JPS61131973A - Video camera - Google Patents

Abstract

PURPOSE:To display an external video signal independently of a video output by using a reproduced output of video tape recorders of the VHS system and the beta system to control a switch provided between a video output circuit and an electronic view finder. CONSTITUTION:A picked-up image by a video camera 1 is fed from the video output circuit 3 to a VHS system video tape recorder 6 via an output transistor (TR)Q0 and fed to an electronic viewfinder 2 via a switch circuit 8 and an input TRQi. The reproduced output of the recorder 6 is fed to the finder 2 via the circuit 8 and the Qi and the Q0 is turned off by a DC signal in the reproduced output. On the other hand, the picked-up image of the camera 1 is fed to the beta type video recorder 7 via the TRQ0 and fed to the finder 2. The reproduced output of the recorder 7 is fed to the finder 2, a Q1 in the circuit 8 is turned off to stop automatically the output of the circuit 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video camera that can be connected to either a VUS or β video tape recorder.

[Conventional technology]

For home use multiple video tape recorders.

β method and VH8 method are available, and connection with video camera is also possible.
A unique connection method is used for each method. That is, in the β system, the signal path from the video camera to the video tape recorder and the signal path from the video tape recorder to the video camera's viewfinder are independent from each other, whereas in the VH8 system, the signal path from the video camera to the video tape recorder and the signal path from the video tape recorder to the viewfinder of the video camera are independent of each other. A predetermined DC signal is superimposed on the signal sent from the video tape recorder to the viewfinder of the video camera, and the signal path is switched.

[Problem that the invention seeks to solve]

The above-mentioned conventional video cameras are classified into β system and VH8 system, depending on the system standard to which they are connected.

Therefore, a single unit can also be used as a β format video tape recorder.
There are no devices that can be connected to 8 format video tape recorders, and compatibility can only be achieved by using a special adapter, which leads to problems such as a decline in the desire of users to purchase and a limited number of purchasers. there were.

[Means for solving problems]

The present invention solves the above problems, and includes an output transistor that outputs a video signal to an electronic viewfinder and an externally connected video tape recorder, and a video signal from the output transistor and a first DC level. A first transistor to which a first external video signal is input and a second transistor to which a second external video signal having a second DC level is input are a differential pair, and the differential output is the electronic a switch circuit that supplies the finder and operates properly when the second external video signal is input;
and a third transistor that turns off the first transistor, and the output transistor is configured to turn off when the first external video signal is supplied to the differential pair. The gist of this is that

[Effect]

The present invention provides a first circuit that constitutes a differential pair provided between a video output circuit and an electronic viewfinder. Of the second transistors, the first transistor is supplied with the video output of the VH8 video tape recorder, and the second transistor is supplied with the video output of the β video tape recorder.

〔Example〕

Embodiments of the present invention will be described below with reference to one drawing. The figure is a circuit diagram showing an embodiment of the video camera of the present invention.

In the figure, a video camera 1 has an electronic viewfinder 2, and receives not only video signals from a video output circuit 3, but also video signals from a video output circuit 3.
The configuration is such that the first degree ta2 external video signal sent from the VH8 video tape recorder 6 or β video tape recorder 7 connected to the external connection terminal 4 or 5 can also be supplied to the electronic viewfinder 2. A video signal obtained from an optical system and a video processing circuit (not shown) is applied to the base of the output transistor Q0 via a video output circuit 3t. The emitter of this output transistor Qo is connected to the external connection terminal 4 via a resistor R0, and is connected to the base of the first transistor Q in the switch circuit 8 via a resistor R1 and a pace resistor R7. There is.

The switch circuit 8 includes a first . It consists of second transistors Q, , Q, and its differential output is from the midpoint of the emitters of both transistors QI, Q (commonly connected emitter resistors Rs, R4) to the input transistor Q.
1 to an electronic viewfinder 2. Second
The base of the transistor Q, is connected to the external connection terminal 5 via the base resistor R5, and the base of the third transistor Q1, whose collector is connected to the base resistor R, of the first transistor Q, is connected to the external connection terminal 5 via the base resistor R5. Base resistance R6 and resistance R
1 to an external connection terminal 5.

In this embodiment, a V)(S system video tape recorder 6 is connected to the external connection terminal 4 via a connection cable 6a that is common to both the video player and output terminals.

In the β-type video tape recorder 7, the video input terminal is connected to the external connection terminal 4, and the video output terminal is connected to the external connection terminal 5 by a connection cable 7a having two signal paths. As is well known, the video output of the VH8 system is superimposed with DC No. 7 of approximately 6 volts (first DC level), and the video output of the β system is approximately 2 volts (second DC level).
(DC level) is superimposed on the DC signal.

9 is an in-finder display signal generation circuit which displays in the finder of the child viewfinder 2;

For example, it is a circuit for generating signals that display information necessary for photographing, such as white balance, imaging sensitivity, two color temperatures, and illuminance. This in-finder display signal generation circuit 9 is connected to the midpoint of emitter resistors Rs and Ri via resistors Rs and Re and capacitor C1. Further, the resistor RS includes a transistor Q4. Each collector of Ql is connected.

One transistor Q4 has a base connected to the external connection terminal 4 via a resistor R0o, and resistors R3°, R,, which determine the base voltage, and emitter voltage, so that it becomes conductive only by the external video signal. Resistance R, t, R
, , are set to appropriate values.

Electrolytic capacitors Ct and Cs are connected to the base and emitter of the transistor Q4, respectively.

The other transistor Qs has its base connected to the base resistor R@ of the third transistor Q through the resistor Rttt, and the resistor R14 is connected to the voltage dividing resistor R1! A 1-solution capacitor C2 is connected in parallel with this.

Here, the operation when the video camera 1t is connected to the VH8 video tape recorder 6 will be described. In this case, the external connection terminal 5 is in an open state.

First, the image taken by video camera 1 is as follows.

The video output circuit 3 is supplied to the video tape recorder 6 via the output transistor Q6, while the switch circuit 8
is supplied to the electronic viewfinder 2 via the input transistor Qtlk. At this time, since the transistor Q4 is in a cut-off state, information necessary for photographing is displayed in the electronic viewfinder 2 based on the display signal generated by the in-finder display signal generation circuit 9.

Next, when the playback output of the video tape recorder 6 is supplied to the video camera 1, the playback output is as follows.

It is supplied to the electronic viewfinder 2 via the first transistor Q in the switch circuit 8 and the input transistor Qit-. At this time, the DC signal included in the playback output of the video tape recorder 6 is used.

Since the output transistor Qo becomes non-conductive and the transistor Q4 becomes conductive, the supply of the output of the video output circuit 3 is automatically stopped, and the supply of the in-finder display signal is also stopped.

Next, the operation when the video camera is connected to a 1t-β type video tape recorder will be explained.

In this case, the external connection terminals 4 and 5 are connected to corresponding signal paths within the connection cable 7a.

First, the image taken by video camera 1 is as follows.

The video output circuit 3 is supplied to the video tape recorder 7 via the output transistor Q(I), while the electronic viewfinder 2 is supplied via the switch circuit 8 and the input transistor Q(I).Transistor Q4 is cut off. state, the child viewfinder 2
The information necessary for shooting will be displayed inside.

Next, when the playback output of the video tape recorder 7 is supplied to the video camera 1, this playback output is transferred to the switch circuit 8.
the second transistor Q, and the input transistor Qit
- It is supplied to the electronic viewfinder 2 via. In addition,
At this time, due to the playback output of the video tape recorder 7,
Third transistor Qs! : Since both transistors Q and Q are conductive, the first transistor Q1 in the switch circuit 8 is rendered non-conductive, and the supply of the output of the video output circuit 3 is automatically stopped, as well as the supply of the display signal in the viewfinder. do.

In this way, the video camera 1 has the first transistor Q and the first transistor Q, which forms a differential pair between the output transistor Q and the telescopic viewfinder 2. The first transistor Q of the second transistor Q++Q is supplied with the video output of the VH8 video tape recorder 6, and the second transistor Q is supplied with the video output of the β video tape recorder 7. Because it is possible to do this, there is no need to install a manual changeover switch or the like.

It is possible to connect to both the VH8 and β video tape recorders; In the VH8 system, the DC signal added to the first external video signal stops the output of the output transistor Q0 for the video signal sent from the output transistor Q0.

In addition, in the β method, the third external video signal is
The transistor Q is the first transistor Q.

), an external video signal can be displayed on the electronic viewfinder 2 regardless of the video output of the output transistor Qo.

〔Effect of the invention〕

As described above, according to the present invention, the first transistor constituting the differential pair provided between the output transistor and the electronic viewfinder. Of the second transistors, the first transistor can be supplied with the video output of a VH8 video tape recorder, and the second transistor can be supplied with the video output of a β video tape recorder. It is possible to connect to both VH8 and β type video tape recorders without installing a changeover switch, and it is also possible to connect to both VH8 and β type video tape recorders, and when the output transistor is sending out a video signal, it can be connected to the video tape recorder. In the VH8 system, in response to an incoming video signal, the DC signal having the first DC level superimposed on the first external video signal stops the output of the output transistor.
In the tβ method, the third transistor operated by the second external video signal having a DC level of tJ/c2 is connected to the first transistor.
By turning off the transistor, excellent effects such as being able to display an external video signal on the electronic viewfinder regardless of the video output of the output transistor can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a circuit diagram showing an embodiment of the video camera of the present invention. 1...Video camera, 2...Electronic viewfinder. 3... Video output circuit, 6... VUS system video tape recorder, 7... β system video tape recorder, 8
...switch circuit, Qo...output transistor,
Qt...first transistor, Q,...second transistor, Qs...third transistor.

Claims (1)

[Claims] an output transistor that outputs a video signal to an electronic viewfinder and an externally connected video tape recorder; and a first transistor to which the video signal from the output transistor and a first external video signal having a first DC level are input. and a switch circuit including a second transistor to which a second external video signal having a second DC level is input as a differential pair and supplies a differential output to the electronic viewfinder, and the second external video signal. and a third transistor that operates when the first external video signal is input and turns off the first transistor, and the output transistor is configured such that the first external video signal is supplied to the differential pair. A video camera configured to be in a cut-off state at times.