JP2979006B2 - Camera with electronic viewfinder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a camera provided with an electronic viewfinder.

[Prior art] In addition to an optical viewfinder, some cameras have an electronic viewfinder that electrically captures a captured image and displays an electronic image. The electronic viewfinder easily checks the state of a subject during shooting. By obtaining a still image at the time of photographing, the photographing state can be confirmed in advance, so that there is an advantage that useless photographing can be prevented.

An electronic viewfinder is fixed to a camera, and as disclosed in, for example, Japanese Patent Application Laid-Open No. 62-34138,
Some cameras allow the user to turn the electronic viewfinder toward the user, while others allow the camera to be viewed from either the front or the rear of the camera as disclosed in Japanese Patent Application Laid-Open No. 62-35330.

[Problems to be Solved by the Invention] The electronic viewfinder is of course fixed,
Depending on the shooting environment, the amount of external light that hits the screen of the electronic viewfinder differs depending on the shooting environment. In some cases, the contrast is reduced and the image is difficult to see.

For this reason, the electronic viewfinder used for the camera needs to perform brightness adjustment for changing the gain and level of the video signal. In this case, if the adjustment is performed manually, it takes time and the adjustment operation is troublesome. Alternatively, a rubber member is provided in front of the eyepiece lens so that light does not impinge on the finder screen, and light is blocked by pressing the face against the rubber member so that light does not impinge on the finder screen.

In the ones that use liquid crystal for the electronic viewfinder and display images with transmitted light by the backlight,
In particular, the power consumption of the backlight is large, and the power consumption is large even within a few seconds required for the brightness adjustment.
Furthermore, in the case of a camera that cannot be increased in size due to portability, power is supplied by a battery having a small power capacity of, for example, 3 V or 6 V, and wasteful power loss should be avoided as much as possible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and can quickly and optimally adjust the amount of light of a backlight based on optimal photometric information according to a shooting environment, thereby providing an image with an optimal contrast and suppressing power consumption. It is an object of the present invention to provide a camera provided with an electronic view finder capable of performing such operations.

[Means for Solving the Problems] In order to solve the problems and achieve the object, the present invention is configured as follows.

The invention according to claim 1 is based on an electronic viewfinder having a backlight, a photometric unit having a light receiving element, a light amount varying unit for controlling a light amount of the backlight, and a photometric information detected by the photometric unit. Control means for operating the light amount varying means, and a light receiving direction of the light receiving element is arranged in a direction substantially coincident with a viewing window direction of the electronic view finder. ].

According to the first aspect of the present invention, the backlight of the electronic viewfinder operates the light amount varying means based on the photometric information detected by the photometric means, thereby adjusting the light amount of the backlight. In response to,
Based on the photometric information, the amount of light of the backlight of the electronic viewfinder can be quickly adjusted. Also, since the light receiving direction of the photometric means is a direction substantially matching the viewing window direction of the electronic viewfinder, based on the optimal photometric information,
The light amount of the backlight can be adjusted.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a camera provided with an electronic viewfinder.

In FIG. 1, reference numeral 1 denotes a camera, a photographing lens 2 is provided on the front side, and a release button 3 is provided on the right side. A back cover 4 is provided on the left half on the rear side of the camera 1, and the back cover 4 is opened by an open / close button 5 provided on the side,
The film container 6 is mounted.

The camera 1 includes an electronic viewfinder 8 having a backlight 7 and a photometric device 10 having a light receiving element 9, a light intensity varying device 11 for controlling the light intensity of the backlight 7, and a photometric information detected by the photometric device 10. Light intensity variable means 11
And control means 12 for activating the operation.

The light receiving element 9 of the photometric means 10 is arranged in a direction in which the light receiving direction thereof substantially coincides with the direction of the viewing window of the electronic viewfinder 8, and detects the amount of external light impinging on the viewing window.

Therefore, when strong external light hits the electronic viewfinder 8, for example, in normal light shooting in which the photographer is shooting with the sun behind, the electronic viewfinder 8 becomes very difficult to see. The light is detected, and the light amount information is input to the control means 12 via the photometry means 10.

In the control means 12, since the light amount information detected by the photometric means 10 is large, the light amount varying means 11 is operated by this, and the light amount of the backlight 7 is increased to make it easier to see.

Conversely, when external light impinging on the electronic viewfinder 8 is small, for example, at the time of retrograde photographing with a light source behind the subject, the electronic viewfinder 8 is hardly affected by external light. Therefore, the light amount information detected by the light metering means 10 becomes smaller, and the controller 12 operates the light amount varying means 11 based on this light metering information to reduce the light amount of the backlight,
The glare of the electronic viewfinder 8 is reduced and the power consumption is suppressed.

Further, the photometric means 10 of the electronic viewfinder 8 can also serve as a photometric means for controlling the exposure of the camera to the image recording means. In this case, it is determined from the photometric information of the subject whether the light is backlight or normal light. In this case, there is no need to provide special photometric means, so that the structure is simplified.

Further, a light receiving element 9 is provided directly near the electronic viewfinder 8 as a photometric means 10 for detecting an external light level,
The external light amount that directly strikes the electronic viewfinder 8 may be measured. In this case, it is preferable to form the electronic viewfinder device integrally with the electronic viewfinder device in terms of circuit arrangement.

In addition, it is possible to determine the external light hitting the electronic viewfinder 8 by the photometric means for photographing provided in the camera. In this case, the determination is made by calculating from the position of the electronic viewfinder 8 and the photometry range.

For example, the electronic viewfinder 8 is usually provided for a photographer or the like opposite to the photometric range of photometric means for photographing. Therefore, by detecting the light output of the image sensor for constituting the electronic viewfinder 8 such as a CCD or a MOS imager, the photographing screen is divided into a plurality of parts to perform the photometry, and by comparing the divided parts, the reverse measurement is detected. You can do so.

Note that the light receiving element 9 is unnecessary when the light receiving element 9 is also used as an image sensor or a photometric element of a camera.

FIG. 2 shows an embodiment in which the brightness level is switched.

This embodiment shows a case where the brightness level is switched to three levels, and the brightness is a step value, so that the control is simple. In addition, since the switching of the brightness has a hysteresis characteristic, the brightness does not change due to a small change in the external light luminance near the threshold, so that the flicker of the screen of the electronic viewfinder 8 is suppressed. You can also.

Also, the human eye, in the change of dark → bright, bright → dark,
Even with the same brightness, since the former feels bright and the latter feels dark, the compensation effect can be obtained by providing a hysteresis characteristic.

3rd electronic viewfinder backlight control circuit
Shown in the figure.

In FIG. 3, cadmium sulfide CdS is used as a light receiving element.
Is a detecting means for converting the intensity of light into a resistance value. The resistance value decreases as the light intensity increases, and the resistance value increases as the light intensity decreases. The cadmium sulfide CdS is connected to the battery E via the capacitor C1 and the primary side of the transformer T1. A backlight 7 is connected to the secondary side of the transformer T1, and the backlight 7 is formed of, for example, a fluorescent tube.

Cadmium sulfide CdS is grounded via a variable resistor R1 connected in series, and a variable resistor R2 is connected in parallel. The base of the transistor Tr1 is connected to an intermediate point between the cadmium sulfide CdS and the capacitor C1. The emitter of the transistor Tr1 is connected to the battery E, the collector is connected to the base of the transistor Tr2, the emitter of the transistor Tr2 is grounded, and the collector is connected to an intermediate point between the capacitor C1 and the transformer T1.

Therefore, as the external light becomes brighter, the resistance value of the cadmium sulfide CdS decreases, and the current Ib1 flowing to the base of the transistor Tr1 increases. According to this, the transistor Tr2
Since the base current Ib2 of the transistor T2 increases, the collector current Ic flowing through the transistor Tr2 increases, and the frequency of the oscillation circuit formed on the primary side of the transformer T1 increases.
The backlight 7 connected to the secondary side of T1 becomes bright.

Next, another embodiment of the backlight control circuit of the electronic viewfinder is shown in FIG.

In this embodiment, an image sensor 20 such as a CCD or a MOS imager is used as a photometric device, and an image signal from the image sensor 20 is amplified via a preamplifier 21 and noise is reduced by a CDS circuit 22 by a correlated double sampling method. The signal is removed and input to the matrix circuit 23. The matrix circuit 23 separates the color signals into color difference signals, and the color signal output circuit 24 extracts the primary color signals.

On the other hand, the imaging signal from the imaging device 20 is input to the synchronization circuit 27 via the driver 26, and the color signal reproduction circuit 25 sends the signal to the LCD monitor 30 via the X driver 28 and the Y driver 29 based on the synchronization signal. As a result, an image of the subject is displayed on the LCD monitor 30.

The color signal reproducing circuit 25 and the synchronizing circuit 27 are connected to a CPU 31, which receives photometric information from a photometric circuit 32, outputs a control signal based on the photometric information, and outputs a control signal to the base of the transistor Tr1. The transistors Tr21 to Tr2n connected via R21 to R2n are selected and made conductive. The base current of the transistor Tr1 is controlled by the conduction of the selected transistors Tr21 to Tr2n, the current of the transistor Tr2 is also controlled by the conduction of the transistor Tr1, and the frequency of the primary side of the transformer T1 changes.
The brightness of the backlight 7 connected to the secondary side is adjusted.

The backlight 7 includes a cold cathode tube and an EL in addition to a fluorescent tube.
It can be composed of a display or the like.

[Effect of the Invention] As described above, according to the first aspect of the present invention, the backlight of the electronic viewfinder operates the light quantity varying means based on the photometry information detected by the photometry means, thereby the light quantity of the backlight. , The amount of light of the backlight of the electronic viewfinder can be quickly adjusted according to the shooting environment.

Further, since the light receiving direction of the measuring means is substantially the same as the direction of the viewing window of the electronic viewfinder, the amount of light of the backlight can be adjusted based on the optimal light measuring means.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a camera provided with an electronic viewfinder, FIG. 2 is a diagram showing an embodiment in which a brightness level is switched, and FIG. 3 is a backlight adjustment control circuit of a backlight of the electronic viewfinder. FIG. 4 is a circuit diagram of a backlight adjustment control circuit for another backlight of the electronic viewfinder. In the figure, reference numeral 1 denotes a camera, 7 denotes a backlight, 8 denotes an electronic viewfinder, 9 denotes a light receiving element, 10 denotes a photometric unit, 11 denotes a light amount varying unit, and 12 denotes a control unit.

Claims (1)

(57) [Claims] An electronic viewfinder having a backlight; photometric means having a light receiving element; a light quantity varying means for controlling a light quantity of the backlight; and a light quantity varying means based on photometric information detected by the photometric means. A camera having an electronic viewfinder, wherein the light receiving direction of the light receiving element is arranged in a direction substantially coincident with a viewing window direction of the electronic viewfinder.