FR2586332A1 - VIDEO VISUALIZATION APPARATUS FOR PRODUCING FRAMES OF DIFFERENT SIZES - Google Patents

Abstract

THE INVENTION RELATES TO A VIDEO DISPLAY APPARATUS INCLUDING A MEANS FOR PRODUCING FRAMES HAVING DIFFERENT HORIZONTAL AND VERTICAL AMPLITUDATIONS. ACCORDING TO THE INVENTION, AN ASSEMBLY 41 FOR CONTROLLING THE SIZE ALLOWS THE CHOICE OF A CERTAIN NUMBER OF DIFFERENT COMBINATIONS OF WEFT HEIGHTS AND WIDTHS; A WEFT SIZE SELECTION SIGNAL A, B IS DECODED TO DETERMINE ONE OF A NUMBER OF POSSIBLE COMBINATIONS OF HEIGHTS AND WIDTHS; THE HEIGHT IS DETERMINED BY VARIING THE VERTICAL DIMENSION REACTION SIGNAL APPLIED TO VERTICAL DEVIATION CIRCUIT 11; THE FRAME WIDTH IS DETERMINED BY VARIING THE OPERATION OF A MODULATOR CIRCUIT WITH A LATERAL BEARING CORRECTION DIODE 26, 27, 30 31. THE INVENTION APPLIES IN PARTICULAR TO TELEVISION AND TO COMPUTER MONITORS.

Description

The present invention relates to a video display apparatus and,

in particular, to a device

  video display that offers a different ability to

rents frame sizes.

  A video display apparatus, such as a television receiver or computer monitor, typically contains a cathode ray tube that produces one or more electron beams that are deflected or scanned through a phosphor display of the tube. to form a grid or grid. The frame defines the size and shape of the visible area on the screen when a video signal

is present.

  When the video display device is used as a computer monitor, it is desirable that the monitor can be used with devices from different computer manufacturers or different computer systems from the same manufacturer. Different computers can produce different video signals having different amounts of video information per horizontal scan line or different numbers of scan lines per frame. For example, the ratio of the active video information to the erase interval may be different-for video signals

  having different resolution characteristics.

  If the horizontal and vertical deflection amplitudes are not chosen according to the characteristics of the signal

  video, there may be an overscan or

  scanning the video signal on the frame or grid, with

  result in an inefficient use of the visualization screen

  in the case of under-scanning or loss of

  the image information in the case of an overscan.

  According to one aspect of the present invention, a video display apparatus having an arrangement for producing frames having different amplitudes of horizontal and vertical deflection comprises a circuit for receiving a signal indicating one of a certain

  number of horizontal and vertical deflection amplitudes.

  The circuit responds to the indication signal to produce one of a number of first signals identifying a selectable horizontal deflection magnitude, and to the indication signal to produce one of a number of second signals. identifying one of a selective vertical deviation amplitude. The assembly produces a horizontal deflection current having a maximum amplitude determined in response to the first signal and a vertical deflection current having a magnitude

  determined in response to the second signal.

  According to another aspect of the present invention, a video display apparatus contains an arrangement for changing the width of the frame, comprising a circuit for receiving a signal indicating one of a number of frame widths. An assembly produces and controls the horizontal deflection current to correct horizontal deflection distortion. A circuit modifies the circuit controlling the current in response to the signal

  indicating the width of the frame to produce changes

  frame widths that can be selected.

  In another aspect of the present invention, a video display apparatus contains an arrangement for changing the pitch of the frame, including a circuit for receiving a signal indicative of one of a number of selectable frame heights. An assembly produces a vertical deflection current. A circuit, including a feedback circuit, samples the vertical deflection current to control its

  magnitude. An assembly is coupled to the sample circuit-

  and changes the reaction circuit in response to the signal indicating the height of the frame to produce selectable changes in the height of the frame. The invention will be better understood, and other purposes, features, details and advantages thereof

  will become clearer during the description

  explanatory text which will follow with reference to the accompanying schematic drawings given solely by way of example illustrating an embodiment of the invention and in which: the single figure gives a block diagram of part of a display apparatus video according to a

aspect of the present invention.

  Referring to the figure, it shows a part of a video display apparatus comprising a horizontal deflection fixture 10, a mounting of

  vertical deflection 11 and a cathode ray tube 12.

  The cathode ray tube 12 receives, by way of example, drive signals D from a video processing circuit (not shown), which are applied to a set of electron guns 18. electron guns 18 produces one or more electron beams that are

  forced to impact and illuminate a visualization screen

  phosphor 19. The horizontal deflection

  Figure 10, which may for example contain an integrated circuit identified by TDA 2595, applies a switching signal to the base of a driver transistor 13. Switching of the driver transistor 13 forces a horizontal output transistor 14 to be switched via an attack transformer 15. The collector of the

  horizontal output transistor 14 is connected by the winding

  16 of a power transformer 17 to a supply voltage source V + of the order of + 97V. Transformer 17 is exemplified as having a secondary winding 20 which produces a high voltage level which is applied to the high terminal.

  voltage or anode 21 of the cathode ray tube 12.

  The horizontal deflection circuit also contains a damping diode 22 and a return capacitor 23 which operate in a conventional manner to produce return pulses in the winding

  primary 16 when the transistor 14 is off.

  The switching of the horizontal output transistor 14 also forces the horizontal deflection current to flow into the horizontal deflection winding 24, placed on the neck of the cathode ray tube 12, through the terminals H and H '. The horizontal deflection winding 24 is part of the deflection block which deflects the electron beam of the electron gun assembly 18 to

  to form a frame on the display screen 19.

  The horizontal deflection circuit also contains a linearity coil 25, an S-shaped capacitor 29, and a diode modulator circuit which corrects the distortion of the East-West frame or side pad. The diode modulator comprises a modulator inductor 27, a damping diode 30, a modulator feedback capacitor 31, a modulator forward capacitor 26 and control transistors

  32 and 33. The modulator operates in a conventional manner

  to modulate the horizontal deflection current in a parabolic manner at the vertical deflection frequency to correct pincushion distortion

Is West.

  The vertical deflection assembly 4, which may for example contain an integrated circuit identified by TDA 2653A, produces a vertical deflection current in a vertical deflection winding 34, through terminals V and V '. The deflection winding 34 is also placed on the neck of the tube 12 and forms part of the deflection block as well as the horizontal deflection winding 24. The sawtooth signal of the vertical deflection current is applied to the integration fitting comprising a resistor 35 and a capacitor s6 for forming the parabolic signal at the vertical frequency which is applied to the base of the control transistor 32 of the circuit

  diode modulator previously described.

  According to one aspect of the present invention, the video display apparatus of the figure comprises a frame size selecting circuit 40 which includes a decoder 41. The decoder 41 is illustrated as a demultiplexing circuit identified by CD 4052B, manufactured by RCA Corporation. The decoder 41 receives a two-bit digital signal through input terminals A and B, which define one of four possible combinations of the horizontal and vertical dimensions of the frame based on the four possible digital input values. . The desired horizontal and vertical dimensions are determined in the following manner. A sample signal developed in a resistor 39 and derived from the vertical deflection current is applied by a resistor 42 of manual height adjustment to the terminal 43 of the decoder 41. The decoder 41 operates essentially as a switch, and selectively applies the signal applied to the terminal 43 by a path of low resistance of the order of 400 ohms at one of the terminals 44, 45, 46 or 47, in response to the signals received at the terminals A and B. For example, according to the logic of decoding or demultiplexing the decoder 41, a signal at the high level, corresponding to a digital "1" present at the two terminals A and B, will force the decoder 41 to apply the signal to its terminal 43 at the terminal 46. The terminal 46 is connected by a resistor 50 to a reaction input terminal 48 of the vertical deflection assembly 11, for example the pad 4 of the TDA 2653A. The terminals 44, 45 and 47 are also connected by resistors having different values to the reaction input terminal 48 of the vertical deflection assembly 11. As the value of the resistance in the feedback path between the resistance slider manually adjusting the height 42 and the writing input terminal 48 will determine the height of the frame, the decoder 41 will therefore serve to control the vertical dimension of the frame in response to the selected dimension signal applied by the terminals A and B. As the decoder 41, which determines the chosen height of the frame, is incorporated in the height and linearity feedback loop, all the variations of the deflection current, caused by variations of the supply voltage, for example , will be compensated by the reaction circuit of the vertical deflection circuit 11. The height of the frame will therefore remain stable, regardless of the chosen height. According to another characteristic of the invention, in order to obtain control of the width of the frame, the decoder 41 couples, by a path of low resistance, the terminal 51 to one of the terminals 52, 53, 54 or 55 , depending on the signal levels applied to the terminals A and B. According to its operating logic, the decoder 41 will simultaneously select one of the terminals 44, 45, 46 or 47 and one of the terminals 52, 53, 54 or 55 for be connected to the terminals 43 and 51, respectively, so there is a maximum of four combinations of the two terminal choices. The choice of one of the terminals 52, 53, 54 or 55 will therefore be

  used to determine the horizontal frame width.

  As can be seen, terminals 53, 54 and 55 are

  connected together as are terminals 45 and 47.

  In this way, the specific combinations of the

  height of the frame to the width of the weft are

  Lées. The width of the frame is determined as follows: the base of the transistor 56 is connected by a voltage divider 60 to the terminal 52. The base of the transistor 57 is connected by a voltage divider 61 to the terminals 53, 54 and 55. The The collectors of the transistors 56 and 57 are connected, by resistors 62 and 63 respectively, and a resistor 64 to the base of the control transistor 32 of the diode modulator. As the terminal 51 is grounded, when the terminal 52 or the terminals 53, 54 or 55 are connected to the terminal 51 in response to the signals at the terminals A and B, the bases of the respective transistors 56 and 57 are

  down and the associated transistor is turned on.

  The resistors 62 and 63 have different values, therefore the DC bias to the control transistor 32 is different in which transistors 56 or 57 is conductive, which in turn depends on the terminals chosen by the size selection signal. of the frame which is applied to the terminals A and B. The DC bias to the control transistor 32 determines the degree of conduction of this transistor and the transistor 33 in response to the parabolic waveform of the vertical deflection assembly 11, which basically determines the amount of modulation of the current of

  deviation and therefore the width of the frame.

  For the particular embodiment shown in the figure, the following table illustrates which of the terminals 44, 45, 46 or 47 is connected to the terminal 43 and which of the terminals 52, 53, 54 or 55 is connected to the terminal 51 to each of the four possible logical combinations of the signals applied to the terminals A and B. Terminal 43 connected Terminal 51 connected

A B at the terminal - at the terminal -

0 44 54

0 1 45 52

1 0 47 53

1 1 46 55

  The previously described frame size selection arrangement can therefore be used to select up to four combinations of different heights and widths of the frame. Stable weft patterns are maintained for each

selected frame sizes.

R E V E ND I C A TI 0 N S

  A video display apparatus comprising means for generating frames having different magnitudes of horizontal and vertical deflection characterized by means for receiving a signal indicative of one of a number of horizontal and vertical deflection magnitudes ; 2) generating a number of first signals in response to said indication signal, each signal of said first signals identifying one of a selectable horizontal deviation magnitude; and 3) generating one of a number of second signals in response to said indication signal, each of said second signals identifying one of a selectable vertical deviation magnitude; means (14, 32, 33, 56, 57) for producing a horizontal deflection current having a determined maximum amplitude in response to said first signals; and means (11,48) for producing a vertical deflection current having a determined maximum amplitude

  in response to said second signals.

  2. Apparatus according to claim 1, characterized in that the aforesaid means (14, 32, 33, 56, 57) for producing a horizontal deflection current comprises means (32, 33) for controlling the amplitude of horizontal deflection to correct the horizontal deflection distortion, said means controlling amplitude responsive to said first signals for controlling said horizontal deflection amplitude to change said width

frame.

  Apparatus according to claim 1, characterized in that said means (11, 48) for producing a vertical deflection current comprises means (48) for controlling said vertical deflection amplitude, said means controlling amplitude responsive to said second signals for controlling said vertical deviation amplitude to change the height of the frame. 4. Apparatus according to claim 3, characterized in that said means (11, 48) for producing a vertical deflection current comprises a reaction means (48) for reducing a non-varying variation.

  desirable height of the frame.

  5. Apparatus according to claim 4, characterized in that the aforementioned means for controlling the vertical deviation amplitude comprises means for selectively coupling impedance networks (resistors) to the feedback means (48) to change the pitch of the the frame. 6. A means for changing the width of the frame of a video display apparatus characterized by: means (A, B) for receiving a signal indicative of one of a number of predetermined frame widths;

  means (14) for producing a deflection current

  horizontal means (32, 33) for controlling said horizontal deflection current to correct horizontal deflection distortion; and means (41, 56, 57) for modifying said current controlling means (32, 33) in response to said indication signal to produce said selected frame width. 7. Apparatus according to claim 6, characterized in that the means for controlling the horizontal deflection current comprises a diode modulator circuit (26, 27, 30, 31) for correcting the distortion

cushioned.

  8. Apparatus according to claim 7, characterized in that the means for modifying the means for controlling the horizontal deflection current comprises a transistor switch (56, 57) defining

  switchable parallel current paths.

  9. Apparatus according to claim 8, characterized in that the transistor switch (56, 57) controls the bias current of the modulator circuit at

diode (26, 27, 30, 31).

  10. A means for changing the height of the frame in a video display apparatus, characterized by means (A, B) for receiving a signal indicative of one of a number of selectable frame heights; means (1i) for producing a vertical deflection current; means (39) including a reaction means (48) for sampling said vertical deflection current to control the magnitude of said vertical deflection current; and means (41) connected to said sampling means (39) for modifying said reaction means (48) in response to said indication signal to produce

  changes in the frame height that can be selected.

  11. Apparatus according to claim 10, characterized in that the aforesaid means (41) modifying the reaction changes the impedance of the reaction path

vertical deflection current.