DE3940233A1 - VISUAL DISPLAY DEVICE FOR CATHODE RAY TUBES - Google Patents

Abstract

A brighter display is formed by a beam index CRT driven in raster scan mode by providing the CRT with a plurality of electron beams Bm1, Bm2 all caused to pass over the same regions of the screen in scanning the raster. The beams may be brought to impinge superimposed and modulated with the same video signal. Alternatively the beams may be separated in the direction of line scan by being delayed for a fraction of the line period or separated in the field scan direction by being delayed for a multiple of the line period and the video signal to the trailing beam(s) delayed by a corresponding interval so that the image is reinforced (Fig 3). The video signal delay may be effected in digital form by a store addressed throughout the scan and variations in delay due to scan corrections accommodated by correction map store. The delayed beam technique may be applied to a shadow mask CRT. <IMAGE>

Description

The invention relates to display devices which Katho Use the jet tubes, and especially a Vorrich device to increase the maximum screen brightness beyond what was previously achievable.

Cathode ray tubes are increasingly used in the cockpit of flight witness used to generate colored ads and when a high strength or robustness and a high umbrella Brightness in sunlight is required are common Index tubes used instead of the previously known mask Tubes.

Mask tubes or shadow mask tubes are several restrictions Operational conditions are subject to fragility the shadow mask structure and the absorption of considerable elec Trone beam energy from each of the three beams that are used to define each color pixel, the Scatter or loss of this energy input due to the mask at a single point that surrounds an opening, through which the rays currently pass, the maxi times usable beam current and thus the screen brightness Right.

Such mask tubes can have a suitable light output bring when in the so-called italic method operated in which line pictures are drawn, that take up any small portion of the screen area and are surrounded by unaddressed areas that allow that the shadow mask dissipates locally absorbed energy where where the pictures are drawn through the rest of the shadow mask or being represented.  

When viewing information, however, that's increasing are generated by the computer and often have a graphic form, it is necessary that many display devices from Cathode ray tubes work in the raster scanning method, at which a point (which is the neighboring point of each of a triplet made of phosphorus) can be repeated scanned across the screen in one direction as a line that is for each scan in a vertical direction this is offset by a field or grid of scan lines to build. A modified form of the shadow mask tube ver applies a mask with slits that run across the lines scanning direction and extends to the phosphorus triplets.

A larger proportion of the screen is registered and the electron beams have to be at such a speed be distracted that they are at a shorter time at everyone Phosphorus pixels remain. The restoration of the local umbrella brightness by increasing the energies of the Electron beams at every point on the shadow mask are superimposed is prevented by scattering the energy through the shadow mask when all points are turned on one after the other be written.

The beam index tube, on the other hand, has no such energy absorbent mask, and it allows a beam of higher strength strikes the screen directly.

She usually has an electron gun that one individual electron beam which is directed onto a screen that is focused with streaks of through the electrons is excitable phosphor coated, which ver different primary colors emit in a repeated Sequence of triplets are lined up according to the emit  tated colors, also at intervals in this Series of index strips are lined up in the same direction, which respond to the electron beam and one through the tube or a detector emit measurable radiation.

The beam index tube is operated in the raster scanning method ben, an electron beam modulation in multiplex wise takes place between channels of an electrical color sig nales, which corresponds to the three primary colors of the phosphorus of the Tri pletten-stripe is assigned one after the other in each Line can be scanned, the radiation emission of the index strip serves to synchronize the color signal in multiplex mode when the beam strikes on the right phosphor strip.

To ensure sufficient image resolution in the line scanning direction to achieve, the phosphor stripes are narrow and given if separated by protective strips to prevent color contamination to prevent, with the result that here also an restriction regarding the permissible point dimension in the Line scanning direction exists.

However, it is difficult to get a high intensity beam to focus on a point of small dimensions and yourself with protective strips between adjacent phosphor strips there is a limitation on the beam current and thus with regard to the screen brightness. This can in some ways The scope can be countered by focusing the beam below Formation of a point that is transverse to the direction of the lines is elongated, i.e. along the strip the field scanning direction. But this is limited by the Separation of adjacent scan lines.

It is therefore an object of the invention to use a cathode Jet tube display device and a method for loading urged to create such a facility that made it possible to display light, brighter raster-scanned images.

An embodiment of the invention is described below the drawing explains in the

Fig. 1 shows schematically in section a beam index tube with an associated control circuit for a first embodiment of a device according to the invention, wherein two electrons radiate in the tube on the screen overlap.

Fig. 2 shows schematically similar to Fig. 1, a second embodiment of a display device, wherein the electron beams in the tube are offset on the screen and one of the modulation grids of the tube is assigned a delay circuit.

Fig. 3 shows similar to Fig. 2 is a view of a third embodiment of a display device according to the invention, wherein another embodiment of a modulation signal delay circuit is shown.

Fig. 1 shows a visual display device 10 for Dar position multiple, ie complete, color images of the raster scan type with a beam index tube 11 and an assigned driver and control circuit 12 , both of which are known in some details and are described here only in outline.

The cathode ray tube has an evacuated housing 13 with a pair of electron guns 14 ₁ and 14 ₂ , which form a pair of cathodes, each of which a control grid 14 _{1 '} and 14 _{2' is} assigned and with common electrons acceleration and beam focusing electrodes (not shown) which generates a pair of electron beams Bm 1 and Bm 2 between the cathode and an anode 15 , which is arranged adjacent to a screen section 16 , on which strips of red, green and blue phosphor 17 _R , 17 _G and 17 _B are formed accordingly are separated from each other by protective strips 18 . The color emitting phosphor strips are grouped in a repeating sequence or series of triplets, each containing a phosphor of each color. Reference in the specification to phosphor of one color means the color of the visible radiation which is emitted mainly by this phosphor when excited by the electron beam accelerated between the electron gun and the anode it strikes.

The rays are focused so that they are on the image hitting the screen as circular or elliptical points, that are slightly larger than in the direction of the stripe width the stripe width, thereby giving maximum excitement to the Cause phosphor of a strip that they hit while the color purity of the light emitted by the Protective tapes are preserved, which are adjacent strips separate different color phosphors.

At intervals across the screen, index strips 19 are formed from a phosphor or other material that is responsive to excitation by the electron beams and emits radiation that may be invisible or causes secondary electron emission back into the tube housing, and these index strips can be applied to the Protective strips 18 may be arranged or take up part of the sequence of colored strips.

The control circuit 12 has an energy source 20 for generating a potential difference between the anode 15 and the cathodes, by which each electron beam energy is determined and thus the light output on the tube or the brightness or luminosity of the displayed image. In the embodiment according to FIG. 1, the cathodes are aligned with respect to one another in such a way that both rays are focused on the same point on the screen and are combined to form a light-emitting point, the brightness of which is determined by both rays. If one considers for the moment the mode of operation of a beam, for example the beam Bm 1 , an image is formed, ie a contrast is generated, by modulating the beam current by means of red, green and blue video signals from a source, not shown, for example a camera or Computer graphics generator, on a video multiplexer 21 , which in accordance with color synchronization signals from a format circuit 22 each of the color signals one after the other to a video amplifier 23 ₁ and then to the control grid 14 _{1 'of} the cathode ray tube to modulate the electron beam current. The format circuit 22 can also receive synchronization signals with the video signals from their source.

The circuit 12 also has a beam deflection generator amplifier 24 , which is also synchronized with the format circuit 22 , and deflection coils 25 , which cause the electron beam to perform a repeated line scan across the phosphor strips perpendicular to their length, ie in the plane of the image. Orthogonal field scanning circuits are also available, but are not shown for reasons of clarity.

A photodetector or, if appropriate, a secondary emission detector 26 is provided to record emissions of the index strips 19 and an index signal generated by it, which is applied to the format circuit 22 via the amplifier 27 , represents the crossing of the index strips by a line scan Electron beam.

The fixed spatial relationships between the colors phosphor stripes and the index stripe make it possible Format circuit to generate a signal that with the Elek is synchronized with the red, green and blue phosphor stripes scans, causing the multiplex Show red, green and blue video signals can be synchronized with the crossing of the corresponding Phos phore through the electron beam and it creates the color picture by varying the electron beam current with the video signals.

The grid 14 _{2 '} , which controls the beam Bm 2 , receives modulation signals from the output of the video multiplexer 21 via a driver amplifier 23 _2, so that during each scan both beams are modulated with the same information and the superimposed points on the screen as one appear.

The radiation energy that is on some phosphor stripe strikes, can thus be kept larger than one single beam without recourse to an individual Beam current that is focusing down on you as well locked point, which causes excitation of neighboring Phos avoid stripes.  

By simply reducing the electron beam energy to two Beams are split or split and the beam len are modulated with the same color signal information, can have a stronger beam current and a stronger picture screen brightness can be realized.

This results in every raster scanning cathode ray tube the visible picture from a very brief excitement of a Part of the phosphor on the screen that is in field scan intervals is repeated or in double-field scanning if nesting is used followed from a relatively short phosphor emission decay interval and a relatively long non-emitting interval, which is not wanted because the viewer again brought emissions in a seemingly consistent or permanent way of the picture integrated.

This image can be amplified within each field scan become and appear brighter by increasing the light output from the screen by delaying a beam right relative to the other so that the different rays are on hit the same part of the screen one after the other, time Lich delayed, but with the same image information liert, which is delayed to the same extent.

Fig. 2 shows a second embodiment 30 of a display device according to the invention in section through a beam index tube with a control circuit similar to that of FIG. 1, so that corresponding parts have the same reference numerals, but with the difference that the tube 11 ' Electron gun or the cathodes 14 ₃ and 14 ₄ are aligned or aligned relative to one another and to the screen, so that the beams Bm 1 and Bm 2 impinge on the screen at a predetermined distance d in the direction of the line scan, wherein in the control circuit 12 'one Modulating signal delay circuit 31 is provided, which is connected between the color signal multiplexer 21 and the grid amplifier 23 ₂ .

The distance d on the screen between the impingement points of the beams is chosen so that they impinge on corresponding points with respect to the phosphor strips 17 _R , 17 _G , 17 _B and the index strips 18 .

In the screen shown, the index strips 18 appear with a division of two phosphor strips, which are repeated in triplets, so that corresponding points appear in a division of six phosphor strips. An identical or similar structure is also used in other constructions.

The distance d is thus a multiple of six times the phosphor stripe division and depending on the line scanning rate of the beam, it determines a delay between the trailing beam Bm 2 , which strikes the same point on the screen as the beam Bm 1 . The delay circuit 31 is set so that it generates such a delay interval in the modulation signal to the grating 14 _{2 '} so that the same piece of video information modulates both beams Bm 1 and Bm 2 when they strike any phosphor part of the screen, ie some index strip.

The delay can be more than one line scan period amount, but less than the field period, so that the offset points of impact on different scan lines of the grid and in a suitable embodiment the delay can be an exact multiple of the lines period, so that the two rays on the same  Stripes, but encounter in different grid lines.

The delay circuit 31 can be of any suitable form for generating the delay interval, from a few microseconds when the beams hit the same raster line to hundreds of microseconds when they hit different raster lines.

For short delays, it is appropriate to arrange to use, which ver the analog modulation signals hesitate, e.g. Charge-coupled devices, for longer ver However, delays are preferred to digital storage technologies moved such as Shift registers or addressable memories, such as. Direct access storage.

Such digital storage is mainly used when the video signals for image display are digital in any system or computer and the delay circuit can expediently be actuated before the digital signals are converted into analog form delt are applied to as modulation signals Control grille.

Fig. 3 shows a third embodiment of a display device 40 as a section through a beam index tube 11 'and a control circuit 12 ''similar to that of FIG. 2, so that corresponding parts have the same reference numerals, but there are differences with respect to the video signals .

The video signals of the three main colors are generated in a digital generator circuit 41 , which can be a computer or a special video card, and they are applied via data lines 42 to a multiplexer and digital / analog converter 43 , which is the signal multiplexer 21 according to the devices 10 and 30 , and which receives the synchronization signal from the aspect ratio circuit 22 to apply to the amplifier 23 ₁ analog grating control signals of color corresponding to the incident position of the leading beam Bm 2 determined by the index system.

The data lines 42 also supply a delay memory 44 , which is controlled by read / write input / output circuits 44 'by means of an address circuit 45 , which in turn is controlled or synchronized by the image format circuit 22 to each of the digital video words save over a predetermined delay interval before they are applied to a multiplexer and digital / analog converter 46 , which is similar to the converter 42 , but is controlled by the address circuit 45 instead of by the format circuit 22 .

The analog output of the converter 46 controls the amplifier 23 ₂ and the grid 14 _{2 '} with the corresponding delay.

The digital delay circuit and the digital-to-analog converter can also be designed in another suitable form and can, for example, perform the multiplexing as part of the write-in in the delay memory, so that the only stored signal data are those which are applied to the grid 14 _{2 '} .

The duration of the delay is again immaterial and there they just a function of the interval between the shouting ben of the video data in and when reading from the memory they are easily changeable, even during operation and continuously.  

It is not uncommon to scan an electron beam to correct les of a cathode ray tube various distortions caused by the geometry of the Tubes are generated and interactions of the deflection fields, i.e. the beam deflection forces vary according to the Position of the beam in the tube housing to ensure that the point the beam is pointing at on the screen hits, follows a uniform grid pattern.

If there is more than one electron beam and the Rays are deliberately offset, as is the case after Invention is the case, however, the same deflection forces are set, the influence of the scanning correction forces on the leading beam cause a lagging Beam so slightly offset against its nominal scan path is that it is on a phosphor strip of wrong color hits or two phosphor strips overlap.

The arrangement 40 of FIG. 3 can be modified and a correction memory 47 can be provided, controlled by the address circuit 45 , whereby the delay applied to the video signal can be changed as a function of the position of the leading beam in the field scan. Conveniently, the variable delay may include a map of the retarding beam's deviations from its nominal beam position with respect to the leading beam for each position of the leading beam in the raster, ie for each index strip or phosphor strip triplet that are crossed when the beams Scanning correction forces are exposed.

The deviations recorded or recorded in this way can contain changes in position which, when read out, relate to the sampling rate in order to determine changes in the delay interval by means of a suitable process circuit (for example the computer 41 ) and which are then added to the minimum delay interval or directly as changes in the nominal delay interval. More simply, however, these changes or deviations are stored as delay intervals, each being combined with the nominal delay interval, that is, as the actual delay interval to be used for each position of the beam and thus signaled by the aspect ratio circuit 22 .

Although the invention has been described with reference on a two-beam beam index tube, it is not limited to this number of rays, not even how the rays are generated or used on the Type of cathode ray tube, provided the rays all follow the same path in each scan.

For example, the cathode ray tube shown has individual cathodes for generating the individual rays. But it can also be seen a cathode construction which generates a beam along an axis, for example in the direction of the stripe course, with individual control grids being exposed in different areas of these stripes in the manner of 14 _{1 '} and 14 _2' .

In such a case, the areas of the beam hit on the screen and effectively form two separately points that can be modulated in the field scanning direction are separated and with a delay interval of one Scanning line periods operate in a manner similar to that above described where two separate beams ver sets are.  

Furthermore, the display device according to the invention use a mask tube where a group of three beams through an opening of the shadow mask on one Triplet made of phosphorus is aimed at the screen corresponding to the normal single ray of a ray index tube. A shadow mask tube can be made according to the inven be provided with two or more groups of three rays, each group on different Parts of the shadow mask is aimed so that each is not too much energy at any point on the shadow mask brings and improved scatter through the mask be will work.

Alternatively, a single group of three rays be aligned so that the rays on different but close openings of the hole mask are directed, making each beam on one other part of the screen falls and it can be of elevated Strength is due to the time-separated encounter of these three rays on the same part of the screen, which provides all visual information for that part is delivered with only a slight overlap of colors priority due to excitation of the phosphors to something different times.

The reference to the same modulation used for more than applying a beam means that the same mo mental part of a modulation signal that functions as a function is running out of time, is placed on both electron beams. But it does not necessarily mean that the module with the same signal level.

Claims (14)

1. Display device with a raster-scanned cathode ray tube with a screen which carries an array of color-emitting phosphor triplets, where the tube generates a plurality of individually modulatable electron beams which impinge on phosphors of the triplets, scanning devices for repeatedly scanning the rays and to allow each beam to strike the screen so that a grid of line scans is formed which is offset in the transverse direction against one another to form a field, such that the fields for all beams are spatially superimposed on one another, characterized in that that the individually modulatable electron beams are arranged relative to each other so that they strike corresponding phosphors of the triplet series, further by modulating means for modulating the strength of each electron beam with an electrical modulation signal that is representative of a visual image that is on the bi is generated in such a way that the same modulation is applied to the different beams when they strike the phosphors on the same part of the overlaid fields to enhance excitation of the phosphors at those locations. 2. Device according to claim 1, characterized in that the rays are directed towards the screen that they're on this in different positions impinge, with all rays as leading and after rushing rays are scanned and the modulation  device has a delay circuit to delay the modulation signal for each beam, the leading beam in every scanned grid lagging by a time interval based on the distance of the Point of impact of this beam from the leading beam is related in the direction of the beam scanning. 3. Device according to claim 2, characterized in that that each time interval is less than one field down sampling interval. 4. Apparatus according to claim 2 or 3, characterized records that the cathode ray tube is a beam dex tube is where the screen is a plurality of phosphor strip triplets and index strips points, each stripe in the field scan direction extends, and lined up in the grid lines scanning direction so that the rays are further directed are that they are on corresponding sections of phosphorus stripe triplets and rows of index strips. 5. The device according to claim 4, characterized in that the rays are directed to the same streak that strikes in the field scan direction by a whole number of line scans are offset. 6. Device according to one of claims 2 to 5, characterized characterized in that the delay circuit is a digital delay line to the module tion signal in digital form.   7. Device according to one of claims 2 to 6, characterized is characterized by a correction circuit to the Modu Lation signal delay to vary for everyone rushing beam across the entire grid accordingly Changes in current relative positions between between the trailing and the leading beam in follow sample non-linearities and applied Ab tactile corrections to cause the leading Beam describes a uniform grid. 8. The device according to claim 7, characterized in that that the correction circuit has a correction memory in which for each trailing ray a function is recorded that affects the actual Chen distance between this beam and the leading one Ray is related in the direction of scanning for each addressable position in which the leading beam hits the screen and that Ausleseeinrich are provided which are in accordance with the current position of the leading beam during the entire field scan this stored function for read out each trailing ray and a delay of the modulation signal in accordance with this testify. 9. The device according to claim 8, characterized in that contained in the correction memory or up function plotted the current size of the modulation signal delay interval of the trailing beam les is. 10. The device according to claim 8, characterized in that that the function contained in the memory is a reject the nominal delay inter vall or the nominal distance between the lagging is the ray and the leading ray.   11. Process for creating a visible image a cathode ray tube, with a plurality of individually modulatable electron beams, whereby the rays on a screen so who focused the fact that they have radiation-emitting phosphors excite each ray repeatedly in a ra pattern of scan lines is performed, the Rows are offset from each other in the transverse direction, to form an array of scan lines, thereby ge indicates that these fields are spatially superimposed are that the strengths of each of the scanned beams len are modulated with electrical modulation signals representative of one on the screen visual image to be generated, and that the same modulation to the different beams is placed on the same parts of the overlay fields hit the emissions from these Reinforce parts or sections. 12. The method according to claim 11, characterized in that the rays are brought to the same Hitting parts or sections of the screen which the lines of the grid as leading and after form rushing rays that are staggered in time, which currently put the rays on physically Sections of the screen hit and the modu tion signals delayed for each trailing beam be delayed by an interval that this Includes time shift. 13. The method according to claim 12 using a Beam index cathode ray tube, the radiation emitting phosphors triplets of different Color emitting phosphor stripes and beam index  have stripes that are essentially transverse extend to the line scanning direction, characterized thereby records that this time shift is a function of Sampling rate and the distance between the beam index stripes and phosphor stripes of the same color emission is. 14. The method according to claim 12 or 13, characterized records that the delay interval between the Modulation of the leading beam and trailing the beam is changed accordingly by changes due to the dislocations between the rays of changes in the scanning deflection forces applied to the leading beam placed during field scanning to create a uniform grid.