JP2002341238A - Adjusting device for auto-focusing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that an auto-focusing device which is mounted on a conventional camera and measures a distance by active triangulation by using a PSD easily measures a distance incorrectly since the output current of the PSD becomes small when the distance to a subject in a long-distance area is measured. SOLUTION: This adjusting device for the auto-focusing device of a camera computes an adjustment value from two charts which have the same distance and different reflection factors and stores it in a storage means in the adjusting process of the range finder in the manufacture of the camera and corrects the adjustment value (error component) corresponding to a long-distance area through the correcting operation of a computing means when the long-distance area wherein noise affects measured distance data is decided when a photograph is taken.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring apparatus for a camera, and more particularly to an adjustment for an active distance measuring apparatus which projects distance measuring light onto a subject and detects the subject distance from the reflected signal light. Related to the device.

[0002]

2. Description of the Related Art Conventionally, infrared light or the like is projected toward a subject as an object, and reflected signal light from the subject is received via a light receiving lens separated from the light projecting unit by a base line length.
An active triangulation-type distance measuring device that detects the incident position to detect the subject distance is known.

The light incident position is determined by a semiconductor position detecting element (P
The detection by SD) is known, and is described in, for example, JP-A-50-23247.

[0004] The present applicant has disclosed in Japanese Patent Application Laid-Open No. 1-211111.
According to the publication, distance measurement is performed by switching to a different distance, and at that time, not only a light incident position but also an incident light amount is calculated from a PSD output signal, and a distance measuring device that calculates a subject distance is proposed. ing.

[0005]

However, it is very difficult to measure a subject located in a distant range with a distance measuring device using a PSD for the active triangulation as described above. In other words, reflected light from a subject at a long distance
When the light quantity of the incident signal is converted into a photocurrent value, 1n
Since the level is about A, 2 nA, the output current of the PSD naturally becomes 1 nA or less, and noise generated from the circuit at the time of amplifying the signal is easily superimposed.

Accordingly, the applicant of the present invention disclosed in the above-mentioned Japanese Patent Laid-Open No. 1-291.
As described in Japanese Patent Publication No. 111, a distance measuring device using the amount of reflected signal light of a subject at such a distance has been proposed. There is a problem that a person and a person in black clothes may obtain different distance measurement results even if they are at the same distance.

Accordingly, the present invention provides a distance measuring apparatus capable of measuring a distance with high accuracy without being affected by the reflectance of the object, even if the object is in a distance range where a sufficient amount of reflected light cannot be obtained. It is an object of the present invention to provide an adjusting device.

[0008]

In order to achieve the above object, the present invention firstly provides an adjusting device for adjusting a distance measuring device of a camera, comprising: a first chart arranged at a predetermined distance; The first chart, which can be arranged at the same distance as the first chart, the second chart having a different reflectance from the first chart, and an output when the distance measuring device measures the distance between the first chart and the second chart. A distance measuring unit configured to calculate an adjustment value at a distance different from the predetermined distance of the distance measuring device from each data; and a storage unit configured to store the adjustment value calculated by the calculating unit in a camera. An adjusting device for the device is provided.

Secondly, a light projecting means for projecting light for distance measurement to a subject, and receiving reflected signal light from the subject,
A first signal that depends on the amount of the reflected signal light; and a light receiving unit that outputs a second signal that depends on the incident position of the reflected signal light. In an adjusting device for adjusting a distance measuring device of a camera capable of calculating a distance, a first chart that can be arranged at a first distance and the first chart that can be arranged at the same distance as the first chart. A second chart having different reflectivity, a third chart that can be arranged at a second distance different from the first distance, and a third chart that can be arranged at a third distance different from the first and second distances A fourth chart, the second signal output when the distance measuring device measures the distances of the first, third, and fourth charts, and a second signal output when the distance measuring device measures the distances of the second chart. A distance measuring device comprising: the first signal; and a calculating means for calculating an adjustment value from the first signal. Providing an adjusting device for.

In the adjusting device for the distance measuring device having the above-described configuration, in the adjusting process of the distance measuring device at the time of manufacturing the camera, the adjusting value is calculated based on two charts having the same distance and different reflectances. If the noise is determined to be a long distance affecting the measured distance data when the actual shooting is performed, the adjustment value (error component) is corrected by the correction calculation. Done.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1A is a diagram showing a conceptual configuration of a distance measuring apparatus according to a first embodiment of the present invention.

In this distance measuring device, an arithmetic control circuit (CPU) 1 composed of a one-chip microcomputer or the like performs sequence control of the entire device, performs an operation by receiving output signals from respective circuit units described later, and determines an object distance. calculate. This CP
U1 is connected to an infrared light emitting diode (I
RED) 3 is driven, and the generated light is condensed by a lens 4 and becomes distance measuring light projected toward a subject (not shown).

The signal light reflected from the subject is condensed by the lens 5 and enters the PSD 6. This PSD6
Converts the reflected signal light into a current I proportional to the intensity of the light.
0, and further, at a rate depending on the incident position x, I0
Is divided into two current signals I1 and I2. The length of the light receiving surface of this PSD 6 is t
And the origin of x is a,

(Equation 1) Becomes

The output currents I1 and I2 are amplified by preamplifiers 7 and 8, respectively.
It is input to a ratio calculation circuit 9 for calculating I0 and a sum calculation circuit 10 for detecting I0 by I1 + I2. In addition, an electrically writable memory (E ² PROM)
Reference numeral 11 is used to store in advance the error components of the ratio calculation circuit 9 and the sum calculation circuit 10. As described above, the CPU 1 includes these ratio operation circuit 9 and sum operation circuit 10,
The subject distance is calculated according to the result of the E ² PROM 11.

Next, with reference to FIGS. 1B and 1C, the error components of the above-described circuits (ratio operation circuit 9 and sum operation circuit 10) will be described.

FIG. 1B shows the relationship between the output of the ratio calculation circuit 9 and the reciprocal of the subject distance L. According to the principle of triangulation, the distance between the principal points of the lenses 4 and 5 is s, the focal length of the light receiving lens 5 is fJ, and the relationship between the signal light incident position x on the PSD 6 is

(Equation 2) Becomes Here, considering equation (2),

[0018]

(Equation 3) Becomes

Accordingly, the output of the ratio calculation circuit 9 is ideally as shown by a solid line graph proportional to 1 / L. However, in practice, the reflected signal light decreases and the output current I0 decreases as the distance increases, so that the influence of the error component iN1 applied to the ratio calculation circuit 9 cannot be ignored. The graph becomes as shown.

FIG. 1 (c) is a graph of the output of the sum operation circuit 10 for obtaining the output current I0 from I1 + I2. However, the error component iN0 of the sum operation circuit 10 actually shows a graph shown by a dotted line. Ideal relationship (solid line)
Causes an error between

According to the present invention, error components iN1 and iN0 due to variations in characteristics and the like generated when the above-described circuit is formed are stored in the E ² PROM 11 at the manufacturing stage, and these values are added to the sum calculation circuit 10 for distance measurement. Is used to correct the output result of the ratio calculation circuit 9 to perform a correct distance measurement calculation.

The factors that cause such an error component of the circuit include the fluctuation of the power supply voltage due to the light emission of the IRED 3 and the directionality of the induction noise or the noise of the CPU 1 and the noise with the reproducibility. There are variations due to the offset and the quality of each circuit, imbalance, leakage of capacitors, and the like.

Next, the operation of the distance measuring apparatus having the configuration shown in FIG. 1 will be described with reference to the flowchart of FIG.

First, the IRED 3 is made to emit light, and the output I0 proportional to the photocurrent generated from the PSD 6 is calculated by the sum operation circuit 1.
CPU 1 reads from 0 (step S1). Next, similarly, the calculation result of I1 / I0 is input from the ratio calculation circuit 9 (step S2).

Then, the CPU 1 reads out the correction values IN1 and IN0 stored in advance from the E ² PROM 11 (step S3). These correction values IN1 and IN0 are values for canceling the error components iN1 and iN0 of the circuit, respectively.

The output current I0 of the sum operation circuit 10 is
Actually, it is I0 + iN0,

(Equation 4) The CPU 1 can calculate the correct output current I0 in the following form.

The output I1 / I of the ratio operation circuit 9
Since 0 is actually (I1−iN1) / I0, a correct value can be obtained by adding IN1 / I0. This I0 is calculated by the equation (5).
Corrects the outputs I0, I1 / I0 of the respective circuits to calculate the correct I1 / I0 (step S4). Using I1 / I0 obtained in this manner, the distance L is calculated according to the equation (4) (step S4).
5).

Here, the correction coefficients IN0 and IN1 described above are used.
Is input to the E ² PROM 11 at the factory or the like at the time of manufacturing.
Description will be made with reference to the configuration diagram of FIG.

In this configuration, a personal computer (hereinafter, referred to as a personal computer) 13 is connected to the camera 12 equipped with the distance measuring device of the present embodiment. This personal computer 13
It is to perform the distance measurement operation in the camera 12, so that the correction coefficient IN 0, IN1 calculates the in-camera body ^E 2 PR
OM11 (shown in FIG. 1). In performing the distance measuring operation, the mask slide device 14 and the chart switching devices 15, 16, and 17 are controlled.

The slide device 14 is provided with the light shielding mask 1.
8 is moved to cover the projection lens of the camera 12,
Two open states can be created. By covering the PSD 6 with the light shielding mask 18, the distance measurement is performed in a blind state so that reflected light does not enter the PSD 6.

Each of the switching devices 15 to 17 is connected to each of the distances L1
, L2, L3 placed on charts 15a, 16
a and 17a can be moved in and out of the distance measuring point.

FIG. 3 shows a process of calculating a correction coefficient and writing the correction coefficient into the E ² PROM by such an adjusting device.
This will be described with reference to the flowchart of FIG.

First, the light-shielding mask 18 is moved in front of the light-projecting lens of the camera 12 using the mask slide device 14 to block light from the light-projecting lens 10 (step S10). Next, in the state where the light is shielded, the sum calculation result is read using the distance measuring circuit (the sum calculation circuit 10 shown in FIG. 1) (step S11). At this time, since the output current I0 does not occur in the PSD 6, the output at this time becomes an error component.
The personal computer 13 stores this result as the correction coefficient IN0.

Next, the light-shielding mask 18 is moved by the slide device 14 to release the light-shielding, so that the distance-measuring light can be projected onto each chart (step S12).
Then, the chart 1 at the distance L1 by the switching device 15
5a and set it so that the distance can be measured (step S
13).

In this set state, distance measurement is performed, and the personal computer 1
3 stores the output of the ratio calculation circuit 9 (not shown) as A1 (step S14).

Next, switching to each chart at distances L2 and L3, the same distance measurement is repeated (step S1).
5-18), the ratio calculation result of the output A2 of the distance L2 and the output A3 of the distance L3 is obtained.

Further, the distance is measured by the chart 17a of the distance L3, and the result B3 of the sum operation from the sum operation circuit 10 (not shown) is obtained.
Is input to the personal computer 13.

In the above steps, the correction data IN1 is calculated using the data A1, A2, A3, B3 obtained by the personal computer 13. First, theoretical data A30 (see FIG. 1B) at the distance L3 is calculated from the distance data A1 and A2 of L1 and L2 (step S2).
0). At this time, the distances L1 and L2 are assumed to be relatively short. At these distances, the signal light current is sufficiently larger than the error iN1 of the circuit, and the output A1 of the switching device 15 is output.
, A2 are considered to be as theoretical as shown in FIG.

The distance L is added to A30 thus obtained.
Correction coefficient IN1 for matching the distance measurement result A3 of No. 3
Is obtained (step S21).

As shown in step S4 shown in FIG.

[0041]

(Equation 5) It is required in the relationship. And I asked, write the correction coefficient IN 0, IN1 to ^E 2 PROM 11 (step S22).

In the embodiment described above, the error component iN1 of the circuit is supplied to the ratio operation circuit 9 by (I1-iN1) / I0.
However, depending on the circuit configuration and the type of noise to be mixed, (I1-iN1) / (I0
−iN3) in some cases, two error components iN1 and iN3 must be considered.

FIG. 4 shows a configuration and a flowchart for obtaining a coefficient for correcting an error due to such two error components.

In contrast to FIG. 3A described above, FIG.
Is such that a chart 17b (black chart) having a different reflectance from the chart 17a of the distance L3 can be set. Steps S30 to S39 in FIG.
Since this corresponds to S10 to S19 in FIG. 3B, the description is omitted here.

Next, the black chart 17b (distance L3)
Is set (step S40), and the black chart 17b is set.
, And a ratio calculation result A4 is obtained from the ratio calculation circuit 9 shown in FIG. 1 (step S41).
The sum operation result B4 is obtained from 0 (step S4
2) Input each result to the personal computer 13. Next, the personal computer 13 performs calculations and calculates IN1 and IN3 from the obtained distance measurement results (step S43). Assuming that the theoretical value at the distance L3 is A30 as in FIG.

(Equation 6) By solving the simultaneous equations of

[0046]

(Equation 7) Are obtained as the correction coefficients IN1 and IN3.

The correction coefficient IN thus obtained
0, IN1, IN3 and write to ^E 2 PROM (step S44), and ends.

As described above, even if the error components iN1 and iN3 are involved in the form of (I1-iN1) / (I0-iN3) in the ratio calculation circuit (not shown) due to the circuit configuration, accurate distance measurement is performed. Becomes possible.

Next, FIG. 5 shows a specific configuration of a distance measuring apparatus according to a second embodiment of the present invention, and will be described. Here, the constituent members in the second embodiment that are the same as the members illustrated in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted. In addition, the photocurrents I1,
The two signals of I2 are amplified respectively, and a sum operation circuit 1
Since the circuit systems to be compared to 0 and the ratio operation circuit 9 are formed in exactly the same manner, only the circuit system for one photocurrent I1 will be described here.

In general, a subject is constantly irradiated with light by sunlight or artificial illumination light. Therefore, in addition to the signal light, the regular light due to the light is incident on the PSD 6 built in the camera. The PSD 6 includes the steady light current IBO and outputs the light due to the steady light.

Therefore, in the calculation of the distance measurement (AF),
This steady light current IBO is removed, and an IRED (not shown)
It is necessary to discriminate and extract only the signal light currents I1 and I2 caused by the above.

First, the removal of the stationary photocurrent will be described.

The stationary light current IBO and the signal light current I1
, I2 is basically determined by the fact that the component of the steady light current IBO does not change between the state in which the IRED does not emit light and the state in which the IRED emits light.
This is performed by determining that Here, the reference numbers of the members for processing the signal light current I2 side are shown in parentheses () attached to the respective members.

First, before emitting light from the IRED, the PSD6
Is amplified by the transistor 40 (51). This amplified current is supplied to the current mirror circuit 4
1, 43 (52, 54) by the compression diode 46
(57). At this time, the compression diode 46
When the potential of (57) increases due to the inflow of the current IBO, the hold amplifier 48 (59) operates to control the base potential of the transistor 50 (61), and emits the steady-state photocurrent IBO to GND.

The voltage of the compression diode 46 (57) biased by the constant current IDB of the constant current source 45 (56) is supplied to the + input terminal of the hold amplifier 48 (59), and the negative input terminal. The voltage of the compression diode 69, also biased by the constant current IDB, is applied by the constant current source 68 via the buffer 47 (58) and the buffer 67, respectively.

Therefore, as long as the hold amplifier 48 (59) is functioning, the compression diode 46 (57)
The current due to the steady light current IBO does not flow. That is, this circuit is stable in a state where no current flows between the lines indicated by the arrow x in the drawing.

Next, when the IRED emits light, it is input to the preamplifier 7 (8) in a state where the signal light current I1 (I2) is added to the steady light current IBO. At this time, the hold amplifier 48 (59) is turned off in synchronization with the light emission of the IRED. Therefore, the transistor 50 (61) is turned on by the potential charged in the hold capacitor 49 (60), and the steady photocurrent IBO is changed to GND.
Will be released.

However, only the signal light current I1 (I2) is amplified by the transistor 40 (51) and flows into the compression diode 46 (57) via the current mirror circuits 41, 43 (52, 54). At this time, like the hold amplifier 48 (59), the constant current source 45 (56)
In the figure, the line indicated by reference numeral B0 is turned off by the bias cut signal B output from the timing circuit 33, so that a compression voltage is generated in the compression diode 46 by only the signal light current I1. Similarly, the signal light current I2 flows into the compression diode 57 after the stationary light current IB0 is removed.

The compressed voltages VA and VB are supplied to the transistor 6 via the buffers 47 and 58, respectively.
2, 63, a constant current source 64, and an integration capacitor 65. Also, this ratio calculation circuit 9
Together with the reset circuit 66, the second integration circuit 31 is configured.

When the constant current source 64 is turned on in synchronization with the light emission of the IRED, the ratio calculation circuit 9 calculates the integrated current IINT.

(Equation 8) Therefore, the integration capacitor 65 includes

[0061]

(Equation 9) Voltage signal is generated.

Where n is the number of times the IRED emits light,
E is the current value of the constant current source 64, τ is one integration time, C
Is the capacity of the integrating capacitor 65.

The reset circuit 66 functions to set the potential of the integration capacitor 65 to an initial state and to set the integration voltage VINT = 0 before the light emission of the IRED.

The VINT of the above equation (8) is read by the CPU 1 after A / D conversion.
From the equation, assuming that a = t / 2,

(Equation 10)

Since the above holds, the distance information 1 / L is obtained from VINT. The above is the operation of the ratio calculation circuit in the present embodiment.

Next, the sum operation will be described.

In this sum operation, similarly to the above-described ratio operation, the amplified signal light current I1 is guided to the sum signal integration circuit by the current mirror circuits 41 and 42. Similarly, the amplified signal light current I2 is supplied to the current mirror circuit 5
2 and 53 are added to the signal light current I1. Hereinafter, reference numerals in parentheses indicate members on the signal light current I2 side.

Here, the signal light current I1 is supplied to the transistors 42 and 53 constituting the current mirror circuit.
, I2, a bias current is constantly flowing. This is because the transistors 40, 41, 42, 43
(51, 52, 53, 54) are constantly biased to prevent the responsiveness of the IRED to the signal current from being deteriorated. The arrow x
Of the constant current source 44
Each of them is biased by the constant current IPB flowing in (55).

Therefore, the sum signal integration circuit is configured to remove the bias due to the constant current IPB and integrate only the signal light currents I1 and I2. That is,
Before light emission of an IRED (not shown), transistors 42 and 53 are used.
The current flowing in is removed, and the current I1 + I2
Only the above operation is integrated, and the same operation as that of the above-described steady light removing circuit is performed.

In the switching circuit connected to the sum operation circuit 10, the switches 72 and 73 are on and the switches 70 and 71 are off before the IRED emits light.

For this reason, the combined current (2 × IPB) of both channels of the bias current is caused by the voltage drop when the current flows to the resistor 75, the hold amplifier 76 operates, and the transistor 78 is turned on. , GND.

In this case, when a current flows in the direction of arrow (a), the potential of the input terminal on the + side of the hold amplifier 76 increases, and the transistor 78 increases the collector current and flows in the direction of (a). Try to suppress. Conversely, when a current flows in the direction of the arrow (b), the potential of the negative input terminal of the hold amplifier 76 rises, and the transistor 78 reduces the collector current, and the flow in the direction of the arrow (b) is reduced. Try to suppress. Therefore, the bias current (2
Regardless of the direction in which current flows through the resistor 75 due to the noise component included in (× IPB), this circuit removes the current sensitively.

Next, when the IRED emits light, the switches 72 and 73 switch the integration signal IN from the timing circuit 33.
The switch is turned off by T, and the switches 70 and 71 are turned on. Therefore, based on the charge stored in the hold capacitor 77, the bias current is discharged to the GND by the transistor 78, and only the current based on the signal light currents I1 and I2 flows in the direction of the arrow (c) in the first integrating circuit. 30. The first integration circuit 30 is constituted by a sum signal circuit including an integration amplifier 79 and an integration capacitor 80, and integrates the signal light currents I1 and I2.

This integration is based on the amplification transistor 4
Assuming that the current gain of 0, 51 is β, the output voltage VpINT of the integrating amplifier 79 is

[Equation 11] Becomes Here, Cp is the capacity of the integration capacitor 80.

As in the case of the above ratio operation, the reset circuit 81
Functions to reset the output voltage VpINT of the integrating amplifier 79 to an initial state before the IRED emits light. Then, the CPU 1 reads the A / D-converted VpINT, and obtains distance information 1 / L according to Expression (12) described later.

Here, the reflectance of the subject is constant,
Assuming that all of the light spots hit the subject, by the principle of light diffusion,

(Equation 12)

Therefore, from the above equations (11) and (10),

(Equation 13) The distance information 1 / L can be obtained.

Next, FIG. 6 is a timing chart showing an auto-focusing (AF) operation by the distance measuring apparatus having the above-described configuration.

As shown in the figure, the CPU 1 controls the light intensity integration signal VpINT at the time points (a) and (b).
And the ratio operation signal VINT. In addition, when performing A / D conversion by generally known double integration, t1 and t2 are respectively set at timings (a ') and (b').
To read the time.

Further, the constant K in the above equation (12) is
Although it greatly changes depending on the light amount of the RED, the photoelectric conversion efficiency of the PSD 6, the amplification factors of the preamplifiers 7 and 8, and the dispersion of the AF projecting / receiving lenses 4 and 5, here, the E ² PR
The OM 11 (see FIG. 1) stores correction data for correcting these variations for each of the products, so that the distance measurement calculation by the above equation (11) can be realized with higher accuracy. I have.

Next, FIG. 7 shows an example of a flowchart for determining the actual distance in the distance measuring device. In this flowchart, the above equation (12) is simplified,

[Equation 14]

In the form of Here, Ip DA
TA is a digital value obtained by the CPU 1 reading the light intensity integration signal VpINT. Further, the above equation (9) also indicates that the ratio operation signal V
The digital value read by the CPU 1 from INT is expressed as AD,

[0083]

(Equation 15) Is simplified. Here, K, A, and B are constants.

First, in the step as shown in FIG. 4B, the CPU 1 reads out the correction coefficients IN1, IN3, IN0 inputted to the E ² PROM 11 (step S).
50). Next, the number of times of light emission n is reset (step S5).
1) The light emission and integration of the IRED described with reference to FIGS. 5 and 6 are performed (step S52). Then, n is incremented (step S53), and a determination is made as to whether or not the operation has been performed a predetermined number of times, for example, 16 times (step S154). As a result, the emission and integration of the IRED are repeated 16 times.

After performing a predetermined number of light emission and integration,
As a result of integration of the sum signal in the capacitor 80, Ip DA
The TA is read (step S55). Next, a distance calculation based on the equation (11) is performed (step S56). The data obtained by this calculation has a result as shown in FIG. 8B with respect to the reciprocal of the subject distance L. That is, there is a dependency on the reflectance of the subject. However, at the distance of ∞, the output current I1 + I2 becomes “0” irrespective of the reflectivity of the object, and it is understood that the influence of the reflectivity is small at a long distance.

Next, it is determined whether or not the result is longer than 10 m (step S57). If the subject distance L is longer than 10 m (YES), the calculated distance obtained in step S56 is adopted. However, if the subject distance L is less than 10 m (NO), the ratio calculation I1 /
CPU 1 reads the result AD of I0 (step S5)
8). Next, the result of step S56 is that the subject distance L
Is longer than 7 m (step S59), and when it is determined that the subject distance L is longer than 7 m (NO),
Assuming that the signal has a value sufficiently larger than the error component of the circuit, the subject distance L is calculated by the distance calculation based on the equation (9) (step S61).

However, if the subject distance L is less than 7 m in step S 59, that is, if the distance is between 7 m and 10 m (YES), the condition for performing the correction operation characteristic of the present invention is satisfied. The error component iN0,
Correction of iN1 and iN3 is performed. The AD in the equation (14) is easy to understand, and is set to I1 / I0 used for the description in FIG.
If Ip DATA in S56 is simplified to be equal to I0 according to equation (6a), similar to equation (6a),

[0088]

(Equation 16) Then, the process proceeds to step S61, and the correct distance measurement calculation can be performed.

Next, FIG. 8 shows each data and the reciprocal 1 / of the distance.
The relationship of L is shown.

The solid line shown in FIG. 8A shows the relationship between the ratio calculation result and the reciprocal 1 / L of the distance. As shown in the figure, the greater the distance due to the random noise of the circuit, the greater the width, and the linearity is lost as the distance increases due to directional noise and error components of the circuit. This is the performance of the conventional distance measuring device. The dotted line shown in FIG. 8A is an example in which the solid line is improved in linearity by the correction operation of the present invention. FIG. 8B is a diagram showing the result of the above-described sum calculation distance measurement and the reciprocal 1 / L of the distance. If the distance is measured by the distance measuring step shown in FIG.
As shown in (c), the error is extremely reduced from a long distance to a short distance.

Next, FIG. 9 shows a third embodiment according to the present invention, in which two light receiving means are provided (two-light receiving type).
The configuration of the distance measuring device will be shown and described.

In this distance measuring device, the drivers 2a, 2
b, the reflected light is projected onto an object (not shown) from the IRED 3, and the reflected light passes through the light receiving lenses 5 a, 5 b disposed at positions separated by the base line length s, respectively.
6a and 6b are irradiated.

At this time, the output currents I1 and I2 and the output currents I3 and I4 are output from the PSDs 6a and 6b. Then, the preamplifiers 7a, 7b, 8a, and 8b amplify these output currents, respectively, as in the circuit shown in FIG.
The signals are input to the ratio calculation circuits 9a and 9b and the sum calculation circuits 10a and 10b. The results of the ratio calculation circuits 9a and 9b are added by an addition circuit 10c, and the addition result is input to the CPU 1.

In the light receiving binocular distance measuring apparatus according to the present embodiment, when the focal lengths fJ of the two light receiving lenses are equal, the PSD can be used.
Assuming that the respective incident positions to 6a and 6b are xa and xb, the reciprocal of the subject distance L is

[0095]

[Equation 17] Is required. Assuming that the origins of xa and xb are both a,

[0096]

(Equation 18)

Thus, the CPU 1 can obtain the subject distance from the output of the adding circuit 10c. The outputs of the sum operation circuits 10a and 10b are input to the CPU 1,
The CPU 1 calculates the subject distance L according to the correction coefficients stored in the E ² PROM 11 and the results of the addition circuit 10c and the sum calculation circuits 10a and 10b.

Further, a warning device 91 is connected to the CPU 1, and when the outputs of the sum calculation circuits 10a and 10b are extremely unbalanced, the user is supposed to be obstructed by one of the lenses and the like. Warnings are given by sound or light.

An advantage of such a two-lens light receiving distance measuring apparatus is that the entire distance measuring light spot 92 projected in the photographing composition shown in FIG. In other words, even if a so-called spot defect occurs, the deviation of the signal light incident positions on the two PSDs is canceled, and correct distance measurement can be performed.

However, as described with reference to FIG. 1B, even if the incident position x of the signal light is correct, if the amount of the reflected signal is reduced due to the loss of the amount of light caused by the chipping of the spot, the result of the ratio calculation becomes inaccurate. It is difficult to fully utilize the above-mentioned advantages. Therefore, in the distance measuring apparatus according to the third embodiment, distance measurement will be described with reference to the configuration shown in FIG. 9 and the flowchart shown in FIG.

In this distance measuring device, light emission and light reception are performed under the control of the CPU 1, and the sum calculation circuits 10a and 10b
The sum operation results I0a and I0b are input to PU1 (step S70). Then, the ratio operation results 90a and 90b from the ratio operation circuits 9a and 9b are added by the sum operation circuit 10c, and C
The result of the ratio calculation is input to PU1 (step S7)
1).

Next, the correction coefficients IN1 and IN0 previously input to the E ² PROM 11 are read out to the CPU 1 in the adjustment step by the method described with reference to FIG. 3 (step S7).
2). Based on the read correction coefficients IN1 and IN0, a correction operation is performed in the same way as described in the equation (5b) (step S73).

Then, according to the corrected value, (1
The reciprocal of the subject distance L is calculated by a method according to the expressions 5) and (16) (step S74).

By focusing the camera on the distance value obtained in this manner, not only the long distance but also the distance value shown in FIG.
Even when the spot deviates as shown in FIG. 1, it is possible to correctly focus, and it is possible to take a photograph in which most of the photographing composition is in focus.

Since the amount of protrusion of the focusing lens of the camera is proportional to the reciprocal of the subject distance L, the CPU 1 calculates 1 / L in the flowcharts of FIGS. 2, 7 and 10.

As described above, the distance measuring apparatus of the present embodiment realizes highly accurate distance measurement from a short distance to a long distance without being affected by the reflectance of the subject.

The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications and applications can be made without departing from the spirit of the invention.

[0108]

As described above, according to the present invention, even if the subject is in a range where a sufficient amount of reflected light cannot be obtained, the distance can be measured with high accuracy without being affected by the reflectance of the subject. Can be provided.

[Brief description of the drawings]

FIG. 1A is a diagram showing a conceptual configuration of a distance measuring apparatus as a first embodiment according to the present invention, and FIGS.
(C) is a figure for explaining an error component.

FIG. 2 is a flowchart illustrating the operation of the distance measuring apparatus having the configuration shown in FIG. 1;

FIG. 3A is a diagram illustrating, as a first example, an adjustment device for storing a correction coefficient in a memory;
(B) is a flowchart showing the process.

FIG. 4A is a diagram illustrating, as a second example, an adjustment device for storing a correction coefficient including a black chart in a memory, and FIG. 4B is a flowchart illustrating the process; It is.

FIG. 5 is a diagram showing a specific configuration of a distance measuring apparatus as a second embodiment according to the present invention.

FIG. 6 is a timing chart for explaining a distance measuring operation by the distance measuring apparatus according to the second embodiment.

FIG. 7 is a flowchart for explaining a distance measuring operation by the distance measuring apparatus shown in FIG. 5;

FIG. 8 is a diagram showing a relationship between data and a reciprocal 1 / L of a distance.

FIG. 9 is a diagram showing a configuration of a (light receiving binocular type) distance measuring apparatus provided with two light receiving means as a third embodiment according to the present invention.

FIG. 10 is a flowchart for explaining a distance measuring operation of the distance measuring apparatus shown in FIG. 9;

FIG. 11 is a diagram illustrating a composition example of photographing.

[Explanation of symbols]

1 ... arithmetic control circuit (CPU) 2 ... driver 3 ... infrared emitting diode (IRED) 4, 5 ... lens 6 ... PSD 7, 8 ... the preamplifier 9 ... The ratio calculation circuit 10 ... sum calculation circuit 11 ... memory ^(E 2 PROM )

Continued on the front page F-term (reference) 2F065 AA06 AA19 AA20 BB05 DD04 DD10 EE03 EE11 FF09 FF23 FF41 FF61 FF67 GG07 HH04 JJ02 JJ05 JJ25 NN01 NN17 NN20 QQ03 QQ23 QQ25 QQ27 QQ28 SS11 BA12A012A11 CB23

Claims (2)

[Claims] 1. An adjusting device for adjusting a distance measuring device of a camera, comprising: a first chart arranged at a predetermined distance; a first chart arranged at the same distance as the first chart; and a reflectance. A second chart different from the first chart and an adjustment value at a distance different from the predetermined distance of the distance measuring apparatus from respective data output when the distance measuring apparatus measures the distances of the first chart and the second chart. An adjusting device for a distance measuring device, comprising: calculating means for calculating the distance; and storage means for storing the adjustment value calculated by the calculating means in the camera. 2. A light projecting means for projecting light for distance measurement to a subject, a first signal which receives reflected signal light from the subject, and which depends on the amount of the reflected signal light; A light receiving unit that outputs a second signal depending on the incident position of light, and an adjusting device that adjusts a distance measuring device of a camera that can calculate a subject distance based on the incident position of the reflected signal light; A first chart that can be arranged at a first distance, a second chart that has a different reflectance from the first chart that can be arranged at the same distance as the first chart, and is different from the first distance A third positionable at a second distance
, A fourth chart that can be arranged at a third distance different from the first and second distances, and output when the distance measuring device measures the first, third, and fourth charts Calculating means for calculating an adjustment value from the second signal and the first signal output when the distance of the second chart is measured. Adjustment device for.