JP2754837B2 - Camera with electronic viewfinder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silver halide camera, and more particularly to a camera with an electronic finder that electrically displays a subject image.

[Conventional technology]

In general, an electronic finder is used for a video camera, but an electronic finder adopting an electronic finder for a silver halide camera has been proposed (Japanese Patent Laid-Open No. 63-284528).

[Problems to be solved by the invention]

By the way, silver halide cameras use strobes, etc.
Although it is possible to photograph a subject with lower brightness than a video camera, there is a problem that the manufacture of such a low-brightness subject cannot be clearly displayed with an electronic viewfinder.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a camera with an electronic finder that can reduce the cost of a light receiving unit of the electronic finder and can display a low-luminance object.

[Means for solving the problem]

According to the present invention, in order to achieve the above object, various circuits including an image pickup unit and a display unit are driven by various drive signals generated based on a reference clock generated from a reference frequency generation unit, so that a silver halide film is formed. In a camera with an electronic finder for electrically displaying a subject image to be projected on the display means, a photometric means for measuring the brightness of the subject, and the reference frequency generation as the subject brightness measured by the photometric means decreases. The frequency of the reference clock generated from the means is lowered, and the frequency of the reference clock generated from the reference frequency generating means is increased as the luminance of the object increases, and the brightness of the object image displayed on the display means is increased. Adjustment means.

[Action]

In video cameras and electronic still cameras, the frequency of the synchronization signal cannot be changed due to the standard, and the charge storage time in the imaging means is limited (up to 1/60 second in the case of the NTSC system).
The present invention focuses on the fact that there is no standard restriction on the frequency of the drive signal for driving the imaging means, since it is only necessary to be able to display on the display means mounted on the camera.

That is, according to the present invention, the frequency of the reference clock generated from the reference frequency generating means is changed based on the luminance of the subject measured by the photometric means, whereby the driving signal for driving the imaging means, the display means, etc. Is changed.

〔Example〕

Hereinafter, preferred embodiments of a camera with an electronic finder according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a main block diagram showing an embodiment of a camera with an electronic finder according to the present invention. In FIG. 1, light from a subject is focused on a light receiving unit of a solid-state imaging device (CCD) 12 via a finder lens 10.

Each of the two-dimensionally arranged photoelectric conversion elements of the CCD 12 generates a signal corresponding to the intensity of light incident on that part, and this signal charge is applied to each photoelectric conversion element for one vertical period (one field period). Stored. Then, in the vertical blanking period, signal charge accumulated by the read pulse phi _TG applied from the CCD driver 14 to be described later is read out to the vertical transfer CCD.

The signal charges read out to the vertical transfer CCD, by a vertical drive pulse phi _V applied from the CCD driver 14 is applied to the vertical transfer CCD every horizontal period (IH), sequentially transferred toward the horizontal transfer CCD Is done.

Then, the signal charges transferred to the final stage of the vertical transfer CCD are sequentially transferred to the horizontal transfer stage every horizontal retrace period,
A horizontal drive pulse φ _H applied from the CCD driver 14 during the next one horizontal scanning period is applied to the horizontal transfer CCD, so that the signal is sequentially extracted as a signal voltage and applied to the display signal processing circuit 16.

Thus, the signal charges accumulated in the photoelectric conversion element during one field period are sequentially output as a signal voltage during the next one field period.

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

The LCD 20 is provided as a liquid crystal finder, for example, on the back of the camera, and is driven by an X driver 22 and a Y driver 24 that output an LCD drive signal in synchronization with a synchronization signal applied from a synchronization circuit 18. A finder image is displayed on a liquid crystal display based on an image signal input from the circuit 16.

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 has a function of changing a reference frequency in accordance with a signal from the AE sensor 26, and the lower frequency of the reference clock fck as the subject luminance becomes darker.
And outputs a reference clock fck having a higher frequency as the subject brightness becomes brighter.

The synchronization circuit 18 generates a signal for driving each of the above-described circuits 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, the horizontal synchronization signal VD obtained by dividing the reference clock fck and the vertical synchronization signal HD to the CCD driver 14, and thereby the read pulse output from the CCD driver 14. φ _TG , vertical drive pulse φ _V , and horizontal drive pulse φ _H are synchronously controlled. Further, 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 the electronic finder having the above-described configuration, the frequency of the reference clock serving as a reference for synchronously controlling each circuit is changed according to the brightness of the subject. (Usually 1/60
Sec), that is, the charge accumulation time in each photoelectric conversion element of the CCD 12 becomes longer, whereby sufficient subject information can be obtained even for a dark subject.

In this embodiment, the LCD is used as the display means. However, the present invention is not limited to this, and a small CRT may be used. Further, the imaging means is not limited to a CCD, and for example, a CID
The device may be used for imaging, and a MOS transistor type imaging device may be used.

〔The invention's effect〕

As described above, according to the camera with the electronic finder according to the present invention, the diaphragm can be formed electrically and there is no mechanical restriction, so that the light receiving section of the imaging means can be inexpensive. Also, by setting an image display interval, a low-luminance subject can be displayed.

[Brief description of the drawings]

FIG. 1 is a main block diagram showing an embodiment of a camera with an electronic fan according to the present invention. 10: finder lens, 12: solid-state image sensor (CCD), 14: CCD driver, 16: display signal processing circuit, 18: synchronous circuit, 20: liquid crystal display (LCD), 22 ... ... X driver, 24 ... Y driver, 26 ... AE sensor, 28 ... Reference frequency generation circuit.

Claims (1)

(57) [Claims] An image of an object to be printed on a silver halide film is driven by driving various circuits including an image pickup means and a display means by various drive signals generated based on a reference clock generated from a reference frequency generation means. An electronic viewfinder-equipped camera for electrically displaying on the display means, a photometric means for measuring the brightness of the subject, and a reference clock generated from the reference frequency generating means as the subject brightness measured by the photometric means decreases. Means for lowering the frequency of the object clock, increasing the frequency of the reference clock generated from the reference frequency generating means as the object luminance increases, and adjusting the brightness of the object image displayed on the display means. A camera with an electronic viewfinder.