JPS61246711A - Instrument for measuring distance and brightness of object - Google Patents

Abstract

PURPOSE:To expose a range-found main object properly by automatically discriminating the range-found main object and optically measuring the main object as a spot or a focus. CONSTITUTION:When a release button is depressed, a release switch 22 is turned on to send a range-finding start signal to a microcomputer 23. Clock pulses are sent from a pulse generator 24 to drivers 25, 26 to drive a photodetecting sensor for AF (for detecting near infrared light reflected by an object and returned) 13 and a photodetecting sensor for AE (for measuring the brightness of the object) 17 respectively. An area sensor obtained by arraying plural pixels like a matrix is used as the sensor 13 and a filler for cutting visible rays is arranged in front on the sensor 13. An area sensor is also used for the sensor 17 and a filter for cutting near infrared rays is arranged in front of the sensor 17. The distance of the object is detected from the position of near infrared rays incident on the sensor 13, the output of an equivalent position of the sensor 17 which corresponds to the incident position of the sensor 13 is taken out and the brightness of the object is calculated in accordance with the output.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a subject distance and subject brightness measuring device used in a camera, and more specifically, the present invention relates to a subject distance and subject brightness measurement device used in a camera, and more specifically, the present invention relates to a subject distance and subject brightness measuring device used in a camera. The present invention relates to a device for extracting .

[Conventional technology]

Most of today's compact cameras have a built-in autofocus device and automatic exposure control device, which measures the distance by pressing the release button halfway, positions the photographing lens according to the obtained subject distance, and then releases the camera. When the button is pressed, the camera measures the brightness of the subject and automatically controls exposure. The autofocus device includes a subject distance measuring device that measures a subject distance, and a lens driving device that positions a photographic lens at a predetermined position using a signal from the subject distance measuring device. Triangulation-type devices are widely used as subject distance measuring devices, which project near-infrared light onto the subject, receive the light reflected by the subject with a light-receiving sensor, and measure the subject distance from the light-receiving position. It is being Further, the automatic exposure control device calculates the subject brightness by measuring the average light of the subject with a light receiving sensor or by spot metering the center of the screen, and calculates the exposure amount using this subject brightness and exposure information such as film sensitivity. The exposure amount is calculated, and the operation of a shutter, for example, is controlled according to this exposure amount.

[Problem that the invention seeks to solve]

However, in conventional cameras, the light-receiving sensor for measuring subject brightness (hereinafter referred to as the AE light-receiving sensor) operates independently of the subject distance measuring device, resulting in the following problems. In other words, in order to properly expose a main subject, such as a person, in a backlit scene, etc., it is best to perform spot metering or weighted metering on the main subject and control the exposure according to the obtained subject brightness. The AE light receiving sensor cannot detect where the main subject is, so it is set to perform spot metering or weighted metering at the center of the screen. However, depending on the composition, the main subject may not be at the center of the screen, so in such shooting scenes it is not possible to properly expose the main subject.

By associating distance measurement and brightness measurement, the present invention
It is an object of the present invention to provide a subject distance and subject brightness measuring device that can properly expose a main subject whose distance has been measured.

[Means for solving problems]

In order to solve the above problems, the present invention provides a light receiving sensor (referred to as an AF light receiving sensor) that receives near-infrared light emitted from a light projecting unit, reflected by a subject, and returned, using a plurality of pixels. Using an area sensor arranged in a matrix, an area sensor is also used for the AE light receiving sensor, and the distance to the subject is detected from the position of near-infrared light incident on the AF light receiving sensor. The output of the equivalent position of the AE light receiving sensor corresponding to the incident position is extracted, and the subject brightness is calculated according to this output.

The light receiving sensor for AF and the light receiving sensor for AE are CCDs in which a plurality of pixels are arranged in a matrix.
An area sensor, MO3 type area sensor, etc. are used. This AF light receiving sensor is provided with a filter that cuts visible light on its front surface or a lens placed in front of it.

Similarly, the AE light receiving sensor is also provided with a filter that cuts near-infrared light.

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

〔Example〕

In FIG. 2, a camera body 1 has a photographic lens 2 fixed to the center of its front surface, a finder 3 and a strobe light emitting unit 4 arranged at the top, and a release button above the camera body 1. 5 is provided.

When the release button 5 is pressed halfway, the photographing lens 2 is adjusted in accordance with the subject distance, and when the release button 5 is further pressed halfway, the shutter is operated after metering the brightness of the subject. A light projecting unit 6 that projects near-infrared light in the form of a slit is arranged above the photographing lens 2, and a predetermined baseline length is maintained below.
A temporary light receiver 7 is arranged. An AE light receiving section 8 is arranged next to the AF period light receiving section 7. Note that the light projecting section 6
and the AF period light receiver 7 may be arranged diagonally with respect to the camera body 1, and when arranged in this way, distance measurement can be performed even when the camera posture is not only horizontal but also vertical.

FIG. 1 illustrates the principle of the invention. A light emitting diode 10 that generates near-infrared light is used as a light source, and a slit plate 11 and a cylindrical lens 12 are arranged on the front surface of the light emitting diode 10.
is configured. The AF light receiving section 7 is composed of an AFF light receiving sensor 13 equipped with a filter for cutting visible light on the front surface thereof, and a lens 14, and the AF light receiving section 7 is composed of an AFF light receiving sensor 13 equipped with a filter for cutting visible light on the front surface thereof, and a lens 14. An image is formed on the AFF light receiving sensor 13, and the object distance is measured from the image formation position. This AFF light receiving sensor 13 is COD,
An MO5 storage type image area sensor is used, and each row is arranged parallel to the baseline length. In addition, the AE light receiving section 8 cuffs near-infrared light)
The AE light receiving sensor 1 includes a lens 18 and a lens 18, and receives external light present in a photographic scene. The imaging state of this AE light receiving sensor 1 is set to be the same as that of the AF light receiving sensor 3.

When the release button 5 is pressed, the light emitting diode 10 emits light for a predetermined period of time before the shutter is activated, and the emitted light passes through the slit plate 11 and the cylindrical lens 12 to become a slit-shaped light beam 19.

This slit-shaped light beam 19 extends in a negative direction in the lateral direction of the photographing screen 20, as shown in FIG. 3(A). Further, the slit-shaped light beam 19 has a length of approximately 173 times the angle of view of the photographing screen 20, and it is possible to range the object within the range illuminated by the slit-shaped light beam 19. Therefore, unlike conventional object distance measuring devices, the distance measuring device does not measure only the center of the screen, so there is no need to provide a target in the finder, and the composition can be determined freely.

The light reflected by the objects 15 and 16 enters different AF pixels depending on the distance. In other words, Fig. 3 (
As shown in B), the light reflected by the subject 15 at a short distance is imaged on the AF pixel in the first row counting from the short distance side and photoelectrically converted, as shown by reference numeral 15a.

Then, the light reflected by the object 16 located far away is imaged on the AF pixel in the fourth row, as indicated by reference numeral I6a. When two or more reflected lights are incident on different rows, priority is given to the AF pixel on the closer row.

The photographing lens 2 is positioned according to the position of this prioritized AF pixel. That is, in this case, the photographing lens 2 is set at the closest position among the six lens set positions including the infinite position. After setting this lens, measure the external light (visible light) on the AE light receiving sensor 1, and extract the appearance of the AE pixel in the 1st row, 4th column, which is oriented toward the main subject among the many AE pixels. Spot photometry is performed by this, and the exposure amount is calculated using the obtained subject brightness. Note that this spot metering is
By calculating the average value of the output of the light receiving sensor 1, selecting a coefficient according to this average value, and weighting the output of the AE pixel in the 1st row and 4th column with this coefficient, the subject brightness can be adjusted. It can also be calculated. Alternatively, it is also possible to perform weighted photometry in which the weight of the output of the AE pixel in the first row and fourth column is increased.

After calculating the exposure amount, the shutter is operated to expose the film. During this film exposure, the shutter speed or aperture value is controlled according to the exposure amount so that the main subject is properly exposed. Note that when exposure is program-controlled, both the shutter speed and the aperture value are controlled according to the exposure amount.

FIG. 4 shows one embodiment of the present invention, and the same parts as shown in FIGS. 1 to 3 are given the same reference numerals. When the release button 5 is pressed, the release switch 22 sends a distance measurement start signal to the ONL and microcomputer 23. This microcomputer 23
executes predetermined sequence control according to a program stored in the ROM. The clock pulses from the pulse generator 24 are sent to the drivers 25.26 and the AFF light receiving sensors 13.26. Each of the AE light receiving sensors is driven.

Note that the reference numeral 27 is a visible light cut filter, and the reference numeral 2 is a visible light cut filter.
8 is an infrared light cant filter.

The light receiving sensor 3 for AF and the light receiving sensor 1 for AE are storage type image area sensors of COD and MOS type, and as shown in FIG. ing. Here, the first row, where i=l, receives reflected light from a subject located at a close distance, and the pixel in the nth row, where i=n, receives reflected light from a subject located at a far distance. Receive light.

The light receiving sensors 13.17 are read out in order from the first row to the first row by clock pulses from the driver 25.26, and within each row, the data are read out in order from the first column to the nth column. Read out. The time-series signals read out in this manner are each amplified by amplifiers 29 and 30, and then converted into digital signals Fij and Eij by A/D converters 31 and 32, respectively, and taken into the RAM of the microcomputer 23. The microcomputer 23 drives the light emitting diode 10 that emits near-infrared light through a driver 34, and controls the direction and amount of rotation of a motor 36 through a driver 35 to focus the photographic lens 2. Move to the position where it matches. Furthermore, the microcomputer 23 calculates the exposure amount from the digital signal Eij, sends it to the exposure control circuit 37, and controls the shutter drive mechanism 38. This shutter drive mechanism 38
controls the operation of a shutter 40 disposed between the photographic lens 2 and the film 39.

FIG. 6 shows the functions of the microcomputer. In order to eliminate the influence of near-infrared light contained in external light,
The reference signal S is sent to the comparison section 42. This reference signal S may be constant regardless of the shooting scene, but it is preferable to measure near-infrared light contained in outside light and determine it according to the amount. The output signal Fij of the AF light receiving sensor 13 stored in the RAM is sequentially read out row by row and in column order in the same row, sent to the comparison section 42, and compared with the reference signal S. This comparison section 42 outputs a signal of "1" when the output signal Fij of the AF light receiving sensor 13 is larger than the reference signal. This output signal is
1'', it is determined that near-infrared light reflected by the subject is being incident.

When a signal of "1" is output from the comparison section 42, the incident position detection section 43 identifies the pixel of the AF light receiving sensor that received the reflected light from the subject from the access address in the RAM. A signal indicating the row of the identified AF pixel (referred to as AF detection pixel) is sent to the photographing lens set position determining section 44, which determines the lens set position.

The weighting section 45 weights the AE at the same position as the AF detection pixel of the AE light receiving sensor 1 output signal Eij.
pixels (referred to as equivalent AE pixels) and other AE
For each pixel, different weighting coefficients are used to integrate the output signal E L j of the AE light receiving sensor 1, and this is added in an adder 46 to perform weighted photometry and calculate the subject brightness.

Here, for those that are not equivalent AE pixels, if the weighting coefficient is set to "0", spot photometry is performed. The subject brightness added by the adder 46 is sent to the exposure amount calculation section 47, where it is calculated together with the film sensitivity to calculate the exposure amount, as is well known.

FIG. 7 shows another example of calculating subject brightness. The output signal Eij of the AE light receiving sensor 1 is sent to the average value calculating section 50, and the average value thereof is calculated. The weighting unit 52 calculates the subject brightness by multiplying the signal extracted by the signal extraction unit 51 of the equivalent AE pixel by the average value.

FIG. 8 is a flowchart showing the operation of the apparatus shown in FIG. 4. Release switch 2 when release button 5 is pressed
2 is turned on, the microcomputer 23 sends a reset signal to the driver 25 to activate the AF light receiving sensor 13.
The charges accumulated in each pixel pH to Pnn are read out at high speed and reset. After this reset, the microcomputer 23 drives the driver 34 to cause the light emitting diode 10 to emit light for a predetermined period of time, and projects a slit-shaped light beam 19 toward the subject. The light reflected by the subject is imaged on an AF pixel corresponding to the shooting distance.

Each AF pixel pH to P of the AF light receiving sensor 13
nn is sequentially read out by the driver 25, amplified by the amplifier 29, converted into a digital signal Fij by the A/D converter 31, and then stored in a memory assigned an address for each AF pixel.

Next, the microcomputer 23 sequentially reads out the signals Fij stored in the RAM. That is, first, the signal F11 of the AF pixel pH in the first row and first column is read out, and it is determined whether it is larger than the reference signal S. Then, when it is determined that the signal F21 is smaller than the reference signal S, the signal F21 of the AF pixel P12 in the first row and second column is read out, and a determination is made as to whether it is larger than the reference signal S. Each AF pixel belonging to the first row When the determination is completed, determination of each AF pixel belonging to the second row is started.Thereafter, determination is performed in the same manner in order toward the first row.

During the comparison of the signal Fij and the reference signal S mentioned above, the signal F
When it is detected that ij is larger, the photographing lens 2 is positioned at the first stage of lens set positions of 1 to n stages. For example, if the signal of the AF pixel, for example Pd2, belonging to the fourth row is larger than the reference signal S, the photographing lens 2 is positioned at the fourth stage from the short distance position. Note that the signal Fij of each AF pixel from the 1st row to the nth row
If both are smaller than the reference signal S, the photographing lens 2 is positioned at an infinite position.

In this embodiment, after the lens is set, spot photometry is performed to detect the subject brightness. That is, the AE light receiving sensor 1 is reset, external light is measured for a predetermined period of time, and then read out, and the A/D converter 32 converts the digital signal Eij.
, and then input into the microcomputer 23. Since the AF detection pixel Pij that detected the main subject is known, the corresponding output Eij of the equivalent pixel of the AE light receiving sensor 1 is extracted. for example,
Assuming that the AF detection pixel of the AF light receiving sensor 17 that detected the main subject is Pd2, the output of the AE light receiving sensor 1 equivalent AE pixel P46 is extracted and used as subject brightness information to calculate the exposure amount. . The operation of the shutter 40 is controlled according to the exposure amount calculated in this way, so that the main subject whose distance has been measured is properly exposed.

FIG. 9 shows an example of arrangement of filters.

A visible light cut filter 27 is deposited or attached to the front surface of the lens 14, and a near infrared light cut filter 28 is also attached to the front surface of the lens 14.
is attached to the lens 18.

FIG. 10 shows an embodiment in which a visible light cut filter 27 is attached to the front surface (light receiving surface) of the light receiving sensor 13 for AF, and a near infrared light cut filter 28 is attached to the front surface of the light receiving sensor 1 for AE. be.

When the subject is large, the reflected light from the subject enters a plurality of AF pixels. In the above embodiment, the AF pixel closest to the AF detection pixel is used as the AF detection pixel, but for example, one pixel located in the middle of a plurality of AF pixels that have received reflected light may be determined to be the AF detection pixel.

In this case, the AEE corresponding to this AF detection pixel
In addition to extracting the output of the equivalent AE pixel of the light receiving sensor as brightness information, it is also possible to use a plurality of AE pixels corresponding to a plurality of AF pixels into which reflected light has entered as equal AE pixels, and use their average value as brightness information. .

〔Effect of the invention〕

The present invention having the above configuration uses an AF light receiving sensor and an AEE light receiving sensor in which a plurality of pixels are arranged in a matrix, and emits a slit-shaped light beam from a light projecting unit toward a subject, and reflects the light from the subject. The light is received by the AF light receiving sensor, and the distance to the subject is measured from the light receiving position.
Then, since the exposure amount is calculated by extracting the output of the pixel of the AEE light receiving sensor corresponding to the reflected light incident position of the AF light receiving sensor, the main subject of the distance measurement is automatically determined and this is set as a spot or a focus. By metering, the main subject can be properly exposed.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the principle of the present invention. FIG. 2 is a front view of a camera implementing the present invention. FIG. 3 is an explanatory diagram showing the light projection range of the slit-shaped light beam and the light receiving range of the AF light receiving sensor. FIG. 4 is a block diagram showing an example of a device implementing the present invention. FIG. 5 is an explanatory diagram showing pixels of a light receiving sensor. FIG. 6 is a functional block diagram of a microcomputer showing an example of exposure amount calculation. FIG. 7 is a functional block diagram of a microcomputer showing another example of exposure amount calculation. FIG. 8 is a flowchart showing the operating state of the apparatus shown in FIG. 4. FIGS. 9 and 10 are side views of the light-receiving section, respectively showing how the filter is attached. l...Camera body 2...Photographing lens 6...Light emitter 7...AF light receiving part 8...AE light receiving part 10...Light emitting diode 11...Slit plate 13...For AF Light receiving sensor 15.16...Subject 17...Photographing sensor 19...Slit-shaped light flux 20...Photographing screen pH~Pnn...Pixel. Figure 3 (A) (9) Figure 9

Claims (2)

[Claims] (1) A light projection unit that emits a slit-shaped light beam containing a near-infrared light component toward the subject, and a plurality of pixels arranged in a matrix, and the reflected light that is reflected from the subject and returns. a distance-measuring light-receiving sensor that receives light, a filter that is placed in front of the distance-measuring light-receiving sensor and cuts visible light, a means for detecting a subject distance from a position where the reflected light is incident, and a plurality of pixels. A light receiving sensor for measuring brightness, which is arranged in a matrix and receives external light present in a shooting scene; a filter which is arranged in front of the light receiving sensor for measuring brightness and cuts near-infrared light; and the distance measuring sensor. 1. A subject distance and subject brightness measuring device comprising means for calculating subject brightness by extracting an output at a position of a light receiving sensor for measuring brightness corresponding to a position of incidence of reflected light on the light receiving sensor. (2) Claim 1, wherein the two types of filters are provided in front of each light receiving sensor.
The object distance and object brightness measuring device described in 2.