JPH03255431A - Camera with electronic finder - Google Patents

Abstract

PURPOSE:To reduce the cost of the light reception part of an image pickup means and to display an object of low luminance by changing the frequency of a reference clock based on the object luminance measured by a light measuring means to change the frequency of a driving signal of the image pickup means, a display means, or the like. CONSTITUTION:An AE sensor 26 measures the luminance of the object to output a signal indicating the object luminance to a reference frequency generating circuit 28. This circuit 28 changes the reference frequency in accordance with this signal, and a synchronizing circuit 18 outputs a reference clock fck and horizontal and vertical synchronizing signals VD and HD obtained by frequency division of this clock fck to a CCD driver 14. Consequently, a read pulse phiTG, a vertical driving pulse phiV, and a horizontal driving pulse phiH outputted from the CCD driver 14 are synchronously controlled. Synchronizing signals outputted to a signal processing circuit 16 for display and an X driver are controlled based on the frequency of the reference clock fck. Thus, the cost of the light reception part of an electronic finder is reduced, and the object of low luminance can be displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a silver halide camera, and more particularly to a camera with an electronic viewfinder that electrically displays a subject image.

[Conventional technology]

Generally, electronic viewfinders are used in video cameras, but a silver halide camera employing an electronic viewfinder has also been proposed (Japanese Patent Application Laid-Open No. 63-284528).

[Problem to be solved by the invention: By the way, by using a strobe, etc., a silver-halide camera can photograph subjects with lower brightness than a video camera, but an electronic viewfinder cannot photograph such low-brightness subjects. There is a problem that the image cannot be displayed clearly.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a camera with an electronic viewfinder that can have a light-receiving section of the electronic viewfinder at a low cost and can also display low-luminance objects.

[i1! Means for Solving the Problem 2 In order to achieve the above object, the present invention provides various driving signals generated based on a reference clock generated from a reference frequency generating means to improve each circuit including an imaging means and a display means. In a camera with an electronic viewfinder that electrically displays a subject image on the display means to be transferred to a silver halide film, the camera includes a photometer for measuring the brightness of the subject; and means for changing the frequency of the reference clock generated from the reference frequency generating means based on the reference frequency generating means.

[Effect]

According to the standards of video cameras and electronic still cameras, the frequency of the synchronizing signal cannot be varied, and there is a limit to the charge accumulation time in the imaging means (maximum 1760 seconds in the case of the NTSC system). It is noted that there is no standard restriction on the frequency of the drive signal that drives the imaging means, since it is only necessary to display the image on the image.

That is, according to the present invention, the frequency of the reference clock generated from the reference frequency generation means is changed based on the subject brightness measured by the photometry means, thereby generating a drive signal for driving the imaging means, display means, etc. I am trying to change the frequency of.

〔Example〕

Preferred embodiments of a camera with an electronic viewfinder according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram of essential parts showing an embodiment of a camera with an electronic viewfinder according to the present invention. In the figure, light from a subject is imaged on a light receiving section of a solid-state image sensor (CCD) 12 via a finder lens 10.

Each photoelectric conversion element arrayed two-dimensionally on the CCD 12 has
A signal corresponding to the intensity of light incident on that portion is generated, and this signal charge is accumulated in each photoelectric conversion element for one vertical period (one field period). Then, during the vertical retrace period, a read pulse φ is applied from a CCD driver 14, which will be described later.
Signal charges accumulated by the TG are read out to the vertical transfer CCD.

The signal charge read out to the vertical transfer CCD is sequentially transferred in the direction of the horizontal transfer CCD by applying a vertical drive pulse φ from the CCD driver 14 to the vertical transfer CCD every horizontal period (IH). be done.

Then, the signal charge transferred to the most bonded stage of the vertical transfer CCD is sequentially transferred to the horizontal transfer stage every horizontal retrace period.
The horizontal drive pulse φ8 applied from the CCD driver 14 during the next horizontal scanning period is applied to the horizontal transfer CCD, so that it is sequentially extracted as a signal voltage and applied to the display signal processing circuit 16.

In this way, the signal charges accumulated in the photoelectric conversion element during one field period are sequentially output as signal voltages during the next one field period.

The display signal processing circuit 16 converts the input signal charge input from the CCD 12 into an image signal for liquid crystal display based on a synchronization signal applied from a synchronization circuit 18 (described later), and outputs this to a liquid crystal display (LCD) 20. .

The LCD 20 is disposed as a liquid crystal finder on the back of the camera, for example, and includes an X driver 22 that outputs an LCD drive signal in synchronization with a synchronization signal applied from the synchronization circuit 18.
and Y driver 24, and displays the finder image on a liquid crystal display based on the image signal input from the display signal processing circuit 116.

Now, the AE sensor 26 measures the brightness of the subject and outputs a signal indicating the subject brightness to the reference frequency generation circuit 28.

The reference frequency generation circuit 28 responds to the signal from the AE sensor 26 to generate a reference frequency 2Il! It has a function of changing two numbers, and outputs a reference clock fck with a lower frequency as the brightness of the subject becomes darker, and outputs a reference clock fck with a higher frequency as the brightness of the subject becomes brighter.

The synchronization circuit 18 generates signals for driving each of the circuits described above based on the reference clock fck applied from the reference frequency generation circuit 28. That is, the synchronization circuit 18 outputs the reference clock fck and the horizontal synchronization signal VD and vertical synchronization signal HD obtained by frequency-dividing the reference clock fck to the CCD driver 14, thereby causing the CCD driver 14 to output the read signal S. Pulse φTG, vertical drive pulse φ9, and horizontal drive pulse φH are synchronously controlled. Also,
The synchronization signal output to the display signal processing circuit 16 and the X driver 24 is also controlled based on the frequency of the reference clock fck.

According to the camera with an electronic viewfinder configured as described above, the frequency of the reference clock, which is the reference for synchronously controlling each circuit, is changed depending on the brightness and darkness of the subject. period (usually 176
0 seconds>, that is, the charge accumulation time in each photoelectric conversion element of the CCD 12 becomes longer, and as a result, it becomes possible to obtain sufficient object information even for a dark object.

In this embodiment, an LCD is used as the display means, but the present invention is not limited to this, and a small CRT may also be used. In addition, CCD'! is used as an imaging means. :: For example, an imaging device using a CID or a transistor-type imaging device (MOS) may be used.

〔Effect of the invention〕

As explained above, according to the camera with an electronic viewfinder according to the present invention, the diaphragm can be constructed electrically and is not subject to mechanical restrictions, so that the light receiving section of the imaging means can be made inexpensive. Furthermore, by increasing the image display interval, it is also possible to display low-luminance objects.

[Brief explanation of drawings]

FIG. 1 is a block diagram of essential parts showing an embodiment of a camera with an electronic funder according to the present invention. DESCRIPTION OF SYMBOLS 10... Lens for finder, 12... Solid-state imaging device (CCD), 14... CCD driver 16... Signal processing circuit for display, Engineering 8... Synchronization circuit, 20... Liquid crystal display (
LCD), 22...X driver, 24-Y driver,
26...AE sensor, 28...Reference frequency generation circuit.

Claims (1)

[Claims] Various drive signals generated based on a reference clock generated from a reference frequency generating means drive various circuits including an imaging means and a display means to produce an object image to be imprinted on a silver halide film. A camera with an electronic viewfinder that electrically displays on the display means, a photometry means for measuring the brightness of a subject, and a reference clock generated from the reference frequency generation means based on the subject brightness measured by the photometry means. A camera with an electronic viewfinder, comprising: means for changing the frequency.