Arrangement For Proportioning Actively Or Passively Light-radiating Surfaces

Abstract

An arrangement for displaying characters or symbols on a screen of a display device where characters selected by comparing a predetermined area of the displays stored in a memory with a counter circuit controlled by a column counter, a character counter, a scan line counter and a reading line counter inverts the selected characters in an inverter stage connected between a character generator and the display device.

Description

The invention relates to an arrangement for proportioning actively or passively light-radiating surfaces by means of adjustable superpositions and variations in brightness on these surfaces on which characters or symbols are periodically produced with the aid of a control stage by means of control signals for a character generator which control signals can be read out from a store and counted by column, character, scanning line and reading line counters, which generator provides modulation voltages as character control signals for the purpose of causing the light-radiating surfaces to light up.

In modern electronic data-processing devices increasing use is being made of equipment based on the action of light for feeding and extracting data which are used to exchange information between man and machine in an easier and quicker manner. When this information is displayed in the form of symbols, signs and/or characters on a light-radiating surface a convenient arrangement for satisfactory readability is of great importance. A convenient display is possible with the aid of a given proportioning of the overall image. In addition it is very advantageous when it is possible for the user of the apparatus to accentuate certain pieces of information relative to the rest of the picture contents in order to draw his attention, for example, to very important pieces of information on the image surface.

In the apparatus known so far certain signs or groups of signs are accentuated by means of a "blinking" display, that is to say, to the viewer the intensity in brightness on the image surface seems to vary in a rhythm of approximately 1-10 Hz. at which the light-dark ratio may be chosen differently. However, this method is not very advantageous since the flickering signs may irritate the viewer and give the overall image a jittery impression. There are also methods wherein separate symbols of the signs are accentuated by underlining them which, however, is a limited step as regards a clear characterization.

An object of the present invention is to accentuate areas which are permanently adjustable or are chosen by control information on the light-radiating surfaces by means of a given brightness in contrast with the other areas having symbols. This is solved in the above-mentioned arrangements which to this end are characterized in that in addition to the character control signals modulation voltages are derived from the output signals of the column, character, scanning line and reading line counters, which output signals can be chosen directly or through the control stage which is controlled by the memory, and that an inverter stage is provided behind the character generator.

The means generating the active or passive light is driven line by line or column by column over the overall range of the light-radiating surface upon which the symbols, characters or figures must be displayed.

The information to be displayed is used as a picture signal for the control of the intensity of the means producing the light radiation. The symbols accentuated in the picture areas may be inverted automatically into their brightness intensity, that is to say, generally dark picture dots serving for the display can be inverted into bright picture dots and bright picture dots can be inverted into dark picture dots.

In the arrangement according to the invention it is particularly suitable to insert permanently strips or lines accentuated by a different brightness between characters arranged in lines so that a horizontal division of the overall picture is obtained for the purpose of better readability.

Furthermore, a picture impression which is pleasant to the eye can be obtained by means of a slight increase of the brightness of the overall picture background which appears as a weak grey background. This is effected in a simple manner by the addition of a constant signal to the picture signal.

To explain the invention hereinafter the screen of a cathode-ray tube is used as the actively light-radiating surface and the electron beam of a cathode-ray tube is used as the means causing the light radiation (light conduction).

However, it is alternatively possible to use a passively light-radiating surface which is irradiated by a digital light-deflection arrangement active as a light source. In this case, however, all lines of the surface are composed of closely spaced dots possibly modulated in brightness while coherent scanning and reading lines are also available in an actively light-radiating surface.

A few examples are described with reference to FIGS. 1-7 of the drawings in order to show the possibilities of proportioning the picture according to the invention.

FIG. 8 shows a block diagram of an arrangement with the aid of which characters and symbols can be displayed on the picture screen of a cathode-ray tube while

FIGS. 9-13 show embodiments of the invention which, added to the arrangement according to FIG. 8, permit the display of the proportioned pictures.

DISPLAY OF A CURSOR

A cursor marks the position where symbols or characters supplied by the viewer, for example, through a keyboard are to be written on the picture screen. In case of corrections of the text the viewer moves the cursor to the position to be corrected or to the character to be written again and then writes the new character. The position which is marked by the cursor is a particular picture position to be characterized because changes in the picture content take place in this position. This position should be marked as clearly as possible; marking must, however, not detrimentally influence the readability of a character reproduced in this position. FIGS. 1-3 show how the cursor clearly and simply marks the position by means of inversion of the picture signal. In FIG. 1 a blank position is marked and in FIGS. 2 and 3 a character is marked by the cursor C. FIGS. 1 and 2 show black writing on a white background, FIG. 3 shows white writing on a black background. In these examples the separate characters are displayed by a raster of seven horizontal and eight vertical picture dots.

ACCENTUATING CERTAIN PICTURE AREAS OCCUPIED BY SYMBOLS OR CHARACTERS

To distinguish transmitted and received information a changeover from red to black writing is effected, for example, in a teleprinter exchange so that, for example, the manually fed and transmitted data can be displayed black and white and the data transmitted by the data-processing arrangement can be displayed red on white. The invention makes a different display possible in a corresponding manner. Received information is displayed for example white on black while the information originating from the user appears black on white through the supply station. In FIG. 4 the third line is displayed in white writing on a black background, the other lines are displayed in black writing on a white background.

VERTICAL LINES

Vertical lines can be drawn throughout the picture height by means of inversion of the picture signal for the duration of one or more picture dot widths. This makes it possible to display particularly tabulated additions in a convenient manner. These are efficiently made narrower than the horizontal interspace between two characters (for example, one picture dot width) so that the picture content is not disturbed. The vertical lines may be used as markers for tabulator positions, for example, when activating the tabulator function by means of a special button in the supply keyboard the cursor C moves behind the position of the next vertical straight line. FIG. 5 shows how such a tabulator marking becomes apparent. In white/black picture areas the vertical line V would automatically appear as a white line on a black background.

HORIZONTAL LINES

By inverting the picture signal during the period of the beam covering the picture in a horizontal interspace the line above the space can be underlined (H). In this manner titles can be accentuated. Tables subdivided or lines which are to be fed into the data-processing arrangement can be marked. This possibility is shown in FIG. 6.

ACCENTUATING THE INTERSPACE BETWEEN THE LINES

For better readability of the displayed text especially of tables or many lines of text it is to be recommended to subdivide the picture on the screen in horizontal strips so as to guide the eye during reading. This can be achieved in that the picture screen has a striplike structure so that-- as is shown in FIG. 7-- the characters appear darkly on a white background while the horizontal interspaces Z stand out grey. This "darkening" of light horizontal interspaces is particularly favorable because the picture shows a much slighter flickering effect. In a corresponding manner the dark interspace can be brightened to a slight extent in case of information the characters of which are displayed white or black. In this manner of display it is additionally found that when the entire background is somewhat brightened the viewer's impression of the picture is enhanced in a pleasant manner without the readability being influenced. As is referred to under items 1 and 4 in the case of inversion of the picture signal for the display of a proportioned picture, this brightening to a slight extent can be employed to accentuate special portions of the picture, for example, also columns of arbitrary width in tables, especially when using different grey values whose brightness stages are still clearly distinct from one another.

According to FIG. 8 a control signal BAS (composed of a picture signal B, a blanking signal A and a synchronizing signal S) is produced for a TV-monitor TV functioning in accordance with a television standard. A counter circuit comprising a column counter SpZ, a character counter ZchZ, a scanning line counter LZ and a reading line counter ZlZ is controlled by a clock signal generator TG. The column counter SpZ controls the columns of the raster in the picture field for the display of a character, the character counter ZchZ controls the position of the characters in a reading line; the scanning line counter LZ controls the separate scanned lines in a character (horizontal scanning paths of the electron beam); the reading line counter ZlZ determines the reading lines in the overall field of display. This counter circuit controls a blanking stage A, a synchronizing stage Sy and a control stage St. The stage A produces the picture blanking pulses and the stage Sy produces the synchronizing pulses while the control stage St, which is likewise coupled to the clock-signal generator TG, controls a memory Sp and a character generator ZG coupled thereto. The picture signal B, that is to say, the character control signal from the character generator ZG is applied through an inverter stage CI, which is active or not active in accordance with the user's choice, to an input of a gate D to a second input of which the blanking signal A is applied. In case of character display the inverter stage CI serves for generating a cursor, a conspicuous picture area, horizontal or vertical straight lines and for varying the picture background. The combined picture-blanking signal (BA) and the synchronizing signal (S) are combined in a mixer stage M to form a picture-- blanking-- synchronizing signal (BAS). The characters to be displayed are kept available in the memory Sp. Information is exchanged between memory Sp and a data-processing arrangement through the line E/A while the user can vary the picture content through a keyboard Ta and a lead T. The characters coded with minimum redundance in the memory Sp are converted into a picture signal B by the character generator ZG which for this purpose supplies the corresponding modulation voltage for the electron beam in the monitor TV.

FIG. 9 shows the block diagram for the generation of a cursor. The positions of cursor counters ZC1 and ZC2 which positions can be chosen manually through the keyboard Ta (denoted by key-contacts C1 and C2) are compared in two comparison arrangements VC1 and VC2 with the positions of the character counter ZchZ and the reading line counter ZlZ. In case of equal positions of the counters which are interconnected through the comparison arrangements, a signal is applied through an AND-gate U to a cursor control stage CSt. The vertical dimension of the cursor on the picture screen is limited by the scanning line counter LZ at the character height plus, for example, one line above and below the character. The cursor control stage CSt controls the inverter stage CI which inverts the picture signal B provided by the character generator ZG (FIG. 8) for the fixed duration by means of switching on this inverter stage CI(B or B).

FIG. 10 shows the structure of the different components in details. NAND-gates 1, 2 and 3 and 6, 7 and 8, respectively compare the positions of the counters ZchZ and ZC1 and ZlZ and ZC2 in the comparison arrangements VC1 and VC2. Since these counters comprise different divider stages employing flip-flops, a switching group corresponding to the NAND-gates 1, 2, 3 and 6, 7, 8 respectively is necessary for each pair of flip-flops, the output of said NAND gates being connected to an input of NAND-gates 4 and 5, respectively provided with various inputs. The gate 4 thus marks the column, the gate 5 marks the reading line and hence a NAND-gate 11 connected through two inverters 9 and 10 to the outputs of the gates 4 and 5 marks the position where the cursor is displayed on the picture screen. The width of the cursor is equal to the width of the character which is normally to be displayed plus every time half a horizontal interspace in front of and behind the character. The height of the cursor is determined by the control stage CSt in that the gate 11 is connected through an inverter 12 to a NAND-gate 15 to a different input of which the line counter LZ is connected through an SR flip-flop (Set-Reset flip-flop, i.e., bistable multivibrator) formed by NAND-gates 13 and 14 so that the cursor is limited to the desired number of scanning lines. The NAND-gate 15 is connected directly and through an inverter 17 to NAND-gates 19 and 18, respectively in the inverter stage CI. The picture signal B is applied through an inverter 16 and directly to the gates 18 and 19, respectively the outputs of which are connected to the inputs of a NAND-gate 20. The inverter stage CI controls the picture signal B in such a manner that it arrives at the mixer stage M during the normal picture display through the gates 19, 20 and hence in noninverted form (B), whereas it is inverted (B) through the gates 16, 18, 20 for the period of the display of the cursor.

Arrangements for proportioning the picture with the aid of accentuated picture areas, vertical and horizontal lines as well as grey stripes are further described in principle only.

FIG. 11 shows an arrangement by which arbitrary picture areas can be inverted. The counters ZchZ, LZ and ZlZ correspond to those of FIG. 8. The character counter ZchZ is connected to a decoder D1 which is also connected to the control stage St. The scanning line counter LZ and the reading line counter ZlZ are connected to a decoder D2 which is likewise connected to the control stage St. The counters influence the decoders D1, D2 in such a manner that the commencement and the end of the inversion range for the horizontal (ah and eh, respectively) and vertical (av and ev, respectively) directions are fixed by the control stage St. Two SR flip-flops formed from NAND-gates 21, 22 and 23, 24 and connected to the decoders D1 and D2 control an inverter stage corresponding to CI of FIG. 10 through an AND gate function (NAND-gate 25). Since the control stage St is connected to the memory Sp for the overall picture contents, different arbitrary large picture areas can be inverted therein in case of a corresponding arrangement, for example, when more bits are added for proportioning the picture for each reading line.

FIG. 12 shows an arrangement for generating horizontal or vertical straight lines on the picture screen. The operation corresponds in principle to that of the circuit arrangement according to FIG. 11. In this case, however, there are no SR flip-flops necessary since only one TV reading line and the raster dots of a column of the raster are inverted. The column counter SpZ and the character counter ZchZ are connected to a column decoder DSP, the decoder being denoted by DZ for the counters LZ and ZlZ. The column decoder DSP and the reading line decoder DZ act on an inverter stage, corresponding to CI of FIG. 10 through an OR-gate 26.

The arrangements described may alternatively be used to control the grey hue of the picture background. FIG. 13 shows an example of the mixture stage M (see FIG. 8) which is extended in such a manner that a grey control stage G makes a dark picture background lighter and a light background darker. In the mixer stage M the synchronizing signal S controls a transistor T.sub.1, the picture suppression signal BA controls a transistor T.sub.2. The emitter electrode of transistor T.sub.1 is connected directly to ground while that of transistor T.sub.2 is connected to ground through a variable resistor P.sub.1 parallel to a collector-emitter circuit of a transistor T.sub.3 in series with a resistor R.sub.3. The collector electrodes of the transistors T.sub.1 and T.sub.2 and of a transistor T.sub.4 whose emitter electrode is connected to ground through a variable resistor P.sub.2 are connected through a resistor R.sub.1 to a terminal conveying the voltage +V and are in that case coupled to the monitor TV. The base electrodes of the transistors T.sub.3 and T.sub.4 are coupled to the grey control stage G. The black level is fixed by the resistor R.sub.3 when transistor T.sub.3 conducts. Normally transistor T.sub.3 conducts and transistor T.sub.4 does not conduct. If grey values are to be produced on a black background the transistor T.sub.3 is cut off and the degree of brightness increase can be adjusted with the aid of the variable resistor P.sub.1. If grey values are to be produced on a light background the transistor T.sub.4 becomes conducting and the degree of darkening can be adjusted with the aid of the variable resistor P.sub.2.

The commencement and the end of the variation in grey hue is passed on by the control stage St through leads a and e to the grey control stage G, but it should be taken into account that grey control must not occur during the suppression signals A less the porches of the synchronizing pulses S are tampered with. In addition, a control input g must receive a "1" signal from the control stage St in case of black writing on a light background and a "0" signal in case of light writing on a dark background. The control input g is connected directly and through an inverter 27 to NAND-gates 28 and 29, respectively. The other inputs of the gates 28 and 29 are connected to the output of an SR flip-flop formed from NAND gates the inputs of which are connected to the leads a and e. The output of the gate 29 leads to the transistor T.sub.3, while that of gate 28 leads to transistor T.sub.4 through an inverter 30.

Claims

What is claimed is:

1. An arrangement for displaying characters or symbols on a screen of a display device, which arrangement comprises a clock-signal generator, a counter circuit connected to said generator, a control stage which is connected to said generator, said counter circuit and a character or symbol memory, outputs of said control stage and said memory connected on a character generator having an output for periodically supplying modulation voltages corresponding to the characters or symbols of the memory to the display device, the arrangement further comprising a stage for accentuating characters or symbols on the screen, characterized in that the said stage for accentuating characters or symbols comprises an inverter stage (CI) which is connected between the character generator (ZG) and the display device (TV) and which inverter stage (CI) is connected so as to be controlled to the said counter circuit which comprises a column counter (SpZ), a character counter (ZchZ), a scanning line counter (LZ) and a reading line counter (ZlZ)

2. An arrangement as claimed in claim 1, wherein the display device (TV) comprises a television picture tube which is connected to the output of a mixer stage (M), which mixer stage (M) is connected to a blanking stage (A) and to a synchronizing stage (Sy), which are controlled by the counter circuit, and to the character generator (ZG) through the inverter stage (CI).

3. An arrangement as claimed in claim 1, further comprising comparison arrangements (VCL, VC2) are connected to the character counter (ZchZ) and the reading line counter (ZlZ), respectively, which arrangements are in addition connected to counters (ZC1, ZC2) which can be chosen through keys (C1, C2) and which comparison arrangements are both connected through an AND gate (W) to a cursor control stage (CSt) to which the inverter stage (CI) is connected.

4. An arrangement as claimed in claim 3, wherein the cursor control stage (CSt) comprises a bistable multivibrator (13, 14) which is controlled by the scanning line counter (LZ), the output of said multivibrator being coupled through a NAND gate (15) to the output of the comparison arrangements (VC1, VC2).

5. An arrangement as claimed in claim 2, wherein the comparison arrangements (VC1, VC2) comprise successively connected NAND gates (1 to 10) which are connected together through a further NAND gate (11).

6. An arrangement as claimed in claim 1, wherein a decoder (D1) controlled by the control stage (St) is connected to the character counter (ZCHZ) and that a second decoder (D2) controlled by the control stage (St) is connected to the scanning line counter (LZ) and the reading line counter (ZlZ), the outputs of the decoders (D1, D2) being connected to bistable multivibrators (21, 22; 23, 24) the outputs of which are connected through a NAND gate to the inverter stage (CI).

7. An arrangement as claimed in claim 1, wherein the column counter (SpZ) and the character counter (ZchZ) are connected to a column decoder (DSP), and that the scanning line counter (LZ) and the reading line counter (ZlZ) are connected to a reading line decoder (DZ), the outputs of the decoders (DSP, DZ) being connected through an OR gate (26) to the inverter stage (CI).

8. An arrangement as claimed in claim 2, wherein two transistor stages (T.sub.2, T.sub.3 ; T.sub.4) which are adjustable in amplification are provided in the mixer stage (M) for the purpose of varying the grey hue of the picture background, the inputs of said transistors being connected through NAND gates (G and SR) to the control stage (St).