JP2934346B2 - Autofocus camera and adjustment method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus camera and a method for adjusting the same.

[0002]

2. Description of the Related Art Recent autofocus cameras tend to use a multi-beam type distance measuring device. The distance measuring device sequentially emits a plurality of distance measuring lights along a horizontal direction of a shooting scene, receives each reflected light reflected from the shooting scene, and detects an incident position thereof. And a light receiving unit. A light emitting diode (LED) that emits near-infrared light is arranged in a line as the light projecting unit, and a PSD (semiconductor position detector) is used as a light receiving unit. When a plurality of main subjects are present in a shooting scene, distance data is calculated for each distance measuring light, and an optimum one is selected from these distance data, and shooting is performed based on the distance data. The lens setting position is determined.

The selection of the distance data includes a short distance selection,
There is an intermediate distance selection and the like. For example, in the short distance selection, the distance data of the closest subject is selected as the optimum one. Therefore, in the multi-beam type distance measuring apparatus, even when the main subject is not located at the center of the shooting scene or when shooting a plurality of people standing side by side, troublesome operation such as focus lock is not performed. There is an advantage that the main subject can be focused.

In the assembly process of an autofocus camera,
After assembling the distance measuring device into the camera body, an inspection is performed to determine whether the distance measuring device is operating properly.
In this inspection, for example, a test object at a known distance is used, and the moving position of the imaging lens is measured for each ranging light so that the same distance data can be obtained with the ranging light emitted from any of the LEDs. While adjusting the mounting positions of the light emitting unit and the light receiving unit.

[0005]

As described above, in the conventional inspection method, the set position of the photographing lens is measured for each distance measuring light, and the positions of the light projecting unit and the light receiving unit are determined in accordance with the measurement results. It is necessary to make adjustments, and the distance must be measured again to confirm the adjustment.
There has been a problem that the ranging accuracy of each ranging light tends to vary.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to provide an autofocus camera and an adjustment method thereof that can easily perform inspection and adjustment.

[0007]

In order to achieve the above object, according to the present invention, a storage means for writing correction data is provided by a camera.
To store the correction data obtained during test ranging.
You can write it on the column and use it for actual distance measurement.
That's what I did .

In particular, the present invention relates to a multi-beam type auto
For focus cameras, multiple
One of the distance measuring lights is set as the reference distance measuring light and the distance is measured.
The reference distance data obtained in this way
When the distance data obtained by the distance measuring light is different,
Correction data corresponding to the difference is written to the storage means.
It is. At the time of actual distance measurement, measurement other than the standard
The distance data obtained by the distance meter
At the same time based on the correction data read from the storage means.
Corrected.

[0009] Further, the control of the auto-focus camera of the present invention.
The adjusting method is based on one of a plurality of distance measuring lights, a first step of measuring a test object with the reference distance measuring light to calculate reference distance data, and using another distance measuring light. A second step of measuring the distance of the test object to calculate the distance data, and a third step of writing correction data corresponding to the difference between each distance data and the reference distance data into the storage unit, respectively. The light receiving unit is adjusted in a software manner without mechanical adjustment.

[0010]

FIG. 2 schematically shows a configuration of a multi-beam type distance measuring device. In FIG. 2, a light projecting unit 2 is composed of a light source unit 3 and a light projecting lens 4, and an optical axis 4a of the light projecting lens 4 is It is substantially parallel to the optical axis 5a of the taking lens 5. Light source 3
Is composed of three LEDs (light emitting diodes) 3a, 3b, 3c each emitting near-infrared light. These LEDs 3
a to 3c are arranged horizontally, and the central LED 3a is
The LEDs 3b and 3c are located on the left side and the right side, respectively, and project spot-shaped distance measuring light toward three points in the shooting scene.

The light receiving section 7 comprises a light receiving lens 8 and a PSD 9 having a rectangular shape. The optical axis 8a of the light receiving lens 8 is substantially parallel to the optical axis 5a of the photographing lens 5. PS
D9 is provided with a filter 10 (see FIG. 1) that transmits only near-infrared light on its light receiving surface, and outputs signals corresponding to the amount and position of incident light that has passed through the output terminals 9a and 9b.
Output from The reflected light from the subject enters a position closer to the output terminal 9b as the subject distance is shorter. Also,
The shorter the subject distance, the greater the intensity of the reflected light and the greater the absolute value of the signal from the output terminals 9a and 9b.
By taking the ratio of the sum and difference of these signals, a signal corresponding only to the incident position can be obtained without depending on the intensity of the reflected light.

The LEDs 3a to 3c have an auto focus I
Light emission is controlled via the LED driver 11 by a signal from C12. The autofocus IC 12 executes a predetermined distance measurement sequence according to a command from the microcomputer 14. The autofocus IC 12 amplifies the respective signals from the output terminals 9 a and 9 b of the PSD 9, performs sample hold processing, and sends the signals to the microcomputer 14.

A general-purpose microcomputer is used as the microcomputer 14. The microcomputer 14 performs an operation based on the first and second channel signals output from the output terminals 9a and 9b of the PSD 9, and calculates distance data for each of the LEDs 3a to 3c. Is calculated. The microcomputer 14 selects an optimum one from the three distance data, and sends the number of drive pulses corresponding to the distance data to the lens drive control circuit 15. The lens drive control circuit 15 includes a stepping motor 15a
To set the photographing lens 5 at a lens position corresponding to the distance data.

As shown in FIG. 1, the microcomputer 14 includes an exposure control IC 16 and a film transfer control IC 1.
7. Controls the flash control IC 18, the external data input unit 30, and the display control IC 31. The exposure control IC 16 calculates an exposure time and an aperture value for proper exposure from the film sensitivity and the subject brightness detected by the photometric element 16a, and drives the stepping motor 16b to drive the program shutter 2
0 operation is controlled. The external data input unit 30 includes a shutter button 19, a self-timer button 40, a daylight sync button 41, an exposure correction button 42, and the like, as shown in FIG. The liquid crystal display 43 and the display LEDs 46 and 47 are connected to the display control IC 31. The liquid crystal display 43 displays the number of shots and the shooting mode by numbers, characters, and symbols. The display LED 46 indicates that the distance measurement is completed, and the display LED 47 is turned on when the shooting scene is switched to flash shooting due to low brightness. In FIG. 3, reference numeral 45 denotes a finder, and reference numeral 48 denotes a camera body.

The microcomputer 14 has a CPU
24, a ROM 25, a RAM 26, a bus line 27, a serial I / O port 28, and an A / D converter 29. As is well known, the CPU 24 includes various registers and logic operation circuits, and executes a shooting sequence according to a sequence program written in the ROM 25. The RAM 26 executes the shooting sequence,
Auto focus IC 12 and exposure control IC 1 described above
6, film transfer control IC 17, strobe control IC 18
, Address data and flag data output during the execution of the sequence program are temporarily stored. The bus line 27 is composed of an address bus and a data bus.
Various data are transferred between the PU 24 and the RAM 26.

The serial I / O port 28 has a built-in parallel / serial conversion circuit, converts command data output from the CPU 24 as parallel data into serial data, and outputs the serial data to each IC. The analog data output from each IC is digitized by an A / D converter 29 and supplied to a serial I / O port 28 as parallel data of a predetermined number of bits.
Sent out to

When a command is sent from the microcomputer 14 to the film transfer control IC 17 after the exposure is completed,
The film transfer mechanism 21 is driven via the motor 17a, and the transfer of the film is started. When the transfer amount reaches one frame (8 perforations), a stop command is output to the film transfer control IC 17 and the film transfer is stopped. Also, a strobe control IC 18
Starts the flash device 22 when the exposure time calculated by the exposure control IC 16 becomes too long, and causes the flash discharge tube 23 to emit light in synchronization with the opening and closing of the program shutter 20. When the power switch (not shown) of the camera is turned on, the strobe control IC 18 monitors the charge level of the main capacitor (not shown) in the strobe device 22, and when the charge level falls below a predetermined level. When this happens, the battery is automatically charged.

In a normal use state, a self-timer mode button 40, a daylight sync button 41,
When one of the exposure correction buttons 42 is pressed, a desired photographing mode is selected. Further, if the self-timer mode button 40 is operated while the shutter button 19 is half-pressed to perform the distance measurement process, a hidden command is input from the external data input unit 30 to the CPU 24. When this hidden command is input to the CPU 24, the RAM 2
An inspection mode in which the data stored in 6 is sequentially displayed.

In FIG. 4, the auto focus IC 12
Is composed of a one-chip IC, and includes a logic circuit 32,
The gain controller 33 and the output terminal 9a of the PSD 9
It has preamplifiers 34a and 34b for converting currents of the first and second channels output from 9b into voltages, gain control amplifiers 35a and 35b, sample and hold circuits 36a and 36b, and buffer amplifiers 37a and 37b.

Gain control amplifiers 35a and 35b
Is provided in consideration of the fact that when the subject is at a long distance, the amount of reflected light incident on the PSD 9 decreases and the absolute value of the current from the output terminals 9a and 9b decreases, and will be described later. The optimum gain is given by the gain control processing performed. Sample hold circuits 36a, 36
b receives the sampling pulse from the logic circuit 32, samples and holds the signals amplified by the gain control amplifiers 35a and 35b, and converts these signals through the buffer amplifiers 37a and 37b to the A / D converter 29 of the microcomputer 14. Send to The logic circuit 32 basically comprises a serial-in / parallel-out shift register, and the gain controller 33 reads out gain control data set at a predetermined bit position of the shift register, and based on the read data, sets a gain control amplifier 35a. , 35b are set to a common optimum gain.

The serial I / O port 28 converts the parallel command data from the CPU 24 into a serial data pulse (AFSD) as described above, and
2, a transfer pulse (AFSCK) for transferring the serial data to the shift register, a latch of parallel data from the shift register, and an LED 3.
a to 3c control pulses (A
FLCK). Also, the auto focus IC1
The analog signal output from the A / D converter 2
9 converts it into a 7-bit digital signal (representing 0 to 127 in decimal) corresponding to the signal voltage level.

FIG. 5 conceptually shows a shift register 38 used in the logic circuit 32. "D0
The gain control data (G
AIN), two bits “D5 to D6” contain LED emission data (LED), and a bit “D7” contains LED light emission data.
Of light emission / reset switching data (SET). The 5-bit gain control data is
It can represent gain levels from “0” level to “31” level. The 2-bit LED emission data can represent four states of “0”, “1”, “2”, and “3” in decimal, and when “0”, the LEDs 3a to 3c
Are turned off, only LED 3a emits light when "1", and LED 3b and LED 3 when "2" and "3".
c emits light.

FIG. 6 showing the procedure of a basic ranging sequence.
In the processing for detecting the offset value of the amplifier system of the auto focus IC 12, the gain control amplifiers 35a, 35
5b for determining the gain according to the output signal of the LED 5a.
The process of calculating distance data for each of the steps 3c to 3c and the process of selecting an optimum one from a plurality of distance data are sequentially executed.

Next, the operation of the above embodiment will be described with reference to FIGS. As shown in FIG. 7, when the power switch of the camera is turned on, each data storage area in the RAM 26 is reset to an initial state, and data is read from the external data input unit 30. And
When it is confirmed that the camera is in a photographing standby state such as completion of film loading and opening of the lens barrier, the microcomputer 14 sends a strobe check command prepared in advance in the ROM 25 to the bus line 27 and the serial I / O port 28. And supplies it to the flash control IC 18 as serial command data. The strobe control IC 18 reads the command data, monitors the charge level of the main capacitor of the strobe device 22, performs a charging process if the battery is not charged, and sends a completion signal to the A / D converter 29 and the serial I / O when the charging is completed. CPU 2 via port 28
Send to 4. When the charging of the main capacitor of the strobe device 22 is completed, the shutter button 19 is unlocked and can be depressed.

After adjusting the direction of the camera so that a part of the subject is located in the horizontally long target mark displayed in the viewfinder, the shutter button 19 is half-pressed. The half-press signal is sent from the external data input unit 30 to the CPU.
24, and the CPU 24
A distance measurement command is output to C12. Auto Focus I
The C12 drives the light projecting unit 2 to periodically generate spot-shaped near-infrared light, and projects these toward the subject.
By detecting the near-infrared light reflected by the subject with the light receiving unit 7, the subject distance is measured.

After this distance measurement, the CPU 24 sends photometric command data to the exposure control IC 16 to start measuring the subject luminance. This command data also includes film sensitivity information from the external data input unit 30 and is command data of a plurality of bits. However, as in the case where the command is transferred to the autofocus IC 12, the serial I / O By passing through the O port 28, it can be transferred to the exposure control IC 16 as serial command data.

The exposure control IC 16 performs an exposure calculation based on the subject luminance signal detected by the photometric element 16a and the film sensitivity signal transferred from the CPU 24, and calculates an exposure time for obtaining an appropriate exposure. Although the calculated exposure time data is an analog quantity, the A / D converter 2
After being converted into a digital value by the CPU 9, the data is sent to the CPU 24 via the serial port 28 and the bus line 27 and stored in the RAM 26. After the exposure calculation, the CPU 24 sends the number of clock pulses corresponding to the distance data already stored in the RAM 26 to the lens position control circuit 15. This drives the stepping motor 15a,
The taking lens 5 is extended to a lens position corresponding to the distance data.

When the shutter button 19 is fully depressed,
A full-press signal is input from the external data input unit 30 to the CPU 24, and the program shutter 20 is operated based on the exposure time obtained in the exposure calculation processing to perform photographing. RAM
The exposure time data read from 26 is converted into the number of clock pulses by the CPU 24, and then supplied from the serial I / O port 28 to the exposure control IC 16 as serial clock pulses of the number corresponding to the exposure time data. As a result, the stepping motor 16b operates the program shutter 20 for the calculated exposure time.

When the photographing is completed, the CPU 24 sends a film transfer command to the film transfer control IC 17, whereby the motor 17a is driven and the film transfer mechanism 21 is driven.
Is operated to feed the film one frame. During the film feeding, the CPU 24 monitors the number of perforations moved based on a signal fed back from the film transfer control IC 17, and when the number of perforations reaches just one frame (eight), the film is moved. Transfer control I
A stop command is sent to C17 to stop the film transfer. When the film transfer for one frame is completed, the CPU 24
Sends a reset signal to the lens position control circuit 15, returns the photographing lens 5 to the initial position, and completes one photographing sequence.

It should be noted that the film transfer control IC 17
The data representing the magnitude of the current flowing through the motor 17a is also represented by A /
It is sent to the CPU 24 via the D converter 29.
Therefore, the film cannot be transferred, and the motor 17
When the value of the load current a exceeds a certain value, the process can be automatically shifted to the film rewinding process.

By the way, as shown in the flowchart of FIG. 7, when the self-timer mode button 40 is pressed while the shutter button 19 is half-pressed, the operation sequence of the camera is shifted from the normal photographing mode to the inspection mode. Then, various data obtained by the distance measurement processing are externally displayed. This inspection mode is released by pressing the daylight sync button 41. During the inspection mode, even if the shutter button 19 is fully pressed, it is ignored.

Next, the ranging sequence will be described in detail. When the ranging sequence is started, first, as shown in FIG. 8, an offset value detection process is executed. In this offset value detection processing, “D0
"01000000" is set in each bit of "~ D7". Thereby, “GAIN = 8”, “LED =
0 "and" SET = 0 "are set. This command data is set at the time point P1 shown in the timing chart of FIG.
After K sends eight pulses, the control pulse AFLCK
Is performed at the timing when the signal becomes low level. The transfer of the serial data pulse is sequentially transferred to the shift register 38 at the rise of the transfer pulse AFSCK. After the transfer of the command data, the CPU
"COUNT = 8" is set in a predetermined register in the register 24.

Of the command data set in the shift register 38, the data of “GAIN = 8” is sent to the gain control amplifier 3 via the gain controller 33.
5a and 35b, and these gains are set to an initial value (minimum value) “8”. In the distance measuring apparatus of this embodiment, “GAIN” is set so that the linearity of the amplification characteristic is maintained.
Is used in the range of "8" to "31", but this range is appropriately determined by the specifications of the camera, the amount of light emitted from the LED, and the like.

After the transfer of the serial data, the first, second
The output signals from the channels are sampled and held, and digital signals AFD1 and AFD2 obtained by A / D conversion of the output signals are read into the microcomputer 14. As shown in the timing chart of FIG. 9 and the flowchart of FIG.
Is set to the low level during the period ΔT1. At time P2 when the control pulse AFLCK is at the low level, one of the LEDs determined by the command data emits light. Then, at the timing when AFSD becomes high after the period ΔT2, the sample hold circuits 36a and 36b
Sample and hold the outputs of the gain control amplifiers 35a and 35b. Further, at the time point P3 when the level becomes low after the period ΔT3, the emission of the LED is stopped. When AFSD goes high after the period ΔT4, the sample hold process ends.

In FIG. 9, the control pulse AFLCK is at the low level during the period ΔT1, which is the same as LE.
D is turned on. In the offset value detection processing performed by the command of “LED = 0”, AFLCK is used.
Is kept at a high level. Therefore, in the offset value detection processing, the LED is turned off and the gain control amplifiers 35a and 35b are set to "GAIN = 8". In this state, the output signals of the gain control amplifiers 35a and 35b
Samples are held at 6a and 36b.

When a time ΔT6 elapses from the time point P3 when AFSD becomes low level, the sample hold circuit 36
a, 36b are output from buffer amplifiers 37a, 37b.
The signal is converted into a 7-bit digital signal by the A / D converter 29 via b, and these are sequentially taken into the CPU 24 as the measurement data AFD1 and AFD2 of the first and second channels, and stored at a predetermined address in the RAM 26. .

On the other hand, in the gain determination processing and the distance measurement processing,
The designated LED is lit once during the period ΔT1 in which the AFLCK is maintained at the low level. During this lighting, the output signals of the gain control amplifiers 35a and 35b are sampled and held by the sample and hold circuits 36a and 36b. You. Then, regardless of whether the LED is turned on or off, when the high-level period ΔT5 of AFLCK has elapsed, the cycle of acquiring one piece of measurement data ends.

In the offset value detection processing, measurement data is taken in eight times, and the measurement data AFD1, AFD2
Are obtained eight each. These eight measurement data are averaged for each channel, and the average value is determined as offset values OF1 and OF2. As described above, since the LEDs 3a to 3c are turned off in the offset value detection processing, the offset values OF1 and OF2 are set to PS
This is caused by noise light from a shooting scene incident on D9, noise of a signal processing system, and the like.

After the offset value detection processing, gain determination processing and distance measurement processing are performed. These processes are LED3
This is executed individually for a to 3c. The gain determination process is performed according to the flowchart of FIG. When the gain determination process is started, “GFLAG”, “OFLAG”, “GCOUN”
T "is set to an initial value" 0 ". Thereafter, the serial data representing the new command is transferred from the serial port 28 to the logic circuit 32, and the binary data of “01000011” is set in each bit of the shift register 38 at the point P1 when the AFLCK goes low. You. Thereby, “GAIN = 8”, “LED = 1”,
The command of “SET = 1” is set, and only the LED 3a is enabled to emit light. After setting this command, the LED 3a is turned on once during the period “ΔT2 + ΔT3”,
Sampling processing is performed during this lighting. Thereafter, reading processing of the measurement data AFD1 and AFD2 is performed.
The lighting cycle of the LEDs 3a to 3c is, for example, 1 ms.

As shown in FIG. 2, when the distance measuring light from the LED 3a is applied to the main subject S1, the reflected light enters the PSD 9 through the light receiving lens 8. At this time PS
The signal output from both terminals 9a and 9b of D9 is a PSD.
9 includes information on the intensity of incident light and the incident position. These signals are digitally converted by the A / D converter 24, and are then taken in as measurement data AFD1 and AFD2.

Next, the CPU 24 sets the measurement data AFD
It is determined whether one of AFD1 and AFD2 has reached “127” in decimal. If the value of AFD1 and AFD2 is "1"
27, it is determined that one of them is in a saturated state (overflow). Since this measurement data has extremely low reliability, it was confirmed that “GAIN = 8”, and then “AFRESULTa ← 127”
("AFRESULTa" will be described later), and the distance measurement by the LED 3a ends. In this state, the subject in the center of the screen is quite close,
Even when “GAIN = 8”, the reflected light is too strong.

When the measurement data AFD1 and AFD2 are not saturated, each measurement data AFD1 and AFD2
Then, the calculation processing of the addition measurement data AFADD and the subtraction measurement data AFDIF shown in FIG. 12 is performed. In this process, the measurement data AFD1, AFD
The offset values OF1 and OF2 are subtracted from FD2. Then, the calculated addition measurement data AFADD
It is determined whether or not the value is equal to or more than “136”. When this value is equal to or larger than "136", it is determined that the absolute value of each of the measurement data AFD1 and AFD2 is within a range suitable for executing the subsequent distance calculation, and the gains of the gain control amplifiers 35a and 35b are determined. The value of "GAIN" at that time is determined, and the distance measurement processing by the LED 3a shown in FIG.

On the other hand, when the value of the additional measurement data AFADD is less than "136", the value of "GAI"
After confirming that “GFLAG” indicating that the value of “N” was inappropriate was not “1”, the gain was changed to increase the absolute values of the measurement data AFD1 and AFD2. Will be "GAIN" after this change is obtained by adding the correction value "N" to the original value of "GAIN", and this new "GAIN" is written to the RAM 26. The value of the correction value “N” is calculated based on the addition measurement data AFA.
The values are set as shown in the following table according to the size of the DD.

[0044]

[Table 1]

The change of "GAIN" is performed by setting command data including a new gain in the shift register 38. At this time, only the bits "D0" to "D4" change, and the other bits are changed. The data does not change. Then, the gain controller 33 outputs the new “GAI
N ”according to the value of“ N ”.
The gains of a and 35b are adjusted, and the same processing is repeated. At the time of this repetition processing, “GAIN> 8”
May be saturated, but in this case, "GFL
After setting "AG" to "1", the value of "GAIN" is set lower by "1".

When the addition measurement data AFADD having an appropriate absolute value is not obtained even when "GAIN" reaches the maximum value "31", the reflected light from the subject is extremely weak or has not returned to PSD9. It is. In this case, since the subject distance is infinity, it does not make much sense to perform the distance measurement described below. Therefore, in this case, the processing of “AFRESULTa ← 0” is performed without performing the distance measurement processing.

Further, the number of times of re-setting of the gain RN in the gain determination processing is obtained from the initial value IG of the gain, the maximum value GM of the gain, and the maximum correction value "NM". RN = (GM−IG) ÷ NM In this embodiment, since GM = 31, IG = 8, and NM = 8, RN = 2.9 ≒ 3. Therefore, the number of times RN of resetting the gain is limited to three times, and “GCOUN”
When T = 3 ”, the change of the gain ends at that point. Due to this limitation, even if the intensity of the reflected light from the subject changes and the values of the measurement data AFD1 and AFD2 change, no time is required for the gain determination process, and the gain can be determined quickly. Moreover,
Since the upper limit of the number of repetitions of gain adjustment is determined, AF
Even when the value of ADD is extremely small, the gain value can be adjusted to the maximum value “31”.

When the value of "GAIN" is determined by the above-described processing, the value is written into the RAM 26, and the distance measurement processing by the LED 3a is subsequently performed while keeping the gains of the gain control amplifiers 35a and 35b. FIG. 13 and FIG. 14 show this distance measurement processing procedure. In this distance measuring process, after the initial data is set in the RAM 26, the LED 3a is turned on 18 times.
FD1 and AFD2 are read. And every time AFD
At the time of reading AFD2, it is determined whether any one of them is saturated, or whether the value is less than "15" and is not sufficient as the absolute value of the measurement data. "O" for distance
VCOUNT ”is counted up by“ 1 ”.
In addition, the measurement data which became "OVCOUNT"
Since the light is not used for the distance measurement calculation, the light emission is performed again to capture the measurement data.

When "OVCOUNT" reaches "4", it is determined that the value of the gain determined in the gain determination processing is inappropriate, "OFLAG" is set to "1", and "GAIN" is set to "1". The distance is reset by "1" and the distance measurement process is restarted from the beginning. Further, in order to prevent the ranging process from being repeated many times, once “OVFLAG” is set to “1” and then “OVCOUNT” reaches “4” again, “GAIN” at that time is used. The value of “AFRESULTa” is determined as “M” corresponding to the value of “. At the time of this determination, the table of Table 2 is referred to.

[0050]

[Table 2]

In the process of taking in the 18 measurement data AFD1 and AFD2, the minimum value and the maximum value are identified, and the AFD1 and ADF2 are set to “SUM1”,
It is summed up as “SUM2”. Then, in order to increase the reliability of the average value, these total values “SUM1”,
After subtracting the maximum value and the minimum value of each of AFD1 and AFD2 from “SUM2”, the average value is calculated. Although the distance measurement accuracy is reduced, the average value may be calculated without excluding the maximum value, the minimum value, and the like. In this case, the divisor is set to “1”.
8 ".

The average value obtained for each channel is obtained by adding the offset measurement data AFADD and the subtraction measurement data AFD after correcting the offset value according to the processing of FIG.
Converted to IF. Then, “12” is added to the value of these ratios.
7 ”to calculate“ AFRESULTa ”
The distance measurement processing using 3a ends. Note that "SUM1,""SUM2," and "AFAD" obtained in the process of the distance measurement process.
D, AFDIF, and AFRESULTa are written to the RAM 26.

Subsequently, the gain determination process and the distance measurement process are performed while the LED 3b is turned on.
Is performed for the gain determination-distance measurement. Then, “AFRESULTb”, “AFRESULT
The value of "c" is obtained and written to the RAM 26 together with data such as "AFADD" and "AFDIF" obtained for each of the LEDs 3b and 3c. In the calculation of the average value and the distance data, division is performed, and the result is converted to an integer by rounding down, rounding up, rounding off, or the like.

The value of these “AFRESULT” is L
There are three corresponding to the EDs 3a to 3c, and in the shooting scene shown in FIG. 2, "AFRESULTa" is the main subject S1.
"AFRESULTb" is the background subject S2
The value corresponding to the distance to
“LTc” is “0” (see FIG. 11) because the pulse light is not reflected. In such a case, the microcomputer 14 follows the program stored in the ROM 25 and sets “AFRESULTa”,
The closest distance data is selected from “AFRESULTb” and “AFRESULTc”, and the distance measurement sequence is completed.

When the measurement data AFD1 and AFD2 are saturated, the value of “AFRESULT” is set to “12”.
7 ", which corresponds to the closest subject distance, but this singular value is ignored when determining optimal distance data. After the optimum distance data is determined in this way, the stepping motor 15a is driven via the lens position control circuit 15, and the photographing lens 5 is set to the lens position corresponding to the optimum distance data.

Next, the inspection mode will be described. The transition to the inspection mode is performed by a special operation of pressing the self-timer mode button 40 while the shutter button 19 is half-pressed. In this inspection mode, various data obtained in the process of the ranging process performed up to that time are output in a predetermined order every time the self-timer mode button 40 is pressed. That is, offset value, LED
In addition to the gain values of the gain control amplifiers 35a and 35b determined for each of the 3a, 3b and 3c, addition measurement data, subtraction measurement data, "AFRESULT", optimum distance measurement data used for the lens set, and the like are sequentially stored in the RAM 26.
From the liquid crystal display 43 and the display LED 46.
Is displayed with. In addition to the data related to the distance measurement process,
Photometric data and data obtained by exposure calculation may also be displayed externally.

In the display on the liquid crystal display 43, various data are displayed by numbers, and the display LED 46 sequentially displays a plurality of data by an optical signal by blinking light emission. FIG. 15 shows an example of the blinking display, in which four bits are one unit (one decimal number), and one data is displayed in a plurality of units. That is, in FIG. 15, the binary code “0” is changed by the short lighting time Δt1 (100 μsec or less) to the long lighting time Δt2 (200 μsec or more).
Represents “1”. Each bit has a turn-off time Δt
3 (100 μsec) is displayed. Then, the division of the data unit is represented by the light-off time Δt4 of 1 msec. As a result, instead of visually checking the data on the liquid crystal display 43, the blinking is received by the photo sensor of the measuring device, so that the data analysis can be automated by computer processing. In this case, a plurality of data are automatically read in a predetermined order,
The display LED 46 preferably outputs the light signal.

By preparing the inspection mode described above, in the final inspection process after the manufacture of the camera, when confirming the operation of the distance measuring apparatus for a test object having a known distance, the distance measurement is actually performed. Various data obtained after the operation can be easily known. Therefore, a highly reliable inspection can be performed without, for example, measuring the extension amount of the photographing lens. Also, each LED 3a, 3b,
"AFRESULTa" representing the distance measurement result by 3c,
By comparing the data of “AFRESULTb” and “AFRESULTc”, the mounting position of the PSD 9, particularly the inclination of the PSD 9 (rotation about the optical axis 8 a, which tends to cause erroneous ranging in a multi-beam type distance measuring device) Can also be adjusted accurately.

In the above-described embodiment, the data relating to the distance measurement is read to check whether the distance measuring device is operating correctly. If an erroneous distance measurement has occurred, the data based on the read data is used. This adjusts the positions of the light projecting unit and the light receiving unit. In the multi-beam system, it is necessary to make adjustments so that proper ranging data can be obtained for all the ranging lights, and the adjustment is extremely troublesome. Instead of making such complicated adjustments, one distance measuring light is used as a reference, and adjustment is performed so that proper distance measurement is performed for this reference distance measuring light, and the remaining distance measuring light is adjusted. The correction data is prepared in advance, and the distance data of each distance measuring light is respectively corrected using the correction data, so that troublesome adjustment can be omitted. FIGS. 16 to 21 show this embodiment, and the same members as those in the above embodiment are denoted by the same reference numerals. Of course, if the difference between the correct distance data and the actually measured distance data is prepared as correction data for the reference distance measurement light, the adjustment is unnecessary. Of course, in order to clarify the cause of the erroneous distance measurement, data related to the distance measurement calculation may be written to the RAM and these data may be output in the inspection mode, as in the above-described embodiment.

In FIG. 16, a cover 50 is provided on the side surface of the camera body 48. When the cover 50 is opened at the time of inspection of the distance measuring device, the connection terminal 51 is exposed. The plug 53 of the correction data input device 52 is connected to the connection terminal 51. The correction data input device 52 is provided with a dial 54. By operating with reference to a comparison table 55, correction data can be input.

As shown in FIG. 17, the correction data input device 52 is provided with a potentiometer 5
8, an A / D converter 59 and a liquid crystal display 56 are built in. The A / D converter 59 converts a voltage value associated with a change in the resistance value of the potentiometer 58 into a digital value, and sends this to the liquid crystal display 56 as correction data. Further, by performing the correction data writing process, the correction data is transferred to the microcomputer 14 via the A / D converter 29.
And written into the erasable ROM 25.

The R0M 25 stores a correction data comparison table 25a as shown in FIG. The correction data comparison table 25a is used to correct the same subject so that the distance data obtained from each of the three LEDs 3a, 3b, and 3c is the same. That is, this correction data comparison table 25a
It shows the relationship between the deviation amount of each of the distance measurement data of the left and right LEDs 3b and 3c and the "A / D bit value" based on the distance data by the LED 3a for measuring the center of the shooting scene. Then, one correction data is designated by the correction data input device 52 according to a test result at the time of manufacturing the camera. The same contents as those of the correction data comparison table 25a are printed in the comparison table 55.

As described above, the LEDs 3b, 3
c, the distance data “AFRESULT
is different from the distance data “AFRESULTa” obtained when the LED 3a is turned on, is corrected by the correction amount “Y” determined in the correction data comparison table 25a. This correction is performed for the following reason. by. For example, when the subject distance is the same, as in the case of a wall surface, the distance measurement light by turning on the LED 3a is reflected by the subject, and when the distance measurement light enters the position SP1 of the PSD 9 in FIG.
Even when b and 3c are turned on, the direction (vertical direction) of the base line of the triangular distance measurement should originally be incident on the same height position SP2 and SP3 as the position SP1 as shown by the solid line. It is.

However, if the mounting position accuracy of the LEDs 3b, 3c or PSD 9 is insufficient, or if the projecting / receiving lenses 4, 8 are eccentric, the LEDs 3b, 3c are not eccentric.
As shown by the broken line in the figure, the reflected light when the light source 3c is turned on is y1 above the original incident positions SP2 and SP3.
The light enters the positions SP2 'and SP3' shifted downward by y2. In such a case, even if “AFRESULTa = 85” is obtained by the distance measurement calculation using the incident position SP1, for example, “AFRESULTb = 81”, “AFRESULTc” at the incident positions SP2 ′ and SP3 ′.
= 88 ”, and the distance data that should originally match is different.

An error between a plurality of distance data is represented by an LED.
In order to solve the problem by mechanically adjusting the mounting position of the PSDs 3a, 3b, 3c and the PSD 9, extremely fine adjustment work is required. To eliminate such mechanical adjustment work, the correction data comparison table 25a is required. Is used to correct the distance data. When specifying this correction data,
As shown in FIG. 16, the cover 50 is opened and the connection terminals 51 are opened.
To the plug 53 of the correction data input device 52. As shown in FIG. 20, when the daylight synchronization button 41 and the exposure correction button 42 are simultaneously pressed to input a hidden command, a focus correction mode program is executed. When this focus correction mode program is executed, distance measurement is performed on the test object in the same manner as described above, and three distance data are obtained for each of the LEDs 3a, 3b, and 3c, and then each distance data "AFRESULT" is obtained.
a), "AFRESULTb", "AFRESULT
The value of “c” is determined by the LC built into the camera body 48.
The message is displayed on D43, and enters an input waiting state.

Referring to the values of the respective distance data displayed on the LCD 43, the other distance data “AFRESULTb” and “AFR” for the distance data “AFRESULTa” are referred to.
Read the difference of "ESULTc". Then, as described above, “AFRESULTa = 85”, “AFRESULT
b = 81 "and" AFRESULTc = 88 ", the shift amounts are" -4 "and" 3 ", assuming that the shift to the far distance side is negative and the shift to the short distance side is positive. Because
By checking the separately prepared comparison table 55, “192 to 186” is obtained as the “A / D bit value” corresponding to the combination of the correction data of “−4, 3”.

Next, the correction dial 54 of the correction data input device 52 is operated. As a result, the resistance value of the potentiometer 58 shown in FIG. 17 changes, and the terminal voltage also changes. The terminal voltage value of the potentiometer 58 is A / D
The value is converted into a digital value by the converter 59, and the value is displayed on the liquid crystal display 56 by a numeral. This liquid crystal display 5
The correction dial 54 is adjusted so that the digital value displayed in No. 6 falls within the range of “192 to 186”.

When the self-timer button 40 is pressed after setting the "A / D bit value" in this way, the microcomputer 14 executes the reading process of the "A / D bit value", and the terminal voltage of the potentiometer 58 is set at the camera side. A
The digital signal is converted by the A / D converter 29 and, for example, “A /
A value of "190" is written as a "D bit value" at a predetermined address position in the ROM 25, and the correction data input processing is completed.

After performing the correction data input processing, the distance data “AFRESU” obtained by performing the distance measurement as described above.
LTb ”and“ AFRESULTc ”in FIG.
21, correction is performed with reference to the correction data comparison table 25a. Therefore, even if the distance data “AFRESULTb” and “AFRESULTc” obtained only by the calculation from each measurement data are “81” and “88”, respectively,
ESULTb ← AFRESULTb-Y ”,“ AFRE
Since the correction processing of “SULTc ← AFRESULTc-Y” is performed, the distance data of “85” and “85” are obtained, and the distance data does not differ among the LEDs 3a, 3b, and 3c.

As described above, the correction data comparison table 25a is built in the ROM 25, and the value of the correction amount Y used in the distance measurement calculation is stored in the correction data comparison table 25a.
By writing “A / D bit value” into the ROM 25 as an address for reading from the
It is possible to eliminate an error between the distance data obtained using each of D3a, 3b, and 3c. Moreover,
For this reason, the position of the LEDs 3a, 3b, 3c and the PSD 9 need not be mechanically adjusted, and the work can be performed efficiently. The reason why the "A / D bit value" has a width in the correction data comparison table 25a is that the adjustment by the correction dial 54 is not made too sharp. Further, the correction amount Y is a discrete value, but it is of course possible to determine the value more finely in steps.

Instead of using the correction data comparison table 25a, distance data “AFRESULTa” and
Distance data “AFRESULTb”, “AFRESULb
Tc ”is written to a predetermined address position of the ROM 25 during execution of the focus correction mode program, and this value is written to the distance data“ AFRESULTb ”,“ AFRESU ”.
It may be used as correction data in the process of calculating “LTc”. Further, the calculation of this difference may be automatically performed by the CPU 24, and the obtained difference may be automatically written into the ROM as correction data.

Although the embodiment in which three LEDs 3a, 3b, and 3c are used to sequentially measure the distances at three locations in the photographing scene has been described, the present invention employs one or two or even four LEDs. The above method can be similarly applied to an object that projects distance measuring light to a subject. Also, one L
When an ED is used, an elongated slit light may be generated instead of a spot light, or an LED may be swung to scan a shooting scene with one distance measuring light. Further, similarly to the conventional distance measuring device, the distance may be measured by one light projection. Furthermore, the attitude of the light projecting unit 2 may be changed according to the camera attitude, and the distance measuring light may be always emitted along a direction parallel to the ground. As a light receiving element, a CCD image sensor or the like can be used, and as a light source, a flash discharge tube, a lamp, or the like can be used.

[0073]

As described above, according to the autofocus camera of the present invention, a light emitting display or a liquid crystal display built in the camera in advance for displaying the number of shots and the shooting mode is used. Since various data written in the storage means can be externally displayed by the operation of the autofocus device, almost no cost burden is involved.
There is an advantage that the operation inspection of the autofocus device can be easily performed even during the manufacturing.

In addition, with respect to the reference distance data of the plurality of distance data, an error included in the other distance data is written in the storage means in advance, and when calculating the other distance data, Since the corresponding correction data is read out from the storage means and the distance data is obtained by performing the correction based on the correction data, the mounting positions of the light emitting means and the light receiving means do not have to be precisely adjusted. Can be greatly saved.

Further, when writing the correction data, the distance measuring device is actually operated to compare the distance data obtained by the respective distance measuring lights to obtain the correction data. It can be used, eliminating the need for complicated measurement circuits and analysis equipment, simplifying its work,
Efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of an autofocus camera according to the present invention.

FIG. 2 is a schematic configuration diagram of a distance measuring device.

FIG. 3 is a rear perspective view of the autofocus camera.

FIG. 4 is a block diagram illustrating a configuration of an autofocus IC.

FIG. 5 is a conceptual diagram of a shift register used in a logic circuit.

FIG. 6 is a flowchart showing an outline of a distance measurement sequence.

FIG. 7 is a flowchart illustrating a photographing sequence.

FIG. 8 is a flowchart illustrating a processing procedure of offset value detection.

FIG. 9 is a time chart for explaining reading timing of measurement data.

FIG. 10 is a flowchart showing a procedure for reading measurement data.

FIG. 11 is a flowchart illustrating a processing procedure for determining a gain.

FIG. 12 is a flowchart showing a procedure of calculating addition distance measurement data and subtraction distance measurement data.

FIG. 13 is a flowchart illustrating a first half of a distance measurement processing procedure.

FIG. 14 is a flowchart illustrating the latter half of the distance measurement processing procedure.

FIG. 15 is a time chart showing an example of blinking display of an LED in an inspection mode.

FIG. 16 is a perspective view showing a state in which a correction data input device is connected to the autofocus camera.

FIG. 17 is a block diagram showing a state in which a correction data input device is connected to an autofocus camera.

FIG. 18 is a conceptual diagram of a correction data comparison table.

FIG. 19 is an explanatory diagram showing incident positions of reflected light on a PSD.

FIG. 20 is a flowchart showing a procedure for inputting correction data.

FIG. 21 is a flowchart illustrating the latter half of the distance measurement processing procedure.

[Explanation of symbols]

 2 Emitter 3a-3c Distance measuring LED 7 Light receiver 9 PSD 12 Autofocus IC 14 Microcomputer 19 Shutter button 35, 35b Gain control amplifier 40 Self-timer mode button 41 Daylight sync button 43 Liquid crystal display 46, 47 Display LED

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigenken Goto 1-324 Uetake-cho, Omiya City, Saitama Prefecture Inside Fuji Photo Optical Co., Ltd. (72) Tatsuo Saito 1-324 Uetake-cho, Omiya City, Saitama Prefecture (56) References JP-A-3-130730 (JP, A) JP-A-2-24828 (JP, U) JP-A-63-66826 (JP, U) JP 7 -22669 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03B 13/36 G02B 7/32

Claims (2)

(57) [Claims] 1. A light projecting unit for projecting distance measuring light to different places in a photographing scene, a light receiving unit for receiving each distance measuring light reflected from a subject, and each light output from the light receiving unit. An auto-focus camera including a microcomputer that calculates measurement data, calculates distance data for each measurement data, and selects one of the distance data. Storage means is provided in which the difference between the reference distance data obtained by measuring the distance to the test object using the reference distance measuring light and each distance data obtained by other distance measuring light is previously written as correction data. An auto-focus camera, wherein when calculating distance data using the other distance measuring light, correction is performed using corresponding correction data. 2. A light projecting unit for projecting distance measuring light to different portions of a photographing scene, a light receiving unit for receiving each distance measuring light reflected from a subject, and each of the light emitting units output from the light receiving unit. An auto-focus camera including a microcomputer that calculates measurement data, calculates distance data for each measurement data, and selects one of the distance data. A first step of measuring the distance of the test object with the reference distance measuring light to calculate the reference distance data, and a second step of measuring the distance of the test object using the other distance measuring light to calculate the distance data. And a third step of writing correction data corresponding to the difference between each distance data and the reference distance data into the storage means.