KR920002763B1 - Power window switch for an automobile picture control for tv receiver on-screen display - Google Patents

Abstract

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Description

Video signal processing device

1 shows a portion of a television receiver comprising a video and graphics image control device according to the invention.

FIG. 2 is a circuit diagram detailing a graphics signal conversion circuit used in the system of FIG.

3 shows a portion of the graphical thimbles generated and displayed by the system of FIG.

4 shows a diagram illustrating an operating state of a circuit element related to a graphics signal display system.

5 is a circuit diagram detailing video and graphics image control mechanisms.

* Explanation of symbols for the main parts of the drawings

10 color TV graphics generator 12 frequency selection circuit

14: chromatic processor 16: luminance processor

60: graphics signal source 62: television graphics generator

64: conversion circuit 68: image control circuit

20a: R (red) signal processing circuit 20b: G (green) signal processing circuit

20c: B (blue) signal processing circuit 25a: R (red) driver

25b: B (green) driver 25c: B (blue) driver

32: matrix amplifier

The present invention relates to an apparatus for controlling the contrast of a picture reproduced by a color television receiver or such a system in response to an auxiliary graphics information signal.

Many color television receivers include, for example, fixtures for electronic on-screen kinescope displays of graphics characters that indicate the number of channels that tune the receiver. Such displays are typically generated by replacing typical video information with a signal generated by a suitable graphics character generator in the receiver to represent a properly horizontally and vertically synchronized graphics. Thus, the graphics information is displayed in a given portion of the kinescope screen. One system of this type is described in US Pat. No. 3,984,828 to Bayer. The information displayed by such a system may only be alphanumeric and graphics information (eg, "video games" and data displays), or mixed video and graphics information, using suitable electronic control circuitry in the receiver. (E.g., number of overlapping channels, time, subtitles, weather, sports, or road traffic information). Graphics information signals are commonly associated with teletext systems that transmit graphics information via conventional television transmission devices and that receive, decode and display graphics information by television receivers in known manner.

Television receivers and similar video signal processing systems manually control the contrast of the displayed video information by controlling the peak-to-peak amplitude of the video signal processed by the system (eg, via a viewer-adjustable potentiometer). Includes equipment for Some television receivers also include fixtures for automatically controlling the contrast of the displayed picture.

More preferred television receivers include fixtures for the on-screen display of auxiliary graphics information, which are generated in response to broadcast video signals with the same sense of contrast of the displayed auxiliary graphics information, typically controlling the contrast of the displayed picture at the same time. This simultaneous contrast control (e.g., contrast tracking) allows the displayed graphics information (e.g., number of channels or time of date) to be at an appropriate intensity level related to the surrounding video signal image display. Ensure that it can be shown. In the absence of such contrast tracking, the displayed graphics information will appear or disappear at a disturbing intensity compared to the surrounding video signal picture display.

The preferred content described herein provides graphics and video picture contrast tracking in such a way as to reliably set the color of the displayed graphics information and greatly reduce the likelihood of a shift to the color of the displayed graphics information as the picture contrast changes. Is that. In order to surely set the color of the graphic information as described above and to provide graphics and video image contrast tracking, the apparatus according to the present invention is performed.

According to the principles of the present invention. The apparatus described herein is an apparatus for simultaneously controlling the contrast (eg, image level) of a reproduced color image in response to a typical broadcast video signal and an auxiliary graphics signal. The control device is included in one video signal processing system, wherein the color video signal is applied to one color kinescope through multiple color signal coupling paths. In addition, one graphics color drive signal and a plurality of graphics blocking signals are also applied to the signal coupling path. The graphics color drive signal is commonly applied to multiple signal paths with a sense of enabling the kinescope to display color graphics information during the graphics interval. The plurality of graphics blanking signals are separately applied to the signal path for selectively blanking the output of the signal path to determine the color of the displayed graphics information. One image control signal simultaneously changes the level of the color video signal and the level of the pain graphics color drive signal with the same sense, so that the contrast of the displayed color video information tracks the contrast of the displayed color graphics information.

In FIG. 1, the color television signal output from the signal source 10 is processed by the frequency selection circuit 12 (a circuit including a comb filter) to separate the luminance (Y) and chromaticity (C) of the television signal. Generate components. In response to the separated chroma components, one chroma processor 14 generates Y-R, Y-G, and Y-B color difference signals applied to the red green and blue signal processing circuits 20a, 20b, and 20c, respectively. The separated luminance signal is applied to each of the circuits 20a, 20b and 20c via the luminance processor 16 and the emitter follower transistor 18, in which the respective chrominance signal and the luminance signal are combined. To output red green and blue video signals. These color signals are applied to the color kinescope 24 via respective red, green and blue video output drivers 25a, 25b and 25c to reproduce an image on that color kinescope.

The color signal processing circuits 20a, 20b and 20c are similar in structure and operation to each other. Therefore, the red signal processing circuit 20a described below also applies to the circuits 20b and 20c.

The circuit 20a includes an input matrix amplifier 32 which receives the chrominance signal Y-R of the luminance signal and the red signal. The red output signal from the amplifier 32 is supplied to the red signal driver 25a by a coupling circuit comprising a plurality of cascaded emitter follower transistors 40, 41 and 42.

The circuit 20a also includes emitter follower transistors 52 and 54 connected in a Darlington structure, differentially connected transistors 56 and 57 and sterrrrng transistors 56 and 57. And a switched current regulation circuit 55 having a coupled current source transistor 58 for supplying an operating current. Transistors 52 and 54 and circuit 55 may enable the receiver to operate in an on-screen display mode for displaying auxiliary graphics information for a defined period of time, as described below. have.

A signal indicative of the graphics information to be displayed is provided by the graphics signal source 60. For example, when the graphics information to be displayed matches the number of broadcast channels that tune the receiver, graphics signal source 60 tunes the receiver in response to the signal derived from the channel tuning system of the receiver. Generate a binary coded signal representing the number of channels. The signal is applied to a suitable graphics signal generator 62 (e.g., microprocessor). The graphics signal generator 62 is synchronized by the horizontal (H) and vertical (V) scanning rate signals, such that the graphics data is displayed in a particular segment of the viewing screen of the kinescope. Other information, such as the time of the date and teletext information, may also be applied to the generator 62 to be appropriately converted to the video signal display format. The signal from the graphics signal source 60 includes intelligence that determines when graphics information is displayed instead of regular broadcast video information, including, for example, the color (color) of the displayed graphics information.

,

,

)와 ＂백색 구동＂(white drive) 그래픽스 스위칭 신호(W 및 W')를 출력으로 제공하는 그래픽스 신호 변환 회로(64)에 공급된다. 제2도는 그 변환 회로(64)를 상세히 도시한 회로도이다.The graphics character generator 62 provides a plurality of output signals corresponding to the red, green, and blue graphics signal information, respectively, which are appropriately time-adjusted output signals G _R, G _G, and G _B. These signals are the “black drive” graphics switching signals.

,

,

And a white drive graphics switching signals W and W 'are supplied to the graphics signal conversion circuit 64 for output. 2 is a circuit diagram showing the conversion circuit 64 in detail.

In FIG. 2, the graphics generator 62 provides three state logic outputs for each of the graphics signals G _R , G _G and G _B. As indicated by waveform 110, the three state logic output signals are at +1.6 volts when graphics information is not displayed (e.g., when the kinescope responds regularly to the display broadcast video signal). A first logic level, a second logic level lower than +0.8 volts when graphics information is displayed in a color other than black, and a third logic level greater than +2.4 volts when black graphics information is displayed. The output of the graphics generator 62 is coupled to the input of the signal conversion circuit 64 via current determining resistors 70, 71, 72 and leads (e.g., sheathed cables) 73, 74, 75, respectively. .

)는 트랜지스터(90,92 및 94)의 콜렉터 출력으로부터 유도된다. 스위칭 제어 신호(

)의 레벨은 그래픽스 신호(G_R, G_G및 G_B)의 레벨에 응답하여 관련된 전류 미러 트랜지스터(90,92 및 94)의 전도 상태의 함수이다. 트랜지스터(80,82 및 84)에 의해 전도된 콜렉터 전류는 다이오드가 접속된 트랜지스터(100 및 101), 다이오드(104) 및 트랜지스터(106)와, 다이오드(104) 및 트랜지스터(108)를 포함하는 전류 미러 회로에 의해 조합 및 복사된다. 그래픽스 스위칭 제어 신호(W 및 W')는 시간 및 크기면에서 유사하고, 트랜지스터(108 및 106)의 각각의 콜렉터 출력으로부터 유도된다. 스위칭 제어 신호(W 및 W')의 레벨은 그래픽스 발생기(62)로부터의 그래픽스 신호에 응답하여 전류 미러 트랜지스터(108 및 106)의 전도 상태의 함수이다. 변환 회로(64)는 알,엘,샌리 2세 등에 의해 발명의 명칭이 ＂온-스크린 그래픽스 디스플레이 신호 텔레비젼 수상기용 변환회로＂인 미합중국 특허출원 번호 제323,351호에 상세히 기술되어 있다.Signal conversion circuit 64 includes complementary conductive emitter coupled emitter input transistor pairs 80 and 81,82 and 83,84,85 responsive to graphics signals G _R , G _G and G _B , respectively. do. The collector current conducted by transistors 81, 83, and 85 is a current mirror comprising transistors 90 and diodes 91, transistors 92 and diodes 93, and transistors 94 and diodes 95. Each is replicated by a mirror circuit. Graphics switching control signal (

) Is derived from the collector outputs of transistors 90, 92 and 94. Switching control signal (

Is a function of the conduction state of the associated current mirror transistors 90,92 and 94 in response to the levels of the graphics signals G _R , G _G and G _B. The collector current conducted by transistors 80, 82, and 84 is a current comprising transistors 100 and 101, diodes 104 and 106 with diodes connected, and diodes 104 and 108. Combined and copied by the mirror circuit. The graphics switching control signals W and W 'are similar in time and magnitude and are derived from the respective collector outputs of the transistors 108 and 106. The level of the switching control signals W and W 'is a function of the conduction state of the current mirror transistors 108 and 106 in response to the graphics signal from the graphics generator 62. The conversion circuit 64 is described in detail in US Patent Application No. 323,351, entitled "On-Screen Graphics Display Signal Television Receiver Conversion Circuit" by Al, L, Sanley II, et al.

)는 신호 처리 회로(20a)의 제2그래픽스 제어 입력에 상응하는, 적색 신호 처리 회로(20a)의 차동적으로 접속된 트랜지스터(56)의 베이스 전극에 인가된다. 변환 회로(64)로부터의 신호(

)는 녹색 및 청색 신호 처리 회로(20b 및 20c)의 제2그래픽스 제어 입력에 각각 인가된다.1, the signal W from the conversion circuit 64 is applied to the base input of the transistor 35 arranged with the transistor 36 in a differential configuration. The control signal generated at the collector output of the transistor 35 in response to the level of the signal W is transmitted to the Darlington connected emitter follower transistors 52 and 54 at the first graphics control input of the red signal processing circuit 20a. Is applied to. In addition, the control signal from the transistor 35 is applied to the graphics control input corresponding to the green and blue signal processing circuits 20b and 20c. The signal W 'from the conversion circuit 64 is coupled to the emitter of the current source transistor 19 associated with the luminance signal coupling transistor 18. Signal from the conversion circuit 64 (

Is applied to the base electrode of the differentially connected transistor 56 of the red signal processing circuit 20a, which corresponds to the second graphics control input of the signal processing circuit 20a. Signal from the conversion circuit 64 (

Are applied to the second graphics control inputs of the green and blue signal processing circuits 20b and 20c, respectively.

The system operation of FIG. 1 in a typical video display mode and in a graphics display mode is described with reference to FIG. 1, FIG. 3, and FIG. For the following description, assume that the graphics information to be displayed contains red graphics molecules occurring during the graphics period and is processed as a result, preceded by a narrow black border occurring at the edges of the graphics symbol. 3 illustrates a portion of one horizontal image scanning line. Typical video information is displayed during time T ₀ before time T ₁ and after time T ₄ . On-screen display interval of time (T ₁₎ from time to time in the following black edge interval, the time (T ₂ and T ₃₎ graphics symbol display interval and a time (T ₃₎ between the up (T ₂₎ (T ₄ It includes the next black edge gap up to).

The table shown in FIG. 4 shows the conduction state of the transistors 52, 54, 40, 41, 56 and 57 in the signal processing circuit 20a of FIG. 1 for the display shown in FIG. And the non-conductive state (off state). Thus, for a typical video signal interval after time T ₀ and after time T ₄ , emitter follower transistors 40 and 41 apply a video signal from transistor 32 to transistor 42 and thereafter. The video signal is applied to the driver 25a. At this time, the signal W 'keeps the current source transistor 19 in a typical conducting state such that the luminance signal is typically conducted to the transistor 18, while the signal W is used to make the transistors 52 and 54 non-conductive. The transistor 35 is biased to be in a state. The signal R biases the differentially connected current regulation transistor 56 to be in a conducting state, whereby the current from the current source transistor 58 is driven by the signal coupling follower transistor 40 through the transistor 56. Is inverted. Thus, transistor 58 represents a current source for follower transistor 40 during a typical video signal image interval. During this time, the signal processing circuits 20b and 20c exhibit the same operating state as the signal processing circuit 20a.

)에 응답하여 비전도 상태로 되는데, 트랜지스터(57)는 전도상태로되어 전류원 트랜지스터(58)로부터의 전류는 트랜지스터(57)를 통해 흐른다. 특히, 트랜지스터(58)로부터의 전류는 트랜지스터(41) 및 트랜지스터(57)의 에미터 저항기(43)를 포함하는 경로에 흐른다. 스위칭 트랜지스터(57)의 상기 전도 상태는 에미터 폴로워 트랜지스터(40 및 41)를 비전도 상태로 되게하고, 전류원 트랜지스터(58)가 흑색 디스플레이를 얻기 위해 전류를 공급하는 메카니즘을 제공한다(예를들어, 회로(20a)의 출력이 블랭크됨). 트랜지스터(52 및 54)는 신호(W)에 응답하여 비전도 상태를 유지한다. 따라서, 전형적인 비데오 신호는 회로(20a)의 출력에서 억제되고, 키네스코프는 흑색 디스플레이를 발생한다. 동시에, 회로(20a)의 출력은 키네스코프(24)의 적색 전자총이 차단되는 것을 보장하기 위해＂흑색 보다 더 진한 흑색＂블랭킹 레벨을 나타낸다. 이 경우에, 흑색 디스플레이는 시간(T₁및 T₂)사이의 엣지 간격 동안 발생하고, 상기 시간 동안 신호 처리 회로(20b 및 20c)는 회로(20a)와 동일한 동작 상태를 나타낸다.At the beginning of the on-screen display interval starting at time T ₁ , differential switching transistor 56 is connected to a signal (

In a non-conductive state, the transistor 57 is in a conductive state such that current from the current source transistor 58 flows through the transistor 57. In particular, current from transistor 58 flows in a path comprising transistor 41 and emitter resistor 43 of transistor 57. The conduction state of switching transistor 57 causes emitter follower transistors 40 and 41 to be in a nonconductive state and provides a mechanism by which current source transistor 58 supplies current to obtain a black display (e.g., For example, the output of circuit 20a is blanked). Transistors 52 and 54 maintain a non-conductive state in response to signal W. Thus, a typical video signal is suppressed at the output of circuit 20a, and the kinescope produces a black display. At the same time, the output of circuit 20a exhibits a darker black blanking level than black to ensure that the red electron gun of kinescope 24 is blocked. In this case, the black display occurs during the edge interval between times T ₁ and T ₂ , during which time the signal processing circuits 20b and 20c exhibit the same operating state as the circuit 20a.

At the beginning of the (red) graphics display interval starting at time T ₂ , the differentially connected current regulation transistors 56 and 57 are coupled so that transistor 56 is conducting and transistor 57 is non-conductive. Change the conduction state in response to R). Therefore, the current from current source transistor 58 is conducted by transistor 56. At the same time, graphics drive transistors 52 and 54 are conducted in response to signal W, and the emitter of transistor 54 is supplied by current source transistor 58 through switching transistor 56. The emitter of transistor 40 is reverse biased in response to a bias signal supplied from the emitter of conductive transistor 54, and emitter follower coupling transistor 41 is in response to non-conducting switching transistor 57. Return to conduction state. Therefore, transistors 41 and 42 apply a red graphics enabling signal to red driver 25a for a period between times T ₂ and T ₃ , thereby conducting graphics drive transistors 52, 54. In response to the output of a red graphics display is generated.

The operating current for the graphics signal driving transistor 54 during the graphics interval is supplied by the current source transistor 58 through the transistor 56.

에 응답하여 적색 그래픽스 디스플레이 간격동안 블랭크된다. 그들 신호는 회로(20a)의 스위칭 트랜지스터(56 및 57)에 상응하는 회로(20b 및 20c)의 스위칭 트랜지스터가 트랜지스터(41)에 상응하는 폴로워 트랜지스터를 비전도 시키는데 필요한 전도 상태를 나타낼 수 있도록 하는데, 이미 기술한 방법(예를들어, 회로(20b 및 20c)의 상응 트랜지스터(56 및 57)가 각각 비전도 및 전도되게 하는 방법)으로 나타낼 수 있도록 한다.The output of the green and blue signal processing circuits 20b and 20c is a signal

Blank in response to the red graphics display interval. These signals allow the switching transistors of the circuits 20b and 20c corresponding to the switching transistors 56 and 57 of the circuit 20a to exhibit the conduction state required to nonconduct the following transistors corresponding to the transistor 41. , A method already described (e.g., a method in which corresponding transistors 56 and 57 of circuits 20b and 20c, respectively, are nonconductive and conductive).

During the next black edge interval between the times T ₃ and T ₄ , the operating states of the circuits 20a, 29b and 20c are the same as the operating states during the preceding black edge intervals T ₁ -T ₂ described previously. Similarly, after the time T ₄ , the operating state of those circuits during the typical video interval is the same as the operating state during the video interval including the time T ₀ described previously.

Colors other than red may be displayed during the graphics interval. For example, white may be displayed when the signal processing circuits 20a, 20b, and 20c all exhibit the operating states shown in the table of FIG. 4 during the interval between the times T ₂ and T ₃ . In this case, all outputs of those circuits will not be enabled or blanked in the graphics interval. When both the red signal processing circuit 20a and the green signal processing circuit 20b exhibit the operating state shown in FIG. 4 during the interval from time T ₂ to time T ₃ , the circuit 20c The state shown in FIG. 4 during the interval from the time T ₁ to the time T _{2 of the} blue signal processing circuit 20c except that the corresponding transistors 52 and 54 are turned on or in a conducting state. Yellow graphics may be displayed. In this case, the outputs of the red and green signal processing circuits 20a and 20b will not be enabled or blanked, and the output of the blue signal processing circuit 20c will be blanked, resulting in a yellow kinescope display.

During the graphics interval from time T ₂ to time T ₃ , the current source transistor 19 increases the conductivity in response to the signal W ′, so that the DC level of the luminance signal derived from the collector of the transistor 19. Is shifted in the direction to ensure that the follower transistor 40 remains off.

The system described above can generate several colors during the on-screen display interval, including black and white, primary red, green and blue, and complementary yellow, cyan and magenta, red, green and blue signal processing circuits. Various colors can be generated without blanking and blanking the output of the appropriate combination of 20a, 20b and 20c. Note that in this case, the transistors 52, 54 of the circuit 20a and the corresponding transistors of the circuits 20b and 20c are simultaneously conducted in response to the signal W, with a graphics color ion-screen display other than black. Note that whenever generated during the interval, they are simultaneously conducted in response to the signal W. The small graphics color (color) is generated by blanking one or two of the selected output combinations of the outputs of the signal processing circuits 20a, 20b and 20c through appropriate combinations of the signals R, G and B. A white graphics display is generated when the outputs of the signal processing circuits 20a, 20b and 20c are all not blanked.

In addition, the system of FIG. 1 includes an image control circuit for simultaneously controlling the magnitude of the luminance and chromatic components of the video signal and the magnitude of the graphics display driving signal generated at the base of the transistor 52 in response to the signal W ( 68) (including, for example, a potentiometer adjustable by the viewer). In particular, the variable output control voltage from the control circuit 68 changes the peak-peak amplitude of the luminance signal processed by the luminance processor 16 to control the contrast of the displayed image. The control voltage simultaneously measures the peak-peak amplitude of the chromatic component processed by the chroma processor 14 with a sense to maintain a predetermined relationship between the chromaticity and the amplitude of the luminance signal when the image control voltage changes. To control. At this time, the image control voltage changes the magnitude of the graphics drive signal applied to the base of the transistor 52 so as to establish a predetermined (e.g., tracking) relationship between the level of the graphics drive signal and the level of the luminance and chroma signal. Keep it. Thus, the contrast of the displayed video information generated in response to the control of the luminance and chroma signal is tracked and changed with the same sense as the contrast of the displayed graphics information generated in response to the signal W.

Note that the image control voltage from the image control circuit 68 is commonly applied to the red, green, and blue signal processing circuits 20a, 20b, and 20c, via their common graphics drive signal. Such an apparatus has the advantage of greatly reducing the possibility of causing undesirable graphics drive offsets for graphics drive signals applied to the three color signal processing circuits. As a result, the mutual balance of the graphics drive signal levels required to generate the white graphics display can be surely maintained in advance, and can greatly reduce the possibility of undesirable graphics color change in accordance with the change of the image control voltage. In the latter case, an undesirable offset of the level of the graphics drive signal applied to the color signal processing circuit may appear as a result of a graphics color shift that changes when the image control voltage is changed, because the image This is because the level of the kinescope drive signal required to generate a predetermined color display may vary from the level of mutual balance required when the control voltage is changed.

If the color graphics drive signal consists of three separate drive signals (a common white drive signal as in the device, rather than one signal), the magnitude of the undesirable offset is an amplitude mismatches function between the three separate drive signals. Will be. The magnitude of such offset may also be a complexity function of the circuit that couples the three separate drive signals to the three color signal processing circuits, respectively. In the latter case, the coupling circuit has to be designed deeply so that the effects of temperature change, mismatching of component values, and effects of operating parameter changes between the three graphics drive signal coupling circuits are minimized.

,

,

)는 블랭크되는 그들 비데오 신호 처리 회로의 출력이 관련된 키네스코프 전자총을 그 시간에 차단시키도록 보장하는 ＂흑색 보다 더 진한 흑색＂ 출력 블랭킹 레벨을 나타낼 수 있다. 그

신호사이의 오프셋 효과는 그래픽스 디스플레이 간격동안 실제로 감지되지 않으며, 3개의 분리 백색 구동 그래픽스 신호 사이의 오프셋에 비교되어 디스플레이된 그래픽스 정보의 칼라 상의 가사화 효과에 거의 영향을 받지 않는다.In the above-described system, the graphics blanking control signal (

,

,

) May indicate a darker black output blanking level than black which ensures that the output of those video signal processing circuits that are blanked shut off the associated kinescope electron gun at that time. That

The offset effect between the signals is not actually sensed during the graphics display interval and is hardly affected by the lyricization effect on the color of the displayed graphics information compared to the offset between three separate white drive graphics signals.

5 is a circuit diagram showing in detail how image control is performed in the system of FIG. The image control circuit includes a potentiometer 110 that is adjustable by a viewer coupled to the input of a gain control voltage source 111 providing differential gain control output voltages V ₁ and V ₂ , as shown in FIG. 5. . These control voltages are included in the signal processors 16 and 14 shown in FIG. 1, respectively, to the gain control inputs of the differentially arranged luminance and chroma amplifiers 112 and 114, and to the control inputs of the differential amplifier 116. Is approved. The output currents of the amplifiers 112, 114 and 116 change simultaneously in response to the control voltages V ₁ and V ₂ . The output current of the amplifier 116 is radiated through a first current mirror comprising transistors 120 and 122 and a second current mirror comprising diodes 125 and 126. The output control voltage derived from the collector of transistor 126 is used to change the level of the graphics drive signal at the base of transistor 52 as shown in FIG. The gain control voltage source 111 may be, for example, in the form described in US Patent Application No. 296,865, entitled "Circuit for Linearly Gain Control of Differential Amplifiers" by L.H. Can be.

In a system using an automatic kinescope beam current limiter, the beam current control voltage induced by a known method can be applied to the input of the gain control voltage source 111, so as to limit the luminance in the direction for limiting the excess kinescope beam current. And the peak amplitude level of the chroma signal. Also in this case, the level of the graphics drive signal can be modified at the same time and with the same sense to limit the beam current.

Claims (3)

In a video signal processing system comprising a color kinescope for displaying a color image in response to a signal applied to the plurality of intensity control electrodes, and a plurality of signal paths for respectively applying a signal representing the image to the kinescope electrode. In the apparatus for controlling the contrast of the displayed color image, a graphics driving signal (W) and a plurality of graphics blanking signals (

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Means (62,64) for providing an image color graphics information signal comprising: to apply a color graphics information signal representing the image to the plurality of signal paths, the graphics drive signal to display graphics information; Graphics that are commonly connected to each of the signal paths for enabling the kinescope, and wherein the plurality of graphics blanking signals are each connected to the plurality of signal paths for blanking selected outputs of the signal path Means (20a, 20b, 20c) for determining the color of the information and control means (68) for controlling the contrast of the displayed graphics information to change the level of the common graphics drive signal. controller. 2. The apparatus of claim 1, wherein the plurality of signal paths comprises video signals representing color images derived from the chroma and luminance components for use in a color television receiver upon receipt of a color television signal comprising chroma and luminance components. Provided for application to kinescope electrodes, the control means 68 further changing the level of the luminance component with the same detection as when the level of the graphics drive signal changes, thereby displaying the displayed video information. Contrast control device, characterized by changing the image contrast of the displayed graphics information to the same sense. 3. The contrast control apparatus according to claim 2, wherein the control means (68) additionally changes the level of the chromatic component with the same sense as when the level of the graphics drive signal changes.

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