MXPA97008171A - Deviation circuits for screen image - Google Patents

Abstract

The present invention relates to a television receiver, comprising: a video image having a lattice with a height-to-width ratio, a source of supply voltage, a signal generator for a sawtooth waveform; having a selectable amplitude, a first switch for controlling the amplitude of the sawtooth waveform, a vertical amplifier sensitive to the sawtooth waveform and generating a vertical deflection signal that varies according to the selected amplitude of the sawtooth waveform to allow the selection of a vertical truss dimension, a horizontal deflection circuit energized by the supply voltage and generating a horizontal deflection signal for a horizontal deflecting yoke to provide a first horizontal framing dimension, a signal source coupled to the horizontal yoke to modify the horizontal deviation signal to providing a second dimension of horizontal framing, a second switch for controlling the signal source and selecting one of the first and second dimensions of horizontal framing, and a framing width distortion correction circuit sensitive to the amplitude of the framing dimension vertical and that modulates the supply voltage that energizes the horizontal deflection circuit, the distortion of lattice width is corrected for all combinations of selectable vertical and horizontal framing dimensions

Description

DEVIATION CIRCUITS FOR WIDE DISPLAY IMAGE Background of the Invention 1. Field of the Invention This invention relates to the presentation of wide-screen television receivers and video images and, in particular, to wide-screen television receivers and video images in which different display modes having different sizes are implemented. of image by manipulation of deflection circuits and frame sizes. 2. Description of Related Art When reference is made to television image, there are actually two aspect ratios. An aspect ratio is one that describes the outer boundary or limits of the image. In conventional television receivers, this aspect ratio is 4: 3. The horizontal factor usually appears first. In widescreen television receivers, this aspect ratio is, for most manufacturers, 16: 9. The second aspect ratio is one that describes the images that are displayed on the TV screen. A perfect round circle, for example, that appears on a television screen as a perfect round circle, has a 1: 1 aspect ratio. If the same circle is displayed on a wide-screen television receiver, without corrective measures, the circle will appear oval, which is elongated along the horizontal axis. If the receiver is 16: 9, the circle will have an aspect ratio of approximately 1 .3: 1. if the same circle is displayed on a wide-screen television receiver, with the correct corrective measures, the circle will appear as a perfect circle and, it will have an aspect ratio of 1: 1. Two expressions are used in the present with respect to the aspect ratio to avoid confusion. One expression is the "format display ratio" and the other is the "image aspect ratio". The expression "format ratio ratio" refers to the width to height ratio of the boundaries or edges of an image. The format display ratio of a video signal from a conventional video source is 4: 3. The format display ratio of a conventional television receiver is 4: 3. The format display ratio of a signal Video from a wide-screen video source is 16: 9 (sometimes 5: 3, sometimes other width ratio). The format ratio of a wide-screen television receiver is 16: 9 (sometimes 5: 3, sometimes another width ratio). The expression "image aspect ratio" refers to the ratio of width to height of the images within an image. Images that have an image aspect ratio of 1: 1 will appear without distortion of image aspect ratio. Images that do not have an aspect ratio of 1: 1 will appear with image aspect ratio distortion. Wide screen television receivers and images have several display modes, particularly useful and, in some cases, critical. These display modes include: displaying images from video sources that have conventional format display relationships, without distortion of image aspect ratio; display of images from video sources that have widescreen format display relationships, without distortion of image aspect ratio; display of images from video sources that have conventional format display relationships, of an elongated size, without distortion of image aspect ratio. The display of images from video sources having conventional format display ratios, of an elongated size and without distortion of image aspect ratio, frequently results in a portion of the image being cut off at the top and bottom. This portion is one third, if the wide-screen display is 16: 9 and the size is horizontally and vertically elongated by four-thirds factors. If the elongated image is centered vertically, then a sixth part of the image will be cut from the top and a sixth part will be cut from the bottom of the image. This shortening gives rise to two emissions in an operational way. An emission is one in which the observer may wish to accept a certain amount of distortion of the image aspect ratio to reduce the shortening and see more of the image. In this case, another desirable display mode would be to display images from video sources having conventional format display relationships, in an enlarged size, with a small but acceptable amount of distortion of the image aspect ratio. The other issue is that the subtitles and other types of information can be in the cut part of the image. An observer may consider that subtitles or other information are critical, although it is undesirable to accept the distortion of image aspect ratio. In this situation, even another desirable display mode would be to display the images from the video sources having conventional format display relationships, in elongated size and without image aspect ratio distortion, although tilted upward to display the subtitles or other information and cut only or, substantially only the upper part of the image. Vertical scrolling is required to make visible the hidden portions of the image. This can be achieved by superimposing a CD component on the vertical deflection current. This requires a vertical deflection amplifier with DC coupling and sufficient output current range. The amplifier has the disadvantage of increased dissipation losses. Another approach is to use a floating DC current source connected in parallel to the vertical deflecting yoke. The dynamic range of the output voltage of the current source must be large enough to respond to the return pulse. A disadvantage of current overlap is that the vertical linearity correction and the east-west side cushion distortion correction have to be readjusted when the vertical offset is changed. U.S. Patent 5, 287, 042 discloses a switching arrangement for controlling the horizontal deviation amplitude. In a first condition, a lattice having an amplitude of deviation and a deviation correction parameter corresponding to a first aspect ratio is generated. In a second selectable condition, a lattice having a deviation amplitude and deviation correction parameter corresponding to a second aspect ratio is produced. An additional inductance is coupled to the deflecting yoke and is shorted in a selectable condition to drive the deflection current by means of the inductor. EP A 0578162 discloses a vertical rotation system that includes a turning circuit that produces a vertical restoration signal that is shifted phase by a selected number of horizontal lines relative to the vertical synchronization component of the video signal. The implementation of all the display modes described above can be expensive and requires considerable signal processing power. These display modes can also create problems in correcting typical framing distortion problems, such as lateral cushion distortion, as the image or framing size changes.

Brief Description of the Invention In accordance with the inventive arrangement, a wide-screen television receiver or image implements the various display modes described above in a relatively inexpensive manner and, at the same time, provides correction for typical framing distortion problems, such as distortion in side cushion. In accordance with another inventive arrangement, a wide-screen television receiver or image implements the different display modes described above by manipulating the vertical deflection circuits to provide a lattice for a wide-screen video display having horizontal widths and selectable vertical heights, i.e., having selectable format display ratios According to another inventive arrangement, a wide-screen television receiver or image automatically corrects the cushion distortion as the horizontal and vertical scanning amplitudes are changed to change the modes of display from one to another According to a currently preferred modality, three display modes are defined to show images from conventional video sources, that is, they have 4: 3 format display relations. These modes are designated "Standard", "Wide" and "Approach". The standard display mode will display a conventional image in its normal style and size by changing the format display ratio of the fabric from 16: 9 to 4: 3, without changing the height of vertical deflection. Only the horizontal scanning amplitude is changed; the horizontal scanning amplitude is reduced. Said image will not have distortion of the image aspect ratio and will not be cut. The wide display mode will display a conventional image by changing the format display ratio of the fabric from 16: 9 to 4: 3, without changing the horizontal scan width. Only the vertical scan amplitude is changed; the vertical scan amplitude increases. There is a vertical overshoot of four thirds, which corresponds to the horizontal overshoot resulting from the use of the total width of the frame and wide-screen image. The upper and lower sixth part of the elongated image is cropped, although there is no distortion of the image aspect ratio. The approach display mode is similar to the wide mode, except that the vertical overshoot factor is less than four thirds. The elongated image is slightly compressed vertically. It cuts less than a sixth of the top and bottom of the elongated image, although there is a bit of distortion of the image aspect ratio.

In accordance with another inventive arrangement, an image shift in an upward direction is implemented by the delay of the vertical scan relative to the video signal. This allows the lower part of the ANC HO mode image of 4: 3 to be placed near the bottom edge of the screen. This is particularly useful when subtitles are present. The correction of vertical linearity and the correction of distortion in East-West side cushion remains constant using this method. An alternative method of vertical image placement, which uses digital deviation circuits, is also presented. This allows vertical rotation up and down. A television receiver, in accordance with one or more of the above inventive arrangements, comprises: a video image having a lattice with a height-to-width ratio; a source of supply voltage; a signal generator for a sawtooth waveform having a selectable amplitude, a first switch for controlling the amplitude of the sawtooth waveform; a vertical amplifier sensitive to the sawtooth waveform and which generates a vertical deflection signal that varies according to the selected amplitude of the sawtooth waveform to allow selection of a vertical framing dimension, a horizontal deflection circuit energized by the supply voltage and which generates a horizontal deflection signal for a horizontal deflection yoke to provide a first dimension of horizontal framing; a signal source coupled to the horizontal yoke to modify the horizontal deflection signal to provide a second horizontal framing dimension; a second switch for controlling the signal source and selecting one of the first and second dimensions of horizontal framing; and, a lattice width distortion correction circuit sensitive to the vertical deflection signal and modulating the supply voltage energizing the horizontal deflection circuit, the lattice width distortion being corrected for all combinations of lattice dimensions vertical and horizontal selectable. Another television receiver in accordance with one or more of the above inventive arrangements, comprises: a video image having a lattice with a height-to-width ratio; a source of supply voltage; a sawtooth waveform generator responsive to a source of vertical synchronization signals, the sawtooth waveform having a selectable amplitude; a switchable phase delay circuit for delaying vertical synchronization signals; a first switch for enabling and inhibiting the operation of the phase-lag circuit, the selection of the delayed vertical synchronization signals that provide an upright vertical position of an image on the video image, relative to a nominal vertical position of the image, a second switch to control the amplitude of the sawtooth waveform, a vertical amplifier sensitive to the sawtooth waveform and which generates a vertical deflection signal that varies in amplitude in accordance with the amplitude selected from the sawtooth waveform to allow the selection of a vertical framing dimension and varying in phase in accordance with the selected phase of the vertical synchronization signals to allow the selection of an image position, a horizontal deviation energized by the supply voltage and that generates a signal of horizontal deviation for the horizontal deflection yoke to provide a first dimension of horizontal framing, a signal source coupled to the horizontal yoke to modify the horizontal deflection signal to provide a second dimension of horizontal framing, a third switch to control the signal source and select a of the first and second horizontal frame dimensions Another television receiver, in accordance with one or more of the above inventive arrangements, comprises a video image having a lattice with a height-to-width ratio, a voltage source of supply, a sawtooth waveform generator sensitive to the source of vertical synchronization signals, the sawtooth waveform having a selectable amplitude, a switchable phase delay circuit to delay the vertical synchronization signals , a first switch to enable or inhibit the operation of the circuit phase delay, the selection of the delayed vertical synchronization signals that provide a displaced vertical position of an image on a video image, relative to a nominal vertical position of the image; a second switch for controlling the amplitude of the sawtooth waveform; a vertical amplifier sensitive to the sawtooth waveform and which generates a vertical deflection signal that varies in amplitude in accordance with the selected amplitude of the sawtooth waveform to allow the selection of a vertical framing dimension and which varies in phase according to the selected phase of the vertical synchronization signals to allow the selection of an image position; a horizontal deflection circuit energized by the supply voltage and generating a horizontal deflection signal for a horizontal deflection yoke to provide a first dimension of horizontal framing; a signal source coupled to the horizontal yoke to modify the horizontal deflection signal to provide a second horizontal framing dimension; a third switch for controlling the signal source and selecting one of the first and second dimensions of horizontal framing. Another television receiver, in accordance with one or more of the above inventive arrangements, comprises: a video image with a height-to-width ratio; horizontal and vertical deflection circuits to generate selectable frames of different sizes on the video image by modifying the signals of horizontal deviation; a circuit sensitive to a vertical deflection signal and generating a first control signal; a waveform generator responsive to the first control signal and generating a substantially parabolic signal; a lattice distortion correction circuit sensitive to the substantially parabolic signal; and a source of a second control signal indicative of a selected horizontal frame width, the horizontal deviation being modified in response to the second control signal. Another television receiver according to one or more of the above inventive arrangements, comprises: a video image with a width-to-height ratio; a horizontal deflection circuit to generate a horizontal deflection current; a horizontal deflecting yoke sensitive to the horizontal deflection circuit; an inductor; a switch for operatively coupling the inductor to the horizontal deflecting yoke; and, a source of a control signal indicative of a selected truss width, the switch being responsive to the control signal.

Brief Description of the Drawings Figure 1 is a block diagram of a television receiver in accordance with one or more of the inventive arrangements. Figure 2 is a schematic diagram of the sawtooth generator shown in Fig. 1. Figure 3 is a schematic diagram of the pulse delay circuit shown in FIG. 1. FIG. 4 is a schematic diagram of the parabola generator shown in FIG. 1. FIG. 5 is a schematic diagram of the window discriminator shown in FIG. Figure 6 is a schematic diagram of the horizontal deflection circuit shown in Fig. 1. Figure 7 is a block diagram and schematic of the horizontal output and amplitude switching circuits shown in Fig. 7. Figure 8 is a schematic diagram of the East-West control circuit shown in Figs. 1 and 6. Figure 9 is a useful time control diagram for explaining the operation of the pulse delay circuit shown in Figs. 1 and 3. Figure 10 is a useful time control diagram for explaining the operation of the window discriminator shown in Figs. 1 and 5. Figure 11 is a block diagram of a digital vertical displacement circuit.

Figure 12 is a time control diagram useful for explaining the operation of the vertical displacement circuit shown in Fig 11; Figure 13 is a schematic diagram of the vertical displacement circuit shown in Fig 11; Detailed Description of the Preferred Modalities Figure 1 shows the block diagram of a television receiver 10 in accordance with one or more inventive arrangements FORMAT and ZOOM are control signals for the SAW TOOTH GENERATOR 20 to change the amplitude of vertical deflection towards the different image formats The original vertical drive pulses VIN are fed to the PULSE DELAY circuit 30 The signal VSHIFT is used to control the delay time of the vertical drive pulses VOUT that synchronize the SAW TOOTH GENERATOR These pulses are also used for synchronization vertical of an On-Screen Image circuit, not shown Information on the vertical scanning amplitude is taken from the deviation current sensing resistor Rs of VERTICAL AMPLIFIER 25 and compared to the adjustable reference SUPPRESSION LEVEL OF OVERHEAD in the WINDOW DISCRIMINATOR 60 The output signal SUPPRESSION (BLANKING) is used a to suppress the beam current during excessive vertical overshoot. The voltage across Rs is also applied to the PARABLE GENERATOR 40 which drives the East-West CONTROL CIRCUIT 80. The trapezoidal distortion is corrected by the TRAPEZE setting in the PARABLE GENERATOR. The HORIZONTAL DEFLECTION CIRCUIT 60 has a scanning amplitude adaptation for 4: 3 and 16: 9 image formats. The horizontal and vertical yokes are placed in a cathode ray tube which forms a wide screen video image 12, that is, a video image having a wide format display ratio, for example, 16: 9. Fig. 2 shows the circuit diagram of the sawtooth generator 20 of the vertical deflection circuit formed by the sawtooth generator 20 and the vertical amplifier 25. The vertical scanning amplitude is altered by the change of the output value of the power source Q4 of the sawtooth generator by applying the signal FORMAT A Q3 by means of the switch S3. All switches shown herein, including switches S1 to S6, are illustrated as toggle switches for simplification purposes. Any or all of the switches can be implemented as manual switches or as remotely controlled switches or as switches controlled by a microprocessor, for example sensitive to a remote control signal. Any or all of the switches can also be implemented as semiconductor switches or as relays. The ZOOM S2 image mode switch is open. For 16: 9 format display relationships and 4: 3 standard images with dark side panels, FORMAT is smaller (for example 1V), therefore transistors Q1 to Q3 are off. The amplitude of the sawtooth voltage is defined by the emitter current of Q $ which is adjusted by R13. To display a 4: 3 image in WIDE mode, FORMAT is high (for example 8V), Q2 and Q3 are on. The additional current is supplied by Q2 to the emitter of Q4, increasing the vertical scanning amplitude. The image height for the 4: 3 aspect ratio in the WIDE mode is set by R10. Regardless of the FORMAT signal, the vertical approach is selected when switch S1 is closed. Transistors Q3 and Q4 remain off since D1 is on. Q1 is on, supplying the current to the emitter of Q4. The vertical size is reduced to approximately 85% of the amplitude during the WIDE mode and is adjusted by R4. The sawtooth shape is damped by Q6 by operating the VERTICAL AMPLIFIER. The linearity is adjusted with R20 (VLIN) in the feedback path of Q6. In the pulse delay circuit 30 in FIG. 3, the vertical drive pulses (VIN) are delayed by the double breaker U1 and the associated components. The transistor Q8 drives U1A with the trailing edge of the negative operating pulses differentiated by C10 and R33. The pulse width of the output signal on pin 5 of U1A is selected with switch S4 of VSHIFT. For vertical displacement, S2 is open, therefore Q7 is on, cutting C7 and connecting C8 to ground. The resulting pulse width of approximately 2 msec is the delay time for the displaced image. The VIN and VOUT waveforms are shown in Fig. 9. Switch S $ is closed for vertical centering. This turns off Q7, so that the time control capacitance becomes C7 and the delay is reduced to 2μsec. insignificant. The leading edge of the output pulse from U1A drives U1B by means of R36 and C14. The output pulse of approximately 0.6 msec duration on pin 9 of U1B is used to synchronize the sawtooth generator by means of Q5 and is available as VOUT for future use. The parabola generator 40 is shown in Fig. 4. The input signal for the parabola generator is the sawtooth voltage through the sampling resistor Rs, which may have a value of 0.68 ohms. The sawtooth voltage from Rs is an input to pin 2 of U3. The output voltage from the pin 7 of U3, which is substantially parabolic, is DC coupled to the East-West Control Circuit 80, shown in detail in Fig. 8. This keeps the peaks of the amplitude modulation of the current of horizontal deviation constant during the full range of the vertical scanning amplitude. With the AC coupling, the image width and East-West correction would vary depending on the image height. With reference to Figures 1 and 2, the switch S3 and / or the switch S3 is / are a source of a control signal that selects a height of vertical deflection. The sampling resistor Rs is a source of an additional control signal indicative of the selected vertical deflection height. With reference to Figure 4, the additional control signal establishes the substantially parabolic signal as different vertical deflection heights are selected. The substantially parabolic signal is therefore automatically adjusted also as different vertical heights are selected. With reference to FIG. 8, the substantially parabolic signal controls the operation of transistor Q5. The parabolic modulation of the operation of the transistor Q5 modulates the supply voltage to the horizontal output transistor, which automatically provides correction of lateral cushion distortion for all selected vertical and horizontal scanning amplitudes. With reference to Fig. 5, the peak-to-peak amplitude of the vertical deflection current is monitored by a window discriminator constructed around four OP AMP U2 to protect the picture tube against excessive vertical overshoot. The current sampling voltage from Rs is connected to the non-inverted input of U2B and the inverted input of U2C to detect the overshoot in both directions. The SUPPRESSION SUPPRESSION LEVEL voltage damped with both polarities is applied to other inputs of U2B and U2C respectively. For the duration of the overshoot, its outputs are positive, are combined by diodes D5 and D6 and are available by means of R28 for additional suppression of the beam current. Fig. 10 shows the current sampling voltage, the suppression level is overshoot for both polarities and the output suppression signal resulting from the window discriminator. Figure 6 shows the horizontal deflection circuit 60. FIG. 7 shows the horizontal output circuit 70 and the horizontal switching circuit 72 in more detail. With reference to both Figs. 6 and 7, switch 1 is open for a standard 4: 3 image with dark side panels. Transistor Q8 is on, turning off Q7 and therefore connecting inductor L3 in series with horizontal yoke LH to reduce the deflection current. When S1 is closed the voltage of the hottest winding of the feedback transformer is rectified by diode D12 to turn Q8 off. The transistor Q7 is turned on when cutting L3, thereby increasing the horizontal current to display WIDE images of 16: 9 and 4: 3. The parasitic high frequency oscillations of the horizontal deflection current at the beginning of the trace interval are suppressed with D10, R26, R27, R28 and C16. The oscillations in the high-voltage winding of the feedback transformer caused by the leakage inductance of the feedback transformer are 2.5 mH. The amplitudes of the vertical and horizontal deflection currents in the different image modes are given in Table 1 below.

Vertical downward displacement may be desirable with certain images. To do this, the vertical synchronization impulse must guide the video signal. Delaying the vertical impulses by the duration of a field plus or minus some lines results in the displacement of the image by the same amount upwards or downwards respectively. When such a delay is generated with analog circuits, the entanglement caused by fluctuation can be a problem. Figure 11 shows the block diagram of a circuit 111 using the digital counters 112, 113 and 114 and the decoder 115 to delay the vertical actuator pulses by an integer multiple of the duration of half a horizontal line. The delay time is adjustable in increments of half a line scan period from a field interval minus 36 plus 35.5 line periods This results in a maximum vertical image shift of 36 lines down and 355 lines up from the central position. This is equivalent to minus 72 up to plus 71 counts. The relative phase positions of VOUT are shown in Fig. 12. Fig. 13 shows the detailed circuit diagram 111 having two programmable logic devices (PLD) U4, U5 and a phase closed loop frequency multiplier (PLL) around U6 and U7. PLD U4 contains counter 112 (COUNTER 1) and DECODER 115. PLD U5 contains counters 113 and 114 (COUNTER 2 AND COUNTER 3). The active lower signals for vertical position control are generated by switches S5 and S6. Switch S5 provides the function SHIFT UP or SHIFT DOWN and switch S6 restores to the center position. The input signals for the circuit are VIN and HIN, the vertical and horizontal drive pulses respectively. The PLL frequency duplicator can be omitted if a 2fH clock is available. The proposed deflection system can be easily incorporated into an existing color television chassis that uses a wide-screen picture tube to implement a wide-screen television receiver having the most desirable modes of operation at minimal additional cost.

Claims (4)

1 . A television receiver, comprising: a video image having a lattice with a height-to-width ratio; a source of supply voltage; a signal generator for a sawtooth waveform having a selectable amplitude; a first switch for controlling the amplitude of the sawtooth waveform; a vertical amplifier sensitive to the sawtooth waveform and which generates a vertical deflection signal that varies in accordance with the selected amplitude of the sawtooth waveform to allow the selection of a vertical framing dimension; a horizontal deflection circuit energized by the supply voltage and generating a horizontal deflection signal for a horizontal deflection yoke to provide a first horizontal framing dimension; a signal source coupled to the horizontal yoke to modify the horizontal deflection signal to provide a second horizontal framing dimension; a second switch for controlling the signal source and selecting one of the first and second dimensions of horizontal framing; and a lattice width distortion correction circuit sensitive to the amplitude of the vertical lattice dimension and modulating the supply voltage energizing the horizontal deflection circuit, the lattice width distortion being corrected for all combinations of the lattices. Selectable vertical and horizontal truss dimensions. The receiver of claim 1, wherein the lattice width distortion correction circuit comprises: a vertical scale parabola generator responsive to the vertical deflection signal; and a modulator circuit sensitive to the vertical scale parabola.

3. The receiver of claim 1, further comprising a suppression signal generator operative in accordance with the vertical scale deflection signal.

4. A television receiver comprising: a video image having a lattice with a height-to-width ratio; a source of supply voltage; a sawtooth waveform generator responsive to a source of vertical synchronization signals, the sawtooth waveform having a selectable amplitude; a switchable phase delay circuit for delaying vertical synchronization signals; a first switch for enabling and inhibiting the operation of the phase-lag circuit, the selection of the delayed vertical synchronization signals provides a vertical position shifted upward of an image on the video image, in relation to a vertical position of the image; a second switch for controlling the amplitude of the sawtooth waveform; a vertical amplifier sensitive to the sawtooth waveform and which generates a vertical deflection signal that varies in amplitude in accordance with the selected amplitude of the sawtooth waveform to allow the selection of a vertical framing dimension and which varies in phase according to the selected phase of the vertical synchronization signals to allow the selection of an image position; a horizontal deflection circuit energized by the supply voltage and generating a horizontal deflection signal for a horizontal deflection yoke to provide a first horizontal framing dimension; a signal source coupled to the horizontal yoke to modify the horizontal deflection signal to provide a second horizontal framing dimension; a third switch for controlling the signal source and selecting one of the first and second horizontal frame dimensions; and a lattice width distortion correction circuit sensitive to the vertical deflection signal and which modulates the supply voltage energizing the horizontal deflection circuit, the lattice width distortion being corrected for all combinations of lattice dimensions vertical and horizontal selectable and the phase of vertical synchronization signals. The receiver of claim 4, further comprising a suppression signal generator operative in accordance with the vertical scale deflection signal for each phase of the vertical synchronization signals.