JPH0331994Y2 - - Google Patents

Description

[Detailed explanation of the invention] In addition to video screens such as broadcast screens, this invention can also be used to display pattern screens such as characters and graphics.
CRT (cathode ray tube) display
The present invention relates to a display device.

Conventionally, in addition to dedicated CRT display devices that display only pattern screens such as characters and graphics, as shown in Figure 1, CRT display devices for broadcast reception are used to display broadcast screens. There are CRT display devices that display pattern screens such as characters and graphics on a CRT in addition to video screens such as .

In FIG. 1, a video signal demodulation circuit 11 for a television signal etc. receives a first color difference signal (R-Y), a second color difference signal (G-Y), a third color difference signal (B-Y) and a luminance signal. (-Y) is generated. R (red) is the first primary color, G (green) is the second primary color, and B (blue) is the third primary color.
between the primary colors and the luminance signal Y, Y=0.30R+
There is a relationship of 0.59G + 0.11B.

First, second and third color difference signals (RY), (G
-Y), (B-Y) are connected to the first, second and third driver transistors 1 in the CRT drive circuit 13 surrounded by dotted lines via the switch circuit 12.
Coupled resistors 17, 18, to the bases of 4, 15 and 16
19 respectively.

After passing through the switch circuit 12, the luminance signal (-Y) is sent to the emitter of the first switching transistor 14 via the R drive variable resistor 20, and to the emitter of the second driver transistor 15 via the G drive variable resistor 21. , B drive variable resistor 2
2 to the emitters of the third driver transistors 16, respectively. The resistors connected to each emitter of the first to third driver transistors are an R cut-off variable resistor 23 and a G cut-off variable resistor 23, respectively.
They are a cut-off variable resistor 24 and a B cut-off variable resistor 25.

On the other hand, the first primary color R generated from the pattern generator 26 is applied to the emitter of the fourth driver transistor 30 via the R on-screen variable resistor 27, and the second primary color G is applied to the emitter of the fourth driver transistor 30 via the R on-screen variable resistor 27. The third primary color B is applied via a resistor 28 to the emitter of the fifth driver transistor 31 , and the third primary color B is also applied via a B on-screen variable resistor 29 to the emitter of the sixth driver transistor 32 .

The bases of the fourth, fifth, and sixth driver transistors are connected to coupling resistors 33, 34, and 35, respectively.
It is connected to the bias power supply 36 via.

37 is the first and fourth driver transistor 1
4 and 30 common load resistors output the first primary color R and supply it to the R cathode 41 of the CRT 40.
38 is the second and fifth driver transistor 1
The second primary color G is outputted by the common load resistors 5 and 31, and is supplied to the G cathode 42 of the CRT 40.
39 is the third and sixth driver transistor 1
6 and 32 common load resistors output the third primary color B and supply it to the B cathode 43 of the CRT 40.

Switch control signal from pattern generator 26
SC turns on the four contacts of the switch circuit in common,
Control off.

Next, the operation shown in FIG. 1 will be explained. When the switch circuit 12 is turned on by the switch control signal SC from the pattern generator 26, the first to third color difference signals (R-Y), (G-Y), and (B-Y) are A luminance signal (-Y) is applied to the bases of driver transistors 14, 15 and 16, and a luminance signal (-Y) is applied to each emitter.

On the other hand, the fourth to sixth driver transistors 3
Since the R, G, and B output voltages from the pattern generator 26 are applied to the emitters 0, 31, and 32, these driver transistors are turned off.

As a result, the R signal in the video signal is supplied from the first driver transistor 14 to the R cathode 41 of the CRT 40 . Similarly, from the second and third driver transistors 15 and 16, the G signal of the video signal is supplied to the G cathode 42, and the B signal is supplied to the B cathode 43, so that a video screen is displayed on the CRT 40.

Next, when a pattern signal is output from the pattern generator 26, the switch circuit 12 is turned off by the switch signal SC. Therefore,
The first to third driver transistors 14, 15 and 16 in the CRT drive circuit 13 are cut off. The R signal in the pattern signal is applied to the emitter of the fourth driver transistor 30, amplified, and supplied to the R cathode 41 of the CRT 40. Similarly, the G signal in the pattern signal is amplified by the fifth driver transistor 31 and sent to the G cathode 4.
2, the B signal is amplified by the sixth driver transistor and applied to the B cathode 43,
A pattern screen is displayed on the CRT40.

In this conventional CRT display device, the CRT
Two sets of drive circuits are required, one for video signals (first to third driver transistors 14, 15, 16) and one for pattern signals (fourth to sixth driver transistors 30, 31, 32). In addition to the usual adjustments, cut-off adjustment (by cut-off variable resistors 23 to 25) and drive adjustment (by drive variable resistors 20 to 22), on-screen adjustment (by on-screen variable resistors 27 to 29) is increased. Therefore, there was a drawback that both the circuit configuration and adjustment became complicated.

Furthermore, since the video signal and the pattern signal are exclusive, when the pattern screen is superimposed on the video screen, the portion of the video screen VD that overlaps with the pattern screen PA is erased, as shown in Figure 2. I had the inconvenience of not being able to see it.

The present invention was made to eliminate the above-mentioned drawbacks of conventional CRT display devices.
A color difference signal of a color difference signal or an RGB signal of a pattern signal is selectively input to the base of one set of drive circuits, and a luminance signal of a video signal or a constant level bias voltage is also selectively input to the emitter. By configuring the circuit, it is possible to display a variety of special combinations of video screens and pattern screens with a simple circuit configuration consisting of one set of drive circuits, and adjustments can be made as easily as normal drive adjustment and cutoff adjustment. The purpose of this invention is to provide a CRT display device that requires only a few adjustments.

Hereinafter, the present invention will be explained in detail based on an embodiment shown in FIG.

In FIG. 3, 51 is a video signal demodulation circuit similar to the video signal demodulation circuit 11 in FIG.
The second color difference signal (G-
Y) is applied to the contact a of the second switch 53, the third color difference signal (B-Y) is applied to the contact a of the third switch 54, and the luminance signal (-Y) is applied to the contact a of the fourth switch 55. added to.

Reference numeral 56 designates a pattern generator similar to the pattern generator 26 in FIG. The third primary color B is applied to contact b of the third switch 54. A constant level bias voltage Vc is applied to contact b of the fourth switch 55.

Reference numeral 57 denotes a first driver transistor, the base of which is connected to contact c of the first switch 52 via a coupling resistor 60. The emitter is grounded via a cut-off variable resistor 66 and connected to contact c of the fourth switch 55 via a drive variable resistor 63. A load resistor 69 is connected to the collector, and the R output of the first primary color is supplied to the R cathode 72 of the CRT 75. Similarly, 58 is a second driver transistor whose base is connected to contact c of the second switch 53 via a coupling resistor 61, and whose emitter is grounded via a cut-off variable resistor 67 and which connects a drive variable resistor 64. 4th through
It is connected to the contact c of the switch 55, a load resistor 70 is connected to the collector, and the G output of the second primary color is supplied to the G cathode 73. 59 is a third driver transistor whose base is connected to contact c of the third switch 54 via a coupling resistor 62, and whose emitter is grounded via a cut-off variable resistor 68 and to the third driver transistor via a drive variable resistor 65. 4
It is connected to the contact c of the switch 55, the load resistor 71 is connected to the collector, and the B output of the third primary color is supplied to the B cathode 74.

The first switch control signal SCA generated by the pattern generator 56 is transmitted to the first to third switches 52,
53 and 54 are interlocked to perform an operation of switching to the contact a side or the contact b side.

On the other hand, the second switch control signal SCB operates to switch the fourth switch 55 between the contact a side and the contact b side, independently of the switching operation of the switch control signal SCA.

50 surrounded by a dotted line indicates a CRT drive circuit. Also, the first and second switch control signals
The first and second switch control signal generation circuits for generating SCA and SCB may be provided inside the pattern generator as shown in the figure, or may be provided outside. Note that each driver transistor, drive variable resistor, cut-off variable resistor, and coupling resistor constitute first, second, and third drive circuits, respectively.

Next, the operation shown in FIG. 3 will be explained for each display mode.

(1) Video screen display The first to fourth switches 52, 53, 54, and 55 are all connected to the contact a side by the first and second switch control signals SCA and SCB from the pattern generator 56. At this time, the first driver transistor 57 has the first
The difference signal between the two, that is, the first
The first primary color R is generated in the load resistor 69, and this first primary color R is supplied to the R cathode 72 of the CRT 75.

Similarly, the second driver transistor 58 is
A second color difference signal (G-Y) applied to the base and a luminance signal (-Y) applied to the emitter.
The primary color G of is supplied to the cathode 73 of the CRT 75,
The third driver transistor 59 generates the third primary color B from the third color difference signal (B-Y) applied to the base and the luminance signal (-Y) applied to the emitter.
It is supplied to the B cathode 74 of the CRT 75. As a result, a video screen is displayed on the CRT 75. By changing the drive variable resistors 63, 64 and 65, the intensity of each primary color is adjusted, and by changing the cutoff variable resistance, cutoff adjustment is performed.

(2) Pattern screen display The pattern generator 56 displays the first to fourth switch control signals SCA and SCB using the first and second switch control signals SCA and SCB.
Switches 52, 53, 54 and 55 are all contacts b
Switch to the side. At this time, a constant bias voltage Vc is commonly supplied to each emitter of the first to third driver transistors 57, 58, and 59. Therefore, the first driver transistor 57 outputs the first primary color R added to the base and supplies it to the R cathode 72 of the CRT 75 . Similarly, the second driver transistor 58 outputs the second primary color G applied to the base of the CRT7.
The third driver transistor 59 outputs the third primary color B added to its base and supplies it to the B cathode 74 of the CRT 75. As a result, the pattern screen generated by the pattern generator 56 is displayed on the CRT 75.

(3) Exclusive simultaneous display of video screen and pattern screen The pattern generator 56 normally displays the first and second switch control signals SCA and SCB.
- Connect the fourth switches 52 to 55 to contact a to display the video screen on the CRT 75, and turn the first to fourth switches 52 to 5 only when a pattern signal is generated.
5 to the contact b side, the video screen VD and pattern screen PA are switched as shown in Figure 2.
is displayed exclusively.

Next, the first and second switch control signals SCA
A special composite screen obtained by making the switching of the fourth switch 55 independent of the interlocking switching of the first to third switches 52 to 54 will be described below.

(4) Special composite screen display The pattern generator 56 controls the first to third switch control signals SCA and SCB.
The switches 52 to 54 are connected to the contact b side, and the fourth switch 55 is connected to the contact a side.

In this way, from the pattern generator 56,
R, G, and B outputs of the same level are supplied to the respective bases of the first to third driver transistors 57 to 59, and the luminance signal (-Y) of the video signal is transmitted from the video signal demodulation circuit 51 to the first to third driver transistors 57 to 59. When the emitters of driver transistors 57 to 59 are commonly supplied, a black and white video screen VD and a pattern screen PA are displayed in a superimposed manner as shown in FIG.

R, G, generated from the pattern generator 56
If you change the B output level appropriately, for example, if only the R output is set to high level, the other G and B outputs are set to low level, and each emitter input is set to the same brightness signal (-Y) of the video signal, the entire screen will be A screen in which a reddish video screen and a pattern screen are superimposed is displayed. Adjust the drive variable resistors 63 to 65 to R,
By varying the G and B output levels, it is generally possible to display a screen in which a desired single-color video screen and pattern screen are superimposed.

If you use this display method, the pattern screen may become difficult to see depending on the color or brightness of the video screen that contrasts with the pattern screen. By doing so, the pattern screen can be made easier to see.

Furthermore, even when the pattern screen shows a wide area on the CRT screen, in this display method, as shown in Figure 4, the part of the video screen VD that overlaps the pattern screen PA is shown at a low level through the pattern screen PA. However, since both are displayed, information on both can be known.

Note that the three primary colors used in the video signal and the pattern signal are not limited to red (R), green (G), and blue (B), and other combinations of the three primary colors can be used.

As explained above, according to the present invention, with a simple circuit configuration consisting of one set of drive circuits, in addition to the conventional video screen display, pattern screen display, and exclusive simultaneous display of the video screen and pattern screen, , a superimposed display that allows information on both the video screen and the pattern screen to be known can be displayed in various ways. Further, the adjustment for performing each of these displays is very easy, as it only requires normal drive adjustment and cutoff adjustment, and no other adjustment by a special adjustment circuit is required.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional CRT display device that displays a video screen and a pattern screen, Fig. 2 is an explanatory diagram of the display image of the CRT display device shown in Fig. 1, and Fig. 3 is a video screen according to the present invention. 4 is a block diagram of a CRT display device that displays a pattern screen. FIG. 4 is an explanatory diagram of a display image of the CRT display device of FIG. 52 to 55...1st to 4th switches, 56...
Pattern generator, 57-59...First to third driver transistors, 60-62...Coupling resistor, 63-65...Drive variable resistor, 66-6
8...Cut-off variable resistor, 69-71...Load resistance, 72-74...R, G, B cathodes,
75...CRT.

Claims (1)

[Scope of utility model registration request] In CRT display devices that display pattern screens such as graphics and characters, and video screens, the color difference signal of the video signal and the pattern signal
A switch circuit that selects either the RGB primary color signal, a switch circuit that selects either the brightness signal of the video signal or the constant bias voltage, and two switch circuits that control the above switch circuits independently of each other. and video signal.
The feature is that the CRT drive circuit and the pattern signal CRT drive circuit are integrated into one.
CRT display device.