KR800000935B1 - Set-up arrangement for a color television receiver - Google Patents

Abstract

A serivice switch is provided for a color television receiver of the type including, in the other named, a black level clamping circuit, a brightness control circuit and an amplifier for coupling luminance signals to an image reproducing line scope. A reserve blanking circuit is coupled with the output of the amplifier for rendering the kinescope in operative during the vertical retrace-horizontal trace intervals to inhibit the formation of disconcerting horizontal trace lines. In a raster position, the service switch is operated to provide a blank raster and to automatically increase the brightness of raster to a level sufficient to permit purity adjustment.

Description

Set-up Device for Color Television Receiver

1a and 1b are schematic diagrams showing the general arrangement of a color television receiver using the device according to the invention.

2 is a waveform diagram of a time domain useful for understanding the arrangement of FIGS. 1a and 1b.

3 is a modified view of the apparatus shown in FIGS. 1a and 1b.

FIELD OF THE INVENTION The present invention relates to a color television receiver, and more particularly, to an apparatus for facilitating set-up and servicing of a color kinescope contained within such a receiver.

During many adjustments, the set-up of color kinescopes requires color temperature and purity adjustments.

Color temperature adjustment takes into account the difference in cathode radiation of the kinescope's multiple electron beam generating guns and the difference in the effect of the kinescope's multiple phosphors. Color temperature adjustment involves adjusting the DC gain applied between the kinescope's cathode and the grease and the AC gain of the kinescope driver so that white information is reproduced at the appropriate color temperature at all luminance levels between minimum and maximum white. . The maximum white level is calculated at the maximum level of luminance with good image sharpness.

Purity adjustment refers to the degree of freedom of one color due to dilution by one of the two colors when associated with the color kinescopes of the world. Purity adjustment locates and purifies the electromagnetic deflection yoke to position the deflection center of the three electron beams to limit each electron beam to hit only a selected one of the three phosphors arranged on the kinescope screen. This is achieved by adjusting the magnet device.

Service switch devices included in color television receivers are known to provide a convenient device for service personnel in the factory so that adjustments can be made without the need for any additional equipment. Normally, service switch devices provide "normal" and "service" or "normal", "service" and "raster" positions. When the service switch is in the "normal" state, the receiver operates to couple the video signal to the kinescope to view the orthoimage.

When the service switch is in the "service" state, the vertical deflection circuit is disabled and the chromaticity and brightness signals are decoupled from the kinescope so that the kinescope is in static operation. The DC control signal coupled to the grid (or cathode) of each gun is controlled gradually until the electron gun produces a narrow, visible horizontal line on the kinescope. When all three electron guns are activated, the line appears at a reasonable distance as a white line of low luminance level. In the "raster" state, the service switch operates to provide an erase raster of sufficient brightness to allow for purity and AC kinescope drive gain adjustment. The service switch provides an erasing raster, for example, by suppressing a radio frequency or an intermediate frequency amplifier of the receiver.

There are many types of service switch arrays. Stark. U.S. Patent No. 3,114,794, J., entitled "Color Television Receiver Control Unit" to Jr. et al. US Pat. No. 3,114,796, G., entitled Stark, Jr., entitled “Color Kinescope Set-Up Process for Color Television Receivers”. this. U.S. Patent No. 3,270,125, P., issued to Kelly et al. Entitled "Color Kineskoscope Operation and Testing Arrangement." this. U. S. Patent No. 3,461, 225, D., issued to Crookshank et al. Under the title "Service Assistance for Color Television Receivers." Love. U.S. Patent Nos. 3,525,801 to D. Willis, entitled "Service Assistance for Color Television Receivers," and D. Al. It is described in US Pat. No. 3,820,155, entitled “Television Receiver Service Control System,” and another type of service switch is beeped. children. It is described in US Pat. No. 3,598,905, entitled "White-Balanced Serving Circuits."

When color television receivers include a black level clamping circuit in the channel provided for brightness signal processing, a particular problem is raised in providing a "raster" set-up arrangement. That is, the black level clamping circuit acts to clamp the maximum signal excursion in the black direction to the black display reference voltage. Therefore, when the brightness signal is decoupled from the brightness processing channel during the purity adjustment to provide an erase raster, the black level clamping circuit tends to produce a raster close to black with a luminance insufficient for purity adjustment.

An additional problem arises when designing a "service" set-up arrangement for color temperature adjustment of a type of receiver that includes an extra erase circuit. This circuit, connected to the kinescope, prevents operation during the vertical retrace-to-horizon line and prevents the formation of obstructive horizontal sweep lines. US Pat. No. 580,688, filed under the heading. When using such a device, be prepared so that this “extra erase” does not adversely affect the set-up process.

In addition, the service switch preferably controls various parts of the receiver coupled by the DC control signal rather than the AC control signal to minimize other problems related to the long lead coupling the AC signal and stray pickup.

According to the present invention, a control device is a device for receiving and amplifying a television signal and for providing a composite video signal including chroma, brightness and synchronization signal portions, and a device for processing chroma, brightness and synchronization signals, chroma and brightness signals. For a television image processing device comprising a color image reproduction device having a plurality of color generating electron beam devices responsive thereto, and a deflection device associated with the electron beam device responsive to a synchronization signal to provide horizontal and vertical scanning of the reproduction device. Is provided. The device includes a black level clamping device in the brightness processing channel to clamp the maximum signal excursion in a predetermined direction corresponding to the black tone of the image to the reference voltage. The brightness processing channel includes a brightness control device behind the black level clamping device to control the DC component of the brightness signal. The switching device is coupled to the receiving and amplifying device and to the luminance control device. The switching device first selectively operates the receiving and amplifying device to supply the chroma signal to the chroma processing channel and to supply the brightness signal to the brightness processing channel, and at the same time, provides luminance control corresponding to the normal operation of the television signal processing device. It has a first (normal) position for selectively controlling the device.

The switching device selectively deactivates the receiving and amplifying device to supply a chroma signal to the chroma processing channel and to supply a brightness signal to the brightness processing channel, and at the same time, even if the brightness signal is decoupled from the brightness channel, It has a second (raster) position that controls the brightness control device to provide a brightness level sufficient to allow adjustment of the receiver, such as adjustment and purity adjustment.

In another aspect of the present invention, the switching device is also coupled to the deflection device and to the device for coupling the brightness signal, which has already been processed by the brightness control device, to the video player. The coupling provided by the coupling device depends on the DC component of the brightness signal. The switching device controls the luminance control device to provide a brightness signal with DC component to deactivate the brightness signal coupling device to couple the brightness signal to the kinescope for color temperature control, and to deflect in the vertical direction. It has a third (service) position for selectively deactivating the device.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1A and 1B show a color television receiver comprising a video processing stage 12 for receiving radio frequency signals from an antenna and for varying these signals through intermediate frequency amplification and detectors (not shown) to form a composite video signal. Is shown. This synthesized video signal includes chromaticity, brightness, synchronization and audio signals.

Chromaticity channel 14 including chromaticity processing stage 16 serves to process the chromaticity signal portion of the composite video signal to form R-Y, B-Y and G-Y color difference signals.

The color difference signal is coupled to the respective inputs of the drive stages 18a, 18b and 18c of the kinescope driver 20. The kinescope driving stages 18a, 18b and 18c act to match the G-Y, R-Y and B-Y chrominance signals and the output signal -Y of the brightness channel 22 to form G, R and B color signals, respectively.

The illustrated kinescope drive stages 18a, 18b and 18c are of the type described in US Patent Application No. 504,357 filed by Donald Henry Willis under the heading "Arc for maintaining the operating point stability of the amplifier."

Since the kinescope drive stages 18a, 18b and 18c are similar, the following description of only 18a applies to only 18b and 18c.

The driving stage 18a includes a first NPN transistor 24a. The G-Y color difference signal is coupled to the base of transistor 24a via capacitor 34a. The rectifier of transistor 24a is coupled to the source of the constant voltage source through resistor 35a and its emitter is coupled to ground through variable resistor 36a. The emitter of transistor 24a is coupled to the emitter of PNP transistor 30 through variable resistors 28a and 28c. The base of transistor 30 is coupled to the output signal of brightness channel 22.

The combination of complementary transistors 24a and 30 amplifies and synthesizes -Y and G-Y to drive signal G at the selector of transistor 24a. The variable resistor 28a can be adjusted to control the gain of the driving stage 18a and the variable resistor 36a can be adjusted to control the static operating point of the driving stage 18a. The emitter of transistor 24a is a direct current coupled to the base of the second NPN transistor 26a. The selector of transistor 26a is a direct current coupled to the base of transistor 24a. The emitter of NPN transistor 26a is coupled to gating circuit 32. Capacitors 34a and NPN transistor 26a form a clamping circuit to maintain the voltage generated at the emitter of transistor 24a independent of the DC state of chromaticity stage 16 and the voltage change between base-emitter of transistor 24a. The clamping action occurs when transistor 26a is challenged in response to the clamping pulse generated by gating circuit 32 during the horizontal feedback period, as described below.

The color signals R, G and B are respectively coupled to the cathodes of the three electron guns of the kinescope 38. For example, each electron gun consists of a cathode, control grid, and screen grid to generate and accelerate the electron beam. Focus electrodes and high voltage stages are also provided.

The DC bias control voltage is connected to the control grid from the bias control stage 40 and the DC screen control voltage is connected to the screen grid from the screen control stage 42 to adjust the cutoff point of each electron gun.

The brightness channel 22 includes a brightness processing stage 44 which acts to amplify and process the brightness signal portion of the composite video signal.

The contrast control stage 46 is coupled to the brightness processing stage 44 to control the amplification of the brightness signal.

The service switch 82 is coupled to the video processing stage 12, the brightness channel 22 and the vertical deflection circuit 76 to facilitate the initial adjustment of the receiver operation. Switch 82 is shown to have "normal", "raster" and "service" positions.

When the service switch 82 is in its normal position, the video processing stage 12 applies a brightness signal to the brightness processing stage 44.

The output of the brightness processing stage 44 is coupled to a black level clamping circuit 48 which serves to clamp the maximum signal excursion in the direction corresponding to the black tone of the image reproduced by the kinescope 38 at the reference potential. The black level clamping circuit 48 comprises a complementary emitter-floor 50, the output of which is coupled to the input of the emitter-floor 52 through a capacitor 56. Diode 54 is coupled to the base of emitter-floor 52 and is polarized to charge capacitor 56 toward the maximum signal excursion in the black direction when it becomes conductive. Charge current is provided by a current power source, shown by resistor 53 coupled between the constant voltage source and the anode of diode 54. The reference voltage representing the desired black tone of the image is coupled to the anode of diode 54 through emitter-follower 58.

The horizontal synchronizing pulse provided by the synchronous separator 60 is combined with the horizontal feedback signal provided by the horizontal deflection circuit 62 at the base of the NPN transistor 64 of this clamping circuit to control the operation of the black level clamping circuit 48.

The output of the black level clamping circuit 48 generated in the emitter circuit of transistor 52 is coupled to the erasing and luminance control stage 65 which serves to control the DC component of the brightness signal. Stage 65 acts to add to the brightness signal the vertical and horizontal sweep pulses induced by vertical deflection stage 76 and horizontal deflection stage 62, respectively, so that kinescope 38 is cut off during the horizontal and vertical retrace periods.

65 includes an NPN transistor amplifier 66 which includes in its collector circuit a conductive path between each collector and emitter of NPN transistors 68 and 70. Amplifier 66 inverts the output signal of black level clamping circuit 48. The base of transistor 68 arranged as an emitter-follower is coupled to the movable arm of luminance control potentiometer 96. The voltage generated at the arm of the luminance potentiometer 96 determines that the amplifier 66 determines the DC component of the signal at the collector. The base of transistor 70 is coupled to the output of differential amplifier stage 72 having an input responsive to vertical and horizontal erase pulses. Transistor 70, coupled to differential amplifier 72, acts to insert an erase pulse into the brightness signal. The output of stage 65 (Figure 2B) at the collector of transistor 66 is coupled to the base of the PNP transistor 30 via an emitter follower stage. Video processing stage 12 is coupled to channel 74 to process the synchronization signal. The synchronizing separator 60 acts to derive horizontal and vertical synchronizing pulses from the synthesized video signal and couples these pulses to the vertical deflection circuit 76 and the horizontal deflection circuit 62. Deflection circuits 76 and 62 are coupled to a deflection winding associated with kinescope 38.

The horizontal deflection circuit 62 is coupled to the high voltage stage 78 which serves to provide for the focus and high voltage electrodes of the kinescope 38.

As described above, the gating circuit 32 acts to generate the clamping pulse in response to the horizontal feedback signal to control the clamping operation of the driving stages 18a, 18b and 18c during the horizontal retrace period. In addition, the output of the gating circuit 32 at the emitter of the PNP transistor 80 has an extra erasing pulse during the vertical retrace-horizontal edge, so that the kinescope 38 is cut off so that the disturbing horizontal line is not visible during the vertical retrace-horizon. Is coupled to the emitter of transistor 30 through a series connection of resistor 83 of diode 85 to provide. Gating circuit 32 is described in detail in Donald Henry Willis, above-mentioned US Patent Application No. 580,688.

The service switch 82 does not require any additional test equipment and works to allow purity control and color temperature control of the Kinescope 38 by the plant and service personnel.

Service switch 82 is a three-position switch with two sets of four poles isolated electrically.

The first set includes poles 84a, 86a, 88a and 90a. Pole 84a is coupled to ground through resistor 92. The pole 86a is coupled to one end (terminal 97) of the luminance potentiometer 96 through the conductor 94, and the other end thereof is coupled to the constant voltage source. When service switch 82 is in the "normal" position, poles 84a and 86a are joined together through negligible impedance. Pole 88a is coupled to ground through resistor 98a, which has a resistance lower than resistor 92. When service switch 82 is in the "raster" position, poles 86a and 88a are joined together through negligible impedance. Pole 90a is coupled to the junction of resistor 83 and diode 85 via conductor 100. When service switch 82 is in the "service" position, poles 88a and 90a are coupled together through negligible impedance.

The second set of poles consists of poles 84b, 86b, 88b and 90b. The pole 84b is coupled to the intermediate frequency amplifier of the video processing stage 12 via the conductor 102. Pole 84b is coupled to ground through conductor 104. When service switch 82 is in the "normal" position, poles 84b and 86b are joined together through negligible impedance. Ie 88b is coupled to ground via conductor 106. Service switch 82 is in the "raster" position, or poles 86b and 88b are joined together through negligible impedance. The pole 90b is coupled to the vertical deflection end 76 through the conductor 108. When the service switch 82 is in the "service" position, poles 88b and 90b are coupled together through negligible impedance.

The general arrangement shown in FIG. 1 is shown, for example, in the 1973 R.C. Color Television Service Data No. C-8 (CTC-68 Type Receiver) published by R.C.Coporation, Indianapolis City, Indiana. Suitable for use with one type of color television receiver.

In operation, when service switch 82 is in the “normal” position, the ground potential is applied to the intermediate frequency amplifier of video processing stage 12 via poles 84b and 86b to provide a steady signal gain. The amplified brightness and chroma signals are coupled to brightness channel 22 and chroma channel 14, respectively. Also in the "normal" position, terminal 97 of luminance potentiometer 96 is coupled to ground through resistor 92 of poles 84a and 86a. This arrangement allows the luminance potentiometer 96 to be adjusted in its normal range.

In the "raster" position of service switch 82, the ground potential is removed from the intermediate frequency amplifier of video processing stage 12 because poles 84b and 86b are not already connected to each other. As a result, the gain of the intermediate frequency amplifier of the video processing stage 12 is changed to remove the brightness signal from the brightness channel 22 and to remove the chroma signal from the chroma channel 14. An erase raster is generated. Since the black level clamping circuit 48 clamps the maximum signal excursion in the black direction to the reference potential indicating black, the output signal of the brightness channel 22 to allow adjustment of the AC gain and purity of the kinescope drive stages 18a, 18b and 18a. -Y produces an image of insufficient brightness (i.e. black) under this condition. However, in the "raster" position of service switch 82, terminal 97 of luminance potentiometer 96 is connected to ground via poles 86a and 88a and resistor 98. This resistance has a lower resistance value than the resistance 92. Therefore, the DC voltage at the actuator of the luminance potentiometer 96 is automatically reduced, which is reduced at the emitter of the transistor 68. This reduction in DC voltage is transmitted without changing the polarity of the cathode of the kinescope 38, causing the luminance of the erased image to transition to a level sufficient to allow adjustment of the AC gain and purity of only 18a, 18b and 18c.

The value of resistor 98 is such that when the service switch 82 is in a taster position independent of the setting of the arm of the luminance potentiometer 96, it provides an erasure raster with sufficient brightness to allow for purity and kinescope-driven AC gain adjustment. Is preferably connected to a voltage source (as shown by ground in FIG. 1b). It should be noted that the setting of the mover can be changed to change the luminance while in the "later" position.

In the "service" position of service switch 82, the ground potential is applied to vertical deflection stage 76 via poles 88b and 90b.

This acts to suppress the operation of the vertical deflection circuit 76 so that the image is vertically attenuated by a horizontal thin line in the center of the screen. In addition, the ground potential is removed from the intermediate frequency amplifier of the video processing stage 12 to prevent chromaticity and brightness information from being disturbed within a thin horizontal line that may interfere with color temperature adjustment.

In the "service" position, the conductor 94 is an open circuit such that a large constant voltage near the constant supply voltage applied to the other end of the luminance potentiometer 96 is coupled to the collector circuit of the transistor 66 through the transistor 68. As a result, the large constant voltage causes transistor 30 to become non-conductive and the base of transistor 30 to provide a static direct current voltage to each cathode of kinescope 38, almost as provided by transistors 24a, 24b and 24c due to lack of brightness signals. Is applied to. In this state, the color temperature adjustment of the kinescope 38 can be achieved by adjusting the fixed voltage coupled to the kinescope 38 by the screen control stage 42 so that each electron gun is at the limit between the conduction and the cutoff when the transistor 30 is cut off. .

Note that in the "service" position, conductor 100 is coupled to ground through resistor 98. As a result, diode 85 is reverse biased, so that the extra erase pulses generated by gating device 32 are decoupled to transistors 24a, 24b and 24c to upset the static operating state of transistors 24a, 24b and 24c, thereby reducing the color of kinescope 38. Upset the temperature adjustment.

Note that conductor 100 is not necessary if no extra erase pulses are provided. Conductor 100 is simply an AC signal coupling conductor coupled to switch 82, with the remaining conductors coupled to the DC signal. Therefore, noise pickup, interference signals and other problems, such as capacitive loads associated with long conductors coupling the AC signal to the service switch, are sufficiently reduced by the arrangement of FIGS. 1a and 1b.

It can be seen that the service switch arrangements of FIGS. 1A and 1 can be simplified if the "raster" position is omitted. This arrangement is similar to that shown in FIG. 1 except for the connecting member shown in FIG. 3 and provided for the " raster " position.

In a particular embodiment as described above, the black level clamping circuit 48 constitutes a keyed clamping circuit responsive to a signal formed by matching the horizontal feedback signal and the horizontal sync pulse. In this method, only the front part and the rear part of the basic level of the brightness signal are clamped to the reference voltage representing the black tone of the image. As a result, the error in the black level due to instantaneous noise is reduced.

When the black level clamping circuit 48 is operating, waveform A in FIG. 2A is generated at its input. Waveform A constitutes image information 214 arranged between erase pulses 212. The erase pulse is formed by the sync pulse tip 218 and the base level 216 having a period less than the base level. This sync tip is superimposed on the foundation level to make the front portion 220 and the rear portion 222 of the foundation level.

Diode 54 is used during the front part 220 and rear part 222 of waveform A so that the black level clamping circuit 48 does not clamp the sync tip 218 or noise instantaneous during the video information portion 214 to the reference potential so that an incorrect black level is set. Only the state becomes a challenge. This combines the horizontal synchronous pulses provided by the synchronous separator 60 (waveform C in FIG. 2C) at the base of the NPN transistor 64 of the black level clamping circuit 48 and the horizontal feedback signal provided by the horizontal deflection circuit 62 (waveform D in FIG. 2d). By doing so. The horizontal synchronization pulses, the feedback signal, and the synchronization tip are temporally related as shown in FIGS. 2A, 2C, and 2P.

The horizontal sync pulse is coupled to the base of transistor 64 through resistor 61. The horizontal feedback signal is coupled to the base of transistor 64 through resistor 63. The values of resistors 61 and 63 are selected in relation to the amplitude characteristics of the respective waveforms to which they are combined such that transistor 64 is in a non-conductive state only during the front and rear base portions (waveform E in FIG. 2E).

The black level clamping circuit similar to the black level clamping circuit 48 shown in FIGS. second. Iokanis is described in detail in US Patent 465,891, entitled "Black Level Clamping Circuits for Television Signal Processors."

Representative resistance and voltage values are shown in FIGS. Although the present invention has been described with respect to specific embodiments only, various modifications and changes may be made within the background of the present invention.

Claims (1)

An apparatus for receiving and amplifying a television signal and for deriving a synthesized video signal including chromaticity, brightness and synchronization signals from the signal, an apparatus for processing the chromaticity 16, the brightness 44 and the synchronization signal 60; A color image reproducing apparatus 38 having a plurality of color generating electron beam devices responsive to the chromaticity and lightness signals, an apparatus 20 responsive to the chromaticity and lightness signals to drive the image reproducing apparatus, and the reproducing In a control device for a color television signal processing device comprising deflection devices (62, 76) associated with an electron beam device responsive to said synchronization signal to provide horizontal and vertical scanning of the device, in particular black tones of the reproduced image. A black level clamping device (48) included in the brightness processing device for clamping the maximum signal excursion in the direction corresponding to the reference potential; Coupled to the brightness control device 65 and the brightness control device and the reception and amplification device behind the clamping device in the brightness processing device to control the DC component of the brightness signal, and to provide a color signal to the color processing device. A first position for controlling said luminance control device to selectively operate said receiving and amplifying device to apply and apply a brightness signal to said brightness processing device and at the same time to provide a brightness level corresponding to normal operation of said television signal processing device. Selectively activate the receiving and amplifying device to apply a chroma signal to the color processing device (normal) and to apply the brightness signal to the brightness processing device, and simultaneously while the brightness signal is decoupled from the brightness processing channel. The luminance to provide a luminance level sufficient to allow adjustment of the signal processing apparatus; The second position (raster, Facilities) color telrebijyon Water appointed set, characterized in a switching device 82 having a control device for controlling-up device.

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