JP2002311472A - Photometry device of camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photometry device of a camera capable of performing spot photometry and judgment of backlight with high accuracy even in the camera having a photographic lens of high power zoom. SOLUTION: The photometry device of the camera is provided with a lens position detecting circuit 12 to detect focal distance of the photographic lens 2, an AF sensor unit 14 to enable first spot photometry in a telescopic area by performing ranging by a plurality of arranged pixels and using output of a group of pixels at a center part, a ranging sensor unit 13 to enable second spot photometry and peripheral photometry in a wide-angle area and a control circuit 15 to perform the first spot photometry when the photographic lens 2 is detected as telescopic by the lens position detecting circuit 12, to perform the second spot photometry when the photographic lens is detected as wide and to average the spot photometry by performing the first spot photometry and the second spot photometry when the photographic lens is detected between telescopic and wide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photometric device for a camera, and more particularly, to a photometric device for a camera having a photographic lens with a variable focal length.

[0002]

2. Description of the Related Art Various types of camera photometric devices have been proposed. For example, a circular area at the center of a screen can be spot-metered, and a peripheral area of the circular area can be measured. As an example, a configuration in which center-weighted photometry can be performed by performing weighted addition with the photometry result of (1).

In such a photometric device, the main subject is spot-metered in the circular area, so that the main subject can be photographed in an optimal exposure state, and the center-weighted photometry is performed. In addition, it is possible to take a picture in an exposure state that balances with a background while emphasizing a main subject.

Further, by detecting the difference in brightness between the central circular area and the peripheral area, it is determined whether or not the subject is in a backlight state. When the subject is in the backlight state, exposure correction suitable for a backlight scene is performed. A camera having a so-called backlight compensation function has been proposed and commercialized.

On the other hand, an AF for measuring a subject distance
A number of techniques have also been proposed in which the sensor is also used as a photometric sensor for measuring the luminance of a subject, and a camera that actually performs spot photometry using an AF line sensor has been commercialized.

[0006] In recent years, as the size of the camera has been reduced, the technology of using both the AF sensor and the photometry sensor has also become more important.

[0007] By the way, as a photographing lens mounted on a camera, there is a zoom lens type in which the focal length can be varied.
In recent years, higher magnification ones have been developed and used.

[0008]

However, as the magnification of the zoom lens increases, a camera having a photometric optical system and a distance measuring optical system configured as an optical system independent of the photographing lens will be described below. Such a problem has occurred, and this will be described with reference to FIGS. FIG. 4 is a diagram showing the size of a conventional photometry area of spot photometry in a shooting screen, and FIG. 5 is a diagram showing the size of a conventional distance measurement area in a shooting screen.

The circular area used for spot metering is shown in FIG.
As shown in FIG. 4A, since the size is set as shown by reference numeral 92W in accordance with the shooting screen 91W when the angle of view is wide, when the shooting lens is moved to the telephoto side, FIG. As shown in (B), the size of the circular area occupying in the shooting screen 91T becomes large as shown by reference numeral 92T. In the case of metering a person as a main subject as shown in the figure, spot metering can be performed on the wide-angle side, whereas a circular area used for spot metering becomes larger than a person's head on the telephoto side. For this reason, the photometric result is affected by the luminance of the background, so that it can no longer be said to be spot photometry.

[0010] On the other hand, in the technique of using both an AF sensor and a photometric sensor, a telephoto shooting screen 91 as shown in FIG.
At T, it is possible to perform the function of spot photometry by using only the pixel output indicated by oblique lines of the AF sensor (reference numeral 93T) having a plurality of pixels arranged therein for photometry. However, when the photographing lens is moved to the wide angle side, as shown in FIG. 5A, the size of the distance measurement area occupied in the photographing screen 91W becomes smaller as shown by reference numeral 93W, and especially the vertical width becomes smaller. When only the pixel output indicated by the diagonal line is used for photometry to reduce the size, if the subject corresponding to the diagonal portion has a high luminance part or a low luminance part, the influence of the high luminance part or the low luminance part should be greatly affected and correct photometry should be performed. May not be possible.

As described above, the change in the size of the photometry area and the distance measurement area, which was not a problem when the zoom magnification of the photographing lens is not very large, has become a problem as the zoom magnification increases. .

The present invention has been made in view of the above circumstances, and provides a camera photometric device capable of performing highly accurate spot photometry and backlight determination even in a camera having a high-magnification zoom photographing lens. It is intended to be.

[0013]

In order to achieve the above object, a photometric device for a camera according to a first aspect of the present invention includes a photographing lens having a variable focal length, and a focal length detecting the focal length of the photographing lens. Detecting means, a focusing sensor for outputting a subject image signal corresponding to a subject distance for displacing the photographing lens to a focusing position, the focusing sensor including a plurality of pixels, and the focusing sensor Measuring a luminance value of a subject using a pixel region including a predetermined pixel group
A second light metering means for measuring a luminance value of a subject corresponding to a predetermined area near the center of the photographing angle of view when the focal length of the photographing lens is the shortest; and the focal length detecting means And selecting means for selecting one or both of the first and second photometric means in accordance with the focal length of the photographing lens detected by the method. is there.

The photometric device for a camera according to the second aspect of the present invention is the photometric device for a camera according to the first aspect.
The selecting means enables the first photometric means when the focal length of the taking lens is long, and enables the second photometric means when the focal length of the taking lens is short. .

Further, a photometric device for a camera according to a third aspect of the present invention is the photometric device for a camera according to the first or second aspect, wherein the photometric device is disposed concentrically with the second photometric means and is located around a shooting angle of view. Third light metering means for metering the luminance value of the subject corresponding to the area, and the light metering value obtained by one or both of the first light metering means and the second light metering means, and the third light metering Backlight determination means for determining the backlight state of the subject based on the photometric value obtained by the means.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an embodiment of the present invention, and FIG. 1 is a perspective view showing an appearance of a camera.

As shown in the figure, the camera of the present embodiment is configured as a so-called compact camera that employs a lens shutter and has a miniaturized housing, and is of a type that exposes a silver halide film. But C
Any type that exposes an image pickup device such as a CD may be used.

That is, the camera 1 has a photographing lens 2 for forming a subject image on a film, a CCD, or the like, which is disposed at the center of the front surface. The photographing lens 2 has a zoom function for changing the focal length. And a focus function for focusing on a subject distance according to the AF data.

At the upper right of the photographing lens 2, a strobe 3 for projecting auxiliary light to the subject when the subject has low brightness or backlight is provided.

Further, an objective lens 4 in a finder optical system capable of zooming in response to a change in the focal length of the photographing lens 2 is provided above the photographing lens 2.
A photometric lens 5 having a fixed focus set at an angle of view substantially including the angle of view on the wide (wide angle) end side of the photographing lens 2;
An AF lens 6 comprising a pair of fixed-focus imaging lenses set in accordance with the angle of view on the wide end side of the photographing lens 2;
Are arranged.

On the top of the camera 1, there is provided a release button 7 which is a two-stage operation button for instructing a photographing operation.
And L for displaying various information related to the camera 1.
And a display element 9 made of a CD or the like.

Further, on the back side of the camera 1, a zoom lever 8 comprising a seesaw type lever switch for inputting an instruction to change the focal length of the photographing lens 2 to the telephoto side or the wide side is provided. I have.

FIG. 2 is a block diagram mainly showing the electrical configuration of the camera.

The camera 1 has a lens drive circuit 11 for performing a zoom drive for changing the focal length of the photographic lens 2 and a focus adjustment drive for adjusting the focal position, and detects the position of the photographic lens 2. A lens position detecting circuit 12 serving as a focal length detecting means for performing a focusing operation, a photometric sensor unit 13 for photoelectrically converting light incident from the photometric lens 5 and outputting it as electrical photometric information, and forming an image by the AF lens 6. AF, which is a focusing sensor for outputting a subject image signal corresponding to the subject distance and receiving a pair of subject images respectively received by a pair of sensor arrays,
The sensor unit 14 and the first release switch 1 that operates by half-pressing the release button 7
R, a second release switch 2R that operates by fully pressing the release button 7, a zoom-up switch ZU that operates by tilting the zoom lever 8 to one side, and an operation by tilting the zoom lever 8 to the other. A zoom-down switch ZD, an EEPROM 16 which is an electrically rewritable non-volatile memory for storing adjustment data and the like unique to the camera, and the entire camera electrically connected to the above circuits and including these circuits. And a control circuit 15 which is a selecting means composed of a microprocessor or the like for performing the above control and also serves as a backlight determining means.

The control circuit 15 includes, for example, ROM, RA
M, a timer, a counter, and the like, are internally provided, and operations relating to the entire camera such as an AF operation, a photometry operation, and a zooming operation are performed in accordance with a processing program for operating the camera stored in the ROM in advance. Is controlled.

The photometric sensor unit 13 is disposed at the image forming position of the photometric lens 5 and has a photodiode (wide) as a second photometric means for performing spot photometry at a central portion of the screen in a wide angle range. A photodiode which is arranged concentrically with the photodiode and performs peripheral photometry of a peripheral portion of the screen in a wide-angle region; Is configured. Further, the photometric sensor unit 13 has a processing circuit that logarithmically compresses a photocurrent generated according to the luminance of each subject image formed on these photodiodes and outputs the photocurrent as an analog voltage to the control circuit 15. are doing.

Further, the AF sensor unit 14
It has a pair of sensor arrays in which pixels that receive light and convert them into electric signals are arranged in a line, and by using at least a part of a plurality of pixels arranged on the sensor array, It can also function as a photometric sensor. Specifically, the AF sensor unit 14 is configured to be able to perform spot photometry in a telephoto range by using an output of a pixel group including some pixels at the center.

The EEPROM 16 is connected to the control circuit 15 via a communication line, and outputs stored data to the control circuit 15 or
In addition to storing data from the control circuit 15, predetermined focal length information and the like, which serve as a criterion for switching the photometric sensor as described later, are also stored.

In the configuration shown in FIG. 2, the flow when the zoom lever 8 is operated is as follows.

When the control circuit 15 detects that the zoom-up switch ZU has been turned on by operating the zoom lever 8, the control circuit 15 executes the operation of the lens drive circuit 1.
1, the focal length of the photographing lens 2 is driven in the telephoto direction.

On the other hand, when the control circuit 15 detects that the zoom down switch ZD is turned on by operating the zoom lever 8, the control circuit 15 sends the focus of the photographing lens 2 through the lens drive circuit 11. Drive the distance in the wide angle direction.

In the configuration as shown in FIG. 2, the flow when the release button 7 is operated is as follows.

When the release button 7 is half-pressed to turn on the first release switch 1R, the control circuit 1
5 detects this and performs preparation processing prior to photographing such as AF or photometry.

When the release button 7 is fully depressed to turn on the second release switch 2R, the control circuit 15 detects this and drives the photographing lens 2 to a position corresponding to the AF result. Exposure processing is executed by controlling the drive of an aperture / shutter (not shown) according to luminance information or the like based on the result. At the time of this exposure control, the subject is irradiated with auxiliary light by emitting the strobe light 3 as necessary.

Further, in the configuration as shown in FIG. 2, the flow when driving the photographing lens 2 is as follows.

Upon receiving the instruction signal from the control circuit 15, the lens drive circuit 11 drives the photographing lens 2 to perform zooming and focusing.

The lens position of the taking lens 2 is detected by the lens position detecting circuit 12 and output to the control circuit 15 as focal length information and focal position information.

The control circuit 15 receives the focal length information and the focal position information information and outputs an instruction signal for controlling the driving of the photographing lens 2 to the lens driving circuit 11.

The focal length information obtained here is compared with predetermined focal length information stored in the EEPROM 16 and used as a criterion for switching the photometric sensor, as described later.

The flow of distance measurement and photometry using the AF sensor unit 14 in the configuration shown in FIG. 2 is as follows.

When the AF sensor unit 14 receives the integration start instruction signal from the control circuit 15, the subject image formed by the AF lens 6 is photoelectrically converted by all the pixels of the sensor array at the same time, and its photocurrent is converted. Is started, and similarly, when an integration end instruction signal is received, this integration operation is ended.

The integration result of each pixel of the AF sensor unit 14 is converted into an analog voltage in synchronism with the clock signal supplied from the control circuit 15 as an analog voltage.
Is output to

The control circuit 15 successively A / D converts the analog voltage and stores it in the RAM as digital integrated voltage data, and also stores integration time data, which is time data required for integration, in the RAM. Keep it.

Next, the control circuit 15 calculates the distance to the subject and the brightness of the subject based on the integration time data and the integration voltage data stored in the RAM.

In addition, in the configuration shown in FIG. 2, the flow of photometry using the photometric sensor unit 13 is as follows.
It looks like this:

The photometric sensor unit 13 outputs an analog voltage obtained by logarithmically compressing the photocurrent to the control circuit 15 as described above.

The control circuit 15 A / D-converts the input analog voltage and stores it in the RAM as subject brightness data of each area.

Next, FIG. 3 is a flowchart showing a process performed by the control circuit during the photometry operation.

When the control circuit 15 detects that the first release switch 1R is turned on, this photometric operation is started.

When the operation is started, first, the focal length information of the photographing lens 2 input from the lens position detecting circuit 12 and a first focal length on the telephoto side stored in the EEPROM 16 in advance. Focal length information,
Are compared to determine whether or not the photographing lens 2 is in the telephoto range (step S1).

Here, when it is determined that the photographing lens 2 is in the telephoto range, among the pixels arranged in the sensor array of the AF sensor unit 14, n pixels (n
Calculates the spot photometric value based on the photocurrent integration data and integration time data stored in advance in the EEPROM 16 (step S2).

If it is determined in step S1 that the photographic lens 2 is not in the telephoto range, a spot photometric value is calculated from the luminance data of the photodiode corresponding to the center of the screen of the photometric sensor unit 13. (Step S3).

Then, the focal length information of the photographing lens 2 input from the lens position detection circuit 12 and the EEPR
By comparing with the second focal length information indicating the predetermined focal length on the wide angle side stored in advance in the OM 16, it is determined whether or not the photographing lens 2 is in the wide angle region (step S4).

If it is determined that the photographing lens 2 is not in the wide angle range, m pixels (m) near the center of the pixels arranged in the sensor array of the AF sensor unit 14 are used.
Is stored in advance in the EEPROM 16 and is a predetermined value satisfying m> n), and the spot photometric value is calculated based on the integral time data (step S5).

Next, the average of the spot photometric value calculated in step S5 and the spot photometric value calculated in step S3 is calculated, and this is set as a new spot photometric value (step S6).

If step S2 or step S6 is completed, or if it is determined in step S4 that the photographic lens 2 is in the wide-angle range, the photodiode of the photometric sensor unit 13 corresponding to the periphery of the screen is A peripheral photometric value is calculated from the luminance data (step S7).

Then, the spot photometric value is compared with the peripheral photometric value. If the spot photometric value is lower than the peripheral light value by a predetermined value or more, it is determined that there is backlight (step S8).

Here, when it is determined that the subject is backlit,
By correcting the photometric value of the entire photographic scene calculated in the next step S9, and performing exposure slightly over, or causing the strobe 3 to emit light, it is possible to compensate for the exposure amount at the center of the screen. Become.

The average of the spot photometric value calculated in step S2, step S3, or step S6 and the peripheral photometric value calculated in step S7 is calculated, and this is used as the photometric value of the entire photographic scene (step S9), the photometric operation ends.

If the spot metering mode is selected by an operation member (not shown), the above-described step S
Steps S7 to S9 are not executed, and the spot photometric value calculated in step S2, step S3, or step S6 is set as the photometric value of the entire shooting scene.

The steps S4 to S6 may be omitted depending on the zoom magnification of the taking lens 2.

According to such an embodiment, on the telephoto side where it is more advantageous to perform spot metering with the AF sensor unit 14, the spot metering value is calculated by the AF sensor unit 14 and the spot metering is performed by the metering sensor unit 13. On the wide-angle side where it is more advantageous to perform the measurement, the photometric sensor unit 13 calculates the spot photometric value, and averages the photometric results of the two at an intermediate standard focal length to complement each other. It is possible to obtain an optimum spot photometric value according to a scene (angle of view).

Thus, even in a camera having a high-magnification zoom photographing lens, highly accurate spot metering and backlight determination can be performed.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications and applications can be made without departing from the gist of the invention.

[Appendix] According to the above-described embodiment of the present invention as described in detail above, the following configuration can be obtained.

(1) A photographing lens with a variable focal length, focal length detecting means for detecting the focal length of the photographing lens, and a subject image corresponding to the subject distance for displacing the photographing lens to a focal position. A signal for outputting a signal, and using a focusing sensor having a plurality of pixels and a pixel area of a predetermined pixel group in the focusing sensor to measure a luminance value of the subject. A second photometering means for measuring a brightness value of a subject corresponding to a predetermined area near the center of a photographic angle of view when the focal length of the photographic lens is the shortest; Selecting means for selecting one or both of the first light measuring means and the second light measuring means according to a focal length of the photographing lens detected by the detecting means, and Having A photometric device for a camera.

(2) The selecting means enables the first photometric means when the focal length of the photographing lens is long, and the second light measuring means when the focal length of the photographing lens is short.
The photometric device for a camera according to (1), wherein the photometric device is made effective.

(3) When the focal length of the photographing lens is in an intermediate area, the selecting means may further include the first lens.
(2) wherein both the photometering means and the second photometering means are enabled and an average of the brightness values measured by each of them is set as a new brightness value. Photometric device for camera.

[0069]

As described above, according to the photometric device for a camera of the present invention, it is possible to perform highly accurate spot photometry and backlight determination even in a camera having a high-magnification zoom photographing lens.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a camera according to an embodiment of the present invention.

FIG. 2 is a block diagram mainly showing an electric configuration of the camera of the embodiment.

FIG. 3 is a flowchart showing a process performed by the control circuit during a photometric operation in the embodiment.

FIG. 4 is a diagram showing the size of a light metering area of spot metering in a photographing screen in the related art.

FIG. 5 is a diagram showing the size of a distance measurement area in a photographing screen in the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Camera 2 ... Photographing lens 3 ... Strobe 4 ... Objective lens in a finder optical system 5 ... Photometric lens 6 ... AF lens 7 ... Release button 8 ... Zoom lever 9 ... Display element 11 ... Lens drive circuit 12 ... Lens position detection circuit ( Focal length detection means) 13: photometric sensor unit (second photometric means, third photometric means) 14: AF sensor unit (focusing sensor, first photometric means) 15 ... control circuit (selection means, backlight determination Means) 16: EEPROM 1R: First release switch 2R: Second release switch ZU: Zoom up switch ZD: Zoom down switch

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H002 DB02 DB15 DB20 DB23 DB28 DB32 FB32 FB37 HA04 2H011 AA01 BA01 BB02 CA19 2H051 BB01 BB21 CB20 CB26

Claims (3)

[Claims] 1. A photographing lens having a variable focal length, a focal length detecting means for detecting a focal length of the photographing lens, and a subject image signal corresponding to a subject distance for displacing the photographing lens to a focusing position. A focus sensor having a plurality of pixels, and a first area for measuring a luminance value of a subject using a pixel region of a predetermined pixel group in the focus sensor. A second light metering means for measuring a luminance value of a subject corresponding to a predetermined area near the center of the shooting angle of view when the focal length of the shooting lens is the shortest; Selecting means for selecting one or both of the first photometric means and the second photometric means in accordance with the focal length of the photographing lens detected by the means. That I have Characteristic photometer for camera. 2. The selecting means enables the first photometric means when the focal length of the photographic lens is long, and activates the second photometric means when the focal length of the photographic lens is short. 2. The method according to claim 1, wherein
A photometric device for a camera according to claim 1. 3. A third photometer, which is arranged concentrically with the second photometer and measures the luminance value of a subject corresponding to a peripheral area of a shooting angle of view, and the first photometer. Backlight determining means for determining a backlight state of a subject based on a photometric value obtained by one or both of the second photometric means and a photometric value obtained by the third photometric means; The photometric device for a camera according to claim 1 or 2, further comprising: