JPS59161984A - Display device within electro-viewfinder of television camera - Google Patents

Abstract

PURPOSE:To understand easily an underexposure or overexposure state by providing a photodetector which converts the brightness of an object into the electric quantity and delivering an alarm when the signal sent from the photodetector is outside an exposure controllable range. CONSTITUTION:The output signal sent from a photometric circuit 20 incorporating a photodetector is sent to an inverse terminal of a comparator 21, a non-inverse terminal of a comparator 22 and a non-inverse terminal of a differential amplifier 25 respectively. The comparator 21 delivers an H level when the output signal of the circuit 20 is smaller than the lower limit of an exposure amount controllable range; while the comparator 22 delivers an H level when the output signal is larger than the upper limit of said range. Both comparators 21 and 22 deliver no output when the brightness of an object is proper and the control is possible for exposure amount. Therefore a bar blinking circuit 24 has no actuation, and a bar position shifting circuit 26 is actuated by the output of the amplifier 25. Then the bar position varies in response to the brightness of the object. When the object is outside the exposure controllable range, either one of comparators 21 and 22 delivers output to actuate the circuit 24. Thus the bar blinks to produce an alarm.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device in an electroviewfinder in a television camera.

In conventional television cameras, various display devices are provided within the electroviewfinder, one of which is a device that displays the open/closed state of the iris. As this display device, there is one shown in Fig. 1.
In order to perform proper exposure, the degree of opening of the iris is determined according to the brightness of the subject, and the display position of the iris open/closed state display bar 10 is changed in accordance with this degree of opening. Therefore, if the bar 10 is located at the top, it indicates that the iris opening is large and the brightness of the subject is low, and conversely, if the bar 10 is located at the bottom, the iris opening is large and the brightness of the subject is low. The low brightness indicates that the brightness of the subject at that time is high. Note that l is an electronic viewfinder, which is convenient for the photographer because it allows him to see the brightness of the subject at any given time.

However, the conventional example described above has a problem in that underexposure or overexposure is not noticed during photographing. In other words, in the conventional example, the bar 10 moves within a predetermined range, and when the brightness of the subject decreases, the position of the bar 10 gradually rises to -, which is the lower limit of the exposure adjustment range. At position 11 the bar 10 stops moving. For this.

When /<-10 is at the lower limit position 11 of the exposure amount adjustable range, it is unclear whether the exposure amount can be automatically adjusted or whether the exposure is insufficient.

Conversely, if the bar 10 is at the 4-limit position 12 of the exposure amount adjustable range, it is unclear whether the exposure amount can be automatically adjusted or whether there is overexposure.

The present invention has been made in view of the above-mentioned conventional problems, and is a display device in which the state of underexposure or overexposure can be easily known in a display device in an electro-view finder of a television camera. The purpose is to provide the following.

To achieve this objective, the present invention has a light receiving element that converts the brightness of a subject of a television camera into an electrical quantity, and a light receiving element that is activated when the value of a signal from this light receiving element is outside the adjustable exposure range. The present invention is characterized in that it has a comparison circuit that operates, and a warning means that visually warns within the electroview finder when the comparison circuit is activated.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings. Note that the same members are given the same reference numerals. FIG. 1 is a circuit diagram showing one embodiment of the present invention. A photometric circuit 20 is provided, and this photometric circuit 20 includes a built-in light receiving element that converts the brightness of a subject of a television camera into an amount of electricity. Moreover, the output signal of this photometric circuit 20 is
an inverting terminal of the comparator circuit 21, a non-inverting terminal of the comparator circuit 22,
The signal is sent to the non-inverting terminal of the differential amplifier 25. In addition, 2
Reference voltage sources 1s, 22s, and 2js have different voltages. Here, the comparison circuit 21 outputs an H level signal when the output reliability value of the photometry circuit 20 is smaller than the lower limit of the exposure adjustment range, and the comparison circuit 22 outputs an H level signal when the output reliability value of the photometry circuit 20 is smaller than the lower limit of the exposure adjustment range. It outputs an H level signal when the value is greater than the upper limit of the possible range. A differential amplifier 25 connects the output voltage of the photometric circuit 20 and the reference voltage source 2.
It outputs according to the difference from the voltage of 5 seconds. The bar blinking circuit 24 blinks the bar 10 when the output signal of the OR circuit 23 is at H level. The bar position moving circuit 26 operates to move the bar 10 closer to the upper limit position 12 as the value of the output signal of the differential amplifier 25 increases.

Next, the operation of the above embodiment will be explained. First, when the brightness of the subject is appropriate and the exposure amount can be adjusted automatically, both the comparison circuits 21 and 22 do not output, so the common flashing circuit 24 does not operate and the bar 10 does not flash. In this case, depending on the brightness of the subject,
Bar 10 changes its position. On the other hand, if the brightness of the subject falls below a predetermined value (a range in which exposure can be adjusted automatically), the comparison circuit 21 outputs an output, and the blinking circuit 24 is activated, as shown in FIG. As shown in (A), the bar 10 blinks at the lower limit position 11. Conversely, when the brightness of the subject is higher than the predetermined value, the comparison circuit 22
is output, the bar blinking circuit 24 is activated, and the bar 10 blinks at the upper limit position 12, as shown in FIG. 3(B).

Therefore, even during shooting, the photographer can easily visually recognize underexposure or overexposure.

In the embodiment shown in FIG. 82, the blinking circuit 24 is activated when the comparator circuits 21 and 22 output an H level signal, but this logic may be reversed. That is, instead of the comparison circuits 21 and 22, a comparison circuit that operates when the exposure amount adjustment range is outside the range may be used. The bar IO corresponds to one of the warning means that visually warns within the electroview finder when the comparison circuits 21 and 22 are activated.

This warning means may be one that changes the brightness of the bar 10, such as making it brighter, when the comparator circuit 10 is activated, or one that changes the color of the bar 10.

Furthermore, the following display may be used in conjunction with the iris open/close state display.

FIG. 4 shows the photometry positions in spot photometry. FIG. 4(A) shows a case where photometry is performed on a subject located at the center of the finder 1, and there is a photometry position display 31 at the center of the finder. Figure 4 (B) shows the case of metering a subject located at the center F side of the finder.
There is a photometry position display 32 at the bottom center of the finder. These photometric position displays 31 and 32 can be realized by making the brightness of that part higher (or lower) than the surrounding area.

Furthermore, in the embodiments of FIGS. 4A and 4B, the spot photometry display 31, 37 may be used in common with the autofocus display. By doing this,
The complexity of these displays is reduced.

FIG. 5 shows the white balance displayed. In a color video camera, it is necessary to adjust the white balance, and when the adjustment is completed, a white balance adjustment completed display 41 is displayed in a corner of the viewfinder, as shown in Figure 5 (A). will be carried out. Of course, it may be displayed in other corners.

Further, the white balance may be adjusted manually, and in that case, the degree of adjustment is displayed on the display 42. For example, the closer the display 42 is to the center position, the better the white balance is adjusted.

Note that both of FIGS. 5(A) and 5(B) can also be used together. Further, it is preferable to blink the display 41 when adjusting the white balance, and this is particularly important for confirmation when adjusting the white balance.

FIG. 6 shows a synthesis of the above embodiments, and also takes other functions into consideration. Here, the display 43 not only indicates that the white balance has been adjusted, but also indicates that the image is in a fade state. Black may be used to indicate that the white balance has been adjusted, or may be displayed by blinking. In this case, white is used to indicate the fade state. In addition, display 51
indicates the recording status, and the display blinks when recording is stopped.In the embodiment shown in FIG. In addition to displaying the white balance, ig
The J adjustment state may be displayed. In this case, the opening degree of the iris is displayed in white, and the white balance is displayed in black.

As described in Section I, the present invention has the effect that when there is underexposure or overexposure in the display device in the electronic viewfinder of a television camera, the condition can be easily known.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a display in an electroview finder of a conventional television camera, FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIG. 3 (A). (B) is a diagram showing the case where electro-optical display is also performed in the above embodiment, and FIGS. 5(A) and (B) are diagrams each showing the case where white balance display is also performed in the embodiment of FIG. 2. 6 are diagrams showing other embodiments of the present invention. ■...Electro viewfinder, 10...Iris open/close status display bar, 21.22...Comparison circuit, 2
5...Differential amplifier. Patent applicant: Asahi Optical Industry Co., Ltd. Agent: Kunio Miura Figure 1 Figure 1 Figure 3 Figure 4 (A) Figure 6 Figure 5 (B) ■

Claims (1)

[Claims] A light-receiving element that converts the brightness of the subject of the TV camera into an electrical quantity, a comparison circuit that operates when the value of the signal from this light-receiving element is outside the adjustable exposure range, and when this comparison circuit operates. 41. A display device in an electro-viewfinder in a television camera, characterized in that a warning means for visually warning in the electro-viewfinder is provided.