JPS60170A - Television camera - Google Patents

Abstract

PURPOSE:To make photometry and a photmetric pattern display easy by providing a control means for utilizing a part of an image pickup output to perform photometry and for giving only the image pickup output utilized for photometry to a display. CONSTITUTION:A luminance signal obtained by a luminance process circuit 10 is removed by an analog gate 15 only of a part subjected to photometry and averaged by an averaging circuit 8 to obtain a diaphragm signal, which is given to a diaphragm controller 9 to control a diaphragm 2. Various photometric patterns are realized by changing a gate signal from a gate signal generating circuit 16 in this case. In turning a switch 19 to the position of an SH command signal generating circuit 5, a conventional SH operation is performed and all images of an object are displayed to an electronic view finder 13. On the other hand, in turning the switch 19 to the position of a weighted SH command signal generating circuit 17, the photometric pattern decided by the gate signal generating circuit 16 is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a television camera, and particularly to improvements in its photometric system.

(Prior Art?r1) A television camera requires a device that controls the amount of light incident on the imaging means to a constant amount. In other words, regardless of the use of the television camera or public safety camera, the S is always good.
It is necessary to obtain a certain level of video signal output with N ratio,
For this reason, the scene incident on the imaging means must be at an appropriate level that is sufficiently larger than the dark current level of the imaging means and partially smaller than the saturation level. Automatic sight control equipment (hereinafter abbreviated as ALC equipment) automatically performs such control.
It is.

FIG. 1 shows an example of a television camera using a conventional ALG@ arrangement. In FIG. 1, 1PL and 1bFi,
Imaging optical system, 2-digit aperture, 5 is solid-state image sensor, 4 is sample and hold (hereinafter abbreviated as S, H) circuit, 5 is S, H
, command signal generation circuit, 6 is an analog multiplier, 7 is a weighting signal generation circuit, 8 is an averaging circuit, 9 is an aperture control device, 10 is a brightness gloss circuit, 11 is a color process circuit, 12 1 is an NTSC encoder, 15 is an electronic viewfinder (EVF), and 14 is an output terminal.

The light incident on the camera is optical system 1a, aperture 2 and optical system 1.
13, it reaches the solid-state image sensor 6 and is converted into an electrical signal. The output of the solid-state image sensor B is converted into a continuous signal by the S, H0 circuit 4, and then applied to a brightness process circuit 10 and a color process circuit 11, where a brightness output and a color output are obtained. A signal is extracted from the middle of the brightness process O and sent to multiplier 6.
Accordingly, the weighting generated by the signal generation circuit 7 is multiplied by the signal and averaged by the averaging circuit 8 to become the aperture control signal. This aperture control signal causes the aperture control frame*:
9 controls the aperture of the diaphragm 2; Above, 2-3-4-10
The elements indicated by -6-8-9 constitute a closed loop, and maintain the amount of light incident on the solid-state image sensor 3 constant.

Note that the outputs of the luminance process circuit 10 and the color process circuit 11 are given to the NTSC encoder 12, where they are converted into NTSC encoders.
The C signal is converted into a C signal, and the subject image is displayed on the electronic viewfinder 13 and outputted from the terminal 14.

In Fig. 2, the weighting in Fig. 1 shows the output waveform of the signal generation circuit 7. Fig. 2 (a) and (1,) show the horizontal section and vertical section in the case of center-weighted average photometry. When weighting as shown in Figures 2(,) and (b) is done using signals, the central part of the trap subject is heavily weighted, as shown in Figure 6(a). Average photometry is obtained.

Figures 2 (C) and (d) show the horizontal and vertical intervals in the case of center-part photometry;
Weighting as shown in d) can be done using signals as shown in Figure 6(b).
As shown in , center-part metering is achieved in which only the center of the subject is sidelit.

In the conventional example described above, weighting involves changing the waveform of the signal.
Therefore, it is possible to arbitrarily change the ALC photometry pattern.
However, since the signal generation circuit for weighting is an analysis circuit, an enlarged scale circuit is required to generate a complicated pattern. Furthermore, when attempting to display such a photometric pattern in an electronic viewfinder, there are also disadvantages such as the need for an additional pattern generator to generate a complex display pattern corresponding to the photometric pattern.

(Purpose) In view of the above circumstances, the present invention provides a television camera that makes it possible to perform photometry using a part of the imaging output and to display the photometry pattern at a low cost in an emergency office. The purpose is to provide

(Embodiments) Hereinafter, embodiments of the present invention will be described with continued reference to the attached drawings.

First, referring to FIG. 4, K. In the figure, the same reference numerals as in FIG. 1 refer to the same components. In the figure,
15 is an analog gate for extracting a part of the luminance signal for photometry; 1611. A gate signal generation circuit generates a gate signal for controlling the analog gate 15, 17 is a weighting S, H, and command signal generation circuit controlled by the gate signal from the gate signal generation circuit 16, and 18 generates a reference clock signal. 19 is a switch for displaying a photometric pattern.

In such a configuration, only the photometric portion of the luminance signal obtained from the luminance processing circuit 10 is taken out by the analog gate 15, averaged by the averaging circuit 8 to become an aperture control signal, and provided to the aperture control device 9. to control aperture 2. At this time, the 0 photometry pattern display switch 19, which can realize various photometry patterns by switching the gate signal generated by the gate signal generation circuit 16, is operated in 8. H,
If the command signal generation circuit 5 side is set, normal S, H operations are performed in this state, and the electronic viewfinder 1
6, the entire image of the subject is displayed. On the other hand, when the photometric pattern display switch 19 is set to the weighting S, I-1 command signal generating circuit 17 side, a photometric pattern determined by the gate signal from the gate signal generating circuit 16 is displayed. This will be explained in detail with reference to FIG. Figure 5 (-1 is the output signal of solid-state image sensor B, (bl
Company S, H, output signal of command signal generation circuit 5, (c)
(d) shows the output signal of the gate signal generation circuit 16, and (d) shows the output signal of the weighting S, H, and command signal generation circuit 17, respectively. If you do not want to display the photometric pattern, turn switch 19 to circuit 5 (Ill K, then S,
Normal S, H by H, command signal (Fig. 5(b))
, perform the action. As a result, the entire image of the subject is displayed on the finder 16. On the other hand, when displaying the photometric pattern, switch 19 is set to circuit 171111, weighting S, H, command signal (FIG. 5(d)) is applied to S, H6.
perform an action. Here, weighting S, H, command signal (
Figure 5(d)) shows S, H, command signals (Figure 5(b))
), the gate signal (Fig. 5 (C)) extracts the part where it is in the state of...
C)) It is a balanced signal with one pulse added at the falling edge of the signal. This signal causes analog 1 gog gate 15 to open and y, S, I (, S, H) operation to be started by circuit 4, and when the analog goto is closed, the operation output signal (Fig. 5 (FL)) is activated. The dark areas between the signals are changed to S, H, and L, and this is maintained from then on. With this operation, the j-1 image of the area to be photometered appears on the electronic viewfinder 160 screen, and the photometry pattern can be confirmed. .

Incidentally, as a modification of this embodiment, the analog gate 15 is omitted and the luminance signal obtained during the luminance process is sent to the averaging circuit 8.
It is also possible to give it directly to . In that case, switch 1
When switch 9 is set to the circuit 5 side, full-scale average metering is performed, and the entire image of the subject is displayed on the electronic viewfinder 13. On the other hand, when switch 19 is set to the circuit 17 side, partial metering is performed, and at this time, the electronic viewfinder Only the image of the portion of the subject corresponding to the photometered portion is displayed on the finder 13.

In the above embodiment, as shown in FIG. 5(d), the S, H, and command signals ((), and one H(A') were added at the falling edge of the gate signal in FIG. 5(C). , the same effect can be obtained by widening the pulse width only at the falling edge of this good signal [7] by stocking the dark signal, or by separately resetting S, H, and circuits 4 in 1. .tadaS,H.

The circuit 4 can be configured to be automatically reset after a certain period of time has elapsed since the start of holding. However, using the S, H circuit (・weighting -f3'i: tgl: with #S, H, pressure to supply the command signal. Also, this S,
If the H9 circuit is configured to be reset after a certain period of time after being held, or to be reset automatically, it is possible to increase the measurement 5Y signal when the photometry area on the screen is small. Furthermore, if the S, H1 circuit is used, the output of the photometric signal may be the output of the solid-state projection element.

(Effects) As explained above, according to the Xylophone 91V, it is very simple and therefore easy to operate, and it is an inexpensive projection means that can perform photometry using a part of the imaging output and the photometry pattern at this time. This makes it possible to display the area to be photometered very clearly, which is very useful in television cameras.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the circuit configuration of an example of a television camera using a conventional ALG device, and Fig. 2 explains the operation of the ALO device in the camera shown in Fig. 1. Figure 3 is a schematic diagram showing an example of a photometric pattern obtained from the ALU device described above; Figure 5 is a block diagram showing a schematic configuration of a circuit system according to an embodiment of the present invention; FIG. 4 is a signal waveform diagram for explaining the operation of the ALOP position in the camera shown in the fourth figure. 3..Fist..Imaging means 13..Couple..Disgray means

Claims (1)

[Claims] an imaging means; a display means for projecting a subject image using the imaging output of the imaging means; a photometry means for performing photometry using a part of the imaging output; and a display means for displaying only the imaging output used for the photometry. Television camera 0 comprising control means for imparting to the means