JP2003075715A - Range-finding device for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform accurate autofocusing realizing high visual field by increasing the degree of freedom in selecting a memory at the time of designing a camera by utilizing a microcomputer whose memory capacity is small. SOLUTION: At the first range-finding time, range-finding arithmetic operation is performed by storing what is obtained by integrating and controlling sensor array output in an area L and an area C in the monitor area 11 of a sensor array in a RAM 6, and at the second range-finding time, the range-finding arithmetic operation is performed by storing what is obtained by integrating and controlling the sensor array output in an area R narrower than the area L and the area C in the monitor area 11 of the sensor array in the RAM 6. By repeatedly using the common memory area of the RAM 6 in the range- finding performed twice, the range-finding in a wide range is performed even by the microcomputer whose memory capacity is small. Then, the more accurate range-finding is realized by performing the range-finding twice in the center area C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a distance measuring device for an autofocus camera.

[0002]

2. Description of the Related Art The distance measuring devices for cameras are roughly classified into
There are two types: an active type that projects light from the camera toward the subject and uses the reflected signal light that is reflected from the subject to perform distance measurement, and a passive type that performs distance measurement using the subject image signal by a sensor array. In recent years, the sensor array has a function of extracting reflected signal light from a subject by the projection light from the camera side to the subject as in the active type, and in the passive type, distance measurement is performed in recent years. A hybrid type is also known, which is capable of measuring a distance even for a difficult low-luminance or low-contrast subject.

Further, in a distance measuring device using the above sensor array, a technique capable of measuring a wider area within a photographic screen is disclosed in Japanese Patent No. 3058184.

According to the distance measuring device disclosed in Japanese Patent No. 3058184, it becomes possible to arbitrarily specify a plurality of areas within a photographic screen for distance measurement. For example, as shown in FIG. Correct focus can be achieved even in a scene in which the main subject 100 exists in the periphery of 10.

[0005]

However, when trying to measure distances in many areas in a photographic screen at the same time, a sensor array having many pixels is required. If a sensor array having many pixels is used, naturally, the memory area for storing the output of the sensor array also becomes large. However, a microcomputer or the like having a large memory area is very expensive and causes a great limitation in selection when designing a camera.

The present invention has been made in view of the above circumstances, and a microcomputer having a small memory capacity that does not impair the freedom of design in a distance measuring device for a camera that measures a distance using a sensor array. An object of the present invention is to provide a distance measuring device for a camera, which is capable of performing high-field-of-view and highly-accurate autofocus while using it.

[0007]

In order to achieve the above object, a distance measuring device for a camera according to the present invention comprises a sensor array including a plurality of pixels for detecting an image signal in a photographic screen, and an output of the sensor array. A distance measuring device for a camera having digital storage means having a storage area smaller than the number of pixels of the sensor array for storing signals, and calculation means for calculating a subject distance in the photographic screen based on the stored contents of the digital storage means. At the first timing, the output from the first area of the sensor array is input to the digital storage means, and at the second timing subsequent to the first timing, the output from the second area of the sensor array is output. , The first and second areas have a common area.

That is, according to the distance measuring apparatus for a camera of the present invention, in order to input a large amount of sensor array output data into a small memory area, image compression and data thinning are not performed, and one memory area is repeated. By using distance measurement in multiple areas by using the distance measurement, it is possible to increase the field of view by measuring the distance in multiple areas, and at the same time, improve the reliability and accuracy of distance measurement by measuring multiple times. It can be carried out.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an AF camera equipped with a distance measuring device for a camera according to an embodiment of the present invention.

That is, the distance measuring device for a camera according to one embodiment of the present invention comprises an arithmetic control circuit (CPU) 1, light receiving lenses 2a and 2b, sensor arrays 3a and 3b, and an A / D converter 4. And a switch (SW) 5.
Then, the distance measuring device of this camera and the lens drive (L
The D) unit 7 and the taking lens 8 constitute an AF device. The camera also has a strobe 9.

The CPU 1 is a control circuit for controlling the operation of the entire camera and performing various calculations, and is composed of a one-chip microcomputer. Further, the CPU 1 has a built-in RAM 6 so that various calculation results in the CPU 1 and data output from each pixel of the sensor array can be stored. The details of the RAM 6 will be described later.

The light receiving lenses 2a and 2b are lenses for forming an image of the subject 100 on the sensor arrays 3a and 3b.

Each of the sensor arrays 3a and 3b is formed by arranging a light receiving sensor, for example, a photodiode, which constitutes a plurality of pixels, in a one-dimensional array, and each photodiode is made incident by the light receiving lenses 2a and 2b. The subject image is photoelectrically converted according to its light intensity. Further, as will be described later in detail, each photodiode is connected with an integrating circuit composed of an integrating capacitor, an integrating amplifier and the like, and under the control of the CPU 1, these integrating circuits photoelectrically convert the photodiodes. The luminance distribution of the subject is acquired by integrating the subject image and output to the A / D conversion unit 4.

The A / D conversion section 4 includes the sensor array 3 described above.
The brightness distribution of the subject output from a and 3b is converted into a digital signal and output to the CPU 1 (hereinafter, this A / D converted brightness distribution is referred to as image data, and indicates individual data corresponding to each pixel. In the case described as pixel data.).

SW5 is a switch for starting the operation of the distance measuring apparatus of the present embodiment in response to the switch operation of the photographer.

The LD section 7 is connected to the CPU 1,
This is a circuit for driving the taking lens 8 under the control of the CPU 1 based on the result of the distance calculation calculation described later.

The taking lens 8 is a lens for forming an image of the subject 100 on a film (not shown).

As described above, the CPU 1, the light receiving lenses 2a and 2b,
The distance measuring device according to the present embodiment including the sensor arrays 3a and 3b, the A / D conversion unit 4, and the SW5, and the LD unit 7.
And the taking lens 8 constitute an AF device. The AF device adjusts the focus of the taking lens 8 based on the distance of the subject 100 measured by the distance measuring device.

The strobe 9 is controlled to emit light as auxiliary light at the time of exposure depending on the case, but this light can also be used as auxiliary light at the time of distance measurement.

In the present embodiment, the image of the subject 100 is guided to the sensor arrays 3a and 3b through the two light receiving lenses 2a and 2b in order to correctly focus the subject lens 8 on the subject 100. The distance L to the subject is calculated based on the principle of triangulation using the parallax B of the lenses 2a and 2b.

For this reason, the output of the photodiode constituting each pixel of the sensor array is integrated by the integrating circuit and then input to the CPU 1 via the A / D conversion section 4. Therefore, the size of each pixel data is stored in the RAM 6 in the CPU 1 as the size of the digital value.

The CPU 1 has two light receiving lenses 2
Due to the parallax B due to a and 2b, the displacement of the subject image is relative to the sensor array 3a and the sensor array 3b.
It is referred to as the image shift amount. ) When it is determined that there are only x, the distance L
Is calculated by the formula L = B · f / x (where f is the focal length of the light receiving lens).

Further, the CPU 1 is connected with a SW 5 for detecting an instruction to start the distance measuring operation of the camera by the photographer,
When the CPU 1 detects the ON operation of the SW 5, the distance measuring device operates, the distance L is calculated, and then the distance L calculated by the photographing lens 8 is calculated via the lens drive (LD) unit 7. The drive is controlled according to the.

Next, the RAM 6 will be described with reference to FIG.

FIG. 3 is a view conceptually showing the monitor area 11 of the sensor array 3a in the photographic screen 10 and the storage area of the RAM 6 for storing the image data from the sensor array 3a. Although not shown in FIG. 3, a RAM
Of course, 6 also has a storage area for storing the image data of the sensor array 3b. That is, RAM
The actual storage area of 6 is twice the storage area shown in FIG.

Further, the example of FIG. 3 is an example using a line sensor, but it goes without saying that the distance measuring apparatus of the present embodiment can be applied to an area sensor.

The CPU 1 uses the data in the RAM 6 to compare the position of the subject image on the sensor array 3a with the position of the subject image on the sensor array 3b. However, in the present embodiment, as shown in the figure, the RAM 6 does not have a storage capacity capable of storing the image data of all the pixels of the sensor array. That is, assuming that one pixel data is entered for each address of the RAM 6, the image data of the area C in FIG. 3A can be stored in the RAM 6, but the image data in the area C and both sides of the image data can be stored. Regions L and R which are regions of
It is impossible to simultaneously store the image data in the RAM 6 in the RAM 6. Of course, in order to deal with this, a large-capacity memory that can cover the entire area can be used, but such a large-capacity memory is expensive, which is not desirable.

Therefore, the L, C, and R are stored in a small capacity memory.
As a method for enabling the distance measurement of all the areas in FIG. 3A, first, the distance measurement is performed only in the area C that can be stored in the RAM 6 as shown in FIG. )
As described above, it is conceivable that the distance measurement is performed twice, such that the remaining L and R areas are input again to the RAM 6 and distance measurement is performed. By repeatedly using the RAM 6 in this way, it is possible to measure the distances in the L and R regions at the same time, whereas the distance can be measured only in the C region due to the problem of the memory capacity in the related art. Even if it exists at the end position of 10, the focus can be correctly adjusted. Note that the number of times of distance measurement is not limited to two and may be other than two.

Next, a method of calculating the image shift amount x will be described with reference to FIG. FIG. 4 is a diagram showing image data of the two sensor arrays 3a and 3b stored in the RAM 6. Here, FIG. 4A shows the sensor array 3
FIG. 4B is a diagram showing image data of a, and FIGS. 4B to 4D are diagrams showing image data of the sensor array 3b. Also,
Each bar of the bar graph in FIG. 4 shows an example of each pixel data of the sensor array stored in each address of the RAM 6, and the numerical value shown on the bar graph shows the size of each pixel data. And It should be noted that these figures show only six addresses for the sake of simplification of the drawing, and in reality, comparison is performed with more pixel data.

To compare the image data of the sensor array 3a and the image data of the sensor array 3b, first, the pixel data are compared in FIGS. 4 (A) and 4 (B). The comparison of these pixel data is
The corresponding addresses are used together. For example, in FIG.
The pixel data of size 30 in (A) is compared with the pixel data of size 25 in FIG. 4 (B), and a difference of 5 occurs. Further, at the address where the pixel data of size 25 in FIG. 4 (A) is stored, there is a difference of 15 compared with the pixel data of size 10 in FIG. 4 (B). In this way, the pixel data of other addresses are similarly compared.

Next, the image data of the sensor array 3a in FIG. 4A and the image data of the sensor array 3b in the state as shown in FIG. 4C are compared. That is, at the time of comparison, FIG.
By shifting the pixel data from the image data of (B) by one address and reading the pixel data for comparison, as a result, as shown in FIG.
It is compared with the image data as shown in (C). In addition,
The method of comparison is the same as that described above.
The pixel data of size 30 in (A) is 0 when compared with the pixel data of size 30 in FIG. 4 (C). Also, FIG.
The pixel data of size 25 in (A) is also 0 when compared with the pixel data of size 25 in FIG. 4 (C). If pixel data at other addresses are compared in the same manner, the difference becomes zero.

Next, the image data of the sensor array 3a in FIG. 4A and the image data of the sensor array 3b in the state as shown in FIG. 4D are compared. That is, at the time of comparison, FIG.
By shifting the pixel data by 2 addresses from the image data in (B) and reading the pixel data for comparison, as a result, the pixel data in FIG.
It is compared with the image data as shown in (D). The method of comparison is the same as that described above, and FIG.
Pixel data of size 30 corresponds to size 20 of FIG.
Compared with the pixel data of 10 to generate 10 differences. In addition, the pixel data of size 25 in FIG. 4A is compared with the pixel data of size 30 in FIG. Pixel data at other addresses are similarly compared.

After that, the image data of the sensor array 3b is compared with the image data of the sensor array 3a while shifting the image data by one address. The same comparison is performed while shifting the image data of the sensor array 3b of FIG. 4B by one address in the reverse direction.

As a result of the comparison performed as described above, FIG.
From the comparison results of (A) and FIGS. 4 (B) and 4 (D),
It can be seen that the difference in pixel data between corresponding positions is large in both states of FIG. 4B and FIG. 4D, and it cannot be said that the degree of coincidence between the sensor array 3a and the sensor array 3b is high.

However, the image data of the sensor array 3a,
When the image data of the sensor array 3b in the state as shown in FIG. 4C is compared, it can be easily determined that the two images match. This is also apparent from the fact that if the difference between the pixel data in FIGS. 4A and 4C is taken, all the values are 0.

By thus obtaining the difference between the image data of the sensor array 3a and the image data of the sensor array 3b, the address of the image data of the sensor array 3b having the smallest difference (FIG. 4C in the example) is shifted. The image shift amount x can be obtained by knowing whether or not the image shift amount is obtained. That is, as described above, the image data of the sensor array 3a is compared while changing the image data of the sensor array 3b by one address, and the degree of coincidence between the image data of the sensor array 3a and the image data of the sensor array 3b is determined. The image shift amount x can be obtained from the distance corresponding to the address of the difference between the image data of the sensor array 3a and the image data of the sensor array 3b that was first compared with the image data of the sensor array 3a when the image height becomes the highest. That is, as in the example, assuming that the output of one pixel of the sensor array, that is, the pixel data can be stored in only one address of the RAM 6, the address shift becomes the pixel shift as it is. Therefore, by determining the distance between each pixel in advance, the image shift amount x can be obtained from the shift of the address. (In the example, the image shift amount x in FIG. 4C is the difference between the addresses in FIGS. 4B and 4C, which is the distance for one pixel corresponding to one address.) The difference between the image data obtained as described above is called a correlation coefficient and is an amount indicating the degree of coincidence between the two images. That is, the smaller this is, the more 2
It can be seen that the agreement of the images is high. Also, in a scene in which a long-distance subject and a short-distance subject are mixed, 2
The images monitored by the two sensor arrays 3a and 3b become unbalanced and the result of distance measurement becomes inaccurate, resulting in a large correlation coefficient.

On the premise of such a configuration, in the present embodiment, as shown in FIG.
Monitor area 1 of both sensor arrays 3a and 3b within 0
The image data in the central area C and the left area L of 1 are RA
The distance to the subject in the area L + C is obtained from the calculation of the image shift amount and the principle of triangulation, which is input to M6, and then, as shown in FIG. The image data in the area R is input to the RAM 6 again, and the distance of the object in the area C + R is obtained. Here, in the area C + R input to the RAM 6 at the time of the second distance measurement, the area C is common to the first time and the area R is made narrower than the first time area L. The reason for this will be described later.

If the integration condition of the brightness distribution at the time of A / D conversion is changed at two timings, that is, when measuring the area L + C and when measuring the distance C + R, the brightness distribution of the area C in the center of the screen is the same. , 2 types can be acquired as shown in FIG. 5 (C) and FIG. 5 (D). That is, of these luminance distributions, the one more suitable as the distance measurement data is preferentially used for focusing, or the two obtained distance measurement data are averaged to improve reliability in distance measurement in the central area. be able to. It is needless to say that the memory area of the RAM 6 in the present embodiment must be such that at least the central area C + the left area L can be stored.

By using a memory having such a small capacity,
Since a wider range can be measured, not only can the main subject 100 located at the edge of the photographic screen 10 be correctly measured as in the example of FIG. 2, but also the photographic screen as in the example of FIG. Even if the main subject 100 is present in the center of 10, the brightness distribution of the main subject 100 can be correctly acquired even in a scene where there is backlighting or a large change in brightness, and accurate distance measurement can be performed.

For example, in the scene shown in FIG.
The left (L) side of the screen is dark and the right (R) side of the screen is bright. At this time, if the luminance distribution of the subject on the L side is correctly obtained, the luminance distribution of the subject in the central portion (C) tends to be overly high (the level is too high) as shown in FIG. 6B.
Becomes Further, if the luminance distribution of the R-side subject is to be obtained correctly, the luminance distribution of the L-side subject will be underexposed (the level is too low) as shown in FIG. 6C. In addition, the sensor No. on the horizontal axis in FIGS. Is a number (for example, 1, 2, 3 ... from the left) assigned to each pixel of both sensor arrays 3a and 3b for the sake of convenience.

However, the brightness distribution in the central portion C is shown in FIG.
Depending on the situation, which of (B) and FIG. 6 (C) is suitable as the distance measurement data, it is possible to select after performing two distance measurements (image acquisition) in this way, or to perform two distance measurements. High-accuracy focusing can be performed by averaging the results and increasing the reliability.

Further, in the present embodiment, the image data of the area L + C is input to the RAM 6 at the time of the first distance measurement, and the distance measurement data obtained from the result is D of FIG.
, That is, the area corresponding to the difference between the area L + C and the area R + C due to the area R being narrower than the area L. In the area D, at the time of the second distance measurement, the area R +
When inputting the image data of C, nothing is input and finally the distance measurement results of the points of the regions L, C, and R can be compared and determined. By doing this, it is possible to focus on the correct distance in consideration of the perspective relationship of the distance measurement data in each area when the distance is measured twice.

Next, referring to the flowchart of FIG.
A distance measuring operation in the camera distance measuring device according to the embodiment will be described.

First, the CPU 1 performs integral control only on the L + C region of the outputs from the photodiodes of the sensor arrays 3a and 3b (step S1).

Here, the integral control of the photodiode output will be described with reference to FIG.

That is, this integration is as shown in FIG.
The current signal output from the photodiode 12 forming each pixel is integrated by the integration amplifier 14 into the integration capacitor 1
It is done by charging to 3.

First, the CPU 1 turns on SW1 and SW2.
Then, the charge of the integrating capacitor 13 is initialized. Next, when SW1 is turned on and SW2 is turned off, an integrated output corresponding to the magnitude of the output of each photodiode 12 is obtained. That is, if the integration time is extended, a large integrated value can be obtained even if the photodiode output is small (dark scene etc.), and if the integration time is shortened, the photodiode output is large (bright scene etc.) within a predetermined dynamic range. Can store the integrated value of each photodiode output, that is, the above luminance distribution.

In this way, the integration time must be switched and controlled depending on whether the scene is bright or dark. Therefore, in the present embodiment, although not particularly shown, the maximum photodiode output is detected in the region of L + C, and the integration time is controlled with this as a reference. In other words, assuming that there is not much difference in brightness between adjacent regions and the luminance distribution can be kept within a predetermined range, the time during which the maximum photodiode output can be integrated within the region L + C is determined as the integration time. Is there.

After the integration control in step S1, the luminance distribution, which is an analog signal, is converted into A by the A / D conversion section 4.
/ D conversion is performed (step S2). Next, the image data obtained by converting the above luminance distribution into a digital signal is processed by RA in the CPU 1.
It is stored in M6 (step S3). Then, the image data stored in the RAM 6 is read out, and the image shift amount x and the distance L described above are calculated (step S4). It should be noted that these calculations are individually performed in the area C and the area L.

Then, the distance L _{L in} the region _L , the distance L _C1 in the region _C and the correlation coefficient S _{L in} the region _L , and the correlation coefficient S _C1 in the region C obtained by the calculation in step S4 are used as the region D in the RAM 6 (Step S5). The correlation coefficient is stored in the RAM in step S5.
The reason for storing in No. 6 is for use in determining reliability in a later step so that a point with poor reliability is not accidentally focused.

Next, integration is performed in the area R + C (step S6). In this integration, the integration time is determined based on the maximum photodiode output in the region R + C. In this way, since optimum integration control is performed in each of the left and right areas within the photographic screen, accurate integration control can be performed even in a scene where the light and darkness of light is unbalanced as shown in FIG. The memory capacity enables distance measurement over a wide range.

After step S6, the sensor array 3
The brightness distributions from a and 3b are A / D converted by the A / D converter 4.
Convert (step S7). Then, the digitally converted luminance distribution (image data) is stored in an area other than the area D of the RAM 6 (step S8). This is the above step S
This is to prevent the distance value and the correlation coefficient stored in the area D of the RAM 6 in 5 from being overwritten and erased.
Next, based on the image data stored in step S8, the image shift amount x and the distance L described above are calculated (step S9). It should be noted that these calculations are individually performed in the area C and the area R.

Then, the distance L _{R in} the region _R , the distance L _C2 in the region C and the correlation coefficient S _{R in} the region _R , and the correlation coefficient S _C2 in the region C, which are obtained by the calculation in step S9, are stored in the region D of the RAM 6. It is stored in an area other than (step S10). That is, in step S8, a part of the area storing the image data is used to store the distance and the correlation coefficient.

Subsequent steps were obtained by two distance measurements.
Select the more preferable one from the two types of central distance measurement results
It is a step. First, the phase relationship in the first region C
Number S _C1And the correlation coefficient S in the second region C_C2With
Correlation coefficient S when the difference is taken _C1Is S_C2Than ten
It is determined whether or not it is large (step S11). S
_C1Is S_C2Larger than S_C1And S_C2Difference from
Is large enough (if it is larger than the predetermined difference
The distance L in the region C measured the second time _C2To
Distance measurement result L at the center_C(Step S12). one
On the other hand, the above correlation coefficient S _C1Is S_C2Less than
Or S_C1And S_C2If the difference between
Go to step S13. In addition, in the determination in step S11,
The reason why the difference in correlation coefficient is sufficiently large is that the two phases are
If there is not much difference in the number of relationships, take the average value of both.
This is to improve the reliability of central distance measurement.

In the next step S13, the second area C
It is determined whether or not sufficiently larger than the correlation coefficient S _C1 better correlation coefficient S _C2 when taking the difference between the correlation coefficient S _C2 and first correlation coefficient S _C1 in region C in (Step S13). S _C2 is greater than _{S C1,} further _S difference between _C2 and _{S C1} is a distance _{L C1} measured at the first time and distance measurement result _{L C} of the central portion when large enough (step S14). On the other hand, when the difference between S _C1 and S _C2 is small, the average value of the distance L _C1 measured at the first time and the distance L _C2 measured at the second time is set as the distance measurement result L _C of the central portion (step S15).

By doing so, it is possible to improve the accuracy of the distance measurement result in the central portion where the main subject is highly likely to exist.

Further, the area L, obtained as described above,
Of the distance measurement results L _L , L _C , and L _R corresponding to C and R,
The one with a large correlation coefficient is deleted as being unreliable (step S16), and the closest distance is determined from the remaining distance measurement results as the distance measurement result L _P with a high possibility that the main subject is present. Yes (step S17). Then, by driving the photographing lens 8 through the LD unit 7 according to the distance measurement result L _P, even when the main subject 100 in the photo screen 10 the center as shown in FIG. 2 is not present, allows the correct focusing is Becomes

A RAM for storing the second image data
The memory area of 6 is made smaller than the memory area of the first time, and the distance and the correlation coefficient calculated at the time of the first distance measurement are stored in the difference portion (area D), and the result of the second operation is stored. Since the calculation result stored for the first time is effectively used for the final focus adjustment control, it is possible to achieve more reliable and highly accurate distance measurement.

As described above, according to this embodiment, it is possible to effectively measure a wide range while using an inexpensive CPU (microcomputer) having a small memory area.
With respect to the central area where the main subject is highly likely to exist, reliability can be taken into consideration, distance measurement can be performed with higher accuracy, and a low-cost camera can be provided without failure in focusing.

The present invention has been described above based on the embodiment, but the present invention is not limited to the above-mentioned embodiment, and various modifications and applications are possible within the scope of the gist of the present invention. Of course, of course.

For example, taking in the area L + C and the area R +
It goes without saying that the order of capturing C may be reversed. However, in that case, the region L is taken in so as to be narrower than the region R.

[0063]

As described in detail above, according to the present invention,
It is possible to provide a distance measuring device for a camera that can measure a wide range within a photographic screen while using a microcomputer with a small memory capacity and that can measure distance with higher accuracy.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a distance measuring device for a camera according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example in which a main subject is present at a screen edge.

FIG. 3 is a diagram showing a relationship between a monitor area of a sensor array and a memory area of a RAM in a photograph screen.

FIG. 4 is a diagram showing a graph of image data stored in a RAM.

5A and 5B are views for explaining a method of storing image data in the present embodiment, and FIG.
FIG. 5D is a diagram showing an example of the luminance distribution in the region C at the time of the second distance measurement, and FIG. 5D is a diagram showing an example of the luminance distribution in the region C at the time of the second distance measurement.

FIG. 6 is a diagram showing an example of a subject whose brightness varies depending on a position.

FIG. 7 is a diagram showing a flowchart for describing a distance measuring operation in the camera distance measuring device according to the embodiment of the present invention.

FIG. 8 is a circuit diagram of an integrating circuit.

[Explanation of symbols]

1 Arithmetic control circuit (CPU) 2a Light receiving lens a 2b Light receiving lens b 3a Sensor array a 3b Sensor array b 4 A / D converter 5 switch (SW) 6 RAM 7 Lens drive (LD) section 8 shooting lens 9 Strobe 12 Photodiode 13 integrating capacitor 14 Integral amplifier

Continued front page    F-term (reference) 2F112 AC03 BA06 BA09 CA02 FA07                       FA12 FA21 FA29 FA41 FA45                 2H011 AA01 BA05 BB02 BB04 BB05                 2H051 AA01 BB07 CB20 CE06 CE16                       CE21 DA28 GB12                 5C022 AB27 AC69

Claims (4)

[Claims] 1. A sensor array composed of a plurality of pixels for detecting an image signal in a photographic screen, a digital storage means for storing an output of the sensor array, the digital storage means having a storage area smaller than the number of pixels of the sensor array, In a distance measuring device for a camera having: a calculating means for calculating a subject distance within the photographic screen based on the stored contents of the storing means, an output in a first area of the sensor array is stored in the digital storing means at a first timing. At the second timing following the first timing, the output of the second area of the sensor array is input to the digital storage means, and the first and second areas are set to a common area. A distance measuring device for a camera having. 2. The common area is located in the center of the photographic screen, and the computing means calculates the object distance in the common area calculated at the first timing and the object distance calculated at the second timing. An average value with a subject distance in a common area is calculated.
The distance measuring device for the camera described in. 3. The digital storage means stores the integration result of the output of the sensor array, and the integration result of the sensor array output input to the digital storage means at the first and second timings. 2. The camera distance measuring device according to claim 1, wherein are integrated under mutually different integration conditions. 4. The second area is smaller than the first area and is the first of the storage areas of the digital storage means.
2. The subject distance calculated by the calculating means based on the output in the first area is stored in a portion corresponding to the difference between the area and the second area. Range finder for camera.