JP2000194028A - Photometric device - Google Patents

Abstract

(57) [Problem] To provide a photometric device and a camera which are inexpensive and which can omit the step of adjusting the position of a sensor for spot photometry and which can determine backlight. SOLUTION: A light receiving means for detecting at least one of distance information to a subject and defocus information, a light measuring means for measuring the average luminance of a photographing screen, and luminance information obtained by the light receiving means. A photometric device and a camera, comprising: a determining unit that compares luminance information obtained from the photometric unit and determines a backlight state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a photometric device used for a camera.

[0002]

2. Description of the Related Art A conventional example according to the present invention will be described with reference to FIGS. FIG. 1 is an image diagram showing an image of a subject viewed from a finder and a position where the photometric sensor is back-projected on the subject. 1 is an average photometric sensor that measures most of the angle of view in the viewfinder, 2 is a spot photometric sensor that measures a part of the center of the viewfinder, 3 is a high-intensity light source such as the sun, 4 is a subject such as a person, and 7 is It is a distance measurement mark indicating a distance measurement position in the viewfinder. The distance measurement mark 7 is usually
It is located at the center of the screen, and the spot photometric sensor 2 and the AF sensor 6 described later are located inside it. FIG.
In this situation, the output Eave of the brightness value of the average photometric sensor 1 is brighter than the output Espot of the brightness value of the spot photometric sensor 2. That is, when the difference between Eave and Espot is larger than a certain value, it is determined that the subject is in a backlight state, and control is performed so that the subject 4 is properly exposed by flash emission or the like. The judgment of this backlight state is made by Eave Espot> Ek (Ek
The determination is made when the expression of (k is a reference value for backlight determination) is satisfied.

FIG. 2 is a configuration diagram of a single photometric sensor. The description of each sensor area is omitted because it has been described above.

[0004]

In this case, the photometric sensor has a unit price higher than that of the photometric sensor having only the average photometric sensor 5 shown in FIG. 3, which has an average photometric sensor and at least one spot photometric sensor for central photometry. Multi-area photometric sensor must be used.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a photometric device and a camera which are inexpensive and which can omit the process of adjusting the position of a sensor for spot photometry and which can determine a backlight. .

[0006]

In order to achieve the above object, the present invention provides a light receiving means for detecting at least one of distance information to a subject and defocus information, and an average brightness of a photographing screen. A photometric device and a camera, comprising: a photometric unit for performing photometry, and a determining unit that compares luminance information obtained by the light receiving unit with luminance information obtained by the photometric unit and determines a backlight state. Things.

[0007]

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

FIG. 4 shows a first embodiment of the present invention.
FIG. 14 is an image diagram in which each sensor is back-projected to a subject viewed from the finder according to the embodiment.

In FIG. 4, reference numeral 6 denotes an image of the AF sensor which is back-projected on the subject viewed from the finder. Other individual explanations are omitted since they have been described above. The average photometry sensor 5 performs the same operation as the conventional photometry that measures the average value of the luminance of the angle of view and determines the exposure amount based on the average value.
When a high-luminance light source as shown in FIG. 5 is located within the angle of view, the average photometric sensor 5 alone may cause a shortage of exposure for the subject, but in the present embodiment, the photometric output of the AF sensor 6 is used. To perform backlight detection.

FIG. 6 shows the AF and A of the camera of this embodiment.
The block diagram of E part is shown. The AF sensor is an active AF that emits signal light and receives reflected light that hits a subject, the PSD 10, an I / V converter 11 that converts a photocurrent output from the PSD 10 into a voltage, and an AF signal processing circuit. 1
2. average light metering sensor 13, analog switches 14 and 15 for switching light metering output of AF sensor 10 and output of average light metering sensor 13, inverter 16, light metering signal processing circuit 1
6, a CPU 17 for controlling each block, and an I / V converter 18 for converting a photocurrent of the average photometric sensor 13 into a voltage. Normally, the AF sensor 10 is matched with the distance measurement mark. The AF process is performed in the AF block 19. The AE process is performed in the AE block 20. Backlight detection is performed by switching a switch 14 between the output of the AF sensor 10 and the output of the average photometry sensor 13 in a state where no signal light is projected. Although the output of the AF sensor 10 is taken from one side of the AF sensor 10 in FIG. 6, the subject brightness is applied to the entire AF sensor 10, so that the output of both sides may be added.

In this embodiment, as described above, the active AF using the PSD for the AF sensor 10 is employed. Since the normal active AF uses infrared light, there is a difference in luminance information between light measurement using normal visible light and a light source. However, in the present embodiment, if the comparison value with the photometry sensor is not an absolute value and is larger than a predetermined value, it is determined that the object is backlit. Not be. In the passive AF for obtaining a distance from a phase difference between output signals of two sensor arrays using visible light, an absolute value of luminance information may be used.

Any AF sensor and AF method (such as one that detects defocus information) may be used as long as the optical output of the AF sensor can be extracted.

The output voltage of the I / V conversion output of AF and AE changes in accordance with the input current.

Next, the operation of the above configuration will be described with reference to FIG.
A description will be given according to the flowchart of U17.

When the photographer releases the shutter (100), the operations of AF (101), average photometry (102), and AF sensor photometry (103) start. These three operations are in no particular order. The backlight determination (104) is based on the output Eaf of the brightness value of the AF sensor and the output Eave of the brightness value of the average photometry sensor. In this case, exposure control for backlight by flash photography (106) is performed, and when it is not backlight, normal exposure control by AE (10) is performed.
5) is performed, and thereafter, the sequence proceeds to a known sequence (107) such as a film winding operation.

That is, even if the photometric sensor does not have a multiphotometric sensor having at least one or more spot photometric sensors for central photometry, it is possible to provide a backlight detection function by combining the average photometric sensor with the AF sensor. it can.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
An embodiment will be described.

The configuration of the present embodiment is the same as the configuration of the first embodiment, but the AF sensor is usually matched with the distance measurement mark. That is, since there is a high probability that the subject exists on the distance measurement mark, if the output of the brightness value of this AF sensor is less than a certain brightness value, flash photography is unconditionally performed.

In this case, steps 102 and 104 in FIG.
Can be omitted, and the time lag from release to exposure can be reduced.

It should be noted that the present invention is not limited to the configurations of these embodiments, and the functions described in the claims or
Any configuration that can achieve the functions of the configuration of the embodiment can be applied.

For example, the software configuration and the hardware configuration of the circuit of the above embodiment can be replaced as appropriate.

Further, the present invention may combine the above-described embodiments or their technical elements as needed.

Further, the present invention may be applied to a case where the whole or one of the constitutions of the claims or the embodiments forms one device or is combined with another device. , Which may be a constituent element of the device.

Further, the present invention provides various types of cameras such as a single-lens reflex camera, a lens shutter camera, and a video camera.
Further, the present invention can be applied to optical devices and other devices other than cameras, and further to devices applied to the cameras, optical devices and other devices, or elements constituting these devices.

[0025]

As described above, according to the present invention, it is possible to provide a photometric device and a camera which are inexpensive and which can omit the step of adjusting the position of the sensor for spot photometry and which can determine the backlight.

[Brief description of the drawings]

FIG. 1 is an image diagram showing a conventional example.

FIG. 2 is a configuration diagram of a conventional photometric sensor for detecting backlight.

FIG. 3 is a configuration diagram of an average photometric sensor.

FIG. 4 is an image diagram according to the embodiment of the present invention.

FIG. 5 is an image diagram according to the embodiment of the present invention.

FIG. 6 is a circuit block diagram of the camera according to the embodiment of the present invention.

FIG. 7 is a flowchart of the CPU of FIG. 6;

[Explanation of symbols]

 Reference Signs List 10 PSD 12 AF signal processing circuit 13 Average photometric sensor 16 Photometric signal processing circuit 17 CPU

Claims (6)

[Claims] 1. A light receiving means for detecting at least one of distance information to a subject and defocus information, a light measuring means for measuring the average luminance of a photographing screen, and luminance information obtained by the light receiving means And a judging means for comparing the luminance information obtained from the photometric means and judging the backlit state. 2. The method according to claim 1, wherein the determining unit determines the backlight state when the luminance information obtained by the light receiving unit is information darker by a predetermined value or more than the luminance information obtained by the photometric unit. The photometric device according to claim 1. 3. The photometric device according to claim 1, wherein the flash photographing is performed when it is determined that the luminance information obtained by the light receiving means is darker than a predetermined value. 4. A light receiving means for detecting at least one of distance information to a subject and defocus information, a light measuring means for measuring the average luminance of a photographing screen, and luminance information obtained by the light receiving means. And a determining means for comparing the brightness information obtained from the photometric means and determining a backlight state. 5. The method according to claim 1, wherein the determining unit determines the backlight state when it determines that the luminance information obtained by the light receiving unit is darker than the luminance information obtained by the photometric unit by a predetermined value or more. The camera according to claim 4, wherein 6. The camera according to claim 4, wherein flash photography is performed when it is determined that the luminance information obtained by said light receiving means is darker than a predetermined value.