embodiment shown in FIG.

Next, the second embodiment will be described with reference to the flow charts and timing charts of FIGS. The flowchart of FIG. 12 shows the first release routine "R1". First, the CPU 15 clears the high brightness flag F0 for pre-spot photometry (see FIG. 12).
S200), "pre-spot photometry" corresponding to the center distance measuring point 102 (S201 in FIG. 12) is performed to determine whether the subject has a high brightness that causes erroneous distance measurement, or the photometric output of the photometry unit 2 and a predetermined value. Judge by comparing with the level (Fig. 12
S202). When the brightness is high, the high brightness flag F0 is set to 1 (S203 in FIG. 12), and “AFRD2” is executed (S204 in FIG. 12). On the other hand, if it is determined that the brightness is not high, the "pre-average photometry" corresponding to the left and right distance measuring points 101 and 103 is executed (S205 in FIG. 12). Then, it is determined whether or not the brightness is high (S206 in FIG. 12). If the brightness is high, the process proceeds to “AFRD3” (S208 in FIG. 12), and if not, the process proceeds to “AFRD1” (S20 in FIG. 12).
7). The distance measurement and photometry routine "AFRD1" will be described below with reference to the timing chart of FIG.

In FIG. 13, description will be given including "pre-spot photometry" and "pre-average photometry". The CPU 15 sets the terminals 69 and 70 of the photometry unit 2 to "L" and "H", respectively, to set the spot photometry mode ((l) in FIG. 13).
(M)). Since the purpose here is to determine whether or not the subject has high brightness, the waiting time may be very short. Next, the CPU 15 AD-converts the photometric output of the photometric unit 2 and takes in it as pre-spot photometric data D _S ((n) in FIG. 13).

Next, the CPU 15 sets the terminals 69 and 70 to "H" and "L" ((l) and (m) of FIG. 13) to enter the average photometry mode to perform pre-average photometry and pre-average photometric data D _A. ((N) in FIG. 13). Here, as described above, the subject does not have high brightness that would cause erroneous distance measurement, so the CPU 15 compares the photometric data D _S , D _A with a predetermined determination level and determines that the brightness is not high. ,
Proceed to "AFRD1" to perform distance measurement and photometry operations.

Here, as described above, it takes a longer time to stabilize the photometric output voltage of the photometric unit 2 during low-luminance photometry, so the waiting time is set so as to satisfy the required stable time at the minimum luminance. .. Further, the distance measurement of the distance measuring unit 1 is performed during the waiting time in order to reduce the release time lag. First, the CPU 15 sets the terminal 69 of the photometry unit 2 from the H level to the L level to start the waiting time for spot photometry ((l) and (m) in FIG. 13).

At the same time, the CPU 15 outputs a clock to the timing generation circuit 120 to measure the distance at the center distance measuring point 102 ((k) in FIG. 13).
The hold signal T ₈ and the ON signals T ₆ of the preamplifiers 112A and 112B and the analog switches 97A and 97B are output to hold the steady photocurrent of the PSD 93 for a predetermined time ((j) in FIG. 13). Next, the timing generation circuit 1
The emission signal T ₂ of the two from IRED90 in synchronism therewith outputs an ON signal T ₄ of the current source 46 of the ratio calculation circuit 47 (FIG. 13 (b), (c)) , off the hold signal T ₈ ((J) in FIG. 13). Integrating is performed in the integrating capacitor 80 in synchronization with the light emission of the IRED 90 ((d) in FIG. 13), and when the IRED 90 finishes emitting light for a predetermined number of times, the light emission signal T from the IRED 90 is generated. ₂ and current source 4
6, the on signal T ₄ is turned off ((b) of FIG. 13,
(C)), the integration operation ends. Next, the CPU 15 performs AD conversion of the integrated voltage ((e) in FIG. 13).
The CPU 15 inversely integrates the integrating capacitor 80 with a constant current source (not shown), and counts the inverse integration time to obtain the distance measurement data D _C by the PSD 93. After that, the preamplifiers 111A and 111B and the analog switches 97A and 97B are turned off by the timing signal T ₆ ((a) of FIG. 13).

Next, distance measurement is performed at the left distance measurement point 101. Similarly, from the timing generation circuit 120,
The hold signal T ₈ and the ON signal T _{5 of} the preamplifiers 110A and 110B and the analog switches 96A and 96B are output ((f) of FIG. 13), and after performing the hold operation for a predetermined time, the light emission signal T ₁ from the IRED 89 is output. Current source 46
The integrating capacitor 80 is integrated by the ON signal T ₄ of ((g) and (d) of FIG. 13). When light emission / integration has been completed a predetermined number of times, the CPU 15 similarly performs AD conversion of the integrated voltage ((e) in FIG. 13) and obtains the distance measurement data D _L by the PSD 92.

Next, when the spot photometric waiting time reaches a predetermined value T _S ((l) in FIG. 13), the CPU 15 AD-converts the photometric output voltage of the photometric unit 2 to generate spot photometric data D _S.
To get At this time, the CPU 15 causes the timing generation circuit 12 to
The clock to 0 is turned off so as not to give noise to the minute photocurrent processing at low luminance.

Thereafter, the CPU 15 sets the terminal 69 to H, 70.
Is set to L and the counting of the average photometric waiting time is started, the clock is again supplied to the timing generation circuit 120, and at the same time, the timer is reset and started, and the hold signal T ₈ and the preamplifiers 112A and 112B and the analog are output from the timing generation circuit 120. Switch 98A,
The ON signal T _{7 of} 98B is output ((h) of FIG. 13),
Hold operation is performed for a predetermined time. And IRED
The light emission signal T _{3 of} 91 and the ON signal T ₄ of the current source 46 cause integration in the integrating capacitor 80 ((i) (c) (d) of FIG. 13). When the light emission integration for a predetermined number of times is completed, the CPU 15 performs AD conversion of the integrated voltage, and P
Distance measurement data D of the right distance measurement point 103 by SD94
_R is obtained ((e) of FIG. 13).

This completes the distance measurement. When the count of the average photometric waiting time reaches the predetermined value T _A , the CPU 1
Reference numeral 5 AD-converts the photometric output voltage of the photometric unit 2 to obtain average photometric data ((n) in FIG. 13). With the above, metering is completed,
“AFRD1” is ended (S207 in FIG. 12).

Next, as a result of the pre-spot photometry, the distance measurement and photometry routine "AFRD2" (S204 in FIG. 12) when the subject has a high luminance that causes an erroneous range measurement will be described with reference to FIG.
It will be described based on 4. In this case, in order to obtain sufficient distance measuring accuracy at the central distance measuring point 102 as described above, a sufficiently long stabilization time is required for the stationary light storage.
In addition, since the idea that the central distance measuring point is considered important, distance measurement is performed only at the central distance measuring point.

In FIG. 14, first, the CPU 15 sets the terminals 69 and 70 of the photometry section 2 to "L" and "H", respectively, and performs pre-spot photometry ((h) (i) of FIG. 14). Here, since the pre-spot photometry result is determined to be high brightness, the high brightness flag F0 is set to 1 as shown in FIG.
Proceed to FRD2 ".

From now on, description will be made including the "AFRD2" flow chart of FIG. The CPU 15 starts the internal timers 1 and 2, and the average photometric waiting time T _A respectively.
And the stationary optical memory operation stabilization time T _C ′ is counted (see FIG. 1
6 S100). At the same time, a predetermined number of clocks are supplied to the timing generation circuit 120 in the distance measuring unit 1 to set the steady optical memory operation state, and then the clock supply is stopped to maintain this state ((g) in FIG. 14). .. When the count of the timer 1 reaches the average photometry waiting time T _A (S10 of FIG. 16)
1), AD conversion of the photometric output voltage of the photometric unit 2 is performed to obtain average photometric data D _A ((n) of FIG. 14, S10 of FIG. 16).
2). Here, since the spot photometric area has sufficiently high brightness, the spot photometric data D _S is the pre-spot photometric data D
_S'can be used instead, and spot photometry will not be performed again.

Next, in S103 of FIG. 16, the film sensitivity is read ("CALSV"), in S104, photometric calculation is performed from the spot average photometric data and the film sensitivity ("BVCNV"), and in S105, the photometric measurement is performed. The exposure calculation for driving the shutter is performed based on the calculation result (“AECAL”). Therefore, as will be described later, in the release sequence “R1”, “C
Since it is not necessary to perform "ALSV", "BVCNV", and "AECAL", the time lag of these processing times can be shortened. In "AECAL", calculation for strobe light emission amount control based on the subject distance is performed. However, since the spot photometric area has high brightness, it is not necessary to emit a strobe light, and the above calculation is omitted.

After that, the timer 2 sets the steady memory stable time T _C.
16 '(S106 in FIG. 16), the CPU 15 supplies the clock again to the distance measuring unit 1 (S10 in FIG. 16).
7, (g) of FIG. Then, in the distance measuring unit 1, the timing generation circuit 120 causes the IRED 90 to emit light, and
6 is turned on synchronously ((b) of FIG. 14,
(C)), the integration operation is performed ((d) of FIG. 14). I
After the RED 90 emits light a predetermined number of times, the CPU 15
Performs AD conversion of the integrated voltage V _INT of the integrating capacitor 80 to obtain distance measurement data D _C ((e) in FIG. 14).

Next, the spot metering area does not have high brightness,
The distance measurement and the photometry routine "AFRD3" when the average photometry area has high brightness will be described with reference to FIG.
In “AFRD3”, left and right distance measuring points 101 and 103
Since the distance measurement accuracy in the case of high brightness is low, reliability is low, and if the stationary light storage stabilization time is long and distance measurement is performed, the time lag increases, so the central distance measurement point 101
Distance measurement is performed only in.

In FIG. 15, pre-spot photometry and pre-average photometry are performed in the same manner as described above. Next, the CPU 15 sets the terminals 69 and 70 of the photometric unit 2 to "L" and "H",
Set to spot metering mode. At this time, since the spot photometry area may have the lowest luminance, a predetermined spot photometry waiting time T _{S is} waited for, and the central distance measuring point 10
In step 1, normal distance measurement is performed. Next, when the spot photometry waiting time T _S is reached, spot photometry is performed and spot photometric data D _S is obtained. On the other hand, since the average photometric data has sufficiently high luminance, the pre-average photometric data D _A ′ is used as it is.

As described above, in the release sequence "R1" of FIG.
One of "1", "AFRD2", and "AFRD3" is executed, then "AFCNV" and "ZMRCV" are executed (S209 and 210 in FIG. 12), and then the high brightness flag F0 = 1. It is determined whether or not (S21 in FIG. 12)
1). If F0 = 0, then “SCHGCK”, “C
ALSV ”,“ BVCNV ”, and“ AECAL ”are executed (S212 to 215 in FIG. 12), but if F0 = 1, then“ CALSV ”and“ BV ”are already set in“ AFRD2 ”.
Since the processing of "CNV" and "AECAL" is being performed,
Skip and continue. That is, the time lag of the processing time can be reduced. For "SCHGCK", since the high brightness flag F0 = 1 and the spot photometric area has high brightness, strobe light emission is not necessary and is omitted, and the time lag of this processing time is also reduced. In this case, it is not necessary to calculate the flash emission amount in "AECAL". The processing after "AFCAL" is the same as the above description and is omitted.

In the multi-AF camera having a plurality of distance measuring areas described above, there is a release time lag between the case where the spot metering area or the average metering area has high brightness and the case where none of the spot average metering areas has high brightness. Find the difference. Based on the release time lag when none of the spot average photometric areas have high brightness, the difference in the release time lag in each brightness situation is calculated and shown below.
First of all, the release time lag difference ΔT _R in the case of high brightness in the spot metering area is ΔT _R = (T _C ′ −T _SC −T _CA −T _BV −T _AE ) − (T _S
+ T _A) = 200-10-10-10-20-100-
There is no difference in release time lag, since it becomes 50 = 0 ms. Next, when the brightness is not high in the spot metering area but high in the average metering area, the difference ΔT _R2 of the release time lag is ΔT _R2 = T _S − (T _S + T _A ) = − T _A = −50 ms. Can be reduced.

As described above, even under high brightness, the release time lag is not increased, and the distance can be measured at the same level as the normal distance measuring accuracy at least in the central distance measuring area.

As described above, the high-brightness state that greatly deteriorates the distance measurement accuracy is detected, and the stationary light storage stabilization time is set sufficiently long for a high-brightness object to reduce the distance measurement accuracy. It is also possible to prevent the release time lag from increasing by changing the sequence in other cameras.

[0095]

As described above, according to the present invention, since the sequence of distance measurement, photometry, etc. is changed according to the brightness of the object, accurate measurement is performed on a high brightness object without increasing the release time lag. It is possible to perform distance.

[Brief description of drawings]

FIG. 1 is a block diagram showing the concept of an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram when one embodiment is applied to a camera.

FIG. 3 is a circuit configuration diagram of a photometric unit shown in FIG.

FIG. 4 is a diagram showing a photometric area in a shooting screen.

FIG. 5 is a diagram showing the response of photometric output.

FIG. 6 is a diagram showing a configuration of an electric circuit of a photometry unit.

FIG. 7 is a flowchart showing an “AFRD” subroutine according to the first embodiment of the present invention.

FIG. 8 is a distance measurement at high brightness according to the first embodiment of the present invention,
It is a photometry timing chart.

FIG. 9 is a flowchart showing a release routine according to the first embodiment of the present invention.

FIG. 10 is a circuit configuration diagram of a distance measuring unit according to a second embodiment of the present invention.

FIG. 11 is a diagram for explaining a distance measuring method according to a second embodiment.

FIG. 12 is a flowchart showing a first release routine according to a second embodiment.

FIG. 13 is a timing chart for explaining pre-spot and pre-average photometry.

FIG. 14 is a timing chart for explaining the “AFRD2” routine of FIG.

FIG. 15 is a timing chart for explaining the “AFRD3” routine of FIG.

16 is a timing chart for explaining the “AFRD2” routine of FIG.

FIG. 17 is a block diagram of a conventional active distance measuring device.

FIG. 18 is a diagram showing a circuit configuration of FIG. 17.

FIG. 19 is a characteristic diagram showing a relationship between a subject distance and a ratio calculation result.

FIG. 20 is a diagram for explaining dielectric absorption.

FIG. 21 is a flowchart showing a release sequence routine of a conventional device.

22 is a time chart for explaining the subroutine "AFRD" of FIG. 21. FIG.

FIG. 23 is a time chart for explaining the subroutine “AFRD” of FIG. 21.

FIG. 24 is a flowchart for explaining the subroutine “AFRD” of FIG. 21.

[Explanation of symbols]

1 ... Distance measuring means, 2 ... Photometric means, 3 ... Judging means, 4 ... Sequence changing means, 5 ... Control means, 6 ... Steady light component storage means.

[Procedure amendment]

[Submission date] June 29, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

The following relationship is established. In principle, the PSD 14 generates a signal photocurrent I _p and outputs a signal depending on the incident position x from two output ends. P on the IRED10 side
Letting a be the distance from the SD end to the origin, i _a = {(a + x) / t} × I _p (2) Here, t represents the length of the PSD 14. Further, from i _a + i _b = I _p (3), the relationship i _a / (i _a + i _b ) = (a + S · f / 1) × 1 / t (4) holds. Therefore, the subject distance 1 can be obtained by performing the ratio calculation based on the equation (4).

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

FIG. 18 is a diagram showing a circuit configuration of the active type distance measuring device of FIG. Output current i from PSD14
_Since the circuits that process _a and i _b have the same configuration, only the circuit that processes i _a will be described below. FIG. 17
The output current i _a from the PSD 14 is amplified by the preamplifier 32A and the amplification transistor 33A via the input terminal 31A. This amplification transistor 33A has a current source 3
4A, 35A, compression diode 36A and buffer 43
A is connected. The amplification transistor 33A is provided at the inverting input end of the amplifier 37A, the compression diode 38A and the current source 39A are provided at the non-inverting input end, and the hold transistor 40A and the hold resistor 41A are provided at the output end.
And the hold capacitor 42A is connected as shown. In addition, the compression diode 3 is connected to the transistors 44A and 45A that form the ratio calculation circuit 47A together with the current source 46A.
The output of 6A is connected via the buffer 43A.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

As described above, the output current of the PSD 14 becomes a voltage compressed by the compression diode, and a circuit for obtaining the above ratio i _a / (I _a + i _b ) using this compressed signal will be described below. _I OUT in FIG, _{I Z} is _{I OUT} + I Z ₌ I O becomes a relationship of (6), also _{V a -V b = V T ln} (i a / I S) -V T ln (i b / I S ) = V _T ln (I _OUT / I _S ) −V _T ln (I _Z / I _S ) (7). Therefore, i _a / i _b = I _OUT / I _Z.
Here, from the _{I Z = I O -I OUT,} i a / i b = I OUT / (I O -I OUT), i b · I OUT = i a (I O -I OUT) becomes, therefore, I _OUT = the _{{i a / (i a +} i b)} × I O (8). By substituting the equation (4) into this, I _OUT = (a + S · f / 1) × 1 / t × I _O (9), and thus an output depending on the subject distance 1 can be obtained.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

A graph obtained by excluding a / t from the equation (9) is as shown in FIG. The straight line indicated by X in the figure is a theoretical line based on the equation (9), but in reality, since the signal light diffuses and the signal light amount decreases on the far distance side, S /
The accuracy on N deteriorates and the error tends to increase as the distance increases, as indicated by Y in the figure. Further high luminance under, that is, relatively large situation stationary light current I _p, cause large disturbances as shown in the figure Z, impossible to distinguish between an object of the subject and the short distance l _d of the long-distance l _c There will be cases.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

[0022]

That is, in the camera having the active distance measuring device of the present invention, it is determined whether or not the object to be measured is a high-luminance object, and the stationary light component is stored based on the result of the determination. The stable time of the stationary light component storage means is changed , and the sequence of the camera is changed.

[Procedure Amendment 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0070

[Correction method] Change

[Correction content]

IRED89 and IRE shown in FIG. 11 (b)
D90, IRED91 and PSD92, PSD9 of FIG.
3 and PSD94 are paired with each other, as shown in FIG.
Distance measuring points 101 and 10 in the photographing screen shown in FIG.
Distance measurement is performed on Nos. 2 and 103. Preamplifier 111A
Is the preamplifier 32A and the amplification transistor 33 of FIG.
A and the current source 34A are collectively described, and similarly, the preamplifier 111B is the collective description of the preamplifier 32B, the amplification transistor 33B, and the current source 34B shown in FIG. Also, the preamplifiers 110A, 110B, 112A, 1
The same circuit is also used for 12B. These preamplifiers can be selectively operated by the timing signals T ₅ , T ₆ , and T ₇ from the timing generation circuit 120. The amplifier 95A is the amplifier 37 shown in FIG.
A, the current sources 35A and 39A are collectively shown. Similarly, the amplifier 95B is also shown in FIG.
9B is collectively described.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0089

[Correction method] Change

[Correction content]

Next, the spot metering area does not have high brightness,
The distance measurement and the photometry routine "AFRD3" when the average photometry area has high brightness will be described with reference to FIG.
In “AFRD3”, left and right distance measuring points 101 and 103
Since the distance measurement accuracy in the measurement is high in brightness, reliability is low, and if the stationary light storage stabilization time is long and distance measurement is performed, a time lag increases, so that the center distance measurement point 10 2
Distance measurement is performed only in.

[Procedure Amendment 8]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

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[Figure 3]

[Procedure Amendment 9]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

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[Figure 7]

[Procedure Amendment 10]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 24

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FIG. 24

Claims (1)

[Claims] 1. A distance measuring means for projecting light toward an object for distance measurement, receiving reflected light of the light projection from the object for distance measurement, and detecting a distance to a subject based on the received light. A photometric means for detecting the brightness of the distance measuring object, a judging means for judging whether or not the distance measuring object is a high-luminance subject based on the output of the light measuring means, and a stationary light component in the distance measuring means. In order to eliminate the above, the stationary light component storage means for storing the stationary light component, and the sequence changing means for changing the stabilization time of the stationary light storage means based on the output of the judging means to change the camera sequence. And a control means for executing a sequence of the camera based on the output of the sequence changing means, the camera having an active distance measuring device.