DE2606591B2 - Method and apparatus for recording a composite image on the viewing screen of a cathode ray tube - Google Patents

Description

The invention relates to a method for recording a composite image, consisting of a raster image and a figure written from lines and / or dots, on the viewing screen of a cathode ray tube with a control unit / to fade in the figure during the control of the line and / or or image jump of the raster image.

It is known to display letters, numbers and graphic information on a screen both in a raster manner as well as in one, the figure essentially from lines and also from points writing Process to represent the so-called "stroke writing" process. With the raster method, that also with the Television is used and provides so-called halftone images, the image is created by bright or Blanking of the electron beam guided over the screen according to a predetermined scheme. As a result, representations of letters, digits, geome-

! 5 trical figures and the like in general not continuous but broken lines, which leads to a stepped course of the same, especially in the case of oblique lines. This has a very negative effect on the legibility of the display . Representations and letters, numbers and graphic information that are generated with the Sirike writing method do not have this disadvantage.

In this process, the electron beam is guided like a pen. For the representation of The stroke writing process has largely established itself as information of this type. Because of the greater brightness that can be achieved with it, it is also the only feasible method for the Image representations under daylight conditions in so-called "head-up displays" in aircraft.

Furthermore, a method is known in which letters, numbers and / or graphic information in the stroke writing process together with a halftone image generated in the raster process on one Screen can be played back. In one such procedure, for example, registered mail easily readable flight guidance information matte in the flight image recorded by an infrared camera, the letters, numbers and graphic information are displayed during the return of the raster image recorded using the stroke writing method. Since the image return time is very small due to the standard and on the other hand, the symbol generators for the information to be represented in the stroke writing method are not can be made as quickly as desired is the maximum writing line length for the stroke writing method the information presented is severely limited.

The object of the invention is to provide a method for recording in the raster method and in the stroke writing method to create images on a screen in which the writing line length of the Stroke writing recording is many times longer than with the known methods. In addition, that should Process can be implemented with as little effort as possible.

This object is achieved according to the invention on the basis of the method described at the beginning solved that each line of the raster image in at least one first buffer with a

bo specified frequency and with a compared to this frequency is read out and recorded that the significantly higher frequency following line of the raster image in at least one second memory in the same way as the first line is written, read out and recorded and that the figure is in each case in the spaces after Readout end of the first memory up to the readout start of the second memory on the screen

is recorded.

By temporarily saving the raster image lines and subsequent rapid readout of the same can be used to display the stroke writing image The available period can be increased considerably. So if the readout frequency doubles as large as the enrollment frequency is chosen, which has proven to be useful, the total period for stroke writing recording to half the time required for the snap image. At a further increase of the read-out frequency also increases for the stroke writing recording Available time, with the maximum possible period for the stroke-writting recording the components required to implement the method are limited.

According to a further idea of the invention, caused by the components used Limitation of the maximum possible read clock frequency for stroke writing image signals is therefore advantageous can be further reduced by at least two partial buffers for each first and second buffer are used, the picture elements of each raster picture line alternating in at least two partial buffers are read in and the partial buffers are offset in parallel and in time be queried. The readout speed for each partial buffer is relatively low, the readout speed of the buffer in comparison to a normal buffer considerably enlarged.

By writing the picture elements of a raster picture line in two or more intermediate buffers in this way and the parallel and time-shifted interrogation of the partial buffers is the readout speed the readout speed of the intermediate memory is relatively low for each partial buffer however, compared to a normal cache, it is considerably larger.

Another concept of the invention relates to a device for performing the above-described Procedure. The device differs from the known ones in that it has two intermediate storage systems and a control unit that alternates between the one temporary storage system to registered and the other to read out and the switched to registered Intermediate storage system with a write clock signal and the intermediate storage system switched to read out acted upon by a readout clock signal and means that at the end of the readout of the a buffer system to switch the stroke writing image signal to the screen and when Start of reading out the other buffer system, switch off the stroke writing image signal from the screen.

According to one embodiment of the device according to the invention, there is each intermediate storage system from at least one series connection, from an analog-to-digital converter, a shift register and a digital-to-analog converter. However, an embodiment is more advantageous in which each intermediate storage system consists of at least one charged-coupled device. In such an embodiment, on an analog-to-digital conversion or digital-to-analog conversion of the raster image signal can be dispensed with. this leads to a particularly low-component structure of low volume and weight, which is particularly useful for is suitable for the purposes of aviation.

The invention is based on the drawing, which a Block diagram of the essential parts of the device for the invention, explained in more detail.

The device comprises two intermediate storage systems 1 and 2, each of which has two charged-coupled devices 3 and 4 or 5 and 6 contains an input stage 7, an output stage 8 and a control unit 9, which of a write-in clock signal generated by the clock generator 10 and one generated by the clock generator

ίο 11 generated readout clock signal is applied.

To explain the mode of operation, it is assumed that the buffer storage selector switch 12 in the input stage 7 the incoming signals to the buffer 1 and the buffer selector switch 13 in the output stage 8 connects the buffer 2 to the output of the output stage 8 has switched. If a raster image line now arrives at the input stage 7, the image elements become the same alternately written into the two charged-coupled devices 3 and 4 via the switch 14, d. H. the first picture element of the P id line is in the charged-coupicb-ucvicc 3, the second in the charged-coupled device 4, the third inscribed again in the charged-coupled device 3 and so on. The registered mail takes place with a certain predetermined registration frequency.

After the first image line has been written, the buffer memory selection switches 12 and 13 are actuated. The second image line is now activated via switch 15

Μ with the same write clock frequency alternating in the two charged-coupled devices 5 and 6 are registered. At the same time, the first line of images is created from the Intermediate storage system 1 with a read-out clock frequency which is greater than that by a factor of 3 Write clock frequency. read out. After reading out the first image line from the buffer system 1, the third picture line is written into this with the write clock frequency and the second Image line is read out from the buffer system with the readout clock frequency, etc.

Since the pixels when reading the raster image line in the order of one, two, three, etc., appear should consequently accessed in this order, reading at a speed can be done that twice ⁱ o is great as the maximum reading speed of a charged-coupled -devices. In the case of alternating writing in three charged-coupled devices, the readout speed is three times as great as the maximum possible readout speed of a charged-coupled device. when registered in four charged-coupled devices four times as large, etc.

By writing in the individual raster image lines',; two intermediate storage systems and the readout the same with three times the clock frequency is achieved that between the readout end oer one line and the read-out start of the next line when recording the raster image is a record-free one Period of time between two raster lines.

ί> 0 of the two-thirds di: r recording time in the present case one line and thus about two thirds of the recording time of the entire raster image amounts to. This period stands; then available for stroke writing recording.

It should be pointed out that, of course, several lines can also be stored in the buffer at the same time can be written in and then read out.

For this 1 sheet of drawing:

Claims (6)

Patent claims: 1. Method of recording a composite image consisting of a Raster image and a figure written from lines and / or points, one on the screen Cathode ray tube with a control unit for fading in the figure while controlling the Line and / or image return of the raster image, characterized in that in each case; one Line of the raster image in at least one first buffer store (1) with a predetermined one Frequency and with a significantly higher frequency compared to this frequency is read out and recorded that the following line of the raster image in at least a second Memory (2) is written, read and recorded in the same way as the first line and that the figure is in the spaces after the end of the readout of the first memory \ I) to to the Ausicsebeginn of the second memory (2) 2. The method according to claim 1, characterized in that the readout frequency is twice as great is like the enrollment frequency. 3. The method according to claim I or 2, characterized characterized in that each first and second buffer store (i and 2) have at least two partial buffers (3, 4 and 5,6) are used that the picture elements of each raster picture line alternate in at least two partial buffers (3.4; 5.6) are enrolled and that the partial buffer can be queried in parallel and at different times. 4. Device for performing the method according to claim 1 or one of the following, characterized by two intermediate storage systems (1, 2) and a control unit (9), which alternately one Intermediate storage system (1; 2) switches to registered and the other (2; 1) switches to readout and that on Write-switched buffer system (1; 2) with a write-in clock signal and that on Read-out switched Z-buffer system i (2; t) acted upon by a readout clock signal and means that at the end of the readout of the one Intermediate storage system (1; 2) switch through the stroke writing image signal to the screen and at the start of reading the other buffer system (2; 1) the stroke writing image signal from Turn off the screen. 5. Device according to claim 4, characterized in that each intermediate storage system (1, 2) from at least one series connection, from an analog-to-digital converter, a shift register and a digital-to-analog converter. 6. Device according to claim 4, characterized in that each intermediate storage system (1, 2) consists of at least one charged-coupled device (3, 4, 5, 6).