DE3112249A1 - ARRANGEMENT FOR PRESENTING CHARACTERS ON A SCREEN - Google Patents

Description

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SI3M3NS MTIENGSSSLLSCHAFT Our mark

Berlin and Munich VPA gj p 6 7 2 8

Arrangement for displaying characters on a screen

The invention relates to an arrangement for displaying characters on a screen of a display unit , by means of which the characters can be displayed in different colors and by means of the except for the characters multicolored graphic patterns and / or multicolored television images can also be displayed.

With the new telecommunication services videotex (interactive videotex) and videotext (broadcast videotex) it is possible, with the help of a television set, to display characters and in addition to the usual television images to represent graphic patterns. In this context, the characters include alphanumeric characters and special characters as well as linear graphic characters understood, while under graphic patterns relatively coarse graphic representations are understood.

In the representation of the characters and graphic patterns, the screen content, which is referred to as a page, is for example divided into 960 character fields, which are arranged in 24 lines with 40 character fields each. When displaying alphanumeric characters, one character is shown in each character field. The drawing field in this case consists of 8x10 or 8x12 pixels, by means of which the individual characters are represented.

The same grid can also be used to display fine graphic characters that span one or more character fields can extend. When displaying the graphic patterns, each field is divided into 2x3 graphic elements and the graphic patterns can be constructed from the possible combinations of light and dark graphic elements will.

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The characters and graphic patterns can be displayed in the basic colors red, green and common in television blue and their complementary colors yellow, cyan and magenta as well as white and black. In the representation these colors can also be selected as background colors.

When displaying characters in relatively dark colors, such as red or blue on dark Background, it was found that because of the relatively low luminous intensity and at the same time low spectral eye sensitivity for red and blue the characters are difficult to read and recognize. Rough graphic However, patterns that are shown in red or blue are easily recognizable.

From DE-OS 27 40 329 and EP-OS 0 004 197 it is already known to change the brightness of the colors when videotex pages are displayed on the screen of a television set instead of television images. The setting of the brightness of the colors in the display of the videotex pages in relation to the brightness of the colors in the display of a television picture takes place in a one-time comparison and applies to both the display of the characters and the display of the graphic patterns. If the brightness of the colors is set in this way, however, there is a risk that either the relatively light colors such as white, yellow and cyan are lightened too much relative to the relatively dark colors such as red and blue when the graphic patterns are displayed, or when the Representation of the characters the relatively dark colors such as red or blue are not brightened enough. This is especially true if on a videoty; -: page both signs and a ^: .ch graphic liuster are displayed v / erden ur.d veriilltriir.mä3i.T c.ur.kle signs in ier Uilho v- ^ n rcrß

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bright areas are displayed.

The invention is therefore based on the object of specifying an arrangement by means of which particularly good readability of characters with different colors on a screen of a display unit is achieved.

According to the invention, the object is achieved in the arrangement of the type mentioned in that a control unit is provided, which in the representation of

Characters with relatively dark colors lighten these colors relative to the relatively light ones that can be displayed Colors causes.

The arrangement according to the invention has the advantage that it requires little effort and is straightforward can be built into existing display units. A pleasant picture appears on the screen for the viewer. Compared to an increase in the overall brightness, the arrangement has the advantage that a flickering of the relatively bright colors are avoided and that the colors in the representation of the graphic pattern or the television pictures are not changed. The color tone is also retained in the representation of the characters, because the colors are only brightened. The mixed colors are not changed and the color contrast remains also received.

The arrangement requires particularly little effort when the control unit is in the display of the characters emits control signals in the relatively dark colors to the display unit, by means of which a brightening of these colors is made. In particular, it is advantageous here if the control signals have the brightness of the illustrated Increase characters by adding appropriate proportions of the basic colors.

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Another possibility for the relative lightening of the relatively dark colors is that the Control unit when displaying the characters in the relatively dark colors, the overall brightness increases the display on the screen and generates signals by means of which the brightness of the displayed is proportionate light colors is diminished.

If a decoding unit is provided, which the respective the characters to be displayed emits ordered color signals to the display unit and which contains an image memory, in which data words assigned to the characters and the associated colors are stored, becomes an advantageous one AusfUhrungsform the arrangement achieved in that the control unit contains a converter that the relatively converts first code words associated with dark colors into second code words which correspond to the corresponding lightened colors are assigned. In particular, it is advantageous that the converter is connected upstream of the image memory is, in which the second code words can be stored instead of the first code words. There is another possibility in that the converter is arranged between the image memory and an image refresh memory. The refresh memory does not have to contain the content of a complete page. For example, it can be sufficient if only the content of one line is stored in the frame buffer.

Good legibility of the characters can also be achieved if the display unit includes the characters Represents increased frame rate and that the characters with the relatively dark colors are displayed more frequently are called the characters with relatively light colors or that the control unit to the display unit Emits signals, by means of which the brightness signals in the representation of the characters in proportion

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moderately light colors are periodically blocked for a short time.

Especially when using a flat screen, in which the display is made using a large number of luminous dots, it is advantageous to that the control unit generates signals that are used in the display of the characters with the relatively dark Colors triggers a display with more luminous dots on the display unit than when displaying the characters with the relatively bright colors.

The arrangement is used in an advantageous manner when in particular as relatively dark colors the basic colors blue and red are provided and, as relatively light colors, especially the colors white, yellow and cyan are provided.

There are also the brightnesses of the characters with the basic colors blue and red are different, it is advantageous if the control unit generates signals by means of which the basic color blue is brightened more than the basic color red relative to the relatively light colors.

An application of the arrangement proves to be expedient in particular when alphanumeric characters Characters and / or linear graphic characters are provided.

The use of the arrangement is not only advantageous if videotex pages are displayed that contain only characters or that are mixed images of characters and graphic patterns, but the use also proves to be expedient when the relative lightening of the relatively dark colors when characters are faded into a TV picture takes place.

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A particularly advantageous display of the characters on the screen is achieved when the relative brightening the relatively dark colors is only done with a dark background color of the characters.

In the following, advantageous embodiments of the arrangement according to the invention with reference to drawings described in more detail. Show it:

Figure 1 shows an excerpt from a videotex page,

Figure 2 shows a first embodiment of the arrangement,

Figure 3 shows a second embodiment of the arrangement,

Figure 4 shows a third embodiment of the arrangement. ·

In the excerpt from a videotex page shown in FIG. 1, characters AZ and GZ and a graphic one Pattern GM shown. The characters are alphanumeric characters AZ and a graphic one made up of fine lines Sign GZ shown. The characters AZ and GZ and the graphic pattern GM are arranged in character fields ZF, the limits of which are only shown for reasons of clarity, but not on the screen are visible. Each character field ZF is displayed in an invisible grid of 8x12 pixels BP divided. The characters AZ shown on the screen. The graphic characters GZ can be displayed in the same grid as the alphanumeric characters AZ. They can also extend over several drawing fields ZF. The characters AZ and GZ can be in the three basic colors red, green, blue, the mixed colors yellow, cyan and magenta and in the colors can be displayed in black and white. However, the color cannot be changed within a character field ZF will. The basic colors, the mixed colors and the colors black and white can also be used as the background will.

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When displaying the graphic pattern GM, the drawing fields ZF are divided into 2x3 graphic elements GE. The graphic patterns GM are then made up of character fields ZF shown with different combinations of the graphic elements GE. The graphic elements GE and the background color can also assume the basic colors, the mixed colors and the colors black and white.

If the characters AZ and GZ are displayed on the screen occurs in relatively dark colors such as red or blue, especially in the case of a dark one Background the danger that the characters AZ, GZ are not easy to read. This is particularly the case if, as shown in Figure 1, a graphic pattern GM for example with a relatively light color, such as white, yellow or cyan comes very close to the characters AZ or GZ in blue or red color.

It was also found that with a pure Dar-20> position of characters these are difficult to read if a part of the videotex page with characters with relatively light color is described and a further offset part is described in a relatively dark color is.

In the first embodiment of the arrangement shown in FIG. 2, there is an image control unit BST and a display unit AE provided with the screen, a control unit SE. The picture control unit BST is designed in a known manner. It contains switching units via which either of color signals coming from a television receiver or color signals coming from a videotex decoder to the display unit AE are switched through. Such switching units are generally known and, for example, in the magazine "Wireless World" May 1976, pages 64-68.

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The color signals R, G and B assigned to the primary colors red, green and blue are transmitted via delay elements V. the display unit AE supplied. In addition, the color signals R, G, B are fed to the control unit SE. at For the display of television images on the display unit AE, the color signals are analog signals, their instantaneous values are the colors to be displayed and their brightness When displaying the characters and the graphic patterns, the color signals are binary signals that take on the binary values 0 or 1. In the representation of the color red, for example, only the color signal R has the binary value 1. In a corresponding manner in the representation of the color blue or green, only the color signal B or G has the binary value 1. The color becomes black shown that all color signals have the binary value 0 and when the color is shown all have color signals the binary value 1. The mixed colors yellow, cyan and magenta are represented by the color signals R and G, G and B or R and B have the binary value 1.

When the videotex decoder determines that a videotex page should be displayed, the corresponding Color signals R, G and B supplied to the display unit AE.

When displaying the graphic pattern GM and when displaying the background colors, the color signals are fed to the display unit AE in a known manner. When displaying alphanumeric characters AZ or graphic characters GZ, the image control unit BST generates corresponding signals SAZ or SGZ. When one of these signals occurs, an OR gate G1 in the control unit SE outputs a signal S1 to two AND gates U1 and U2. If the characters are to be displayed in blue ¹ , the color signal B has the binary value 1, while the color signals R and G have the binary values 0. In this case there

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the AND element U1 sends a signal S2 via a switching stage SS1 and an analog OR element G2 as a signal S3 to the display unit AE off. Using this signal S3 serving as a luminance signal, the blue characters shown brightened relative to the relatively light colors, such as white, yellow or cyan. The brightening can be done in a known manner in that in the display unit AE gsringe portions of the primary colors red and green generated by corresponding additional color signals will. It is also possible to send the signal S3 to the grid of a picture tube designed as a cathode ray tube feed to increase the brightness. In the same way as with the representation of the characters in blue Color, a signal 34 is generated by means of the AND element U2, which, when the characters are displayed in red, lightens them up. Using the switching stages SS1 and SS2, the amplitude of the signals S2 or the signals S4 and thus the signals S3 can be changed so that the Basic colors red and blue can be brightened to different degrees. It is particularly advantageous here when the blue color is lightened more than the red color. The delay elements V are to compensate for additional running times provided by the AND gates U1 and U2, by the switching stages SS1 and SS2 and the OR gate G2 arise, so that the signals S3 occur simultaneously with the corresponding color signals.

With the help of the control unit SE is achieved in a simple manner that when displaying characters in the relatively The colors red and blue are brightened relative to the relatively light colors.

The relative lightening of the relatively dark colors can also take place in that the display unit AE is designed for a higher frame rate and that

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the characters AZ and GZ shown with relatively light colors with a lower frame rate are called the characters AZ and GZ with relatively dark colors. In this case, the signal S3 a higher frame rate is set so that the relatively dark colors then appear lighter.

If the screen is a screen formed from a large number of luminous dots, for example a flat one Screen, is provided, the relative brightening of the relatively dark colors can be done in that the relatively bright colors are displayed with a smaller number of luminous points, while caused by the signal S3 that in the display of the characters in the relatively dark colors accordingly more light points are used.

In the arrangement shown in Figure 3, the relative lightening of the relatively dark colors is thereby achieved that the overall brightness is increased in the display of videotex pages and that in the Representation of graphic patterns GM

or when displaying background colors, the relatively light ones Colors can be selectively darkened. The videotex decoder in the image control unit BST also provides color signals R, G and B again from the signals SAZ and SGZ. When displaying the graphic pattern GM or when displaying of the background, the signals SAZ and SGZ each have the binary value 0, so that three AND gates U3 to U5 to be released. If the graphic pattern GM or the background is shown in the colors white, yellow or cyan is to be, the AND gates U3, U4 and U5 emit a signal S5, S6 and S7, which is via a switching stage SS3, SS4 or SS5 and an analog OR gate G3 is supplied as a signal S8 to the display unit AE and

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darkens these colors so that the comparatively dark colors are also in this way relative to the comparatively light colors appear brightened. The delay elements V are in turn provided to the delay times compensate by the AND elements U3 to U5, the switching stages SS3 to SS5 and the OR element G3, With the switching stages SS3 to SS5, the degree of darkening can in turn be set individually for each color will. The signal S8 is expediently fed to the grid of the cathode ray tube in order to increase the brightness of the corresponding colors to diminish.

If the representation on the display unit with a If the frame rate is increased, the signal S8 can be used to represent the relatively light colors to reduce the frame rate, so that here too the relatively dark colors are brightened appear. When displaying a large number of luminous dots on a flat screen, that can Signal S8 can be used to determine the number of activated luminous dots in the display of the relative to diminish bright colors.

Another way to selectively darken the proportions light colors is that using the signal S8 the corresponding brightness signal chopped up, i.e. periodically interrupted for a short time. This can be done, for example, by means of an AND link take place with a clock signal emitted by an oscillator.

In the block diagram shown in Figure 4 is the Control unit SE Part of the image control unit BST. The videotex decoder only has an image memory BSP represented in which the characters to be represented and graphical Data words assigned to patterns are stored.

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These data words contain, for example, 16 binary characters, 8 of which are alphanumeric characters to be displayed Characters AZ or the graphic elements GE are assigned and of which a further 8 binary characters represent control characters, which identify the color or the type of representation or which indicate that they are data words acts that are assigned to the alphanumeric characters AZ or the graphic elements GE. For the representation of the colors, first code words consisting of 3 binary characters are provided corresponding to the color signals R, G and B.

The control unit SE contains an image repetition memory BWS which, for example, contains the content of a line on the screen caches. With the exception of the first code words assigned to the color signals, all the remaining Binary characters are fed directly to the frame buffer BWS as signals S9. The color signals are over a converter UM1 is fed to the frame buffer 3WS .

More storage spaces are provided for the data words in the frame buffer BWS than in the frame buffer BST. Instead of three binary characters for the first code words, there are four binary characters for the second code words Data words provided so that in addition to the basic colors, their complementary colors and the colors black and white other colors can be saved. Other colors are the colors "lightened blue" and "lightened red" intended. When the videotex decoder emits the signals SAZ or SGZ and the characters in the colors red or blue are to be displayed, the corresponding Combinations of the binary characters associated with these lightened colors are stored. The refresh memory A second converter UM2 is connected downstream of BWS, which converts these four 3-binary characters to three color signals

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R1j maps G1 and B1. These color signals differ differs from the color signals R, G and B in that when the characters are displayed in blue, the Color signals R1 and G1 have predetermined instantaneous values and that when the characters are displayed in red Color, the color signals G1 and B1 also have predetermined instantaneous values in order to, due to the additive mixing of the Colors to lighten the blue or red color.

Another possibility for the design of the image control unit is that the image memory BSP is already expanded in such a way that for the colors 4 binary characters formed second code words are provided. In this case the frame buffer is BWS not required and the converter UM1 is connected upstream of the image memory BSP.

The converter UM2 can also be designed in such a way that it j as shown in Figures 2 and 3, additional Brightness signals generated in accordance with the signals S3 and S8 in order to control the grid of the picture tube, which To change the frame rate or the number of controlled light points of a flat picture tube.

The converter UM1 can also be designed such that he also sends the color signals · = · le R, G and B unchanged to the image repetition memory when displaying characters ESPE passes on. This can be the case, for example, when the characters are displayed on a light background will. For this purpose, the converter UT-H can contain a memory in which the for the respective Character field valid background color is cached and depending on its content the lightening the relatively dark colors can be done. Such a buffer can also be used in the arrangements

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are provided according to Figures 2 or 3, so that the relative brightening of the relatively dark colors only occur if they are displayed on a dark background.

15 claims
4 figures

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Claims (1)

81 P 6728QE Claims Arrangement for displaying characters on a screen of a display unit, by means of which the characters in different colors can be represented and by means of the characters also multicolored graphic patterns and / or multicolored television pictures can be displayed, characterized in that that a control unit (SB) is provided, which in the representation of characters (AZ, GZ) with relatively dark colors (R, B) a lightening of these colors (R, ■ 10 - B) relatively bright relative to the displayable ones Colors causes. 2. Arrangement according to claim 1, characterized, that the control unit (SE) when displaying the characters (AZ, GZ) in the relatively dark colors (R, 3) sends control signals (S3) to the display unit (AS), by means of which these colors (R, B) are brightened he follows, 3. Arrangement according to claim 1 or claim 2, characterized in that that the control signals (S3) the brightness of the displayed characters (AZ, GZ) by adding appropriate Increase the proportions of the basic colors (R, G, 3). 4 "Arrangement according to claim 1,
characterized in that the control unit (SE) increases the overall brightness of the display on the screen when displaying the characters (AZ, GZ) in the relatively dark colors (R, G) and generates signals (S8) by means of which the brightness of the displayed relatively light colors is diminished. -ι- - - * £ - VPA 81 P 6 7 2 8 DE 5. Arrangement according to one of claims 1 to 4, in which the colors to be displayed are binary coded and in the image control unit connected upstream of the display unit an image memory is provided, characterized in that the control unit (SE) contains a converter (UM1), which converts the first code words assigned to the relatively dark colors (R, B) into second code words which assigned to the corresponding lightened colors. 6. Arrangement according to claim 5,
characterized in that the converter (UM1) is connected upstream of the image memory (BSP) in which the second code words can be stored instead of the first code words. 7. Arrangement according to claim 5,
characterized in that the converter (UM1) is arranged between the image memory (BSP) and an image repetition memory (BWS). 8. Arrangement according to one of claims to 7, characterized in that that the display unit (AE) displays the characters (AZ, GZ) with an increased frame rate and that the characters (AZ, GZ) with the relatively dark colors (R, G) are displayed more often than the characters (AZ, GZ) with relatively light colors. 9. Arrangement according to one of claims 1 to 7, characterized in that that the control unit (SE) emits signals (S8) to the display unit (AE) by means of which the brightness signals when displaying the characters (AZ, GZ) in relatively light colors periodically blocked for a short time will . VPA 8ί P 6 7 2 8 QE 10ο arrangement according to one of claims 1 to 9, characterized in that the control unit (SE) generates signals (S3, S8) which when displaying the characters (AZ, GZ) with the proportionally dark colors (R, B) triggers a display with more luminous dots on the display unit (AB) than with the representation of the characters (AZ, GZ) with the relatively light colors. 11 ο arrangement according to one of claims 1 to 10, characterized in that as relatively dark colors (R, B) in particular the basic colors blue (B) and red (R) are provided and that in particular as relatively light colors the colors white, yellow and cyan are provided. 12 = arrangement according to one of claims 1 to 11, characterized in that that the control unit (SE) signals (S3, S8, R1, G1, 31) by means of which the basic color blue (B) is brightened more strongly relative to the relatively light colors becomes red (R) as the primary color. 13ο arrangement according to one of claims 1 to 12, characterized in that alphanumeric characters (AZ) are used as characters (AZ, GZ) and / or linear graphic characters (GZ) are provided » 14. Arrangement according to one of claims 1 to 13, characterized in that the relative brightening of the relatively dark colors (R, B) when characters (AZ, GZ) are faded in takes place in a television picture. ■ Ψ-
--4β- VPA 81 P 6 7 2 8 Qg 15. Arrangement according to one of claims 1 to 14, characterized in that that the relative lightening of the relatively dark colors (R, B) only with a dark background color of the Characters (AZ, GZ). BATH ORIGINAL