Alpha-numeric-display system with selectable crawl
First Claim
1. In a method for displaying an alpha-numeric text in a horizontal line on a face of a television monitor, wherein sequential characters of said text move across said face in a fixed spatial relationship to one another, said characters being prestored in coded form and subsequently decoded into binary signals combined with horizontal and vertical sync pulses and fed to the receiving terminals of said monitor for effectuating the display of said text, signals corresponding to a first character in a horizontal scan being emitted only upon the elapse of a delay time following said horizontal sync pulses, said characters having on said face a common apparent character width correponding to a horizontal-scanning interval TZ substantially less than an interval between consecutive horizontal sync pulses, the improvement comprising the steps of:
- generating a frequency fG which is at least equal to the reciprocal of said interval TZ ; and
successively decreasing, upon said vertical sync pulses, said delay time by an increment TG to implement motion of said characters across said face, said increment TG being equal to the period of said frequency fG andcontrolling said width by application of a horizontal sampling frequency fZ whose period is equal to said interval TZ, said frequency fG being an integral multiple of said sampling frequency fZ.
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Accused Products
Abstract
A television-type system for displaying characters of an alpha-numeric testn a horizontal line moving across the face of a TV monitor includes pulse-generator-fed frequency dividers emitting pulse sequences of which three are transmitted via viewer-operated selectors for forming two frequencies fL and fZ applied to shift registers of a character generator to determine character height and width and another frequency fG applied to the stepping input of a delay-increment counter to determine character speed. In response to character codes transmitted from an input unit via a read/write memory, the character generator emits binary signals combinable with horizontal and vertical sync pulses into a video signal fed to the monitor. The counter is reset upon every horizontal sync pulse to have a modulus n equal to the contents of a total-delay counter stepped by the vertical sync pulses and reset after N of the same by a divder calculating the quotient N=TZ /TG in response to signals from the selectors coding the periods TZ, TG of sequences fZ, fG. The delay-increment counter enables the emission of frequency fZ only after counting n pulses of sequence fG, whereby the character display is shifted leftwardly upon each vertical sync pulse by distance corresponding to period TG. Upon completing N counts the total-delay counter enables its own resetting by the divider and increments an initial address of a counter addressing the read/write memory. An arithmetic unit resets the contents n of the total-delay counter upon a change in the selected sequence fG.
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Citations
10 Claims
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1. In a method for displaying an alpha-numeric text in a horizontal line on a face of a television monitor, wherein sequential characters of said text move across said face in a fixed spatial relationship to one another, said characters being prestored in coded form and subsequently decoded into binary signals combined with horizontal and vertical sync pulses and fed to the receiving terminals of said monitor for effectuating the display of said text, signals corresponding to a first character in a horizontal scan being emitted only upon the elapse of a delay time following said horizontal sync pulses, said characters having on said face a common apparent character width correponding to a horizontal-scanning interval TZ substantially less than an interval between consecutive horizontal sync pulses, the improvement comprising the steps of:
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generating a frequency fG which is at least equal to the reciprocal of said interval TZ ; and successively decreasing, upon said vertical sync pulses, said delay time by an increment TG to implement motion of said characters across said face, said increment TG being equal to the period of said frequency fG and controlling said width by application of a horizontal sampling frequency fZ whose period is equal to said interval TZ, said frequency fG being an integral multiple of said sampling frequency fZ. - View Dependent Claims (2, 3, 4)
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5. In a television display system, the combination comprising:
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a TV monitor having a viewing face; memory means for storing a sequence of characters of an alpha-numeric text to be displayed in a moving horizontal line on said face; pulse-generating means for producing horizontal sync pulses, vertical sync pulses and a pulse train having a period less than the interval between consecutive horizontal sync pulses; a character generator operatively connected to said memory means for emitting in response to signals therefrom binary pulses transmittable to said monitor in synchronous combination with said horizontal sync pulses and said vertical sync pulses for producing on said face a display of said characters; transmission means connected to said character generator, to said pulse-generating means and to said monitor for feeding thereto said binary pulses and said horizontal sync pulses and said vertical sync pulses; addressing means linked to said memory for sequentially reading consecutive character codes therefrom to said character generator; and a control circuit operatively coupled to said character generator for enabling, during each horizontal scan by said monitor, the emission of said binary pulses only upon the elapse of a delay following said horizontal sync pulses, said control circuit including delay-modification means connected to said pulse-generating means for recurrently decreasing said delay upon said vertical sync pulses by an increment equal to said period, whereby said delay is changed from an upper limit to a lower limit to implement motion of said characters across said face, said control circuit further including address-incrementing means connected to said addressing means for modifying an initial address thereof upon the attainment of said lower limit by said delay and to said delay-modification means for simultaneously increasing said delay to said upper limit, wherein said characters are decoded by said character generator to have on said face a common character width corresponding to a horizontal scanning interval, said characters being generated to have a common character width corresponding to a horizontal scanning interval equal to an integral multiple of periods and wherein said lower limit is zero. - View Dependent Claims (6, 7, 8, 9, 10)
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Specification