JPH0239808B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to an improvement in a hard copy device for hard copying an image displayed on a CRT screen of a display device. [Technical background of the invention and its problems] As shown in FIG. 1, a conventional device of this type includes a raster scan type CRT display device 1;
A hard copy device 2 for making a hard copy of an image displayed on the screen of a CRT 11 constituting this device 1 is provided. The CRT display device 1 is
A receiving circuit 12 that receives information sent from an external computer, a refresh memory 13 that stores this received information, a character generator 14 that reads the contents of this refresh memory 13 and generates a luminance signal, and this generator 14. It is given as a refresh timing signal to the drive circuit 15 that raster scans the CRT 11 and the refresh memory 13 based on the data selected luminance signal, and is supplied to the character generator 14.
The CRT 11 is provided with a signal generating circuit 16, etc., which is supplied as a timing signal for data selection to the CRT 11, and to the drive circuit 15 as a synchronization signal for scanning the CRT 11. On the other hand, the hard copy device 2 includes a memory 21 that stores a luminance signal given to the CRT 11, and a control circuit 22 that receives a signal at the same timing as the synchronization signal output from the signal generation circuit 16 and gives write and read commands to the memory 21. A copying device 23 for copying the contents read from the memory 21 is also provided. However, the above configuration has the following drawbacks. That is, the luminance signal to be given to the CRT 11 is also written to the memory 21, but since the writing cycle to this memory 21 is usually very fast, 60 ns, for example, the signal line from the character generator 14 to the memory 21 is long and If there is signal noise, waveform distortion, reflected waves, crosstalk, etc., an erroneous luminance signal will be written to the memory 21 due to these influences. Therefore, the copying device 23 has the disadvantage that an image different from the image on the CRT 11 is copied. [Object of the Invention] The present invention has been made in view of the above-mentioned circumstances. Even if the luminance signal to be given to the CRT is slightly distorted, it can be converted into a correct signal and written into the memory, thereby changing the image displayed on the CRT. An object of the present invention is to provide a hard copy device that makes accurate hard copies. [Summary of the Invention] The present invention obtains a plurality of delayed clock signals each having a different delay time from a timing signal used in a display device, and uses these delayed clock signals to individually output a luminance signal to be applied to a CRT. This is a hard copy device that samples the brightness and then makes a logical decision using majority logic to obtain a brightness correction signal. [Embodiment of the Invention] FIG. 2 is a diagram showing an embodiment of the present invention.
Since the CRT display device 1 is the same as that shown in FIG. 1, the explanation of its configuration will be omitted here.
The hard copy device 3 will be explained below. The hard copy device 3 includes a control circuit 31 that receives a signal with the same timing as the synchronization signal output from the signal generation circuit 16 of the CRT display device 1, creates and outputs a clock signal, and a control circuit 31 that generates and outputs a clock signal. A data correction circuit 32 receives a clock signal from the character generator 14, receives a brightness signal from the character generator 14, and performs correction processing, and a data correction circuit 32 receives the brightness signal after correction based on a command signal from the control circuit 31, and processes the brightness signal from the character generator 14. 33 and a memory 34 for sending data to the memory 33. A busy signal is input from the copying device 33 to the control circuit 31 . The data correction circuit 32 includes a clock delay circuit 321, a plurality of D-type flip-flops 322-324, and a brightness correction signal generation circuit 325, as shown in FIG. The clock delay circuit 321 receives the clock signal from the control circuit 31 and outputs three types of delayed clock signals CP1 to CP3, each having a different delay time. Further, the plurality of D-type flip-flops 322 to 3
24 has a function of rising when the clock signals CP1 to CP3 are input while the luminance signal L is being input, and falling when the clock signals CP1 to CP3 disappear. Further, the luminance correction signal generation circuit 325 has a plurality of D
It logically judges the binary signals outputted from the flip-flops 322 to 324 and outputs a brightness correction signal. Next, the operation of the device configured as above will be explained. It is now assumed that the luminance signal L input from the character generator 14 to the data correction circuit 32 is broken or distorted due to, for example, crosstalk, as shown by the dotted line in FIG.
In the figure, A shows a broken waveform, B shows a distorted waveform, and C shows the center of the luminance signal L, respectively. Therefore,
Even if sampling is performed at the center of the luminance signal L, there is a risk of data errors. Therefore, upon receiving the clock signal CP0 outputted from the signal generation circuit 16 via the control circuit 31, the clock delay circuit 321 operates as follows.
A delayed clock signal CP2 having a delay such that a rising edge occurs at the center of the luminance signal L is output. Furthermore, the clock delay circuit 321 creates and outputs a delayed clock signal CP1 that rises earlier than the clock signal CP2, and a delayed clock signal CP3 that rises later than the clock signal CP2. These delayed clock signals
The timing of occurrence of CP1 to CP3 is as shown in FIG. And these delayed clock signals
CP1-CP3 are supplied to the clock terminal CP of each flip-flop 322-324 to which the luminance signal L is input. Therefore, these flip-flops
The flops 322 to 324, that is, the sampling gate circuits sample the luminance signal of the center part and the luminance signals before and after it, respectively, and
Signals D1 to D3 are outputted with the timing shown in the figure. And these signals D1
~D3 are input to the luminance correction signal generation circuit 325, but here, the signals D1~D3 are inputted to the luminance correction signal generation circuit 325, but here, based on majority logic
By logically determining D3, a brightness correction signal L0 as shown in the table below is obtained.

〔Effect of the invention〕

As described in detail above, according to the present invention, a plurality of clock signals each having a different delay time are created from a timing signal used in a CRT display device, and
Since the brightness signal to be supplied to the CRT is taken in and logically judged to obtain a brightness correction signal, a true brightness signal without distortion can be obtained even if the brightness signal is somewhat distorted due to crosstalk or the like. Therefore,
It is possible to provide a hard copy device that can accurately hard copy images displayed on a CRT screen.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of the conventional device, Figures 2 to 4
The figures are diagrams showing one embodiment of a hard copy device according to the present invention, in which FIG. 2 is a general configuration diagram of the device, and FIG. 3 is a configuration diagram showing a specific example of the data correction circuit of FIG. 2. Figure 4 is a diagram showing the operation timing, Figure 5
The figure is a configuration diagram showing another example of the present invention, and FIG.
FIG. 3 is a timing diagram illustrating the operation shown in FIG. 1...CRT display device, 11...
CRT, 16...Signal generation circuit, 3...Hard copy device, 31...Control circuit, 32...Data correction circuit, 33...Copy device, 34...Memory,
321...Clock delay circuit, 322-324...
...Flip-flop, 325...Brightness correction signal generation circuit.

Claims (1)

[Claims] 1. Raster scan type display device
In a hard copy device that hard copies a luminance signal corresponding to display data displayed on a CRT screen, a clock signal generated from a signal for selecting the luminance signal of the display device is received, and the center of the luminance signal and the center of the luminance signal are selected. A clock delay means for generating a plurality of delayed clock signals having different time delays such that they rise before and after the clock, and a plurality of sampling devices for sampling the luminance signal using respective delayed clock signals generated from the clock delay means. The gate circuit includes a gate circuit, and a brightness correction means that logically judges the signals output from these gate circuits using majority logic to remove unnecessary signals occurring in the brightness signal to obtain a brightness signal at the true level. A hard copy device characterized by copying a luminance signal at a level of 1 to a copy device.