CN1158541A - Complex frequency display for displaying television and computer picture signals - Google Patents

Abstract

A multifrequency display for displaying image signals of both TV and computer is composed of screen, switch to select TV or computer image signals, image signal processor to convert TV image signals into RGB signals and synchronizing signal of TV, synchronizer including a multi-frequency horizontal oscillator for converting the synchronizing signals of TV or computer into vertical and horizontal deflection signals according to switch setting, and display controller for synchronizing RGB signals of TV or computer in order to display them on screen.

Description

Be used to show the complex frequency display of TV and computer picture signals

The present invention is a complex frequency display, is used for showing TV and computer picture signals.

Because the screen of large scale TV is more cheap than the screen of the computer monitor of ad eundem, therefore the large scale video screen often is used to show TV and computer picture signals in the many domestic electronics or the occasion of commercial advertisement.Because television image signal is different with the horizontal sweep speed of computer picture signals, so it must just may be displayed on the video screen after treatment.Fig. 1 is a traditional complex frequency display 10, it can be with television image signal (NTSC system, 15.75KHz horizontal frequency) and computer picture signals (VGA, 31.47KHz horizontal frequency) be presented on the video screen 18 with the horizontal frequency of 31.47KHz.Generally pass in the computer picture signals of this complex frequency display 10 and all include computer rgb signal and computer synchronizing signal.

Complex frequency display 10 include a front stage circuits 11 be used for converting to by the television image signal of port one 11 input TV Y/R-Y/B-Y picture signal to port one 12 and TV synchronousing signal to port one 13, two scanning (dual scan) circuit 12 are used for duplicating TV Y/R-Y/B-Y picture signal makes its frequency multiplication, an imaging signal processing circuit 13 is used for converting the TV Y/R-Y/B-Y picture signal of circuit 12 outputs to the TV rgb signal to port one 31, timing signal generator 16 is used for producing timing signal (clock signal) and is doubled to 31.47KHz by 15.75KHz to two scanning circuits 12 and with TV synchronousing signal, synchronous circuit 17 be used for according to the TV synchronousing signal of the setting self clock in the future signal generator 16 of switch 15 or from the computer synchronizing signal of computer convert to vertical deflection signal to port one 71 and horizontal deflection signal to port one 72.Two scanning circuits 12 include an analog/digital (analog to digital) transducer 121 and are used for the digitlization of TV Y/R-Y/B-Y picture signal, two scanning processor 122 are used for handling digitized TV Y/R-Y/B-Y picture signal reaching the effect with doubling frequency, and a digital/analog converter 123 is used for converting the numeral output of two scanning processors 122 to simulation output.

The analog/digital that two scanning circuit 12 is performed and the transfer process of digital-to-analog can make TV Y/R-Y/B-Y picture signal that certain loss is arranged, and therefore can influence the picture quality that is presented in the video screen 18.In addition, be used for duplicating when two scanning circuits 12 of television image signal and traditional display circuit are compared and seem quite complicated and expensive.

Main purpose of the present invention is used for showing that for a kind of complex frequency display is provided TV and two kinds of picture signals of computer do not reduce image quality, and has overcome the shortcoming of using complicated two scanning circuits 12 in the existing design.

For making structure of the present invention, feature and effect can further be understood and understanding, and this paper cooperates preferred embodiment and accompanying drawing to describe in detail as the back:

Fig. 1 is the calcspar of traditional complex frequency display.

Fig. 2 is the calcspar of complex frequency display of the present invention.

Fig. 3 is the partial circuit figure of synchronous circuit shown in Figure 2.

Please refer to Fig. 2.Fig. 2 is the calcspar of complex frequency display 20 of the present invention.Complex frequency display 20 comprises a screen 21 and is used for showing TV or computer picture signals, a switch 25 is used for selecting TV or computer picture signals, an imaging signal processing circuit 22 is used for converting the television image signal by port 221 inputs to TV rgb signal and TV synchronousing signal, a synchronous circuit 23 is used for converting TV or computer synchronizing signal to vertical deflection signal and horizontal deflection signal according to the setting of switch 25, and a display control circuit 24 is used for according to the setting of switch 25 TV or computer rgb signal being implemented Synchronization Control so that TV or computer picture signals are presented on the screen 21 according to vertical deflection signal and horizontal deflection signal that aforementioned synchronous circuit 23 is produced.

Imaging signal processing circuit 22 is similar with the function of front stage circuits 11 shown in Figure 1 and imaging signal processing circuit 13.The TV rgb signals that imaging signal processing circuit of the present invention 22 simply converts the television image signals of port 221 inputs to same level scanning frequency (15.75KHz) are to port 223, but not as shown in Figure 1 in the prior art with two scanning circuit 12 reflex NTSC television system NTSC picture signals to reach effect with doubling frequency.Synchronous circuit 23 according to the setting of switch 25 with the computer synchronizing signal or from the TV synchronousing signal of port 222 convert to vertical deflection signal to port 231 and horizontal deflection signal to port 232.Synchronous circuit 23 is its horizontal deflection signal that can produce two kinds of different frequencies to port 232 with the difference of synchronous circuit 17 shown in Figure 1, therefore makes display control circuit 24 show the TV rgb signal with the horizontal frequency of 15.75KHz and shows the computer rgb signal with the horizontal frequency of 31.47KHz.Because of the TV rgb signal is to show the transfer process that need not pass through digital-to-analog and analog/digital with its original 15.75KHz horizontal frequency, so the image quality that is presented on the screen 21 can be better than prior art.

Fig. 3 is the partial circuit figure of the synchronous circuit 23 that is used for handling TV or computer synchronizing signal among Fig. 2.It includes a switch 31 of being controlled by switch 25 and is used for selecting TV or computer synchronizing signal, a horizontal-drive signal separator 32 is used for the horizontal-drive signal in the input signal is separated, multiple horizontal oscillator tube 34 frequently is used for producing timing signal the horizontal-drive signal of TV or computer is become horizontal deflection signal with different frequency inverted, one first phase-locked loop 33 (PLL1-phase lock loop 1) is used for making oscillator 34 synchronous with the horizontal-drive signal of input, one second phase-locked loop 35 (PLL2) is used for making oscillator 34 and port 37 synchronous from the flyback signal (flyback) of display control circuit 24, and a horizontal driver 36 is used for producing horizontal deflection signal to display control circuit 24.

The timing signal of oscillator 34 meeting generation different frequencies becomes horizontal deflection signal with the horizontal-drive signal of TV or computer with different frequency inverted.Oscillator 34 includes a RC circuit 341 and is used for controlling its time constant.RC circuit 341 includes one and is connected in the variable resistor that the transistor 344 of resistance R 2 is formed by two parallel resistance R1, R2 and one.The Push And Release of transistor 344 is via port 343 controls by switch 25.When port 343 was high level, transistor 344 can be switched on, and the time constant of RC circuit 341 is C* (R1*R2)/(R1+R2) at this moment.When port 343 was low level, transistor 344 was for ending, and the time constant of RC circuit 341 can rise to C*R1 at this moment.By the time constant of conversion RC circuit 341, the frequency of oscillation of oscillator 34 can be switched between 15.75KHz and 31.47KHz so that handle the horizontal-drive signal of TV or computer.This designs two scanning circuits 12 of complexity shown in Figure 1, therefore except the image quality that can improve screen, can also reduce production costs.

The above only is preferred embodiment of the present invention, and is all according to the equivalent modifications that the present invention did, and all should belong to the protection range of patent of the present invention.

Claims (2)

1, a kind of complex frequency display that is used for showing TV and computer picture signals comprises:

(1) one screen;

(2) one can be used to select the switch of TV or computer picture signals;

(3) one imaging signal processing circuits are used for converting aforementioned television image signal to TV rgb signal and TV synchronousing signal;

(4) one synchronous circuits, be used for according to the setting of aforementioned switches and convert aforementioned TV synchronousing signal or computer synchronizing signal to vertical deflection signal and horizontal deflection signal, this synchronous circuit includes a multiple horizontal oscillator tube frequently, be used for producing the timing signal of different frequency, so that described TV synchronousing signal or computer synchronizing signal are become this horizontal deflection signal with different frequency inverted according to the setting of aforementioned switches; And

(5) one display control circuits, be used for according to the setting of described switch and with aforementioned TV rgb signal or computer rgb signal according to described vertical deflection signal and horizontal deflection signal enforcement Synchronization Control to be presented on the described screen.

2, complex frequency display as claimed in claim 1, its multiple horizontal oscillator tube frequently includes one and has a variable-resistance RC circuit, and this RC circuit can be controlled its variable resistor to change its frequency of oscillation and to produce the timing signal of different frequency by the setting of described switch.

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