JPH02308683A - On-screen circuit integrated device - Google Patents

Abstract

PURPOSE:To decrease number of input terminals by constituting the device such that information of an external signal is displayed in an optional display color in response to a level difference of an external signal and constituting input terminals for an on-screen circuit with 2 pints at most. CONSTITUTION:A channel display data is inputted to an external signal input terminal 26. Switch circuits 15, 16, 17, 18 are switched from a TV signal into an external signal and a blanking voltage V1 by using an external signal. Moreover, the external signal is inputted to a display pulse generator 4 and converted into a display pulse with an optional amplitude. When ternary signals VA(R), VB(G), VC(B) are inputted, the relation of VA(R) red, VB(G) green and VC(B) blue is obtained according to a preset logic. The generated pulse with a prescribed amplitude is inputted further to DC level adjustment circuits 27, 28, 29, where the level is shifted to a proper DC level and inputted to the switch circuits 15, 16, 17.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an on-screen circuit integrated device having a function of displaying images based on general television signals and external signals such as characters and graphics on a CRT.

Conventional technology In general television receivers [1], the text and graphic information that displays the number of channels currently being received on the CRT, the speaker volume level, etc. is mainly displayed in three types: red, green, and blue. has been done. FIG. 3 shows an on-screen circuit constructed from a typical semiconductor integrated device. In FIG. 3, numeral 1 indicates a circuit block of a semiconductor integrated device in which an on-screen circuit is built-in, and a color signal demodulation circuit 2 formed in this on-screen circuit block 1 is as follows:
Color difference signal output terminals 7 and 8 for R-Y, G-Y, and B-Y signals
．． ．． 9, and the brightness No. 13 processing circuit 3 has a brightness signal output terminal 10 to which a negative DC-regenerated signal -Y is output. Switch circuits 15, 16, and 17 connect R-Y and G- from the output terminal 7°8.9 of the color signal demodulator 2.
The Y, B-Y color difference signals and the R, G, B external signals from the on-screen external signal input terminals 12.13.14 are switched by the switching signal of the switching signal input terminal 72, and the switch output terminals 19.20 .21 output. The switch circuit 18 also outputs the brightness signal from the output terminal of the brightness signal processing circuit 3 and the blanking voltage ■1 from the blanking voltage source 11 to the same switching signal input terminal 72.
Switched by the switching signal of switch output terminal 2
Output to 2. Matrix circuit 5 is switch output terminal 1
A primary color signal is generated using the color difference signal or external signal from 9.20.21.22 and the luminance No. 18 or blanking voltage signal, and is displayed on the CRT 6 via the matrix circuit output terminals 23.24.25.

In this circuit, R, G, and B external signals and switching signals of the same level generated by a microcomputer, etc. are input to independent input terminals 12, 13, and 14, and the switching signals are output. It becomes.

Problems to be Solved by the Invention As modern video integrated circuits have become more sophisticated and highly integrated, the number of input and output terminals has also increased considerably.

IC (Integrated Circ) various Re5
(units), the chip area of the IC is a matter of course, but the number of pins (2) is also an important factor in determining the cost of the IC. Therefore, in IC design, reducing the number of pins is an important issue for achieving higher functionality. In the on-screen circuit described above, when trying to display colors using the three primary colors R, G, and B, or a combination thereof, R,
A total of four input terminals are required: three G and B external signal input terminals, and one switching signal input terminal for switching between the video signal and the external signal. Therefore, for the above-mentioned reason, when the number of pins of an IC is restricted, it is often the case that the display is displayed in only green, for example.

The present invention solves problem E, and aims to provide an on-screen circuit integrated device that can reduce the number of 4-pin input terminals required for a conventional on-screen circuit in a semiconductor integrated device. It is something.

Means for Solving the Problems To solve the above problems, the on-screen times of the present invention #
The I-integrated device is configured to be able to express external signals such as characters and graphics in any display color according to the level difference of at least 21 or more signals, and is capable of expressing the information of the external signals in an arbitrary display color. The input terminal of the device is configured with at most two pins.

Further, in the present invention, an external signal is used as a switching signal f8 for switching between a television signal and an external signal, and the input terminal of the on-screen circuit is configured with one pin.

With the configuration described in item 1 of "Operation", the input terminal for the on-screen circuit, which conventionally required 4 pins in total, 3 pins for each R, G, and B external signal input terminal and 1 pin for the switching signal input terminal, has been reduced to 2 pins. Alternatively, a semiconductor integrated device can be constructed with one pin, and the number of pins can be effectively reduced.

Example An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a circuit diagram of an on-screen circuit integrated device according to an embodiment of the present invention. In FIG. 1, channel display data is input to the external signal input terminal 26 as an external signal. This external signal causes the switch circuit 15.16.1
7.18 is switched from the television signal to the external signal and blanking voltage ■1. Further, the external signal is input to the display pulse generator 4 and converted into a display pulse having an arbitrary amplitude.

VA as shown in Figure 1! R1+ VIIGl+ Vc
When the ts+(7) ternary signal is input, VAIR1→Red+VI+01→ according to the preset logic
Green + VC + 81 → Blue. Pulses of constant amplitude are generated. This pulse is further applied to the DC level adjustment circuit 27.2.
The signal is input to switch circuit 8.29, and after being level-shifted to C level, it is input to switch circuits 15, 16, and 17. FIG. 1 shows a case where the external fat signal of the ternary signal is shared as a switching signal, and if it is not shared, a separate input terminal is required for the switching signal.

FIG. 2 is a specific circuit diagram. First, the display pulse generator 4 will be explained. Assume that 3 healing signals as shown in the figure are applied to the external signal input terminal 26. As mentioned above, the color display is VA+R1 → red.

Vll((11" The pulses are converted so that they are displayed in green and Vc+*+-blue respectively.e□1゜e
tk2+e tb) is the threshold voltage of each pulse. PNP transistor 42.40°3
The base of 8 is the reference potential, and the bias resistor is 33°32
, 31.30 6 tbl 10V @@, e t
b2 12V Bl.

It is assumed that they are each biased to e tb3 + 3 V @@. PNP transistor 43.42.4
When the external signal is input from the external signal input terminal 26, the switching circuit configured with 1.40° 39 and 38 passes through the emitter follower transistor 44 and applies it to the base of the transistor 43, 41, and 39. Operates according to signal level. For example, if the amplitude of the pulse is Vc
In this case, the transistor 39 is turned off, the transistor 38 is turned on, and the transistors 40 to 43 are turned off, so that a voltage VB1m5 is generated across the load resistor 34.

At this time, no voltage is generated across the resistors 35 and 36. Similarly, when the pulse 3 is applied, the transistor 3
9.40→ON, transistor 38.41.42.43
- is in the OFF state, and V Or 11 is applied to the load resistor 35.
When the voltage @ 11 is applied and that pulse is applied, transistors 39, 41, 42 → ON, transistors 38, 40° 43 → OFF, and load resistance 3
6, a voltage of VR, 4 is generated. In this way, when a pulse with a preset amplitude is applied for each color, the display pulse V Re
d +V Qr*** + VIlt* is generated.

Next, the DC level adjustment circuit 27 will be explained.

The display pulse 8.4 generated by the display pulse generation 34 is applied to the base of the emitter follower transistor 53. At this time, the emitter of the transistor 51 has a voltage of 5. shown in the first equation. ．． produces a pulse of

I soc ”d (Vcc V-) / R4t
■,. c: Collector current of the transistor 50■,
: Base voltage Vs+- of transistor 49
NV @, a + V ei () lunge 2F52) +
R41B・I so.

...(1) V*aa: Red display pulse voltage generated by the resistor 36 Normally, in the switch circuit 15, this is the color difference signal output terminal 7 of the color signal demodulation circuit and the external signal input terminal for on-screen. The DC potentials of the bases of the transistors 59 are designed to be at the same level.

Therefore, the third term in the first equation is RAM or RAM. . Adjust it to any value.

DC level adjustment circuit 28 for external signals for green and blue on-screen input to switch circuits 816.17
．． 29 also has the same circuit configuration as 27, and operates in the same way.

Next is the switch circuit, switch circuit 15゜1
6, 17, and 18 have the same circuit configuration, and the switch circuit 15 will be explained. A diode 56 and a PNP transistor 55 form a mirror circuit, and serve as an active load for a differential amplifier composed of NPN transistors 57, 58 and 59, 60. The output signal is output from an emitter follower formed by NPN transistor 54. Switching of the signals input to the bases of transistors 57 and 59 is performed by differential amplifiers of transistors 61 and 62. Now, when an external signal is applied to the external signal input terminal 26, one is input to the display pulse generator 4, and the other is input to the transistor 6 of the switch circuit 15.
It is manually powered to the base of 2. At this time, if the base voltage v2 of transceiver 1 is V2 = e thl, then
Transistor 62→ON, transistor 59.60→O
Since the state is N, the external signal for on-screen input to the base of the transistor 59 is output from the switch output terminal 19. Switch circuit 16.18 also 1
The circuit operates in the same manner as in No. 5, but when the external signal for red on-screen is input, the green and blue display pulses input to the DC level adjustment circuits 28 and 29 are Ov. Therefore, from equation (1), V=Vsg+R4g-1soc (V*,a=Ov
)-(2) DC voltage is output. This also applies when external signals for blue and green on-screen are input.

The switch circuit 18 is a brightness signal switch circuit, and is switched by an external signal applied to the external signal input terminal 26, similar to the switch circuits 15, 16, and 17 described above. At this time, the switch output terminal 22 has a brightness signal of C.
64 to 68.71 are constant current sources when the blanking voltage (1) is switched to a suitable C level blanking voltage (1) for blanking on the RT.

Effects of the Invention As shown in E-E, according to the present invention, it is possible to display an external signal consisting of two or more values in any display color. The circuit can be configured with at most two input terminal pins, and the number of pins in a semiconductor integrated device can be effectively reduced.

Furthermore, if the external signal is used as a switching signal for switching between the television signal and the external signal, the on-screen circuit can be configured with a 1-pin input terminal, and the effect of reducing the number of pins is extremely significant.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an on-screen circuit integrated device according to an embodiment of the present invention, FIG. 2 is a specific circuit diagram thereof, and FIG. 3 is a circuit diagram of a conventional device. DESCRIPTION OF SYMBOLS 1... On-screen circuit block, 2... Color signal demodulation circuit, 3... Luminance signal processing circuit, 4... Display pulse generator, 5... Matrix circuit, 6... CR
T, 7.8.9... Color difference signal output terminal, 10... Luminance signal output terminal, 11... Blanking voltage source section, 1
2.13.14...On-screen external signal input terminal, 15.16.17°18...Switch circuit, 19.
20.21.22...Switch output terminal, 26...
External signal input terminal, 27.28.29...DC level adjustment circuit, 30-33.45.46...Bias resistance, 34-36...Load resistance, 47...Current limiting resistor, 64- 68, 71...constant current source. Agent Yoshihiro Morimoto,

Claims (1)

[Claims] 1. An on-screen circuit integrated device that has the function of displaying external signals such as general television signal video, characters, and graphics on a CRT, the external signal consisting of at least two values or more. The on-screen circuit integrated device is configured to be able to display the information of the external signal in any display color according to the signal level difference between the two, and the on-screen circuit has an input terminal of at most two pins. 2. The on-screen circuit integrated device according to claim 1, wherein the external signal is used as a switching signal for switching between the television signal and the external signal, and the input terminal of the on-screen circuit is configured with one pin.