JP3377283B2 - Camera ranging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an active camera.
The present invention relates to a distance measuring device for a vehicle. 2. Description of the Related Art Active type measurement used in cameras
The distance device is a light projecting unit that emits distance measuring light toward the subject
And a light receiver placed at a fixed base line distance from the light emitter
Unit and a signal processing unit that processes signals from the light receiving unit.
You. The light emitting section generally emits near-infrared light.
(IRED) is used and near-infrared light from it is measured
The light is projected toward the subject as light. Of the ranging light,
The light reflected by the subject passes through the light-receiving lens and enters the light-receiving section.
Shoot. The light receiving unit includes, for example, a PSD (Position Sensiti).
ve Devise), and the pair of output terminals
Represents a photoelectric signal corresponding to the light incident position. And
Based on the photoelectric signal, the signal processing unit performs triangulation calculation.
To calculate the distance to the subject.
The focus position of the taking lens accordingly.
Can be A photoelectric signal appearing at a pair of output terminals of a PSD
The output level of the
However, the ratio of these photoelectric signals must be determined.
Therefore, the PSD is not affected by the output level.
Light incident position can be detected. However, above
Calculate the ratio of both signals while the output level of the photoelectric signal is low.
And when the ratio is determined while the output level is high.
, The detection accuracy tends to vary. [0004] The photoelectric signal from the PSD is an analog signal.
Therefore, after converting these signals into digital quantities,
The ratio is usually calculated, but the output level is low.
And the output level.
When the ratio is obtained by A / D converting each photoelectric signal with high
In the case, there is a difference in the accuracy of the operation. These inconveniences
Japanese Patent Laid-Open Publication No. 4-199013 discloses a method for solving the problem.
In the above distance measuring device, each channel is connected to the output terminal of the PSD.
Amplifier system including gain control circuit for each channel
Connected and A / D converted photoelectric signals from both channels.
When the size of each digital data is within a certain range,
Feedback to the gain control circuit so that
And amplify each photoelectric signal with the same amplification factor
Has been done. Further, in the distance measuring device described in the above publication, the gay
Control circuit gain in an appropriate range.
The gain of the gain control circuit
Digital data obtained from each channel
If it is too large, it is determined that the subject is
To focus the taking lens. Also, the gain is
Digital data is too small despite being large
In some cases, it is determined that the subject is
The focus of the lens is adjusted. After the gain is determined,
Digital data obtained from channels is in the proper range
In some cases, the distance measurement light is emitted multiple times to perform the actual distance measurement,
Performs ranging calculations based on the obtained digital data and
The focus position of the lens is determined. [0006] As described above, the gain
If the gain of the control circuit cannot be determined in an appropriate range
Focus the shooting lens at a close distance according to the situation.
Focus on the hyperfocal distance at infinity.
The distance without wasting the actual distance measurement.
Can be focused. However, the gain
After the appropriate gain is determined by the decision process,
Actual distance measurement is repeated several times (for example, 128 times),
Distance measurement is performed based on the digital data obtained in the process.
Distance to determine the focus position of the taking lens.
Has the disadvantage that it takes too much time. Ma
In addition, in order to reduce such adverse effects, repeat the actual distance measurement.
Simply reducing the number will reduce the accuracy of ranging.
Problems arise. The present invention has been made in view of the above circumstances.
In the actual distance measurement after the gain is determined,
Without having to spend too much time,
Aiming to provide a distance measuring device for cameras
I do. [0008] The present invention achieves the above object.
To determine the gain of the gain control circuit.
Sometimes digital data can be obtained from each channel
Focusing on these digital data for distance measurement calculation
It is intended to be used. That is, gain determination
After the actual distance measurement is performed, the distance measurement light is projected N times
Read digital data sequentially for each channel and read
Performs distance measurement based on multiple digital data
When determining the focus position of the shooting lens,
During the determination process, each
P digital data was read for each channel
Sometimes, the number of times of distance measurement light projection during actual distance measurement is NP
Times and the P data obtained in the gain determination process
Digital data combined with digital data obtained during actual distance measurement
In this case, the distance measurement calculation is performed. According to the above, the projection time of the distance measuring light at the time of actual distance measurement is obtained.
While reducing the number to NP times, practically N times actual measurement
Read the same amount of digital data as
Can reduce the distance measurement accuracy.
There is no. FIG. 1 is a schematic diagram showing an electric configuration of a camera using the present invention.
In FIG. 2 shown in FIG.
It comprises an IRED 3 that emits light and a light projecting lens 4.
The optical axis 4a of the projection lens 4 is
And it is almost parallel. The ranging light from IRED3 is
The shooting screen is converted into a small beam by the light-emitting lens 4.
The central part is oriented. The light receiving section 7 comprises a light receiving lens 8 and a PSD 9
The optical axis 8a of the light receiving lens 8 is also
It is almost parallel to a. PSD9 is the amount of incident light
And a signal corresponding to the incident position is output to each output terminal 9a, 9b.
Output from As is clear from FIG.
The closer the distance is, the more the reflected light is on the terminal 9b side of PSD9.
From the output terminals 9a and 9b.
By taking the ratio of the sum and difference of the obtained photoelectric signals,
The signal corresponding to the incident position without depending on the amount of incident light
Can be obtained. Note that PSD 9 is
Has no discriminating action, and the incident height in the vertical direction is
Output is the same even if the horizontal incident position is different
The ratio between the sum and difference of the photoelectric signals from the terminals 9a and 9b is equal.
Become. Is IRED3 an autofocus IC12?
Light emission control is performed through the driver 11 by these signals.
You. The auto focus IC 12 is a microcomputer
Distance measurement according to the command from the
In addition to running the sequence and activating the driver 11,
Amplify the photoelectric signals from the output terminals 9a and 9b of the PSD 9,
Sample and hold processing to microcomputer 14
input. The microcomputer 14 has an AD converter.
And the auto focus IC 12
The photoelectric signal input for each channel from
Convert from log amount to digital amount. Microcomputer
The signal 14 is applied to the signal thus input for each channel.
Based on distance calculation based on the distance to the subject
Calculate the distance signal. And in response to this distance signal
The motor 17 is driven via the lens moving circuit 16 to capture an image.
The lens 5 moves to the set position corresponding to the subject distance
Focusing is performed. The microcomputer 14 has a general-purpose type.
Is used, and after being detected by the photometric circuit 19, the AD converter
The photometric data converted by the converter 20 is also input.
You. The microcomputer 14 is based on the photometric data
The optimum exposure condition is calculated, and the
The program shutter 24 is driven by driving the
Is the aperture value and shutter speed at which the above optimum exposure conditions are satisfied.
To open and close. After the photographing, the film transfer circuit 25
The film feed motor 26 is driven by the
Feeding is performed. The microcomputer 14 has an external device
Connection terminal 14a is provided, and distance measurement is performed when camera assembly is completed.
Perform tests to confirm the operation of the distance measuring device,
Various adjustment data are stored in the terminal so that accurate operation can be performed.
When inputting to the microcomputer 14 from 28
Used. Then, the data input from the terminal 28
Some of them store the data needed to perform the ranging process.
EEPROM (El
Write to ectrically Erasable Programmable ROM) 29
Or can be deleted. FIG. 1 shows an autofocus IC 12 and a microcomputer.
1 schematically shows the configuration of a microcomputer 14. P
Photoelectric signals output from output terminals 9a and 9b of SD9
Are preamplifiers 30a, 30
b, gain control circuits 31a, 31b, sample
Hold circuits 32a, 32b, buffer amplifiers 33a,
33b, and through the main amplifiers 34a and 34b,
It is input to the AD converter 15 of the computer 14. Ma
The autofocus IC 12 further includes a control circuit 3
5, gain controller 36, sampling pulse generation
And a vessel 37. The preamplifiers 30a and 30b are connected to the output terminal 9
a, 9b is converted into a voltage signal. Gay
Control circuits 31a and 31b
The amplified voltage signal is amplified with an appropriate gain. Of each gain
The value is set for each channel by the gain controller 36.
I can decide. The sample and hold circuits 32a and 32b
Sampling pulse from sampling pulse generator 37
Gain control circuit 31 at the timing when
a and 31b are sampled and held. E
The cooled voltage signals are supplied to buffer amplifiers 33a, 33a.
b, the main amplifiers 34a, 34b
Amplified in the original. The control circuit 35 has a serial-in-parallel
Out shift register (8 bits)
The serial data pulse “AFS” is stored in the shift register.
D ”sent from the microcomputer 14
Incoming control data is written. This control data is
In-data "GAIN" (5 bits), IRED selection data
Data "IRED" (2 bits), ON-OFF data
“SET” (1 bit), and the gain data
Read by the in-controller 36 and gain control
Used to determine the gain of troll circuits 31a and 31b
You can. Also, IRED selection data and ON-OFF
The data determines whether the IRED 3 is turned on or off. The control circuit 35 further includes a microcomputer.
Control pulse “AFLCK” is input from the
Control pulses are used to latch control data and emit light from the IRED3.
Used to determine timing and sampling
The sample hold circuit 3 is also sent to the pulse generator 37.
2a and 32b determine data latch timing
It is also used for The microcomputer 14 includes a CPU 4
0, serial port 41, A / D converter 15,
Stores the main ranging program for executing the ranging sequence
ROM 42 and obtained at the time of executing the distance measurement sequence.
RAM 43 for temporarily storing data and various flags
Become. The serial port 41 is a command from the CPU 40.
The output terminal is switched by the
Data pulse “AFSD” or control pulse “AFL”
CK ”is input to the control circuit 35. AD Con
The bar 15 is a main antenna of the auto focus IC 12.
The analog signal voltage sent from the loops 34a and 34b is
An 8-bit digital value (decimal) corresponding to the output level
(Representing 0-255 by a number). FIG. 3 is a block diagram of the control circuit 35 used in the control circuit 35.
Bit serial in-parallel out shift register
FIG. And D0 to D4
The gain data “GAIN” described above, D5 to D
6 are IRED selection data "IRED" and D
ON-OFF data "SET" is in 1 bit of 7
Each has been assigned. The 5-bit gain data of D0 to D4 is
Gays with different values from "0" level to "31" level
Can be represented. In addition, IRED of D5 to D6
The selected data is projected at several locations in the shooting screen.
In order to perform distance measurement at a plurality of locations by light, for example, three IRs
Which IRED emits light when using ED
In this embodiment, one IR is determined.
Since the distance is measured only with ED3, this 2-bit data is
Essentially unnecessary. However, in the following explanation,
When "01" is set as "IRED", IR
Description will be made assuming that ED3 is selected. Hereinafter, a basic distance measuring process of the distance measuring apparatus of the present invention.
Will be described with reference to a flowchart. turtle
When the shutter button is pressed halfway,
As shown, the main distance measurement program stored in the ROM 42 is used.
Gram starts and it is first determined whether it is in the adjustment mode or not.
You. In the adjustment mode, the AF
The microcomputer 1 is used so that the device operates properly.
Input data from the terminal 28 connected to the connection terminal 14a
Data in the EEPROM 29.
It is not used by the user. In the adjustment mode, test distance measurement is performed,
It is determined whether or not the distance processing is properly performed. Te
Various data obtained from the ranging device when performing strike ranging
The data is fed back to the terminal 28, and these data are
Various adjustment data are determined with reference to the data. This
The adjustment data thus determined is IRED3, PSD
9, depending on the electrical characteristics of the amplifier system of each channel, etc.
Although there are individual differences among cameras, refer to the results of test ranging.
While the appropriate value is determined, the command from terminal 28
By writing these adjustment data in EEPROM 29,
Be included. When the user uses the device in a normal state, the distance is measured.
The processing is executed. In the distance measurement process, the adjustment mode
The adjustment data written to the EEPROM 29 by the
The processing is started after storing in a predetermined area of the RAM 43.
Subsequently, as shown in FIG.
In decision processing, actual distance measurement processing, reciprocal calculation processing of subject distance
Is executed. In the offset value detection processing, IRED3
How much signal from output terminals 9a and 9b without turning on
This is performed to detect whether noise is output.
When correcting data obtained during distance measurement (actual distance measurement)
Used for Note that it is necessary to accurately detect the offset value.
32 times each from the output terminals 9a and 9b.
Digital data is acquired and their average is offset.
Value. The gain determination process is performed when an actual distance measurement is performed.
This is to set the gain of the pump system to an appropriate value.
Output level of photoelectric signal from PSD9 due to long object distance
Becomes smaller, a larger gain value is set. Real
In the distance measurement process, basically, the IRED3 is set to, for example, 0.5 seconds.
During 128 times repeatedly, each time AD converter
The digital data obtained from the data
Read as D1 and AFD2. Each distance measurement data
After addition, the average is taken, and based on this average,
The set position of the taking lens 5 is determined by performing the distance measurement calculation.
You. FIG. 6 is a flowchart showing the offset value detection processing.
It is a chart. During offset detection processing,
Gain data "GAIN" and IRED selection for the register 45
Data "IRED", ON-OFF data "SET"
Set. The gain data at this time is
Becomes the minimum value "GAINMIN" determined individually
ing. For example, when "GAINMIN = 8"
Indicates that “01000000” (2
Base number) is set. As a result, “GAIN = 8”,
Each control data of "IRED = 00" and "SET = 0"
Is set. The setting of the control data is performed according to the timing shown in FIG.
At the point P1 shown in the chart, that is, the control data
After transmission, the control pulse AFLCK goes low.
Latched. After sending the above control data
Indicates that "COUNT = 3" is stored in a predetermined register in the CPU 24.
2 "is set. The control data set in the shift register 45
Data of “GAIN = 8” is the gain control
Gain control circuits 31a, 31
b and supplied to the gain control circuits 31a and 31b
Are set to “8”. Basically,
The maximum value of the gain “GAINMAX” is “31”,
The minimum value of GAINMIN is “0”
However, these values are adjusted in the adjustment mode shown in the flowchart of FIG.
At the time of executing the mode, it corresponds to the amplifier system after PSD9.
EEPROM 29 is used as an individual value for each camera.
At the start of the distance measurement process.
It is stored in the RAM 43 from the EPROM 29. After transmitting the control data, the first and second channels
The photoelectric signal from the
Is converted to ADDATA, and micro
It is read by the computer 14. This reading process
When the processing is performed, the processing shown in the flowchart of FIG.
First, the control pulse "AFLCK" goes low.
Is done. After that, the serial data pulse “AFSD”
It goes to low level, and then goes to high level during actual distance measurement.
At timing P2, the IRED 3 is turned on. What
When the offset value is detected, IRED3 remains off.
Up to. When ΔT1 has elapsed from timing P2, the serial
The data pulse “AFSD” goes high again.
You. At this timing P3, the sampling pulse generator 3
7 to the sample hold circuits 32a and 32b.
A tuning pulse is sent out and the gain control circuit 31
a, 31b, the photoelectric signal from the
Is executed. And the timing when IRED3 is turned on
From P2, until the photoelectric signal of each channel reaches the peak.
The value of the deviation ΔT1 is also the amplifier system after PSD9.
It is usually different for each camera corresponding to
Therefore, the value of ΔT1 is also an appropriate value for each camera.
Decided, "SHTIME" in EEPROM29
Has been written. A certain time ΔT2 has elapsed since timing P2
Then, the serial data pulse “AFSD” goes low.
When the actual distance measurement, the timing of stopping the emission of IRED3
It is used as a logging signal. At the timing P3, the sample
The filtered photoelectric signal is then sequentially A
AD conversion is performed by the D converter 15. Digi after AD conversion
Total data ADDATA is provided for each channel.
Read into CPU 40 as distance measurement data AFD1, AFD2
I will. At this time, one of the distance measurement data AFD2 is input.
The read digital value is read as is, but the other
The correction coefficient “GPARA” is used for the distance measurement data AFD1.
Is multiplied. This allows the gain control of each channel
With the gains of the troll circuits 31a and 31b kept the same
So that errors between channels can be corrected.
Become. Therefore, the gain control circuits 31a, 31
The disadvantage of setting the gain of 1b individually can be avoided
You. Thus, the distance measurement data AFD1 and AFD2 are
After reading, the serial data pulse "AFSD",
Each of the control pulses “AFLCK” becomes high level,
Δ after the control pulse “AFLCK” becomes high level
When T3 has elapsed, one cycle of ranging data read processing
Is completed. By repeating the above, for each channel
32 distance measurement data AFD1 and AFD2 are obtained
However, these are added for each channel,
It is divided by the number of embeddings “32”. This allows the channel
Offset values OFS1 and OFS2 for each
And When the offset value is detected
And the digital data output from the AD converter 15.
Set each channel so that the value of ADDATA falls within a certain range.
The circuit constants of the channel amplifier system are set. Accordingly
The AD converter 15 during the offset value detection processing.
If the value of the digital data ADDATA output from the
It cannot be negative. It should be noted that this is also performed in a gain determination process described later.
As described above, the distance measurement data
Monitor the values when reading AFD1 and AFD2
If the value is too small or too large,
The bar counter is incremented by one, for example, 32
The overcount value becomes "4" during the reading
If this happens, repeat the offset value detection process.
It may be. Also, the over count value is "3" or less
Is the average value excluding the distance measurement data at that time
May be calculated. After the offset value detection processing, FIG.
Then, the gain determination processing shown in FIG. 10 is performed. gain
In the determination processing, first, the EEPROM 29 is used as an initial gain.
"GAINMIN" developed in RAM43 from
Is set. Then, “SUBCNT” on the RAM 43
In addition to the data “1” being set in the area,
Alternatively, in an appropriate register in the CPU 40, the step ST
Each data indicated by 1 is set. In ST1,
The generated data has the following contents. OVCNT: Reading for each channel
Reading when the data taken is too small or too large
Allowable times AFADD: Data obtained for each channel
ADSUM1: Addition value of data of the first channel ADSUM2: Addition value of data of the second channel PRECNT: Number of times of reading data with the same gain UND flag: Set when reading data is too small
Flag OV flag: Set when the read data is excessive
Flag CNT: Number of times of data read After initial setting of ST1, gain data
"GAINMIN", IRED selection data "01", O
The shift in the control circuit 35 together with the N-OFF data "1"
Sent to the register 45. 7 and 8
As shown, reading data for each channel
Be started. Distance measurement data read for each channel
The values of AFD1 and AFD2 fall within the standard range.
It is determined in steps ST2 and ST3 whether or not they are present. this
These distance data are represented by 8-bit digital values,
It has a size of “0” to “255”, but these values are
Less than the sub-minimum value "5" or the reference maximum value
It is checked whether it is larger than “230”. This che
Is set in the gain control circuits 31a and 31b
Check if the gain is appropriate for "GAINMIN"
It is for doing. And is determined to be appropriate
In this case, the distance measurement data AFD1,
AFD2 has the added values ADSUM1 and ADSUM, respectively.
2 is stored in the RAM 43. The number of data readings “CNT” becomes “0”
When it is confirmed that it has become, the value of "SUBCUT"
“1” is written as “PRECNT”, and FIG.
Move on to processing. In the initial setting, “CNT =
1 ”, so“ CNT @
When it is set to “0”, it is an error, so read the data again.
An embedding process is performed. At ST2, the distance measurement data AFD1, A
If any value of FD2 is determined to be too small
Is set to the "UND flag". And in ST3
Either the distance measurement data AFD1 or AFD2 is too large
"OVCNT" is changed to "-"
1 "is performed. In the initial setting, "OVCNT
= 1 ”, so usually this process
"OVCNT = 0" and "OV flag" set
Thereafter, the processing shifts to the processing of FIG. 10, but with “OVCNT @ 0”
In some cases, an error occurs and the data
Is performed. In the process of FIG. 10, first, in step ST5,
The presence or absence of the "OV flag" is checked. "OV
In the case of "no flag", "ADSUM1", "ADS
UM2 ”is divided by“ SUBCNT ”.
Is the new distance measurement data “AFD1”, “AFD2”
Will be saved as In step ST6, as shown
To "(AFD1 + AFD2)-(OFS1 + OFS2)
≧ 136 ”is determined. “OFS1”, “OFS
The value of “2” has already been obtained by the offset value detection processing described above.
Have been. In ST6, the data is obtained from the first and second channels.
Of the sum of the measured distance data "AFD1" and "AFD2"
Is large enough even after offset value subtraction
Make sure you have it. Distance measurement as described later
The data "AFD1" and "AFD2" are used for the subsequent distance calculation.
It is used, but in order not to degrade the calculation accuracy,
It is preferable that the sum of them is "136" or more.
You. At ST6, the distance measurement data "AFD1",
The size of the sum of “AFD2” is appropriate for executing the distance measurement calculation.
If it is confirmed that the level is higher than
The gain of the rule circuits 31a and 31b is determined by the “GAI
N ”(initial value“ GAINMIN ”)
Then, the processing shifts to the actual distance measurement processing shown in FIG. At ST6, the distance measurement data "AFD1",
It was confirmed that the size of the sum of “AFD2” was inappropriate.
The “GSNG flag” described later is set.
On the condition that there is no change, the value of “GAIN” is changed.
The value of “GAIN” is “(AFD1 + AFD2) − (O
FS1 + OFS2) ”and the gain table in the following table.
Table according to the table. [Table 1] This GAIN addition value is converted to “GA”
The value added to “IN” becomes a new “GAIN”.
This value exceeds “GAINMAX” by step ST7.
If so, the processing moves to the processing in FIG. "GAIN
In the case of "MAX" or lower, this new "GAIN" is controlled.
The data is transmitted to the shift register 45 as control data. Further
In step ST8, the new value of “GAIN” is changed to “G
AINMAX-16 ”, that is, almost the middle value of the gain
It is determined whether the distance is greater than the threshold value.
The gain determination process is performed again. On the other hand, the new “GAIN” value
If the value is substantially larger than the intermediate value, “SUBCNT ←
8 "and returning to FIG. 9 to determine the gain. This
The new gain value is larger than the middle value.
The reason for increasing the number of data reads when
This is because the noise component increases as the value increases. At ST5, it is determined that "OV flag exists".
And that “GAIN = GAINMIN”
If confirmed in step ST9, EEP for each camera
The maximum gain value “GAINM” written in the ROM 29
AX ”and the minimum value“ GAINMIN ”
Means that normal processing cannot be performed due to noise or disturbance.
I taste. Then, in this case, the processing shifts to the processing of FIG.
I do. In ST9, "GAIN @ GAIN"
MIN ”is confirmed, then“ GSNG
Lag "is set. This “GSNG flag” is set
Set when the specified gain is inappropriate
Is done. After the “GSNG flag” is set, “GA
A new gain is set as "IN ← GAIN-1".
Under the gain, the gain determination process of FIG. 9 is restarted.
You. While performing the above gain determination processing, ST6
When the processing shifts to the processing of FIG.
Actual distance measurement processing is started using “GAIN”. This fruit
In the distance measurement process, basically, IRED3 is 128 times
It is turned on repeatedly, and each time the distance measurement data AFD1, AF
Read D2. Then, as in the case of the gain determination process
Check whether these values are within the appropriate range
Is done. If the values in the appropriate range are
AFD1 and AFD2 are used when the gain is determined.
"ADSUM1" and "ADSUM1"
2 ". And read the ranging data
When the count “CNT” becomes “0”, the measurement shown in FIG.
The process proceeds to distance calculation processing. By the way, as shown in ST10 of FIG.
In addition, the number of readings of the distance measurement data during the actual distance measurement, "CN
“T” is based on “CNT ← SUBCNT-PRECNT”.
Is restricted. "PRECNT" is shown in FIG.
The gain determination process that has already been performed prior to the actual distance measurement
The number of times the distance measurement data has been read. Accordingly
Read the distance measurement data eight times in the gain determination process
If the distance measurement data has been
The number of readings is 120, shortening the processing time of actual distance measurement.
Can be reduced. Further, as described above, during the gain determination process,
The ranging data obtained for each channel is shown in "ADS
UM1 ”and“ ADSUM2 ”during actual distance measurement
Data is also stored, so data can be read during the gain determination process.
When the total number of times of embedding is counted, it becomes "128" times. As a result,
The number of times of basic distance measurement does not decrease, and the distance measurement accuracy is low.
It won't be. Distance measurement data AFD1, AF during actual distance measurement processing
If the value of D2 is too small, the gain
Similarly, the "UND flag" is set. And big
“OVCNT” is decremented by “1”, even if it has passed.
It is. This “OVCNT” value is set to the initial setting of ST10.
Therefore, since it is set to "16", the distance measurement data
While reading "CNT" times, the distance measurement data AFD
Even if one of AFD2 and AFD2 is an inappropriate value
Up to "15" times are allowed, and the actual distance measurement processing continues
Is done. Reading of the distance measurement data of "CNT" times is completed.
Upon completion, the reciprocal of the subject distance is calculated as shown in FIG.
The required calculation is performed. First, “ADSUM1”, “A
DSUM2 ”and offset values“ OFS1 ”and“ O
FS2 "is performed.
Since the total number of times of reading these data is 128,
The value obtained by multiplying each offset value by 128 is referred to as “ADSUM
1 "and" ADSUM2 ". Subsequently, "ADSUM1", "ADSUM
2 "and the subtraction data" AFD "
IF ”and the ratio“ AFRATIO ”
Can be Next, the reciprocal of the subject distance “INV.LEN” is
Is calculated. In this calculation, the EEPROM 29
The coefficient “ADJ0” stored in the RAM 43 from “A”
DJ1 ”is read. These coefficients are
It is a value appropriately set according to the scientific characteristics. Soshi
Thus, the reciprocal of the subject distance thus obtained, “INV.L
EN ”is input to the CPU 40, and based on this,
The focus position of the lens 5 can be determined. In addition,
“Α” is a constant value that does not depend on individual differences between cameras. FIG. 9 shows the gain determination process and FIGS.
In the process of executing the actual distance measurement process shown in FIG.
AIN = GAINMIN "
When the data AFD1 and AFD2 are too large
Is a high-brightness light incident on PSD 9 and the subject distance
This corresponds to a close distance. Therefore,
As shown in FIG. 12, the value of “INV.LEN”
"∞" is set, and the focus position of the photographing lens 5 is set accordingly.
Is a position suitable for the close distance, and a short distance warning is issued.
You. During the execution of the gain determination process, “AFD1
+ AFD2 ”has not reached the appropriate level,
The value of "GAIN" that I tried to set newly in ST7
The maximum value of the gain set for each camera "GAIN
If "MAX" is exceeded, the incidence of light on PSD9 is extremely high
And it is weak. In this case
Means that the subject distance is extremely far
, Set “0” as the value of “INV.LEN”,
As a result, the focus position of the photographing lens 5 is set for infinity photographing.
Be able to adjust to the position. The present invention has been described with reference to the illustrated embodiment.
Has been described, but a part of the distance measurement program
Improvements and modifications are possible as appropriate.
The number of times the distance measurement data is read repeatedly during actual distance measurement
Can be set as appropriate. Also,
Instead of finally calculating the reciprocal of the subject distance, "AFR
ATIO ”to determine the focusing position of the taking lens 5
You may ask for it. Further, the present invention provides a single IR
Not only those that measure distance with the ED3,
Using three IREDs with different directions, the center of the shooting screen
And the distance measurement light is projected to each of the three places on the left and right sides to measure the distance
It is also possible to use it in such a way. As described above, according to the distance measuring apparatus of the present invention,
If the distance measurement light is projected multiple times after the gain
When performing actual ranging to read digital data,
Digital data read at the time of execution of fixed processing up to actual distance measurement
Save this digital data for actual distance measurement.
The distance measurement light during actual distance measurement.
Lighting and reading of digital data can be reduced
When the actual distance measurement is required without lowering the distance measurement accuracy
The time can be shortened.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a schematic configuration of an autofocus IC and a microcomputer. FIG. 2 is a schematic diagram of a camera using the present invention. FIG. 3 is a conceptual diagram of a shift register for storing control data. FIG. 4 is a flowchart showing a process in an adjustment mode when a terminal is connected. FIG. 5 is a flowchart showing basic processing of a distance measurement program. FIG. 6 is a flowchart illustrating an offset value detection process. FIG. 7 is a timing chart showing how control data is transmitted and distance measurement data is read. FIG. 8 is a flowchart showing distance measurement data reading processing. FIG. 9 is a flowchart showing a part of a gain determination process. FIG. 10 is a flowchart illustrating another part of the gain determination process. FIG. 11 is a flowchart showing actual distance measurement processing. FIG. 12 is a flowchart showing a process of calculating the reciprocal of a subject distance. [Description of Signs] 2 Projection unit 3 IRED 5 Photographing lens 9 PSD 12 Autofocus IC 14 Microcomputer 14a Connection terminal 28 Terminal 29 EEPROM 31a, 31b Gain control circuit 32a, 32b Sample hold circuit 42 ROM 43 RAM

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01C 3/06 G02B 7/32 G03B 13/36

Claims (1)

(57) [Claim 1] Distance measuring light is projected on a subject, the reflected light is received by a light receiving element, and output from a pair of output terminals of the light receiving element corresponding to the incident position. Each of the photoelectric signals is digitally converted, and the gains of the gain control circuits respectively connected to the output terminals are determined so that the digital data has a value within a predetermined range, and under the determined gains, When the value obtained by adding the digital data is equal to or more than a certain value, actual distance measurement is performed by repeating the projection of the distance measuring light N times to sequentially read each digital data, and measuring based on the digital data obtained by the actual distance measurement. In a camera distance measuring apparatus which determines a focusing position of a photographing lens by performing a distance calculation, each channel is determined when a gain of the gain control circuit is determined. In addition to storing P digital data obtained for each channel, the number of times the distance measuring light is projected during actual distance measurement is set to N-
A digital distance measuring means for reading the digital data in P times and adding the digital data obtained by actual distance measurement and the stored digital data to use in the distance measurement calculation; apparatus.