JPS6033028B2 - monitor receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color monitor receiver used by being connected to a magnetic recording/reproducing apparatus (VTR).

When viewing video signals reproduced by a magnetic edge image reproducing device on a monitor receiver, even if the monitor receiver is turned on (power-on), the reproduced signal from the magnetic recording and reproducing device is If there is no recorded signal, such as when the magnetic green image reproduction device has stopped its operation, or when it is in operation (the tape is running) but is reproducing a portion with no recorded signal, the monitor image reception Since no video signal is supplied to the input terminal of the monitor, there is no reproduction of the DC component, and the picture tube of the monitor receiver is normally in a cut-off state, and the image receiving screen becomes dark. This condition is not desirable because it may be thought that the monitor receiver is malfunctioning. The present invention has been considered in view of these points, and when there is no input signal to the monitor input terminal, any one of the three primary colors of red, green, and blue that constitutes a color screen is used. is displayed on the receiving screen to indicate that the monitor receiver is operating normally, and it is also configured to have multiple monitor input terminals so that they can be arbitrarily selected for monitoring. By changing the color displayed on the receiving screen when the monitor input terminal is selected, it is possible to tell which monitor input terminal is currently selected by the displayed color. It is configured so that it can also be done.

An example of a monitor receiver according to the present invention will be described below with reference to the drawings. In this embodiment, signals from a first magnetic green image reproduction device (hereinafter referred to as VTR) la, a second VTR 1b, and a color camera lc are selected. This example shows the case where it can be monitored by

It is assumed that composite color video signals of, for example, the NTSC system are obtained from the first and second VTRs 1a and 1b and the camera lc, respectively. 2a, 2b, and 2c are first, second, and third input terminals for monitor input signals, and a selector switch 3 selects one of the monitor input signals.

4a, 4b, and 4c are fixed contacts thereof, and are connected to corresponding input terminals 2a, 2b, and 2c, respectively.

5 is a movable (switching) contact.

A part of the signal obtained from the movable bright spot 5 is supplied to a luminance signal amplification circuit 6, amplified, and supplied to red R, green G, and blue B drive circuits 7a, 7b, and 7c, respectively.

Also, a part of the output from the switch 3 mentioned above is supplied to the color signal processing circuit 8, and the signal obtained from this is further sent to R-Y,
a color demodulation circuit 9a for obtaining G-Y and B-Y color difference signals;
9b and 9c, respectively, so that the above-mentioned color difference signals can be obtained at their respective output terminals.

These color signal processing circuits 8 and each color demodulation circuits 9a, 9b,
Since 9c is well known, detailed explanation thereof will be omitted. The output from the R-Y color demodulation circuit 9a is sent to the R drive circuit 7a, the output from the G-Y color demodulation circuit gb is sent to the G drive circuit 7b, and the output from the B-Y color demodulation circuit 9c is sent to the R drive circuit 7a. are respectively supplied to the B drive circuit 7c, where they are mixed with the luminance signal Y from the luminance signal amplification circuit 6 described above. Each of the drive circuits 7a, 7b and 7c described above
Since these circuits can have the same configuration, the drawings show a specific example of the R drive circuit 7a and omit the others.

That is, the color difference signal RY from the color demodulation circuit 9a is connected to the resistor 10.
and 11 to the base of the mixing transistor 13, and the luminance signal Y from the luminance signal amplification circuit 6 is supplied to the emitter of the above-mentioned transistor 3 through the resistor 14, and this emitter is connected to the ground through the resistor 15. has been done. 12 is a capacitor.

The DC voltage from the DC power supply terminal 16 is applied to the variable resistor 17 and is also applied to the transistor 3 through the resistor 18.
is applied to the collector of The DC voltage obtained at the movable contact 17a of this variable resistor 17 is applied to the emitter of the transistor 13 through a resistor 19, and by adjusting this variable resistor 17, so-called background adjustment is performed. ing. The collector of the transistor 13 described above is connected to the cathode 21a corresponding to red R among the cathodes of the color picture tube 20 corresponding to the three electron beams. 21b and 21c are cathodes corresponding to green G and blue B.

Therefore, when the switch 3 is switched to the state shown in the figure and a reproduced signal is obtained from the first VTR 1a,
In the R drive circuit 7a, the color difference signal R-Y is applied to the base of the transistor 13, and the luminance signal Y is applied to the emitter, so the color signal R is obtained at its collector, and this is applied to the cathode 21a corresponding to R. will be applied.

The same applies to the other drive circuits 7b and 7c.
Therefore, a color image is reproduced in two picture tubes. Note that 22a and 22b are base bias resistors for the transistor 13. In the present invention, the presence or absence of a monitor input signal is determined by the output from the synchronization signal separation circuit 23, and this determination output allows the plurality of cathodes 21a, 21b, 21c of the color picture tube 20 to be detected in the absence of a monitor input signal.
Select at least one of them and control it,
That is, an electron beam corresponding to this is emitted.

For this purpose, as shown in the drawing, a part of the output of the switch 3 is sent to the synchronization signal separation circuit 23 to extract horizontal synchronization pulses, vertical synchronization pulses, or both.
4 and integrate it, and then this integrated output is sent to inverter 2.
5 to obtain an inverted output, and the power of this world is supplied to the drive circuit 7.
By selectively supplying the voltage to transistors a, 7b, and 7c, each transistor 13 is controlled, thereby controlling the cathode.

As described above, in the present invention, the switch 3 is configured to select and monitor a plurality of monitor input terminals 2a, 2b, and 2c. ) 3 is provided, and depending on the selection of the monitor input terminal, the output from the inverter 25 is sent to the R drive circuit 7a or to the G drive circuit 7a.
The signal is selectively supplied to the drive circuit 7b of B or the drive circuit 7c of B, respectively.

27 is a movable (cutting sliding door) contact of this switch 26, 28a,
28b and 28c are fixed contacts, respectively, and these fixed contacts 28a, 28b and 28c are connected to R, G and B drive circuits 7a, 7b and 7c.

However, in order to control the cathode 21a of the picture tube 20 by the output from the inverter 25, a transistor 29 is further provided in this example, and its base is connected to the switch 2.
6, the collector is connected to the emitter of the transistor 13 through the resistor 30, the emitter is grounded through the resistor 30, and the DC power terminal 16 is connected to the emitter of the transistor 13 through the resistor 30.
and ground through the capacitor 33, and these resistors 32
The connection point between the capacitor 33 and the capacitor 33 is connected to the emitter of the transistor 29.

The same applies to the G and B drive circuits 7b and 7c, so the explanation thereof will be omitted. To explain the operation of the above-mentioned configuration, it is assumed that the movable contacts 5 and 27 of the switches 3 and 26 are switched to the fixed contacts 4a and 28a, respectively, and that the first VTR 1a is in the playback state and that the recording signal is is being played. In this state, each of the drive circuits 7a, 7b, and 7c operates as described above, and a color image from the first VTR 1a is obtained in the picture tube 201. On the other hand, a synchronizing signal is separated in a synchronizing signal separation circuit 23, and this is integrated by an integrating circuit 24.

That is, it is determined that an input has arrived at the monitor input terminal 2a. Due to this integrated output, the output of the inverter 25 becomes 0, and the transistor 29 of the R drive circuit 7a is turned off. That is, the emitter of the transistor 13 is connected to the resistor 30 - the collector emitter of the transistor 29.
The series circuit consisting of the resistor 31 is substantially not connected to the fixed contacts 28b and 2 of the functional switch 26.
Since no signal is applied to 8c, the transistors 3 of the G and B drive circuits 7b and 7c are also in the same state as described above, and therefore the respective cathodes 21a, 21b,
21c are supplied with R, G, and B color signals as usual, and the picture tube 20 is also used to reproduce a color image. Next, in this state, when the reproduction signal from the first VTR 1a is cut off, the color signal output from the collector of the transistor 13 of each drive circuit 7a, 7b, 7c is cut off.

That is, the DC reproduction signal disappears, the transistor 13 turns off, and accordingly, each cathode 21a of the picture tube 20
, 21b, and 21c rise to a cutoff state, and the image receiving screen becomes dark. However, in this state, since no synchronizing signal is obtained at the output side of the synchronizing signal separation circuit 23, no integral output is obtained at the output terminal of the integrating circuit 24.

Therefore, an output 1 is obtained at the output terminal of the inverter 25, which is supplied to the base of the transistor 29 of the R drive circuit 7a through the movable contact 27 and the viewing contact 28a of the switch 26. In this case, the voltage applied to this base is applied to the resistor 31 at the emitter of transistor 29.
and 32, so that only the transistor 29 of this R drive circuit 7a is turned on, and the emitter resistor 15 of the transistor 13 and A series circuit of resistor 30 and collector emitter resistor 31 of transistor 29 is connected in parallel, which lowers the voltage at the emitter of transistor 13, turning transistor 13 on, thereby causing its The collector voltage becomes lower, i.e. the cathode 21a of R
The potential of the cathodes 21b and 21c decreases, and an electron beam is emitted from this, while the cathodes 21b and 21c are in the cut-off state as described above, so the entire image receiving screen turns red. That is, it can be seen that the monitor receiver is operating normally. In the above description, the switches 3 and 26 are respectively in the solid line state, but when the movable contacts 5 and 27 are switched to the fixed contacts 4b and 28b, respectively, the second
If the signal is not reproduced from VTR 1b, the cathode 2
1b is controlled, and the entire image receiving screen of the picture tube 20 becomes green.

Similarly, when movable contacts 5 and 27 of switches 3 and 26 are switched to fixed contacts 4c and 28c, respectively,
When there is no signal from the camera lc, the image receiving screen of the picture tube 20 becomes blue. According to the present invention described above, when there is no monitor input signal at the monitor input terminal 2a, 2b, or 2c, red, green, or blue color is transmitted to the picture tube 2.
Since the image can be reproduced on the image receiving surface of 0, it indicates that the monitor receiver is operating normally, that is, is in a standby state.

Also, in such a display state, if the picture tube 20 is placed in a strong external magnetic field, this will cause mislanding of the electron beam, but in the case of displaying in one color as described above, Due to this mislanding, the area changes to a different color, making it easy to tell that it is being affected by an external magnetic field. have an effect. Further, as shown in the embodiment, inputs to a plurality of monitor input terminals 2a, 2b, and 2c can be selected, and the colors reproduced on the picture receiving screen of the picture tube 20 can be changed by switching. Therefore, it is possible to know in advance which VTR or camera the monitor receiver is in the state of monitoring signals from, which is extremely convenient.

The switches 3 and 27 described above can each be formed by so-called electronic switches, and in the above example, when there is no monitor input signal, one of the three colors is selected to emit light, but two colors can be used. You may choose to emit light.

Furthermore, the luminance signal and the color difference signal are sent to color drive circuits 7a and 7b.
It is clear that the present invention can also be applied to a so-called color difference drive system in which the colors are mixed in the picture tube. In this case, it is sufficient to control the grid corresponding to a certain color.

[Brief explanation of the drawing]

The figure is a connection diagram showing an example of a monitor receiver according to the present invention. 2a, 2b, 2c are monitor input terminals, 6 is a luminance signal amplification circuit, 8 is a color signal processing circuit, 7a, 7b, 7c is a color drive circuit, and 9a, 9b, 9c is a color demodulation circuit.

Claims (1)

[Claims] 1. A plurality of monitor input terminals, a first switch connected to the input terminal and selecting one monitor signal from the plurality of monitor signals, means for detecting a synchronization signal from the output of the first switch, a second switch for selectively supplying the output of the means to red, green, and blue drive circuits; the output of the synchronizing signal detecting means in a state where the synchronizing signal is not detected causes one of the drive circuits to be detected; When the monitor signal is not obtained, a different color is displayed on the screen according to the selection of the first switch. A monitor receiver designed to display the image above.