JPH0534584A - Distance detecting device for camera - Google Patents

Abstract

PURPOSE:To provide the distance detecting device for a camera, which can obtain distance measuring information of high reliability by varying the number of times of light emission of light, in the case of deterioration of the distance measuring information which is apt to be generated at the time of measuring a distance, etc., such as at the time of measuring the distance to an object to be photographed or at the time of low temperature, in the case light from a light emitting element is projected plural times toward the object concerned at the time of measuring the distance. CONSTITUTION:By varying the number of times of light emission and a light emission interval from LEDs 3a, 3b and 3c at the time of measuring the distance, in accordance with the case of measuring the distance, and the case of photographing at a low temperature by a control circuit 47, determination of exact distance measured value corresponding to a photographing state can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to so-called distance measurement of a subject by receiving reflected light of light emitted from a light emitting element on a subject by a light receiving element and converting the reflected light into an electric signal by the light receiving element. The present invention relates to an active type distance detecting device for a camera.

[0002]

2. Description of the Related Art Conventionally, in distance detection in this type of camera, light from a light emitting element, for example, a light emitting diode (LED) is projected onto an object a plurality of times, and reflected light for each light emission is used as a light spot. , PSD (Positi)
on Sensitive Device), based on the spot position of each reflected light, when the reflected light is converted into an electric signal to measure the distance to the object, a plurality of distance measurement data is added to calculate the distance measurement information. There is a method of doing so (for example, refer to Japanese Patent Laid-Open No. 1-199109). According to this method, since the distance measurement information is calculated by averaging a plurality of distance data, it is possible to obtain more reliable distance information.

By the way, as a light source used for the light emitting element of the camera as described above, a light emitting diode (L
ED) is used. The light emitting diode has its light emitting frequency and light emitting interval controlled by a microcomputer in the camera body. The reflected light from the subject is P as a light spot.
The position of the spot light received by the SD and related to the distance to the subject is converted into an electric signal, and this signal is AD converted and input to the microcomputer. Based on this signal, the microcomputer averages the distance measurement values by the method described above to determine the distance measurement value.

Next, the distance measuring operation by the above PSD will be described with reference to FIG. In the figure, when the light emitted from the light source 3 is focused into a beam by the light projecting lens 4 having the same optical axis L1 as the light source 3 and radiated to the object 5 to be measured, the reflected light of 5 is emitted. Through the light receiving lens 2 having the optical axis L2 parallel to the optical axis of the light projecting lens 4, the optical axis L2 and the center thereof are aligned and orthogonal to each other on the focal length of the light receiving lens 2. An image is formed at an appropriate position P on the light receiving surface of the PSD 1. At this time, as shown in the figure, the current flowing through the two electrodes A and B of the PSD 1 is reflected light to the point P which is known to be IA, IB and the sum of IA and IB. Is imaged, the current generated according to the reflected light intensity is changed to Io, P
The length from the center point O of SD1 to the point P is x, PSD
If the length of the effective light receiving surface of 1 is m and the resistance values from the point P to the electrode A or B are Ra and Rb, then IA = Rb / (Ra + Rb) × Io ... IB = Ra / (Ra + Rb) × Io The following formula is established.

On the other hand, in the PSD, as is well known, the specific resistance distribution in the length m is uniform, so that the resistance values Ra and Rb are the distances from the point P to the electrodes A and B. Proportion, that is, it can be expressed using the above-mentioned lengths x and m, and the above equation is: IA = (m / 2 + x) / m × Io ... IB = (m / 2−x) / m × Io. Is rewritten as In the above equation, since Io is proportional to the intensity of the reflected light imaged at the point P, the above equation,
Alternatively, it is not possible to obtain the positional information of the point P where the unknown is only x by only one of the expressions, and normally, in order to eliminate the influence of the above Io, the relationship of Io = IA + IB is used and Generally, a process of obtaining a ratio K of the difference between IB and the sum is performed. That is, K = IA / (IA + IB) = (1/2 + x / m) × Io
/ Io = 1/2 + x / m. As a result, it is possible to obtain information including only the unknown number x indicating the position of the point P. That is, the above x can be obtained.

Here, as shown in the figure, the distance from the light projecting lens 4 to the object to be measured is D, the focal length of the light receiving lens 2 is f, and the optical axes L1 and L2 of the light projecting and receiving lenses 3 and 2 are shown. Assuming that the distance is H and the subject on which the reflected light is imaged at the center point O on the PSD1 is an infinite subject, the relational expression H / D = x / f is established by the triangulation method. Then, eventually, the above D becomes D = H × f / x. Therefore, if the numerator x of the above equation is obtained by obtaining the ratio x described above, the distance D to the object 5 to be measured can be obtained. The principle of distance measurement using the PSD has been briefly described above, but a distance measuring device based on this principle will not be described in detail.
2810 and 59-107332.

[0007]

However, in the distance measuring method as described above, when the object is distant or the reflectance of the object is low and the amount of light received by the light receiving section is small, it is not possible to operate normally due to circuit noise or the like. Distance data cannot be obtained. In Japanese Patent Laid-Open No. 1-19111, abnormal distance data is excluded by adding values obtained by removing the highest value and the lowest value among a plurality of distance measurement data, and more reliable distance information is calculated. A method of doing so is disclosed. However, in this method, when there are three or more abnormal data, or when the deviation of the abnormal data from the normal data is in the same direction,
The effect will decrease. In addition, since the distance information is always calculated by excluding the maximum value and the minimum value, even when there is no abnormal data, (number of light emission times-2) pieces of data are added,
On the contrary, the reliability becomes low.

The present invention solves the above-mentioned problems, and eliminates infinity data when distance measurement is performed by projecting light from a light emitting element toward the object a plurality of times during distance measurement of the object. An object of the present invention is to provide a distance detection device for a camera that can obtain highly reliable distance measurement information by averaging distance measurement data and calculating distance information.

[0009]

In order to achieve the above-mentioned object, the invention according to claim 1 receives the reflected light of the light irradiated to the object a plurality of times by the light emitting element as a light spot by the light receiving element, and by this light receiving element In the distance detection device for performing subject distance measurement by averaging distance measurement data obtained by converting reflected light for each light emission into an electric signal based on the position of the light spot, of the distance measurement data obtained by the light receiving element, The object distance is calculated by averaging the values obtained by removing the infinity data. According to the second aspect of the present invention, the object distance is determined to be infinity when the infinity data is a predetermined number or more among the plurality of distance measurement data. Claim 3
According to the invention, the object distance is obtained by averaging the values obtained by removing the protruding values from the plurality of distance measurement data. According to a fourth aspect of the present invention, the number of times of light emitted from the light emitting element to the subject is set to be higher than usual when the subject is distance-measured by the auto standby zoom that automatically controls the zoom lens to keep the image magnification of the subject constant. It is a reduced one.

[0010]

According to the structure of the first aspect, the distance measurement value is determined by a value obtained by removing the infinity data from the distance measurement data obtained for each light emission, thereby more accurately determining the distance measurement value. Guarantee. According to the configuration of claim 2, a more accurate determination of the distance measurement value by setting the value regarded as the infinity data among the plurality of distance measurement data as the value that becomes the infinity data over a predetermined number or more. Guarantee. According to the structure described in claim 3, of the distance measurement data obtained for each light emission, the protruding value is regarded as an abnormal value due to a distance measurement error, and the distance measurement value is determined by a value obtained by removing this abnormal value. This guarantees a more accurate range finding. According to the configuration of claim 4, when the distance to the object is measured during the auto-standby zoom, the light emission is repeated to perform the distance measurement at all times. Eliminates distance mistakes and guarantees more accurate distance measurement determination.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An autofocus camera with an auto standby zoom (hereinafter referred to as a camera) according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a functional block diagram of the camera. In the figure, the microcomputer 20 controls an external circuit to perform a predetermined operation, and controls the entire camera. The distance measuring circuit 21 has the LED 3 as a light emitting element and the PSD 1 as a light receiving element, and outputs a signal according to the distance to the subject to the microcomputer 20 by receiving the light from the LED 3 with the PSD 1. The photometric circuit 22 outputs the brightness information of the subject to the microcomputer 20. The temperature detection circuit 23 detects the temperature at the time of photographing and outputs the result to the microcomputer 20. The remote control reception circuit 24 is a circuit that receives a signal from the outside by a remote control transmission circuit 31 described later, and outputs the reception result to the microcomputer 20. Lens drive circuit 25
Is driven by a command from the microcomputer 20 based on the distance measurement result of the distance measurement circuit 21 and the like to drive and focus the focusing lens. The exposure control circuit 26 controls the exposure according to a command from the microcomputer 20 based on the photometric result of the photometric circuit 22 and the like. The film feeding circuit 27 performs film winding and the like according to a command from the microcomputer 20. The zooming circuit 28 includes the microcomputer 20.
Zoom lens is zoomed by the command.

Further, the E ² PROM 29 is used for distance measurement, photometry,
This circuit stores adjustment data for shutter control and the like, and outputs the data to the microcomputer 20 as needed. The eyepiece detection circuit 30 is a circuit that detects that the photographer has approached the finder. When the photographer approaches the finder, the eyepiece detection circuit 30 detects it and the microcomputer 20 starts operations such as auto standby zoom. To do. The remote control transmission circuit 31 transmits a control signal to the remote control reception circuit 24 described above.
When REM is turned on, light such as an LED is emitted to externally instruct the microcomputer 20 to perform various operations. The switch S0 is the main switch of the camera, and the switch S1 is a switch that is closed by half-pressing a release button (not shown). When closed, photometry and distance measurement are performed. The switch S2 is a switch that is closed by pressing the release button and is an exposure start switch. The switch SZI is for operating the focal length of the zoom lens to the long focal length side.
Is for operating the focal length of the zoom lens to the short focus side.

FIG. 3 is a functional block diagram of the distance measuring circuit 21 described above. In the figure, the distance measuring circuit 21 has LEDs 3a, 3b, 3c as light emitting elements, and PSD 1 (PS corresponding to LED 3a in the figure) as a light receiving element.
Although only one D is shown, the PSD corresponds to each LED. )have. Each of the three LEDs is L
It is driven by the ED drive circuit 40, and the light emission is controlled by the control circuit 47. Below, PSD1 corresponding to LED3a is demonstrated as a representative. PSD1 which received the reflected light from the subject by LED3a as spot light
Are current signals Δi1, Δ corresponding to the position of the spot light.
i2 is output. The photometric circuit (1) 41 and the photometric circuit (2) 42 which have fetched the current signals Δi1 and Δi2 respectively current-amplify and logarithmically compress the signals and output signals lnA and lnB. This photometric circuit (1) 41, photometric circuit (2) 4
Reference numeral 2 is configured to bypass a signal lower than the frequency component of the pulsed signal caused by the LED 3a, that is, a signal corresponding to a stationary component caused by external light, thereby improving the dynamic range for the pulsed signal.
The expansion / addition compression circuit 43 logarithmically compresses the signals lnA and lnB and the current signals Δi1 and Δi by the photometry circuit (1).
2 is a signal ln (A +) obtained by logarithmically compressing the sum (A + B) of the currents amplified by the photometric circuit (1) and the photometric circuit (2).
B) is output. The difference amplifier circuit 44 outputs signals lnA and ln.
Upon receiving (A + B), it outputs a signal lnA / (A + B). The extension integration circuit 45 extends ln (A / (A + B)) and integrates it by the integration capacitor 45d.
The signal A / (A + B) is output as the data ADAF.
The A / D conversion circuit 46 converts the signal into a digital signal and outputs it as distance data ADZ to the microcomputer 20.

The control circuit 47 sends a control signal to the photometric circuit (1) 41, the photometric circuit (2) 42, the expansion integration circuit 45, the A / D conversion circuit 46, and the LED drive circuit 40 based on the signal from the microcomputer. Output and control these. Further, the output signals lnA and lnB of the expansion addition circuit 43 are compared with the reference voltage VINF1 by the infinite level creating circuit 48 by the comparators 49a and 49b, respectively, and an infinity 1 signal (denoted by ∞1) and an infinity 2 signal (∞). 2) indicates “H” when the signal voltage is lower than the reference voltage VINF1, and “L” when the signal voltage is higher.
Is output to the microcomputer 20.

Next, the pulse signal photocurrent detection by the photometric circuit (1) 41 and the photometric circuit (2) 42 described above will be described with reference to FIG. In the figure, the photocurrent from the PSD 1 and the constant current from the constant current source 66 are connected to the base of the NPN transistor 51 via the comparator 65 and the FET 64, and the emitter is grounded. PNP
The collector of the transistor 50 is connected to the base of the transistor 51, and the emitter is grounded via the resistor 67. PNP transistors 53, 54, 55, 5
The collector of the transistor 54 of the mirror circuit composed of 6 is connected to the collector of the transistor 51. NPN
The transistor 52 is the transistor 55 of the mirror circuit.
The collector is connected to the connection point between the collector of the transistor and the base of the transistor 50, and the emitter is grounded. A memory capacitor 63 is connected between the collector of the transistor 52 and the ground point. Then, the current of the current source and the low-frequency component current set in advance are cut by the transistor 50, and the signal component is extracted from the transistor 51.

The diodes 57 and 58 form a logarithmic compression diode for signals. This diode 5
A constant current source 59 is connected in parallel to 7, 58. The comparators 60 and 61 form a sample hold circuit,
The transistor 52 forms an NPN transistor for extracting carrier current. The capacitor 62 is a sample hold capacitor. A feedback loop is formed in the comparator 60 when it is connected to the power supply through the switch SW, and the potentials of the memory capacitor 63 and the sample hold capacitor 62 are determined when the feedback loop is formed, and are synchronized with the light emission of the LED. Then, the potential immediately before the switch SW is turned off is held. This potential causes a steady current,
That is, the current other than the optical signal is cut by the transistor 50.

Next, the principle of the infinity discrimination described above will be described with reference to FIG. The relationship between the signals lnA and lnB by the expansion-addition compression circuit 43 and the distance has a characteristic like a curve shown in the figure. Here, signals lnA and lnB are infinite level voltage V generated by infinite level generation circuit 48 (described later).
When INF1 or less, it is assumed that the reliability of the signal A / (A + B) calculated by the expansion integration circuit 45 is low, and is removed from the average calculation in the subsequent microcomputer, so that the data is infinite. The signals lnA and lnB are the infinite level voltage VINF1.
In the above case, the zone is set by calculation based on the signal A / (A + B).

Next, the infinite level voltage-dependent circuit in the infinite level generating circuit 48 will be described with reference to FIG. When the power supply voltage of the camera rises, the light intensity of the LED also rises and lnA and lnB rise, so the infinite level voltage VIN
If F1 is fixed, the distance at which the subject distance is considered to be infinite increases due to the LED emission. Therefore, this is a circuit for simultaneously increasing the infinite level voltage VINF1 in order to prevent the distance considered as infinity from changing due to the influence of the increase in the power supply voltage. In the figure, as the power supply voltage V of the camera increases, the current i increases and the infinite level voltage VINF1 also increases at the same time. The rate of increase of the current i can be changed by the resistance R∞. This infinite level voltage is different between the circuit for measuring the distance in the center of the screen and the circuit for measuring the distance in the peripheral portion. The central area is lower than the peripheral area.

Next, the PSD in this embodiment will be described with reference to FIGS. 7, 8 and 9. FIG. 7 shows the shape and positional relationship of the PSD provided in this camera, and FIG. 8 shows the LE.
FIG. 9 shows the positions when the reflected light from the object at each distance D3a is received by the PSD 1a.
And (A + B), and the positional relationship between the object distance and the center of gravity of the reflected light of the LED from the object received by the PSD 1a. In these figures, the camera is LED3
It has three PSDs 1a, 1b, 1c for respectively receiving the reflected light from the subject by a, 3b, 3c.
The three PSDs have electrodes A1, B1, A2, B on each end.
2, A3 and B3, of which, outside the electrode A1 of the PSD 1a, an SPC 1d which is a light receiving element having a further elongated shape is provided. As shown in FIG.
As the subject distance becomes closer to infinity, the light receiving position on the PSD 1a moves in the direction of SPC 1d. Conventionally, if a PSD is formed long for distance measurement of a subject at a short distance, the dynamic range at a distance that is normally used is reduced, and the distance measurement accuracy is reduced. Further, since the steady current due to the steady light increases, there is a problem that the S / N ratio decreases. Therefore, light reception at a short distance as described above is performed by the electrodes A1,
The SPC 1d outside of B1 is used to receive light at a distance that is normally used, and the PSD 1a is used to improve the distance measurement accuracy over the entire distance measurement range. In addition, the SPC1
d is thinner than PSD1a. But,
In general, the reflected light from a short-distance subject is stronger than that from a long-distance subject, so that even if the SPC 1d is made thin, a sufficient signal can be obtained by the reflected light.

Next, the remote control transmission circuit 31 is shown in FIG.
It will be described using 0. In the figure, the microcomputer 70 controls the remote control transmission circuit 31. This remote control transmission circuit 31 is an LED for the camera body from the outside.
The remote control operation is performed by the light emission from 71. LED7
Light emission 1 is controlled by the microcomputer 70. Also,
The remote control transmission circuit 31 has a switch SW0,
The switch SW0 is turned on when the transmission circuit 31 is separated from the camera. The switch SW1 is an activation switch, and when turned on, the microcomputer 70 is activated to control the light emission of the LED 71. The circuit also includes a capacitor 73 for supplying power to the LED 71 and a constant current circuit 72.

Next, the remote control operation by the remote control transmitter will be described with reference to the timing chart of FIG. In the figure, when the switch SW1 is turned on, first, the remote control transmission circuit 31 sends a start signal (400
μs) is transmitted. Upon receiving the activation signal, the camera-side microcomputer 20 switches the operation mode from the slow mode to the fast mode, waits for the clock to stabilize (about 15 ms), and then starts the operation in the fast mode to receive the remote control signal. To do. At this time, the remote control transmission circuit 31 emits light for data transmission 50 ms after the activation signal is transmitted. Here, 50 after sending the start signal
The interval of ms is provided in order to allow a sufficient time for the power supply voltage of the current supply capacitor 73 of the remote control transmission circuit to recover. Accordingly, the light emission for data transmission of the remote control signal can be performed after the power supply voltage is restored after a predetermined time, so that the light emission intensity of the LED 71 can be increased and the remote control reach distance can be extended.
Also, the receiving sensitivity can be increased. If it is not necessary to consider the power supply voltage, the microcomputer 20 first receives the remote control signal to set the clock first, and waits until the remote control reception routine is executed, that is, waits about 15 ms before outputting the data. Good.

Next, the remote control receiving circuit 24 provided on the camera side will be described with reference to FIGS. In these drawings, the receiving circuit of the camera includes a light receiving unit 80 for receiving the LED light from the outside and a current-voltage conversion unit 81 for converting the current generated by the light reception into a voltage. In addition, the condenser 8 for cutting the stationary light
2 and a voltage amplification unit (1) 83 for amplifying the voltage, and a capacitor 84 for shaping the waveform. Further, it has a voltage amplification section (2) 85, a threshold level generation circuit 86 for varying the level of the reference voltage G of the integration circuit section 87, an integration circuit section 87, and a comparator section 88. In this receiving circuit, the current-voltage converter 81 forms a voltage follower, and its operation is as shown in FIG. 13B, and FIG.
It is possible to prevent current loss as compared with the conventional circuit system as shown in FIG. As a result, as shown in FIG. 13, the voltage obtained at the connection point between the light receiving element and the resistor R becomes VRA <VRB, and weak reflected light from the LED can be detected,
The reach of the light emission of the LED of the remote control transmission circuit becomes longer, and the reception sensitivity is also improved.

Next, the signal extraction by the above-mentioned receiving circuit will be described with reference to FIG. In the figure, A
To J are voltage waveforms corresponding to points A to J in the circuit of FIG. The light from the light emitting unit is received as the signal A by the light receiving unit 80. The signal A is taken out as the signal B by the current-voltage converter 81, and when the stationary light is cut by the capacitor 82, it becomes a waveform like the signal C. Then, the signal is amplified by the voltage amplification unit (1) 83 to become the signal D, and further waveform-shaped by the capacitor 84 to become the signal E.
The signal E is further amplified by the voltage amplification section (2) 85 to be a signal F. At this point in time, stationary noise is also amplified in the signal F, and the amplitude of the voltage is also large. However, the signal F and the reference voltage G which is higher than the noise potential by the reference voltage Vs by the threshold level generation circuit 86. The noise is cut off by the comparison between C and C by the comparator C. Further, even when the stationary noise has a considerably large amplitude due to high brightness (signal F ′), the reference voltage G is higher than the noise peak by Vs, so that the noise is cut as described above. Therefore, when a signal is input, in other words, when the signal F exceeds the reference voltage G, the comparator of the integrating circuit 87 outputs “H”, and when it is lower, it outputs “L”. The signal H is available at the output of 87. This signal H is compared with the reference voltage VR in the comparator section 88, and the output is finally obtained as the signal J.

Next, the microcomputer 2 of the camera body having the above structure
The operation of 0 will be described with reference to the flowchart of FIG. In the figure, when the operation of the microcomputer 20 is started, first, the slow mode is set (# 100), and the main switch S0 is waited to be turned on (# 101). When the main switch S0 is turned on, it is next checked whether or not the switch S1 is turned on (# 102), and if it is turned on, the process proceeds to the S1 routine. If S1 is OFF, check whether switch SZI is ON (#
103) If it is turned on, the process proceeds to the zoom-in routine to perform the zoom-in operation of the zoom lens. SZI is O
When it is FF, it is checked whether or not the switch SZO is turned on (# 104), and when it is turned on, the process proceeds to the zoom out routine to perform the zoom out operation of the zoom lens. When SZO is OFF, the eyepiece detection circuit checks whether the photographer is looking through the viewfinder (# 10
5) When the eyepiece is detected, the process shifts to the ASZ routine to perform the auto standby zoom. If the eye contact is not detected, it is checked whether or not the remote control receiving circuit 24 is receiving the signal from the remote control transmitting circuit 31 (# 106). If the signal is received, the fast mode is set (# 107), and the process proceeds to the remote control receiving routine. # 101 if not received
Then, this sequence is repeated.

Next, the processing operation of the auto standby zoom will be described with reference to the flowchart of FIG. In the figure, when auto standby zoom is set,
First, the fast mode is set (# 110) and distance measurement is performed (# 111). Next, the focal length is determined by performing a calculation with a predetermined algorithm based on the obtained plurality of zone data (# 112), and zoom drive is performed based on the result (# 113). Then, eyepiece detection is performed (# 114),
When the eyepiece is not detected, the photographing operation is interrupted and the process returns to the start. When the eyepiece is detected, the operation status of the switch S1 is checked (# 115), and when the eyepiece is detected, S is turned on.
Proceed to the processing operation of 1. When it is OFF, the process returns to # 114.

Next, the processing operation of the switch S1 will be described with reference to the flowchart of FIG. In the figure, when the switch S1 is turned on, first, the fast mode is set (# 120) and distance measurement is performed (# 12).
1). From the obtained zones of each LED, the main subject zone is calculated by a predetermined algorithm, the AF calculation for determining the lens extension amount and the like is performed (# 122), and the photometric operation is further performed to measure the luminance of the subject ( # 12
3). Exposure calculation is performed based on the result (# 12
4) Check the memory status of the remote control flag FREM that stores whether or not to release with the remote control (# 12
5) If it is stored in the memory, the procedure proceeds to step # 128 to drive the focusing lens, assuming that shooting is performed by remote control operation (# 128). When it is not stored in # 125, it is checked whether or not the switch S1 is turned on (# 126), and when it is turned on, it is further checked whether or not the switch S2 is turned on (# 12).
7). When the switch S2 is not turned on, # 12
Returning to step 6, this sequence is continued until the switch S1 is turned on, and when the switch S2 is turned on, # 12
In 8 the lens is driven. Switch S1 is open in # 126
In the case of F, the shooting operation is interrupted on the way and the process returns to the start. # After driving the 128 lens, perform exposure (#
129) and then reset the lens (# 13
0), film winding is performed (# 131). Then, the memory of the remote control flag FREM is reset (# 132),
Return to the start.

Next, the remote control processing operation of the remote control receiving circuit 24 will be described with reference to the flowchart of FIG. When the fast mode is set and a remote control signal is received from the outside, first, the remote control signal is determined (#
140). The received remote control signal is the remote control transmission circuit 3
It is checked whether or not it is from 1 (# 141), and if so, the remote control flag FREM is set (# 14).
2), proceed to the processing of the switch S1. When the received signal is not the corresponding remote control signal, the process returns to the start.

Next, the distance measuring operation will be described with reference to the flow charts of FIGS. First, the RAM for distance measurement and all flags are cleared (# 150), and the number of times of light emission and the light emission interval of the LEDs 3a, 3b, 3c determined by the temperature are set (# 151). The setting status of the near flag FNR for setting whether or not the subject is closer than a predetermined distance is checked (# 152), and when it is not set, the setting status of the light emission additional flag FM is subsequently checked (# 153). It should be noted that these flags are not set before the LED emits light. When the light emission additional flag FM is not set, first, the LED 3b is caused to emit light, and distance measurement and infinity determination of the subject are performed (# 155). Next, further check the setting status of the light emission additional flag FM (# 156),
If not set, the LED 3a is caused to emit light, and distance measurement and infinity determination of the subject are performed (# 157). Here, after the setting conditions of the near flag FNR and the light emission addition flag FM are checked again (# 158, # 159), the LED 3c is further caused to emit light to perform distance measurement and infinity discrimination of the subject (# 16).
1).

Next, the program proceeds to # 162 and the counter n of the number of times of light emission is incremented by 1 (# 162), and it is checked whether or not the number of times of light emission at this time has reached the preset number of times of light emission for the auto standby zoom ( # 163). When the number of flashes is reached, it is checked whether or not the auto standby zoom is being performed, and when it is being performed, the process proceeds to step # 170.
If not, the process proceeds to step # 165, and it is checked whether the number of times of light emission has reached a preset number of times Nn1 of near discrimination for determining that the subject distance is short (# 165). When the number of times of near discrimination is not reached, it is further checked whether or not the number of times of light emission is equal to or more than a preset total number of times of light emission (# 16
9) If the total number of flashes has not been reached, the process returns to # 152 for further flashing. When the number of times of light emission reaches the number Nn1 of near discriminations in # 165, it is determined that the near discrimination of the object by the LED 3a is completed, and an average calculation is performed using a plurality of distance measurement data of the LED 3a (# 166). As a result of this calculation, it is checked whether the subject distance is shorter than a predetermined distance (# 16
7) If near, set near flag FNR (FNR = 1)
(# 168) If it is determined that they are not close to each other, the process proceeds to # 169 to check whether or not the total number of times of light emission has been reached. If FNR is set and the total number of flashes is not reached, # 15
When performing the sequence of 2 or less, it is determined that it is not necessary to emit light by the LEDs 3b and 3c. # 152 and # 1
According to the determination of 58, only the light emission process of the LED 3a of # 157 is performed. When the number of times of light emission n reaches the total number of times of light emission NAL in # 169, the process proceeds to # 170.

Next, in # 170, the first LE
The counter L is set to 1 by the calculation process for D, and the setting status of the light emission additional flag FM is checked in # 171.
Since FM = 0 at the beginning, the process proceeds to # 177. # 177
Then, the ratio of ∞1 is checked by the total number of times the LED 3a emits light. That is, the ratio X at which ∞1 stands (∞1 is “H”) in the total number of times of light emission by the LED 3a is calculated (#
177), and in # 178, the ratio Y at which ∞2 is raised (∞2 is “H”) is calculated in the total number of times of light emission (# 17).
8). Here, X and Y for the LED (L) can be expressed as X = INF1N (L) / n Y = INF2N (L) / n. INF1N (L) is LED
The number of times ∞1 has risen for (L), and INF2N (L) is the number of times ∞2 has risen for LED (L). Based on this result, it is checked whether X is 1/4 or less, and when it is the following, that is, when the ratio X at which ∞1 stands is less than or equal to a predetermined value (here, 1/4), infinity Assuming that the data ratio is small, the process proceeds to step # 185 to average the calculated plurality of distance measurement values. When X is 1/4 or more,
That is, when the ratio of infinite data is large, a plurality of zones (indicated by Z (L)) are further added based on the infinite data.
The flow after # 180 is executed so as to be divided into # 1
At 80, it is checked whether X is 1/2 or less (# 180),
In the following cases, set the zone of LED (L) to 3, that is,
The lens stop point is set to the zone position closest to the finite side in the infinite zone (# 181), and the next L is emitted.
ED3b, 3c (LED3b is L = 2, LED3c is L
= 3), the process proceeds to # 194 to perform the same processing. When X is 1/2 or more in # 180, further Y
Is less than 1/2 (# 182), and if less, set the LED zone to 2 (# 183), # 194
Go to. When Y is 1/2 or more in # 182, the LED zone is set to 1, that is, the lens stop point is set to the farthest zone (# 184), and the process proceeds to # 194. Further, in the discrimination of infinity 1 and 2, it is stated that X is 1/4 or less and Y is 1/2 or less, but this number can be changed by the E ² PROM.

After the average calculation of # 185, the near flag FNR
Is checked (# 186), and if not set, the setting status of the light emission addition flag FM is checked (# 187). If neither is set, A /
Proceed to # 188 to check the reliability of the D value. Where L
It is checked whether or not the average value (denoted as ADZ (L)) of the data due to the light emission of ED3a is smaller than the threshold value FAREF for whether or not light emission is added. If smaller than FAREF, the obtained ADZ (L) is obtained. The value should be unreliable and L
The light emission addition flag F1 is set to emit light by the ED 3a (F1 = 1) (# 190), and the process proceeds to # 194. The above flow is similarly performed for the LEDs 3b and 3c. That is, in # 192, the additional light emission flag F2 of the LED 3b is generated.
Is set, the light emission addition flag F3 by the LED 3c is set in # 193, and the flow proceeds to # 194. If the near flag FNR is set in # 186, it is assumed that the data has been obtained, and the flow proceeds to # 230 to perform the linear interpolation flow.
If the light emission addition flag FM is set in # 187, the process immediately proceeds to # 194. Also, AD in # 188
When Z (L) is larger than the threshold value FAREF, the data obtained by the calculation is regarded as reliable and the process proceeds to # 194. #
In 194, the counter L is incremented by +1 because it is the calculation process for the next LED, it is checked whether L is larger than 3 (# 195), and the processes of # 171 and subsequent steps are repeated until L becomes larger than 3.

When L becomes larger than 3, the process proceeds to step # 196 to check whether the light emission additional flag FM is set. Since it is not initially set, the process proceeds to step # 197.
3a light emission additional flag F1, LED3b light emission additional flag F2, LED3c light emission additional flag F3
It is checked whether the sum (F1 + F2 + F3) of 0 is 0. If at least one of these is set, the light emission addition flag FM is set (FM = 1) (# 198) to add the number of times of light emission, assuming that the ADZ (L) value is low and the reliability is low.
Then, the number of times of light emission for auto-standby zoom NAS and the total number of times of light emission NAL are set to be added (# 199), and the process returns to step # 152 to perform distance measurement by additional light emission. If none of F1, F2, and F3 is set in # 197, the data is considered to be reliable, and the process proceeds to # 230 to perform linear interpolation.

The operation when the additional light emission flag FM is set in # 198 will be described below. In # 152, as a result of the above sequence, the setting status of the near flag FNR is checked,
If not set, the process proceeds to the determination of # 153. Since FM = 1 here, the process proceeds to # 154 to check the setting status of the additional light emission flag F2 by the LED 3b. If this is set, the additional light emission is performed (# 155). If it is not set, the process proceeds to # 156 and # 200 to proceed to LED.
The setting status of the additional light emission flag F1 by 3a is checked. If it is set, the additional light emission is performed (# 157),
If not set, proceed to # 159 and # 160 to L
The setting status of the additional light emission flag F3 by the ED3c is checked. If it is set, the additional flash is performed (# 16
1) If not set, the flow from # 162 onward is executed.

When the number of times of light emission n reaches the total number of times of light emission NAL or the number of times of light emission NAS for the auto-standby zoom, the process proceeds from # 171 to # 172 to # 172 to # 17.
According to the determination of 6, the additional light emission flag F for each LED
The processes of # 177 to # 195 are repeated only for those for which additional light emission is performed by checking 1, F2, and F3. In other words, the distance measurement data for the LED for which the additional light emission is performed is to perform the averaging as well as to check the ratio of ∞1 and ∞2 again including the additional amount. When all the data processing including the above additional light emission is completed, the process proceeds to # 230 to perform linear interpolation.

Next, the processing operation of the above-described averaging operation of # 185 will be described with reference to the flowchart of FIG. This averaging process is performed in steps # 171 to # 19 of FIG.
It is performed every time the counter is incremented for the three LEDs 3a, 3b, 3c in the loop of 5. First, the temporary average calculation flag FS is reset (FS = 0) (#
210), and the sum A of data necessary for averaging
D and the number of data ADN are reset (# 211).
Next, n, which is the last number of times of light emission, is set in the counter N (# 212). Then, in # 213, LED (L)
In the distance measurement data by the Nth light emission of, the one for which the infinity bit is set is excluded from the average calculation.
When the infinity bit is set, proceed to # 219. If the infinity bit is not set, the process proceeds to step # 214 to check the setting status of the temporary average calculation flag. Initially, since the provisional calculation flag FS is not set, the process proceeds to # 217 and # 218, where the distance measurement data AD (L, N) by the Nth light emission of the LED (L) is added and the addition data AD is added. Further, ADN is obtained by adding +1 to the number of data ADN. Next, in # 219, the counter N is decremented by 1, and then # 2
At 20, the setting status of the near flag FNR is checked, and if not set, the counter N is checked (# 222), and the loop processing of # 213 to # 222 is repeated until N becomes 0.

In # 222, when N becomes 0 and AD and ADN are calculated for all the light emission times, # 2
23, the temporary average value ADZ (L) of each LED is ADZ
(L) = AD / ADN, and the provisional average calculation flag FS indicating that the provisional average has been calculated based on the total sum of all data is set (FS = 1) (# 225), and the process returns to # 211. After the flag FS is set, the process proceeds from # 214 to # 215,
The absolute value of the value obtained by subtracting the data AD (L, N) at the time of the Nth light emission of the LED (L) from the provisional average value ADZ (L) is defined as F,
Next, in # 216, it is checked whether or not this F is larger than a threshold value S for removing abnormal data, and if it is larger than S, it is judged to be abnormal data, and in # 217 and # 218.
Processing proceeds to step # 219. If F is not larger than S, the process proceeds to # 217, and the average calculation is performed based on the data excluding the protrusion data in the same manner as described above.
Further, when the near flag FNR is set in # 220, since only the data after the average calculation of the LED1 performed in # 166 is performed, it is checked in N221 whether N is the near discrimination number Nn1 or less. If so, the process returns to # 213, and if not, the process proceeds to # 223 to calculate the average of the data.

Next, the processing operation for determining the zone of each LED by linear interpolation will be described with reference to the graph of FIG. 22 and the flowchart of FIG. First, since the distance measurement data is processed by the light emission of the LED 3a, the counter L is set to 1 (# 230), and then it is checked whether or not the near flag FNR is set (# 231). When it is set, the lens stop point zone Z (L) is calculated in # 238 based on the value determined in # 232.
Go to 8. When the near flag FNR is not set in # 231, the average value ADZ in # 233 and # 235.
Whether (L) is less than or equal to b3 (# 223) or less than or equal to b4 is checked, and depending on each condition, # 234, # 237,
The zone Z (L) of the lens stop point is calculated in # 238 based on the value determined in # 236, and the process proceeds to # 239. In # 239, it is checked whether or not the near flag FNR is set. If it is set, it is not necessary to see the data of the LEDs 3b and LED3c, so the process proceeds to the return and the linear interpolation is completed. # 2 if the near flag FNR is not set
40, and proceeds to # 241, and proceeds to # 231 to perform the same linear interpolation for the LEDs 2 and 3.

As shown in FIG. 22, when the near flag FNR is set, the object distance is short, so linear interpolation is performed using the line of FNR = 1. When the near flag FNR is not set, the stop point is interpolated using the line of FNR = 0. This interpolation method is shown below. # 237
Will be described with reference to # 238. First, # 23
ADZ (L) (subject) at 7 exists somewhere from b4 to b3 as an A / D value on the line of FNR = 0, exists from Kz4 to Kz3 as a zone, and has a distance b4. To somewhere in b3. Here, the zone corresponding to b4 is Kz4, and the zone corresponding to b3 is Kz.
Therefore, the zone Z (L) corresponding to the distance measurement data ADZ (L) is Z (L) = (ADZ (L) -b3) / (b3-b4) ×
(Kz3 + Kz4) + Kz4, and the linear interpolation is completed. Kz1 is the latest zone and Kz5 is the farthest zone.

Next, the processing operation when the temperature of the LED is corrected will be described with reference to the flowchart of FIG. First,
The temperature is measured by the temperature detection circuit, the current temperature is set to T (# 250), and it is checked whether T is 20 degrees or more (# 2).
51). After this determination, in # 252 to # 257, the range of the current temperature T is obtained, and when the temperature is less than 20C, 20C or more, and when the temperature is less than 30C, 30C or more, 40C or more.
If it is less than C, it is divided into cases of 40C or more, and according to each temperature level, as shown in # 258 to # 261, the number of times of light emission for auto-standby zoom NAS, the number of times of near determination Nn1, the number of times of near correction light emission Nn2, all the light emission The number of times NAL and the light emission interval t are set, and the process returns. As shown in the above setting, the light emission interval at low temperature and the number of light emission are set to a value that can guarantee the distance measurement performance due to the correlation between the performance deterioration of the battery and the release time lag. Since it could not be changed, the distance was measured at a value determined by the low temperature even at room temperature or high temperature. However, in this embodiment, when the ambient temperature is high, the conditions of the battery and the like are improved, so that the light emission interval is shortened and the number of light emissions is increased, and the distance measurement accuracy is obtained while taking the correlation with the release time lag. I am trying to raise it.

Next, the distance measuring operation of this camera will be described with reference to the timing chart of FIG. When the switch S1 is turned on, the control unit is reset at an appropriate timing and the AF power supply for distance measurement is turned on.
Further, the LEDs 3b, 3a, 3c are sequentially caused to emit light in accordance with the control signal. PSD1a, 1b, 1 according to each light emission
A signal obtained by amplifying the current proportional to the reciprocal from c is integrated at the timing of the integration control signal = “L” to obtain ADAF. Further, the integrated value ADAF is A / D converted and output to the microcomputer 20 immediately after the light emission of the LED, and the microcomputer 20 performs data processing in the various sequences described above to obtain reliable distance measurement data. Immediately before the end of LED emission (timing at which the integration control signal changes from L to H), the output signals lnA and lnB of the expansion addition circuit 43 described above are used to make an infinite determination.

In this embodiment, the distance measurement accuracy is improved by averaging the values obtained by removing the infinity data to obtain the subject distance. However, when the infinity data is output,
It may be replaced with the distance data corresponding to ∞1 and ∞2 shown in FIG. 5, and the average calculation may be performed together with other data. Further, the number of times the LED emits light is determined according to the ambient temperature in the present embodiment. However, in order to increase the number of data to be averaged, whether the number of data other than infinity data is a predetermined number or more, Alternatively, the light may be emitted until the infinity data exceeds the above-mentioned rate of being judged to be infinity.

[0042]

As described above, according to the invention of claim 1,
Among the distance measurement data obtained by multiple distance measurement, the distance measurement value is determined by averaging the values obtained by removing the infinity data. Since the distance information can be calculated based only on the data, more accurate distance measuring operation can be performed. Claim 2
According to the invention of claim 1, the value regarded as the infinity data is regarded as the value regarded as the infinity data a plurality of times, whereby the reliability of the infinity data can be guaranteed, and the more accurate distance measurement can be performed. You can take action. According to the invention of claim 3, among the distance measurement data obtained by a plurality of distance measurements,
Since the distance measurement value is determined by averaging the values with the protruding values removed, even if extreme data due to a distance measurement error is captured, it is excluded and based on reliable data only. Since the distance information can be calculated by using the distance information, a more accurate distance measuring operation can be performed. According to the invention of claim 4, the number of times of light emission by the light emitting element during distance measurement of a subject during auto standby zoom is made smaller than usual, so compared with the conventional auto standby zoom that requires a large number of times of light emission. Since the deterioration of the performance of the light emitting element can be suppressed, the obtained distance measurement value becomes highly reliable, and more accurate distance measurement operation can be performed.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a distance measuring principle of a distance detecting device of the present invention.

FIG. 2 is a block diagram of a control system of a distance detection device in an autofocus camera with an auto standby zoom according to an embodiment of the present invention.

FIG. 3 is a distance measuring circuit diagram of the present apparatus.

FIG. 4 is a circuit diagram of pulse signal photocurrent detection in the distance measuring circuit of the present apparatus.

FIG. 5 is a graph showing the principle of infinity discrimination.

FIG. 6 is a circuit diagram of an infinite level generation circuit depending on an infinite level voltage.

FIG. 7 is a diagram showing a PSD shape of the present device.

FIG. 8 is a diagram showing LED light receiving positions on a PSD at each distance.

FIG. 9 is a diagram showing a relationship between a subject distance, a current signal, and a PSD light receiving position.

FIG. 10 is a circuit diagram of a remote control transmitter of this device.

FIG. 11 is a timing chart when a remote control is operated.

FIG. 12 is a circuit diagram of a remote control receiver of this device.

13A and 13B are circuit diagrams of a current-voltage conversion unit in the remote control receiver, where FIG. 13A is a conventional circuit diagram and FIG. 13B is a circuit diagram according to the present embodiment.

FIG. 14 is a diagram showing signal waveforms of respective parts in the remote control receiving circuit.

FIG. 15 is a flowchart showing the operation of the microcomputer in this apparatus.

FIG. 16 is a flowchart showing a processing operation of auto standby zoom.

FIG. 17 is a flowchart showing the processing operation of the switch S1.

FIG. 18 is a flowchart showing a processing operation of remote control reception.

FIG. 19 is a flowchart showing an AF processing operation.

FIG. 20 is the same flowchart.

FIG. 21 is a flowchart showing the processing operation of average calculation.

FIG. 22 is a graph showing adjustment by linear interpolation.

FIG. 23 is a flowchart showing the processing operation of linear interpolation.

FIG. 24 is a flowchart showing a processing operation at the time of LED temperature correction.

FIG. 25 is a timing chart of a distance measuring operation in this device.

[Explanation of symbols]

1 PSD 3 light emitting element 20 microcomputer 21 Distance measuring circuit 48 infinite level creation circuit 47 control circuit

Claims (4)

[Claims] 1. A light-receiving element receives light reflected by light emitted from a light-emitting element to a subject a plurality of times as a light spot,
In the distance detecting device for averaging the distance measurement data obtained by converting the reflected light of each light emission into an electric signal based on the position of the light spot by the light receiving element, the distance measurement obtained by the light receiving element A distance detecting device for a camera, wherein the object distance is obtained by averaging values obtained by removing infinity data from the data. 2. The distance detection device for a camera according to claim 1, wherein the object distance is determined to be infinity when the infinity data is a predetermined number or more among the plurality of distance measurement data. 3. The distance detecting device for a camera according to claim 1, wherein the object distance is obtained by averaging the values obtained by removing the protruding values from the plurality of distance measurement data. 4. The number of times light is emitted to the subject by the light emitting element is less than usual when measuring the subject with an auto standby zoom that automatically controls the zoom lens to keep the image magnification of the subject constant. The distance detecting device for a camera according to claim 1, wherein: