JPS58100588A - Color video signal decoding circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a color video signal decoding circuit that generates an analog color video signal by decoding a binary coded nine-color video signal, wherein the It has a plurality of input sections, the number of which is equal to the number of components forming the signal, each input section receiving one of the components of the color video signal as a parallel multi-pin signal.
n) input terminals, each combination of the three parallel symbols representing a different amplitude of the aforementioned components;
This input is connected to an associated selector circuit which selects a particular one of the m outputs (with ≦2) that can be identified by each different combination of parallel self-propelled inputs. The present invention relates to a color video signal decoding circuit.

Such a successful decoding circuit is based on British Patent Application No. 10 concerning video signal synthesizers for digital video display devices.
01! It is described in the i00mu specification. This English 13
FIG. 8 of the ILS patent application shows a digital-to-analog converter for producing an analog monochromatic video signal from a triple-encoded monochromatic signal, in which a combination of three-way codes is used to convert a large number of resistors. The resistors connected in parallel form the upper component of the voltage divider, and the lower component of this voltage divider is the analog output or the negative voltage formed. It has a C configuration with an I resistance. It is stated in the aforementioned British patent specification that this arrangement can also be used in the case of color devices. However, if the converter of Figure 8 is to be used for color video signals, it is actually necessary to provide eight of the above-mentioned converters for the red, green and blue components, and the number of resistors required is therefore flexible. Besides the large number of transducers, accurate tracking cannot be done between the eight transducers.

SUMMARY OF THE INVENTION An object of the present invention is to provide an 8-encoded color video signal decoding circuit capable of tracking between various signal components.

The present invention is a color video signal decoding circuit that decodes a triple-encoded color video signal to generate an analog color video signal, the circuit decoding the number of components forming the triple-encoded color video signal. a plurality of inputs, each input receiving one of the components of the color video signal as a parallel multi-bit binary code;
n) input terminals, each combination of parallel ternary codes representing a separate amplitude of said components;
A collar connected to an associated selector circuit which selects a particular one of m outputs (wherein ≦sn) which can be identified by each different combination of parallel octal inputs at this input. In a video signal decoding circuit, the output terminals of the selector circuits are connected to respective control input terminals of a group of analog switches, so that only one different switch of the group of analog switches is connected. The color video signal decoding circuit is further provided with a common reference power supply circuit having m reference level points producing mutually different reference levels, and wherein the reference levels are mutually predetermined. Each reference level point is connected to the input terminal of the corresponding switch between each group of switches, the output terminals of the switches of each group are commonly connected, and the output of each commonly connected switch group is The instantaneous amplitude of the component at the terminal is determined by the associated switch group 0, which is now conducting under the control of the associated selector circuit.
a reference level transmitted by the switches, such that a varying level is obtained at the output terminals of the commonly connected group of switches, and this varying level forms a component of the analog color video signal. It is characterized by having K.

The relationship between the reference levels can be such that the level increments between adjacent reference level points are equal to each other. Alternatively, the relationship between the reference levels may be changed so that the level increments existing between adjacent reference level points do not increase each other, and a gamma-corrected component is generated at the output terminal of each commonly connected switch group. It is possible to create a relationship. However, it is also possible to make K such that the output satisfies some other desired law.

The reference power supply circuit is a voltage source circuit, and the voltage source circuit includes a nine voltage divider connected between first and first terminals receiving the regulated power supply voltage, and the four reference power supply circuits are connected by the first and third terminals. Three level points among the level points of voltage 1 can be configured. If the color video signal decoding circuit has eight input sections, and these eight input sections receive the red, green, and blue components of the three generalized color video signals, respectively, the above-mentioned process is performed. The reference voltage source circuit has a voltage divider connected between first and third terminals that also constitute three of the level points of the reference voltage, and the first and third terminals are connected to the voltage source. However, by making the voltage of this voltage source variable, it is possible to vary the intensity of the hue obtained from the components at the output terminals of the commonly connected switch group. When resistors are used in the voltage divider, less than one-eighth the number of resistors required in a conventional circuit is required.

The reference power supply circuit can be a voltage source circuit or a current source circuit that generates reference currents of different levels.

The invention will be explained with reference to the drawings.

In the example of the decoding circuit of the present invention shown in FIG. It constitutes an input section that receives a train signal. These input terminals are connected to an 8-channel analog multiplexer/
It is connected to the input terminals o1, mu and A of the demultiplexer 4, respectively. This multiplexer/demultiplexer number can be found in the Philips data handbook "Integrated C1rcuit", pa.
rt 4, □ctover1910 all ~81
Page 8 @Digital intagrat6d01rO
uit -LOOMO8HE 4000 B family
Philips II H as described in ly #
EF 4051B. The eight input terminals of this multiplexer/demultiplexer 4 are connected to an analog level conversion circuit IKm, and this circuit 5 is connected to three
The level of the entry 3 signal is shifted appropriately to perform the necessary driving of the selector circuit 6. The selector circuit 6 is a 1-out-of-8 decoder that selects a specific one out of S outputs.
．． Each different combination of parallel ternary encoded inputs at 1 and 8 can be individually identified. These outputs are output line 7
~14 appear separately one at a time, and these output lines are respectively connected to the control input terminals of each separate analog switch 15-38, so that each separate output resulting from the selector circuit has a different output line. Make the analog switch conductive,
Make the remaining switches non-conducting.

A terminal 5sFi connected to the DD terminal of the multiplexer and thus connected to the conversion circuit 6 and the selector circuit 6
Connect to a positive DC power supply, typically a 1s volt power supply,
Multiplexer enable terminal i and terminal v88
, 1m is grounded.The analog switches l!1~!1 are connected to switching input terminals Y.-Y, respectively, of the multiplexer, and these switching input terminals are connected to the point M on the voltage divider consisting of resistors 34 to 80. - H, the lower end of resistor 8G and point Htj are grounded, and the lower end of resistor 14 and point Htj are connected via terminal 81 to a 3 volt DC reference voltage source.

The output terminals of the analog switches 15 to 11 are connected in common to the output terminal 2 of the multiplexer, the output terminal z of which is connected to the output terminal 88 via a buffer amplifier 83 with a high input impedance. The various sign combinations of the three generalization signals at the input terminals 1.3v and 8vζ represent eight different amplitude levels for the red component. resistance 14
If each of ~80 has the same value, H on the voltage divider
The voltage present at various points from to m increases by an equal amount. Various combinations of S-ary encoded signals cause each separate switch to be closed as desired and the voltage at the point on the voltage divider connected to these closed switches to be present at terminal 2 in sequence. Switch by the 4° ternary code combination 000! 3 is made conductive (closed), and the switch 16 is made conductive by the combination 111 of the three major symbols, and the switch 11-16 is made conductive by the increase in the value of the combination of the decimal codes representing the increase in the amplitude of the red component. If 1 . 1 and IK are present. Actual appeal analog switch 1
B-11 has a series resistance of approximately 50,100 ohms in its conductive path, and a high input impedance Vannoer amplification IrF81 is provided between terminal 2 and output terminal 88 to achieve the above-mentioned effect. This significantly reduces the voltage drop across the terminals of the series resistor and the current drawn from the voltage divider. If it is necessary to connect the output terminal 88 to a circuit with a high input impedance, the Patno amplifier 8m can be omitted. Instead of each of the resistors 14 to 80 having the same value as each other, the values of these resistors can be different, in which case the voltage level on points M to H and thus the voltage at the output terminal 83 11 must-haves for level correction! Satisfies the power interruption law such as Hiko's law.

In addition to the S-channel analog multiplexer 4, the circuit of FIG. 1 is provided with a third and @S eight-channel analog multiplexer 4' and 4# of the same construction and type. Corresponding parts of multiplexers 4' and 4'' are given the same reference numerals as the multiplexer numbers and have exactly the same functions.The eight input terminals of multiplexer 4I, MU, MU, and MU1, are connected to input terminals 84, 86 and LU. 6, respectively, and these input terminals 84, 86 and 86 receive parallel ternary signals encoded by the chrominance components of the color video signal. M1 and M2 similarly receive input terminals 87. parallel ternary signals encoded by the green component of the color video signal.
88 and 39, respectively. multiplexer 4
' and 4' analog switch 1 Input terminal Y
The oY matrix is connected to the same points A to H on the voltage divider s4 to sO as the corresponding input terminal for the multiplexer number. The output terminal 2 of the multiplexer t4/ is connected via a buffer amplifier 40 to an output terminal 41 at which the analog blue component appears, and the output terminal 2 of the multiplexer 4' is connected to a buffer amplifier s.
After 4s, it is connected to output terminal 4, where an analog green component is generated. By connecting the corresponding switching input terminals for the eight multiplexers to the same point on the voltage divider, the eight signals originating from these multiplexers follow or track the same level as each other. The red, blue and green components at each separate output terminal 88.41 and 48 can be further processed, for example by a separate video amplification stage, before displaying the color signal.

FIG. 2 shows a modification of a portion of FIG. 1, and the same reference numerals in both figures indicate the same stamps. In FIG. 3, the multiplexers 4' and 4'', their input terminals and other connecting lines, and their associated buffer amplifiers and output terminals have been omitted.

In FIG. 1, the upper end of point and resistor 14 is
Instead of connecting it to a constant DC reference voltage source as shown in the figure, it is instead connected to the output terminal of a buffer amplifier @944, and the high impedance input terminal of this buffer amplifier is connected to the -Philips II HEF 401S1 described on page 3■
33 to the output terminal 2 of a dual channel analog multiplexer/demultiplexer 4IS. This multiplexer t4s has eight input terminals M0 and M1 connected to an input terminal 46 and a number F, to which a parallel 3-bit ternary code is supplied, and which can be used to input different ternary words of the above-mentioned ternary code. The combination represents a reference voltage of 14 that can be applied to the partial voltage IrFs 4-80. multiplexer 4
The input terminals Ao and Ml of 5 are connected to a logic level conversion circuit 48 as in the case of the multiplexer number, and this logic level conversion circuit 48 connects four analog switches bO to 5.
Each separate control signal for one of B is connected to a similarly generated selector circuit 49. In the case of a dual 4-channel device, these control signals are routed to four other analog switches 54-5.
7 are also connected separately, but these other analog switches are not used in the example of FIG. 511. The multiplexer terminals YOA-Y8 for the inputs of switches 50-58 are:
Connect to points U, V, W, and X of a third voltage divider consisting of resistors 58, 59, and 60 connected between terminal 61 and ground for an 8 volt constant DC reference voltage source. Voltage divider 5
Common output terminal ZAK from 8 to 60 to switches 60 to 68
As in the case of multiplexer 4, the voltage applied depends on the combination of ternary codes supplied to input terminals 46 and 4t, thereby causing IJ-f teplexer numbers 4' and 4''
The voltage applied to the partial pressures a34 to 80 is subtracted. If the three-way signal supplied to multiplexers 4, 4' and 4'' is encoded and has nine red, green and blue components, voltage dividers 34 to 80 [depending on the voltage applied to the final color combination Change the hue intensity in stages. Third
In the figure, four different levels of voltage are produced from buffer amplifier 44! Lutibrexa 4
Only three input terminals are shown for b. However, by using new types of multiplexers, the number of input terminals is increased and the number of levels produced at the output terminals is increased, so that the υ level changes are made more gradual and any desired change in the output voltage produced can be achieved. Change can also be achieved.

In the swA, the variable supply voltage for the divided voltage 1rFi14-80 is taken from an analog multiplexer/demultiplexer, but the variable supply voltage is obtained in another way by decoding the digital signal to produce an analog signal of exactly the same value. You can also do that.

The decimal inputs to such a decoding circuit (these ternary inputs may be supplied to input terminals 46 and 47 in FIG. 2) may be taken from a microprocessor or other form of digital control circuit.

In the circuits described above with respect to FIGS. 1 and 3, the inputs to multiplexers 4, 4' and 4' are for the red, blue and green components of the color video signal. However, these eight inputs may be related to some other combination. It is also possible to produce desired hues and their intensities, for example three color difference signals (RY) and (B-Y) and a luminance signal Y.

Furthermore, in the above-described circuit of the present invention, there is a multiplexer 4 that generates S different amplitude levels for each color component.
, 4' and 4', but by appropriate selection of analog multiplexers/demultiplexers the number of amplitude levels can be increased as follows ( or reduce)
be able to.

Level 8... old 40! sll 334 level...
・HKF 40sjl B16 level...HΣ?
4067B82 level...HKF406? B(I
II) All of the above analog multiplexers/demultiplexers are described in the Philips data book mentioned above.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a color video signal decoding circuit according to the present invention, and FIG. 8 is a circuit diagram showing a modification of the circuit in FIG. 1. 1, g, 8, 84.8&, 86.87, 88.19...
・Input terminal, 4.4', 4'...S channel analog multiple-preference player/demultiple player, 5...analog level conversion circuit, 6,49...selector circuit, 16~
ill,! 10 ~ vessel! ...Analog switch, 114
~80...Resistor, 81.40.41.44...Buffer amplifier, 8B, 41,411...Output terminal, 45
...Double channel analog multiplexer/demultiplexer, 48...Logic level conversion circuit.

Claims (1)

Claims: A color video signal decoding circuit for decoding a t211 encoded color video signal to produce an analog color video signal, the circuit comprising a component forming an S-ary encoded color video signal. A plurality of 11 (
n) input-children, such that each combination of parallel triplet codes represents a separate amplitude of said components, each input having:
Parallel control over this input section! m outputs that can be identified by different combinations of I-adc inputs (m≦1 here)
In a color video signal decoding circuit connected to an associated selector circuit for selecting a specific one of the selector circuits, the output terminals of the selector circuits are respectively connected to separate control input terminals of one analog switch as a group. In addition to this, only one different one of the 8y array switches is made conductive for each code combination, and further different reference levels are generated in the color video signal decoding circuit. providing a common reference power supply circuit having multiple reference level points, such that the reference levels have a predetermined relationship with each other, and connecting each reference level point to the input terminal of a corresponding switch between each group of switches; The output terminals of the switches in each group are commonly connected, and the instantaneous amplitude of the component at the output terminal of each switch group is controlled by the selector circuit of this sII series. A reference level is provided to be transmitted by the switches of the group, thereby providing a varying level at the output terminals of the commonly connected group of switches, with this varying level forming a component of the analog color video signal. A color video signal decoding circuit characterized by: The color video signal decoding circuit according to claim 11 is characterized in that the relationship between the reference levels is such that the increments in levels between adjacent reference level points become stronger. color video signal decoding circuit. & In the color video signal decoding circuit according to claim 1, the relationship between the reference levels is such that the increments of levels existing between adjacent reference level points do not increase with each other, and each group of commonly connected switches A color video signal decoding circuit characterized in that a gamma-corrected component is generated at an output terminal of the color video signal decoding circuit. 4 Any one of claims (G) and I (D)
- a video signal decoding circuit, wherein the reference power supply circuit is a voltage source circuit, the voltage source circuit comprising a voltage divider connected between first and third terminals receiving a stabilized power supply voltage; A color video signal oII circuit characterized in that the third terminal also constitutes s level points among the level points of the reference voltage. 4. A color video signal decoding circuit according to claim 4, wherein the 18 inputs are respectively configured to receive the red, green and blue components of the triple encoded color video signal. The circuit is a voltage source circuit, and this voltage source circuit has 8 of the level points of the reference voltage.
a voltage divider connected between first and third terminals also constituting two level points, the first and first terminals being connected to a voltage source such that the voltage of this voltage source can be varied; A color video signal decoding circuit characterized in that the intensity of the hue obtained from the components at the output terminals of a group of connected switches can be changed.