GB2096436A - Picture image display apparatus - Google Patents

Abstract

A picture image display apparatus comprises a flat type vacuum enclosure having a transparent face panel (11), a row of parallel linear thermionic cathodes (1), an electron beam forming electrode (3) which produces a predetermined number of two dimensionally disposed electron beams (e) out of electron emission from the cathodes (1), a row of parallel control electrodes (4) disposed perpendicular to the cathodes (1), a row of vertical deflection electrodes (6,6'), a row of horizontal deflection electrodes (7,7'), a phosphor screen (10) formed on an inner face of the face panel (11), and a metal film anode (9) formed on an inner face of the phosphor screen. A horizontal deflection signal generator provides a horizontal deflection signal comprising a first scanning period wherein the voltage increases and a second scanning period of the same length wherein the voltage decreases. Control signals are applied to the scanning period and the second scanning period to produce image spots in both scanning periods. <IMAGE>

Description

SPECIFICATION Picture image display apparatus This invention relates to picture image display apparatus.

Three of the inventors of the present invention have invented a multiple electron beam type picture display apparatus described in the specification of Japanese Patent Application Sho 53-106788 filed on 30th August, 1978 and also described in the specification of US Patent No.4277 117 patented on 7th October, 1980. The apparatus described in the above-mentioned Japanese patent application and US patent comprises, in a flat type vacuum enclosure, a row of parallel linearthermionic cathodes (i.e.

line cathodes, each of which comprises a linearfila- ment line to be heated by a low voltage, e.g. 1 0V D.C., and an electron emissive oxide coating thereon, and hereinafter referred to as a linearthermionic cathode), electron beam forming electrodes, a row of parallel control electrodes disposed in a direction perpendicular to those of the thermionic cathodes, a row of vertical deflection electrodes, a row of horizontal deflection electrodes, a phosphor screen formed on a a face panel, and an anode layer formed on the phosphor screen.

In the operation of the multiple electron beam type display apparatus described in the above-mentioned specifications, scannings of beam spots on the phosphor screen are made by means of the known line-at-a-time type scanning, wherein an ordinary time-sequential image signal is converted into a plural number of parallel signals. For example, considering the case of displaying an image field raster having numbers of picture elements equal to 240 (in the vertical direction) times 321 (in the horizontal direction), then with regard to horizontal scanning of the beam spots the raster is divided into a plural number N of vertically oblong sections and the horizontal scannings are carried out in parallel manner in all of the N sections. Each such section then hasn = 321/N picture elements in the horizontal direction.

For example, if the number N of vertical sections is 107, the numbern of picture elements in each such section is 3. In such example, 107 beam spots are produced from each linear thermionic cathode and 107 control electrodes are provided in order to control the 107 electron beam intensities. The horizontal scanning is carried out by using a saw-tooth wave having a horizontal scanning period H applied to the horizontal deflection electrode in such a manner that all the N beam spots are deflected simultaneously to scan in the same direction, taking one horizontal scanning period H. The horizontal scanning period H is equal to the horizontal scanning period of an ordinary time sequential television signal.In order to attain such line-at-a-time-scanning, the ordinary time sequential image signal is, in a preliminary operation, converted into the N parallel signals of the line-at-a-time type.

Vertical scanning is carried out in the abovedescribed apparatus by dividing the raster into a plural number M of horizontally oblong sections and, at first in a first section, for example in the uppermost section, the plural number of beam spots, which simultaneously scan, also scan vertically (downwardly).When the vertical scanning in the first section is over and all the beam spots reach the bottoms of the first horizontally oblong sections, then the forming of electron beams from electrons from a first linear thermionic cathode ends and the forming of electron beams from electrons from a second linear thermionic cathode starts, and the vertical scannings of the beam spots start in the second horizontally oblong section and scan downwardly in the same way as in the first section, The vertical scanning is thus carried out down to the bottom or M-th section by using a saw-tooth wave having a period VIM, where V is the vertical scanning period of the ordinary television signal.In the abovementioned example ofthe raster having a number of vertical picture elements equal to 240, when the number M of the horizontally oblong sections is 48, each of the sections has a number of horizontal scanning lines equal to m = 240/48 = 5. That is to say, the examplary apparatus uses 48 linear thermionic cathodes, and each cathode scans vertically to produce 5 horizontal scanning lines.

Figure 1 ofthe accompanying drawings is a block diagram of an example of a circuit for driving the apparatus described in the above-mentioned patent specifications. In the circuit of Figure 1, a video signal is led from an input terminal 12 to a video signal amplifier 13 and a synchronization signal separator 14, an output of which is connected to a sampling pulse generator 15 and a synchronization signal generator 19. A memory circuit 16 receives a time sequential signal from the video amplifier 13 and samples and holds the signal to enable it to be converted to a parallel type video signal by a multiplexer circuit 17.That is, the multiplexer circuit 17 removes the memorized video signal from the memory 16 and rearranges it into the N (=107) parallel signals, in each of which n (=3) data in the memory 16 are rearranged into time sequential signal order to take up the time period of H. The parallel outputs of the multiplexer circuit 17 are applied through amplifiers 18 to the control electrodes of the display apparatus. A horizontal deflection signal generator 20 and a vertical deflection signal generator 22 receive a signal from the synchronization signal generator 19 and issue horizontal and vertical deflection signals through amplifiers 21 and 23, respectively, to the horizontal and vertical deflection electrodes of the display apparatus, respectively.A cathode control circuit 24 receives the signal from the synchronization signal generator 19 and supplies a control signal to the linear therm ionic cathodes, in order that electron beams are formed selectively from electrons from selected linear thermionic cathodes in sequence by the application of negative potential with respect to an electrode 3 thereof, thereby to scan for a period of m x H.

Figure 2 shows waveforms (A), (B), (C), (D), (E), (F) and (G) present at various parts of the circuit of Fig ure 1 fortheexamplewheren = 3 and m = 5. The waveforms (A) and (B) are those of the horizontal synchronization signal and vertical synchronization signal, wherein H shows the time period of one hori zontal scanning and V shows the time period of one vertical scanning of the ordinary television signal.

The waveforms (C) and (D) are voltages to be applied to the first and the second linearthermionic cathodes, respectively, for switching the cathodes in sequence. The waveforms (E) and (F) are issued from the vertical deflection signal generator circuit 22 and the horizontal deflection signal generator circuit 20, respectively, and the waveform (G) is a control signal to be applied to a control electrode 4 of the display apparatus. Accordingly, the scannings of the beam spots seen at enlarged parts ofthe phos phorscreen are as shown in Figure 10(a).

The circuit of Figure 1 uses saw-tooth shaped signals for the horizontal deflection, as shown in Figure 2(E). The horizontal deflection electrodes comprise, for example, in the above mentioned exemplary apparatus, 107 pairs (i.e. 214 rods) of vertically oblong electrodes and the horizontal electrode thus has a large inter-electrode capacitance, for example several hundred pF. Accordingly, to drive such electrodes of large capacitance with a saw-tooth waveform involves the great difficulty of requiring a high voltage signal of around 100 to 200 volts and a large amount of power in orderto ensure the sufficiently short retracing period necessary for accurate horizontal scanning, and accordingly of requiring an expensive circuit such as an emitter fol lower circuit or a single-ended push-pull circuit.

According to the present invention there is pro vided a picture image display apparatus comprising: a flat type vacuum enclosure having a transparent face panel, a row of parallel linear thermionic cathodes, an electron beam forming electrode operative to produce a predetermined number oftwodimensionally disposed electron beams out of electron emission from the linear thermionic cathodes, a row of parallel control electrodes disposed per pendicularto the linear thermionic cathodes, a row of deflection electrodes, a phosphor screen formed on an inner face of the face panel, a metal film anode formed on the phosphor screen, a deflection signal generator for providing a deflection signal to be applied to the deflection electrodes, and circuits for producing control signals to be applied to the control electrodes, said circuits comprising a memory for storing a video signal and a multiplexer for converting said stored video signal into parallel signals for the control electrodes, wherein the deflection signal generator is operative to provide a deflection signal comprising a first scanning period wherein the voltage increases and a second scanning period wherein the voltage decreases, and said circuits are operative to apply the control signals to the control electrodes in both said first scanning period and said second scanning period to produce image spots in both scanning periods.

Embodiments of the present invention described hereinbelow are intended to provide picture image display apparatuses capable of accurate horizontal scanning with smaller driving power and cheaper circuitry, and of simpler configuration than hitherto proposed such apparatuses.

The invention wil[ now be further described, by way of illustrative and non-limiting example, with reference to the accompanying drawings, in which: Figure lisa circuit diagram of a known picture image display apparatus; Figure 2 is a waveform chart showing waveforms of signals at various parts of the circuit of Figure 1; Figure 3(a) is an exploded perspective view of a principal part of a picture image display apparatus embodying the present invention; Figure 3(b) is a sectional view of the apparatus of Figure 3(a); Figure 4 is a waveform chart showing waveforms of signals at various parts of the apparatus of Figures 3(a) and 3(b); Figure 5 is a circuit diagram of the apparatus embodying the present invention; Figure 6 is a waveform chart of signals at various parts of the circuit of Figure 5;; Figure 7(a) is a circuit diagram of a multiplexer of the circuit of Figure 5; Figure 7(b) is a circuit diagram of a multiplexer of a modified circuit; Figure 8(a) is an exploded perspective view of a principal part of a modified display apparatus embodying the present invention; Figure 8(b) is a sectional view of the apparatus of Figure 8(a); Figure 9 is a waveform chart showing the waveforms of signals present at principal parts of the apparatus of Figure 8; and Figures 10(a) to 10(b) are charts comparatively illustrating the ways in which scanning is carried out in the various above-mentioned apparatuses.

An example of a picture image display apparatus embodying the present invention is shown in Figures 3(a) and 3(b) which are, respectively, an exploded perspective view of a principal part of the apparatus and a section through the principal part.

The apparatus comprises, in the direction from the top to the bottom in Figure 3(a), and Figure 3(b), an isolation electrode 2 having a plural number of isolation walls 201 to define oblong isolated spaces 202, a row of a predetermined number M (e.g. M=48) of parallel linear thermionic cathodes 1 each being disposed in one of the isolated spaces 202, an extractor electrode 3 having a predetermined number N (e.g.

N = 107) of electron beam passing apertures 3a disposed under the linear thermionic cathodes 1, a row of parallel control electrodes 4for controlling beam intensity, the electrodes 4 being disposed in directions perpendicular to those of the linear thermionic cathodes 1 and each having electron beam passing openings 4a under the apertures 3a, an electron beam forming electrode 5 having electron beam passing openings 5a under the openings 4a, a row of vertical deflection electrodes comprising pairs of common-connected first electrodes 6 and commonconnected second electrodes 6', a row of horizontal deflection electrodes comprising pairs of commonconnected first electrodes 7 and common-connected second electrodes 7', an electric field shielding electrode 8, an anode 9 in the form of a vapourdeposited thin aluminium film, and a phosphor screen 10 formed on a face panel 11 of a flat type vacuum enclosure. Every one of a plurality of electron beams, e . . passes through deflection spaces 62, 62... and 72,72... defined by the deflection electrodes pairs 6, 6' and 7, 7'....

disposed regularly in the same order with respect to every electron beam as shown in Figure 3(a) and Figure 3(b).

Figure 5 is a block diagram of an example of a circuit for driving the apparatus of Figures 3(a) and 3(b). In the circuit of FigureS, a video signal from an input terminal 12 is led to a video signal amplifier 13 and a synchronization separator 14, an output of which is connected to a sampling pulse generator 15 and a synchronization signal generator 19. Amemory circuit 16 receives a time sequential signal from thevideo amplifier 13 and samples and holds the signal to enable itto be converted to a parallel type video signal by a multiplexer circuit 17.That is, the multiplexer circuit 17 removed the memorized video signal from the memory 16 and rearranges it into the N(e.g. 107) parallel signals, in each ofwhichn (e.g. 3) data in the memory 16 are rearranged into time sequential signal order to take up the time period of H. The parallel outputs of the multiplexer circuit 17 are applied through amplifiers 18 to the control electrodes 4, 4', of the display apparatus of Figures 3(a) and 3(b).A horizontal deflection signal generator 20' and a vertical deflection signal generator 22' receive a signal from the synchronization signal generator 19 and issue horizontal and vertical deflection signals through amplifiers 21 and 23, respectively, to the horizontal deflection electrodes 7,7' and the vertical deflection electrodes 6, 6' of the display apparatus, respectively.A cathode control circuit 24 receives the signal from the synchronization signal generator 19 and supplies a control signal to the linearthermionic cathodes 1, in order that electrons from selected ones of the linear thermionic cathodes 1 selectively form electron beamsforthe period of m x H by the application of a negative potential thereto, so as to allow scanning for the period of mx H, where m is the number of horizontal scannings made by each linear thermionic cathode, for examplem = 5.

Figure 4 shows waveforms (A), (B), (C), (D), (E), (F) and (G) present at various parts of the circuit of Figure 5 for the example whereon = 3 and m = 5. The waveforms (A) and (B) are those of the horizontal synchronization signal and vertical synchronization signal, wherein H shows the time period of one horizontal scanning and V shows the time period of one vertical scanning. The waveform (C) and (D) are voltages to be applied to a selected one and the others of the linear thermionic cathodes, respectively, for switching the cathodes in sequence. The waveform (E) is issued from the horizontal deflection signal generator circuit 20', the waveform (F) is an example of a waveform produced by the vertical deflection signal generator circuit 22', and the waveform (G) is the control signal to be applied from the amplifier circuit 18 to the control electrodes 4 of the display apparatus.

In operation of the picture image display apparatus of multiple electron beam type having the construction described above with reference to Figures 3(a) to 5, scannings of beam spots on the phosphor screen 10 are made by means of known lineat-a-time type scanning, where an ordinary timesequential image signal is converted into a plural number of parallel signals. For example, in the above-mentioned case of displaying an image field raster having numbers of picture elements equal to 240 (in the vertical direction) times 321 (in the horizontal direction), then with regard to horizontal scanning of the beam spots the raster is divided into a plural number N of vertically oblong sections and the horizontal scannings are carried out in parallel manner in all of the N sections. Each such section then hasn = 321/N picture elements in the horizontal direction.For example, if the number N of vertical sections is 107, the numbern of picture elements involved in horizontal scanning in each section is 3.

In such example, 107 beam spots are produced from each linearthermionic cathode 1 and 107 control electrodes 4 are provided in order to control the 107 electron beam intensities. The horizontal scanning is carried out by using a triangular wave, as shown in Figure 4 (E), having a horizontal period of 2H, which comprises a first scanning period of 1 H wherein the voltage increases and a second scanning period of 1H wherein the voltage decreases.The triangular wave is applied across or between the pairs of horizontal deflection electrodes 7, 7'. Since all the deflection spaces are defined by the deflection electrodes 7,7' disposed and connected in the same order, all the N beam spots are simultaneously deflected to scan in the same direction in the first scanning period H, and in the next period H they are deflected to scan in the direction opposite to that of the scanning in the first scanning direction. Therefore, the scannings of the beam spots seen at an enlarged part of the phosphor screen are as shown in Figure 10(b). The horizontal scanning period H is equal to the horizontal scanning period of the ordinary time sequential television signal. In order to attain such line-at-a-time scanning, the ordinary time sequential image signal is, as a preliminary step, converted into the N parallel signals of the line-at-a-time type. As shown in Figure 4 at (B) and (E), the triangular wave to be applied to the horizontal deflection electrodes alternately increases and dcreases its voltage, and each of the increasing and decreasing periods occupies a horizontal scanning period H. That is, the scannings of the beam spots change direction between odd numbers of 1H periods and even numbers of 1 H period. Therefore, the contents of the video signal to be applied to the control electrodes 4 must be inverted as a preliminary step for leftwards scanning.

Figure 6 is a waveform chart showing waveforms for use in the multiplexer circuit 17 of Figure 5 to be operated under the condition wheren = 3 andm = 5, and Figure 7(a) shows an example of the circuit construction of the multiplexer circuit 17. In the waveform chart of Figure 6, the waveform (B) is the horizontal synchonization signal of a television signal likethewaveform (B) of Figure 4 and 1H represent one horizontal scanning period of the television signal. The waveforms (29), (30), (31) and (33) represent signals to be applied to input terminals identified by the same numbers. The waveforms (29), (33) and (31) are produced by known multivibrators or oscillators by using a signal waveform (30) produced by dividing the horizontal synchronization signal of(B).The waveforms (i-1), (i) and (i+1) of Figure 6 are signals to be sent from the multiplexer circuit 17 to read out terminals of memories M1, M2 ... The waveforms Vj~" Vj and Vj+1, having amp litudes a, b and c, show sample and hold levels of the video signal sampled by using a sampling pulse train having a frequency of about 6 MHz, which is obtained by dividing the number of picture elements 321 by the substantial horizontal scanning time of the time horizontal synchronization signal.Under the premise that in all the N-divided sections the video signal has the amplitudes a,b and c for three picture elements disposed from left to right of the section, the rearranged video signals shown at (281), (282) . . . of Figure 6 are produced by the multiplexer circuit 17 and used as the control signals for the first, second .... . control electrodes, respectively. The sample-held video signals of the amplitudes a, b and c appear at the drains of MOS field-effect transistors (FETs) 25, 26 and 27, and, accordingly, the signals of the waveforms (281), (282) .... are applied to input terminals (281), (282) . .. of the composite amplifier 18, which applies amplified output signals in parallel manner to the control electrodes ......... 4107.

The vertical scanning of the apparatus is carried out by dividing the raster into a plural number M of sections from the top to the bottom, and, at first in the first section, for example in the uppermost section, the plural number of beam spots, which simultaneously scan, also scan vertically (downwardly).

When the vertical scanning in the first section is over and all the beam spots reach the bottoms ofthefirst horizontally oblong sections, then the forming of electron beams from electronsfrom afirstofthe linear thermionic cathode ends and the forming of electron beams from electrons from a second linear thermionic cathode starts by means of switching of the cathode control signal applied to the cathodes 1, and the vertical scannings of the beam spots start in the second-from-the-top section and scan downwardly in the same way as in the first-from-the-top section. The vertical scanning is thus carried out down to the bottom or M-th section by using an ordinary saw-tooth wave having a period VIM, where V is the vertical scanning period of the ordi nary television signal.In the above-mentioned example of the raster having a number of vertical picture elements equal to 240, when the number M of the horizontally oblong sections is 48 each of the sections has a number of horizontal scanning lines equal to m = 250/48 = 5. That is to say, in the case of an apparatus using 48 linear thermionic cathodes, each cathode scans vertically to perform 5 horizontal scanning lines.

Figures 8(a) and 8(b) show a principal or characterizing part of another example of a picture image display apparatus embodying the invention, wherein the number of deflection electrodes is halved from that of Figures 3(a) and 3(b), thereby enabling a reduction in the inter-electrode capacitance of the deflection electrodes. As shown in Figure 8(a) and Figure 8(b), the deflection electrodes 6, 6' and 7,7' are disposed to form pairs such that the electron beams e pass through every gap formed by neighbouring deflection electrodes.This is in contradistinction to the example shown in Figure 3(b), where every electron beam passes through gaps ofthe electric field of the same direction, that is through gaps having a first horizontal deflection electrode 7 on the left hand side and a second horizontal deflection electrode 7' on the right hand side, thereby deflecting every electron beam in the same direction (leftwardly). By virtue of the above-mentioned configuration of Figure 8(b), neighbouring electron beams pass through electric fields of opposite directions. That is, the deflection electrodes are disposed with uniform gaps and every gap is disposed below an electron beam passing through the apertures and openings, so that each electron beam passes through a gap which has an electric field of opposite direction to that of the neighbouring or adjacent gaps.Therefore, all neighbouring gaps have symmetrical electric fields to each other. Accordingly, the electron beams e, e .. in neighbouring gaps of the deflection electrodes are deflected substantially symmetrically to each other, as shown in Figure 8(b).

As a result of this symmetrical scanning of neighbouring sections, scanning is carried out as shown in Figure 10(c). Therefore, for producing a video signal for the scanning in the even numbered sections, i.e., 2nd,4th ....106to sections, the control signal must be reversed with respect to its time order. In order to produce such a reversed signal for the even order control electrodes, the multiplexer circuit 17 is modified as shown in Figure 7(b), wherein the connection of the gates of the MOS FETs 25 and 27 for the even order control electrodes is inverted with respect to those of the other order. In this way, the control signal (282') of Figure 6, which is a reversal in time of the signal (282) of Figure 6, can be obtained.

The vertical scanning of the apparatus of Figure 8(a) and Figure 8(b) will now be described. Similarly to the horizontal deflection electrodes 7,7', the vertical deflection electrodes 6, 6' of Figure 8(a) and Figure 8(b) are constructed such that the electrodes 6, 6' are disposed with uniform gaps and all the gaps are disposed below the electron beam passing apertures and openings, so that all neighbouring gaps have symmetrical electric fields with respect to each other. Avertical deflection voltage having the waveform (F) of Figure 4 is impressed between the vertical deflection electrodes 6 and 6'.Then, when the first (the top) linearthermionic cathode has a negative pulse signal applied thereto, electron beams are emitted from the first cathode through the apertures and openings 3a,4a and 5a and the electron beams pass through the first (the top) gap between the vertical deflection electrodes 6 and 6'.

When the electrode 6 is positive with respect to the electrode 6' at first and changes gradually to negative by the application of the vertical deflection signal voltage of the triangular waveform of Figure 4 (E), the electron beam spots them run downwardly by the vertical scanning from each top of the first vertical sections to the bottoms thereof, also scanning horizontally by virtue of the triangular wave.

Accordingly, the beam spots run down in a zig-zag course, as shown in Figure 10(c). When the scanning beam spots reach the bottom positions indicated by numeral (5) of the first vertically divided sections in Figure 10(c), the electron beams from the first linear cathode are extingushed in compliance with the control signal from the circuit 24 and, at the same time, electrons from the second linear cathode start to form electron beams. And at that time in the second vertically divided sections, the beam spots produced by the electron beam from the second linear cathode just come to the top positions of the second sections, which are at the same position (5) of Figure 10(c), by means of the deflection electric field applied to the gap between the electrodes 6' and 6.That is, in the apparatus of Figure 8(a), the relationship between the vertical electrodes 6 and 6' and the electron beams is similar to that for the horizontal electrodes 7, 7' of Figure 8(b) and, therefore, the deflections of the electron beams in the vertical directions are symmetrical between vertically neighbouring sections. Accordingly, when a beam spots scans and reaches the bottom of a section, a beam spot of the lower section also reaches the top position thereof.

Therefore, by relaying the operation of electron beam formation sequentially downwardly at the time when the beam spot in a vertical section reaches its bottom, the overall appearances of the beam spots are as if the beam spots continuously scan downwardly, passing the vertical section boundaries. In this manner, the beam spots scan downwardly in the second divided sections and thereafter. In the same way, the beam spots from the subsequent cathodes follow the scanning in their own vertically divided sections.

In the above-mentioned example of Figures 8(a) and 8(b), the scanning can be satisfactorily effected by using simple triangular waves and using half the number of deflection electrodes. Therefore, the power to generate the scanning signal can be considerably reduced in comparison with the case of using a saw-tooth wave having sharply (abruptly) falling trailing edges, and the stray capacitance between the deflection electrodes can be markediy reduced.

In the above-mentioned examples, the numbersn and m are selected such thatn = 3 and m = 5. These numbers can, however, be selected in other combinations, for example = 6 and m = 15, and soon.

Figure 9 shows some waveforms of a modified example wherein the horizontal deflection signal generator 20' and the vertical deflection signal generator 22' are formed to issue deflection signals in the form of step waves shown at (E) and (F) in Figure 9, respectively. Waveform (B) of Figure 9 is the horizontal synchronization signal. It is known that such step waveform signals can be generated by the use of known up-down counters and D/A converters. By using a horizontal deflection signal and a vertical deflection signal having such step waveforms, the scannings of the beam spots are as shown in Figure 10(d), that is, the spots move in a stepwise manner, stopping for a necessary short time on ideal scanning loci formed with horizontal and vertical lines.Accordingly, the spots are formed with a clear dot shape and move very accurately without overlapping of spots like in a dot-matrix type panel display apparatus. Therefore, when the dots on the phosphor screen are RGB phosphor dots, a high colour saturation is attainable by accurate scanning.

In the application of the deflection signals across the deflection electrodes, both the first technique of fixing the potentials on first electrodes 6 or 7 at a predetermined constant potential and applying the signals on the second electrodes 6' or 7', or the second technique of applying the signal between both the electrodes 6 and 6' or 7 and 7' and retaining the central (averaged) potential thereof constant, can be used.

As has been described in detail, a picture image display apparatus embodying the present invention uses, at least for its horizontal deflection signal, a scanning signal having a voltage increasing during a first period and a voltage decreasing during a second period of the same length, and in both of these periods the control signals is applied to the control electrode, thereby utilizing both the voltage increasing period and the voltage decreasing period for displaying the picture image. Therefore, the scanning signal driving circuit need not have a very short retracing orflyback period as necessary in the prior art apparatus using a saw-tooth wave for horizontal deflection. This leads to a decrease of deflection power and to the ability to dispense with expensive emitter follower circuits or single-ended pushpull amplifiers for the signal deflection circuit.

Claims (10)

1. A picture image display apparatus comprising: a flat type vacuum enclosure having a transparent face panel, a row of parallel linear thermionic cathodes, an electron beam forming electrode operative to produce a predetermined number of twodimensionally disposed electron beams out of electron emission from the linear thermionic cathodes, a row of parallel control electrodes disposed perpendicular to the linear therm ionic cathodes, a row of deflection electrodes, a phosphor screen formed on an inner face of the face panel, a metal film anode formed on the phosphor screen, a deflection signal generator for providing a deflection signal to be applied to the deflection electrodes, and circuits for producing control signals to be applied to the control electrodes, said circuits comprising a memory for storing a video signal and a multiplexer for converting said stored video into parallel signals for the control electrodes, wherein the deflection signal generator is operative to provide a deflection signal comprising a first scanning period wherein the voltage increases and a second scanning period wherein the voltage decreases, and said circuits are operative to apply the control signals to the control electrodes in both said first scanning period and said second scanning period to produce image spots in both scanning periods.

2. Apparatus according to claim 1, wherein said deflection signal is a triangular signal.

3. Apparatus according to claim 1, wherein said deflection signal has a step-shaped waveform having at least two levels in each scanning period.

4. Apparatus according to claim 1, wherein the control electrodes are connected to receive the control signals in a manner such that a set of alternate ones of the control electrodes receives a control signal formed by converting the video signal into parallel signals and another set of alternate ones of the control electrodes receives a control signal formed by converting the video signal into parallel signals of reversed time sequence.

5. A picture image display apparatus comprising: a flat type vacuum enclosure having a transparent face panel, a row of parallel linear thermionic cathodes, an electron beam forming electrode operative to produce a predetermined number of two dirnensionally disposed electron beams out of electron emission from the linear thermionic cathodes, a row of parallel control electrodes disposed perpendicular to the linear thermionic cathodes, a row of vertical deflection electrodes, a row of horizontal deflection electrodes, a phosphor screen formed on an inner face of the face panel, a metal film anode formed on the phosphor screen, a horizontal deflection signal generator for providing a horizontal deflection signal to be applied to the horizontal deflection electrodes, a vertical deflection signal generator for providing a vertical deflection signal to be applied to the vertical deflection electrodes, and circuits for producing control signals to be applied to the control electrodes, said circuits comprising a memory for storing a video signal and a multiplexer for converting said stored video signal into parallel signals for the control electrodes, wherein the horizontal deflection signal generator is operative to provide a horizontal deflection signal comprising a first scanning period wherein the voltage increases and a second scanning period wherein the voltage decreases, and said circuits are operative to apply the control signals to the control electrodes in both said first scanning period and said second scanning period to produce image spots in both scanning periods.

6. Apparatus according to claim5, wherein at least said horizontal deflection signal is a triangular signal.

7. Apparatus according to claim 5, wherein at least said horizontal deflection signal has a stepshaped waveform having at least two levels in each scanning period.

8. Apparatus according to claim 5, claim 6 or claim 7, wherein a set of alternate ones of the horizontal deflection electrodes are connected to have a D.C. potential applied thereto and another set of alternate ones of the horizontal deflection electrodes are connected to receive the horizontal deflection signal.

9. Apparatus according to claim 5, claim 6 or claim 7, wherein a set of alternate ones of the vertical deflection electrodes are connected to have a D.C.

potential applied thereto and another set of alternate ones of the vertical deflection electrodes are connected to receive the vertical deflection signal.

10. A picture image display apparatus comprising: a flat type vacuum enclosure having a transparent face panel, a row of parallel linear thermionic cathodes; an electron beam forming electrode operative to produce a predetermined number of two dimensionally disposed electron beams out of electron emission from the linear thermionic cathodes; a row of parallel control electrodes disposed perpendicular to the linear thermionic cathodes; a row of vertical deflection electrodes; a row of horizontal deflection electrodes; a phosphor screen formed on an inner face of the face panel; a metal film anode formed on the phosphor screen; a horizontal deflection signal generator for providing a horizontal deflection signal for the horizontal deflection electrodes;; a vertical deflection signal generator for providing a vertical deflection signal for the vertical deflection electrodes, and circuits for producing control signals to be applied to the control electrodes, said circuits comprising a memory for storing a video signal and a multiplexer for converting said stored video signal into parallel signals for the control electrodes; wherein:: said row of horizontal electrodes comprises a plurality of first electrodes and a plurality of second electrodes disposed in alternating and parallel manner such that gaps are formed in between them, said electron beams are arranged to be formed to pass through said gaps, said first electrodes are connected to each other, said second electrodes are connected to each other, and said horizontal deflection signal is applied in use between the first electrodes and the second electrodes; ; said horizontal deflection signal generator is operative to provide a horizontal deflection signal comprising a first scanning period wherein the voltage increases and a second scanning period wherein the voltage decreases, and said circuits are operative to apply the control signals to the control electrodes in both said first scanning period and said second scanning period to produce image spots in both scanning periods; and said control electrodes are connected to receive the control signals in a manner such that a set of alternate ones of the control electrodes receive a control signal formed by converting the video signal into parallel signals and another set of alternate ones of the control electrodes receive a control signal formed by converting the video signal into parallel signals of reversed time sequence.

10. A picture image display apparatus comprising: a flat type vacuum enclosure having a transparent face panel, a row of parallel linearthermionic cathodes; an electron beam forming electrode operative to produce a predetermined number of two dimensionally disposed electron beams out of electron emission from the linear thermionic cathodes; a row of parallel control electrodes disposed per pendicularto the linearthermionic cathodes; a row of vertical deflection electrodes; a row of horizontal deflection electrodes; a phosphor screen formed on an inner face of the face panel; a metal film anode formed on the phosphor screen; a horizontal deflection signal generator for providing a horizontal deflection signal for the horizontal deflection electrodes;; a vertical deflection signal generator for providing a vertical deflection signal for the vertical deflection electrodes, and circuits for producing control signals to be applied to the control electrodes, said circuits comprising a memory for storing a video signal and a multiplexer for converting said stored video signal into parallel signals for the control electrodes; wherein:: said row of horizontal vertical electrodes comprises a plurality of first electrodes and a plurality of second electrodes disposed in alternating and parallel manner such that gaps are formed in between them, one row of said electron beams are arranged to be formed to pass through corresponding one gap, said first electrodes are connected to each other, said second electrodes are connected to each other, and said horizontal deflection signal is applied in use between the first electrodes and the second electrodes;; said horizontal deflection signal generator is operative to provide a horizontal deflection signal comprising a first scanning period wherein the voltage increases and a second scanning period wherein the voltage decreases, and said circuits are operative to apply the control signals to the control electrodes in both said first scanning period and said second scanning period to produce image spots in both scanning periods; and said control electrodes are connected to receive the control signals in a manner such that a set of alternate ones of the control electrodes receive a control signal formed by converting the video signal into parallel signals and another set of alternate ones of the control electrodes receive a control signal formed by converting the video signal into parallel signals of reversed time sequence.

11. Apparatus according to claim 10, wherein at least one of said deflection signals is a triangular signal.

12. Apparatus according to claim 10, wherein at least one of said deflection signals has a step-shaped waveform having at least two levels in each scanning period.

13. Apparatus according to claim 1, wherein the control electrodes are connected to receive the control signals in a manner such that a set of alternate ones of the control electrodes receives a control signal formed by converting the video signal into parallel signals, another set of alternate ones of the control electrodes receives a control signal formed by converting the video signal into parallel signals of reversed time sequence, and the arrangement is such that the deflection electrodes have applied thereto a deflection signal wherein an initial potential of a period of deflection is equal to the last potential of the immediately foregoing period of deflection.

14. A picture image display apparatus substantially as herein described with reference to Figures 3(a) to 7(a), Figures 7(b) to 8(b) or Figure 9 ofthe accompanying drawings.

New claim filed on 17 Sep 1981.

Superseded claim 10.

New claim: