JPH06317609A - Display circuit device - Google Patents

Abstract

PURPOSE:To provide a display circuit device through which variable persistence characteristic can be easily obtained. CONSTITUTION:An analog input signal is XY-converted to decide the address in a buffer frame memory 9, and brightness data are written in the decided address. The contents of the buffer frame memory 9 are transferred to a display frame memory 2. Fixed value is subtracted from the output of the display frame memory 2, and the result of subtraction is rewritten in the same address of the display frame memory 2. The value of the data of the display frame memory 2 thereby becomes slowly smaller. The output of the display frame memory 2 is DA converted and displayed in a raster scanning displayer 4. The brightness of the display of the displayer 4 lowers with the elapse of time, and variable persistence characteristic can therefore be obtained. In addition, the output of a CCD image sensor can be A/D converted and written in the display frame memory 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display circuit device capable of displaying waveforms, characters, figures and the like with variable afterglow characteristics.

[0002]

2. Description of the Related Art In a waveform observing device such as an oscilloscope, when observing a waveform of an electric signal having a long repetitive cycle or a waveform of which the waveform changes from moment to moment, it is possible to prevent flicker on the display. A variable afterglow device is used for observing changes in a waveform having a long repetition period. In such a variable afterglow type waveform observing device, an afterglow fluorescent substance is used as a cathode ray tube, or the observed signal is digitized and then the waveform data is calculated by a computer to obtain an afterglow time. Are in control.

[0003]

However, it is difficult to control the afterglow time in a wide range when a CRT made of a phosphor having a afterglow is used. When the waveform data is processed by a computer to control the afterglow time,
All the elapsed time of the waveform data is stored in the memory, and the elapsed time of each is added, and the value is checked to control the brightness. Therefore, it is necessary to manage the elapsed time of each sampling point, the history of past waveforms, the elapsed time, etc., and the processing is complicated. Furthermore, when controlling the elapsed time, many calculations must be performed in order to count the elapsed time of all data. Therefore, in this type of waveform observation device, in addition to the waveform data memory, a memory for storing the history of past waveforms, a memory such as a link table memory for managing the elapsed time, and the like are required. Due to this, there was a drawback that the data acquisition interval becomes long.

Therefore, an object of the present invention is to provide a display circuit device which can easily obtain a variable afterglow characteristic.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a frame memory having a plurality of addresses for storing image data containing brightness information, and image data containing brightness information in the frame memory. Image data supply means, read control means for repeatedly reading the image data from the frame memory at a predetermined cycle, and subtracting a predetermined value from the image data read from the frame memory until now. A subtraction unit for writing the subtracted image data to the same address as the image data was written, and a display unit for obtaining a display corresponding to the image data read from the frame memory were provided. It relates to a display circuit device. In addition,
As described in claim 2, it is desirable to have means for changing the predetermined value to be subtracted. Further, as described in claim 3, addition means can be added between the frame memory and the display means. Further, as described in claim 4, it is desirable to compare the output of the image data supply means and the output of the subtraction means and supply the larger one to the frame memory. Further, as described in claims 5 and 6, the image data supply means is configured to perform analog-to-digital conversion of the luminance signal, or a configuration to perform analog-to-digital conversion of the output of a solid-state image sensor such as a CCD image sensor. Can be Further, as described in claim 7, when the input data is larger than the predetermined value, it can be replaced with the replacement data.

[0006]

In the invention of each claim, the data obtained by subtracting the predetermined value from the data read from the frame memory is written again in the frame memory. Therefore,
Data whose level gradually decreases can be obtained by periodically repeating the reading from the frame memory. The brightness of the display corresponding to the data whose level is gradually decreased decreases with the passage of time, and the variable afterglow characteristic is obtained. If the display is made to have the variable afterglow characteristic, it is possible to know the elapsed time by the magnitude of the brightness. As described above, according to the present invention, the variable afterglow characteristic can be obtained by a simple configuration in which a predetermined value is subtracted from the output of the frame memory and the result is written again in the frame memory. According to claim 2, the variable afterglow characteristic can be easily changed. According to claim 3, the variable afterglow characteristic can be changed. Further, even when the level of the output data of the frame memory becomes lower than the minimum level that can be displayed by the display means, it becomes a displayable level when the predetermined value is added by the addition means. Therefore, the past display can be displayed again. According to the fourth aspect, when high level new data is supplied, the new data is written into the frame memory instead of the subtraction force. Therefore, it is possible to store both old and new images in the frame memory and display them. According to the fifth aspect, the waveform can be displayed with a variable afterglow characteristic. According to claim 6, CCD
A display having afterglow characteristics of an image based on a solid-state image sensor (image sensor) such as is possible. According to claim 7,
Since the high-brightness portion is limited, it is possible to make the display of the other portions easier to see.

[0007]

First Embodiment Next, a display circuit device, that is, a digital storage oscilloscope of the first embodiment will be described with reference to FIGS. This display circuit device includes observed image data, that is, an observed waveform data supply circuit 1, a display frame memory 2, a DAC (digital / analog converter) 3, and a raster such as a CRT or a liquid crystal display device as main components. And a scanning type display 4.

The observed waveform data supply circuit 1 includes an observed analog waveform signal input terminal 5, an ADC (analog / digital converter) 6, a high speed memory 7, and an XY conversion circuit 8.
And a buffer frame memory 9, an A / D clock signal input terminal 10 and a control circuit 11. ADC 6 is an analog input signal of the input terminal 5 (observed waveform input signal)
Is converted into a digital signal based on the clock signal from the A / D clock signal input terminal 10. The output of the ADC 6 is input to the XY conversion circuit 8 via the high speed memory 7. The high-speed memory 7 has a function as a buffer between the ADC 6 and the XY conversion circuit 8, and sends data to the XY conversion circuit 8 under the control of the control circuit 11. The XY conversion circuit 8 is the control circuit 1
Based on the control of 1, the XY address of the buffer frame memory 9 is determined, and the brightness data is written therein. The buffer frame memory 9 has the same structure as the display frame memory 2. That is, the buffer frame memory 9 and the display frame memory 2 are the same as those of the display unit 4 of the raster scanning system.
It has an address corresponding to a dimension (XY) display screen. In other words, each frame memory 9 and 2 has an address corresponding to XY coordinates. Since the data one-dimensionally supplied from the ADC 6 cannot be written in the addresses of the two-dimensional array of the buffer frame memory 9 as it is, the XY conversion circuit 8 converts the amplitude data obtained from the ADC 6 into XY address data. 2 and 3 show an XY conversion circuit 8
The analog input and the waveform writing on the buffer frame memory 9 are shown. The address signal of the buffer frame memory 9 is formed based on the input data whose amplitude changes with time shown in FIG. That is, the time axis of FIG. 2 is converted into the column addresses X1 to X5 of FIG.
The amplitude of FIG. 2 is converted into the row addresses Y1 to Y5 of FIG. Since this type of XY conversion technique is well known, further detailed description will be omitted. In this embodiment, predetermined luminance data is written in the address of the buffer frame memory 9 corresponding to the waveform of FIG. Therefore, the XY conversion circuit 8 can also be called a data writing circuit. The image data including the brightness information stored in the buffer frame memory 9 is read out based on the clock signal of the clock generator 12. That is, the data of the XY addresses illustrated in FIG. 3 are sequentially read. This read addressing corresponds to a raster scan on the display 4.

The output data of the buffer frame memory 9 is written in the display frame memory 2 via the contact a of the changeover switch 13. The changeover switch 13 is shown as a mechanical switch but can be an electronic switch. Since the display frame memory 2 is configured similarly to the buffer frame memory 9 as described above, it is possible to obtain the same data writing state as the buffer frame memory 9. The writing and reading of data in the display frame memory 2 are performed based on the clock of the clock generator 12.

In this embodiment, not only the output data of the buffer frame memory 9 but also the output data of the subtractor 14 is written in the display frame memory 2. The subtractor 14 is connected to the output line 15 of the display frame memory 2 and subtracts a predetermined value from the output data (luminance data) of the display frame memory 2. A subtraction data setting circuit 16 is connected to the subtractor 14, and a predetermined value to be subtracted is given from the subtraction data setting circuit 16. Now, the value of the output data of the display frame memory 2 is B,
Assuming that the predetermined value given from the subtraction data setting circuit 16 is C, the output data of BC = D is obtained from the subtractor 14. This pulling force data D is the contact b of the changeover switch 13.
Is written in the display frame memory 2 via. The writing of the pulling force data D to the display frame memory 2 is performed at the address where the data B used for the calculation of the pulling force data D is read. For example, when the output data B is read from the coordinate address indicated by X2 Y2 in the display frame memory 2, the subtraction force data D is written in the X2 Y2 address. As a result, the display frame memory 2
Data having a lower brightness than before is written in. If the contact b of the changeover switch 13 is continuously turned on, the next reading of the display frame memory 2
The subtracted data D is read from the display frame memory 2, the predetermined value C is again subtracted from this data, and data of a lower brightness level is written in the display frame memory 2. The raster scanning display 4 is connected to the output line 15 of the display frame memory 2 via a DAC (digital / analog converter) 3. Therefore, a display corresponding to the data arrangement and size of the display frame memory 2 can be obtained on the display surface of the display. That is, if the arrangement of the waveform data in the display frame memory 2 is as shown in FIG. 3, the same waveform as that shown in FIG. 3 is displayed on the display surface of the display unit 4. Also,
Since the data in the display frame memory 2 is brightness data, a waveform having a brightness corresponding to the size of the brightness data is displayed on the display unit 4. The display brightness on the display 4 decreases as time passes, as indicated by the characteristic line a in FIG. That is, when the luminance L3 is obtained based on the first output of the display frame memory 2,
The subtraction operation by the subtracter 14 with the read time of all the addresses as the cycle causes the luminance of the constant value K to decrease in sequence.
The brightness changes like L2, L1 and L0. Thus, the value of the data C supplied from the subtraction data setting circuit 16 to the subtractor 14 determines the time during which the brightness of the waveform displayed on the display 4 decreases. The afterglow characteristic can be changed by changing the value of C.
When the value of the data C is large, the luminance data decreases quickly, so that the time for the luminance to decrease as shown by the characteristic line a shown by the solid line in FIG. 4 becomes short. When the value of data C is reduced,
Since the value subtracted from the brightness data is small, it takes a long time for the brightness to decrease as indicated by the characteristic lines b and c shown by the chain line in FIG. Further, when the value of the data C is set to 0, the luminance data once written in the frame memory 2 does not decrease, and the same luminance data can be obtained forever. As a result, the characteristic line of FIG. An infinite afterglow display is obtained as shown in d.

The magnitude comparator 17 is provided to control the changeover switch 13. One input terminal of the size comparator 17 is connected to the buffer frame memory 9, and the other input terminal is connected to the subtractor 14. Therefore,
Output data A of buffer frame memory 9 and subtractor 14
Is compared with the output data D of No. 1 by the comparator 17, the contact a of the changeover switch 13 is turned on when the data A is equal to or more than the data D, and the contact b of the changeover switch 13 is turned on when the data A is smaller than the data B. become. As a result, when the output data A of the buffer frame memory 9 larger than the pulling force data D is generated at any address of the display frame memory 2, this new data A is written at the same address. Generally, high-luminance data is not written in all the addresses of the display frame memory 2, but the luminance data is written in only some of the addresses as shown in FIG. Since it is in the zero state, when waveform data of a different pattern is generated from the buffer frame memory 9, this new waveform data is written in the display frame memory 2. Since the number of subtraction processes for the new waveform and the number of subtraction processes for the old waveform are inevitably different, if the initial brightness of both waveforms is the same, the new waveform is displayed brightly and the old waveform is displayed. Appears darker than the new waveform, and both can be easily distinguished on the display surface.

The magnitude comparator 18 connected to the output line 15 of the display frame memory 2 compares the comparison data E of the comparison data generator 19 with the output data B, and the switch 20
Is sent to the subtraction data setting circuit 16 via. The size comparator 18 is provided to obtain the display brightness as shown in FIG. 5 by turning on the switch 20.
The comparison data E of the comparison data generation circuit 19 is the brightness L of FIG.
It is set to correspond to 2. When the output data B of the display frame memory 2 is larger than the brightness L2 of FIG. 5, the output of the comparator 18 is at a low level, for example, and the subtraction data setting circuit 16 outputs the data C indicating the brightness K1. As a result, the output data B of the display frame memory 2
Gradually decreases, and the display brightness of the display 4 decreases from L4 to L3 and L2 in FIG. When the brightness decreases to L2, the output of the magnitude comparator 18 is switched to a high level, and the size of the subtraction data in the subtraction data setting circuit 16 is switched.
For example, a small data C corresponding to the brightness K2 in FIG. As a result, the decrease rate of the size of the data in the display frame memory 2 becomes slow, and the decrease in the display brightness of the display 4 becomes slow.

When there is no rewriting from the buffer frame memory 9 during the variable afterglow operation, the display on the display 4 disappears after a certain afterglow display. Since the display frame memory 2 can perform the freeze operation, if the afterglow operation due to the subtraction operation is prohibited and the freeze operation is performed, the same waveform data can be repeatedly transmitted, and the infinite afterglow is possible. The display state is changed.

[0014]

[Second Embodiment] A display circuit device according to a second embodiment shown in FIG. 6 will be described below. However, in FIG. 6 and later-described FIGS. 7 and 8, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. The circuit of FIG. 6 is the same as the circuit of FIG.
Adder 21, first addition data generation circuit 22, second addition device 23, second addition data generation circuit 24, comparator 2
5, a comparison data generation circuit 26, and a changeover switch 27 are added. The inside of the data supply circuit 1 is the same as in FIG.

The first adder 21 is connected to the display output line 15, and this output line 28 is connected to the contact a of the switch 27.
And connected to the display 4 via the DAC 3 and
The second adder 23, the contact b of the switch 27, and the DAC 3 are connected via the DAC 3. The first addition data generation circuit 22 gives addition data to the first adder 21.
The second addition data generation circuit 24 gives the addition data to the second adder 23. The comparator 25 is provided to control the second addition data generation circuit 24, and the adder 21
The data on the output line 28 and the comparison data of the comparison data generation circuit 26 are compared in magnitude.

When the circuit of FIG. 6 is operated in the same manner as the circuit of FIG. 1, the output of the first addition data generation circuit 22 is set to zero and the contact a of the switch 27 is turned on. When the contact a of the switch 27 is turned on and the variable afterglow display is performed by the same operation as in FIG. 1, old data having a level lower than the minimum display level of the display 4 remains in the display frame memory. If you want to display on the display 4, first
The addition data generation circuit 22 generates the addition data for raising the old data to the display minimum level or higher. As a result, this addition data is added to the output data of the display frame memory 2, sent to the DAC 3, and displayed on the display unit 4. When the old waveform data and the new waveform data are overwritten in the display frame memory 2, a certain addition data is added to each of them, so that the old waveform and the new waveform can be distinguished by the difference in display brightness. it can.

When the second addition data generation circuit 24 is controlled by the comparator 25, an infinite afterglow display is obtained. That is, when the variable afterglow control is performed by the subtraction operation and the level of the output data of the display frame memory 2 becomes lower than the value of the comparison data of the comparison data generation circuit 26, the comparator 25
And the second addition data generation circuit 24 generates the second addition data. When this second addition data is added to the output data of the display frame memory 2 by the second adder 23, the input of the DAC 3 becomes large and the display 4
The display brightness at increases. This gives an apparently infinite afterglow display. When the level of the data in the display frame memory 2 becomes zero by the subtraction operation, the display waveform on the display 4 disappears regardless of the addition operation.

When the added values of the first and second adders 21 and 23 are raised to the saturated display level of the display 4, a display having substantially the same brightness is obtained during the period when the display frame memory 2 has the waveform data, and the display is infinite. Afterglow is displayed.

[0019]

[Third Embodiment] FIG. 7 shows a part of a display circuit device obtained by modifying the data supply circuit 1 of FIG. The data supply circuit 1a of this embodiment comprises a two-dimensional image sensor 30 using a CCD and an ADC 31. The pixels of the CCD two-dimensional image sensor 30 are arranged in a matrix form (XY coordinate form) and therefore correspond to the address arrangement of the display frame memory 2 of FIG. Therefore, when an optical input is given to the image sensor 30, a writing state substantially the same as the writing states of the buffer frame memory 9 and the display frame memory 2 of FIG. 1 can be obtained. As a result, data can be written in the display frame memory 2 without providing the XY conversion circuit 8 and the buffer frame memory 9 shown in FIG. 1 in the data supply circuit 1a. That is, since the output of the image sensor 30 includes the brightness information, the brightness data is obtained by passing through the ADC 31, and this is written in the display frame memory 2. The writing of data to the display frame memory 2 is executed based on the same clock signal of the clock generator 12 as the ADC 31. The data supply circuit 1 of FIG. 6 can be replaced with the data supply circuit 1a including the CCD image sensor 30 of FIG.

Even if the data supply circuit 1 shown in FIGS. 1 and 6 is replaced with the data supply circuit 1a shown in FIG.
Since it has the same configuration, the same operational effect can be obtained.

[0021]

[Fourth Embodiment] FIG. 8 shows a data supply circuit 1b obtained by modifying the data supply circuit 1 of FIG. Except for the data supply circuit 1b, it is the same as FIG. The data supply circuit 1b of this embodiment is similar to that shown in FIG.
It is composed of a two-dimensional image sensor 30 and an ADC 31,
Further, the replacement data generator 32, the switch 33, and the comparator 3
4 and a comparison data generation circuit 35. The replacement data generator 32 generates relatively low level luminance data.
The contact a of the switch 33 is connected to the ADC 31, and the contact b
Are connected to the replacement data generator 32. Therefore, one of the output of the ADC 31 and the output of the replacement data generator 32 is sent to the output line 36 of the switch 33. The comparator 34 is for controlling the switch 33, and outputs the output data of the ADC 31 and the comparison data generation circuit 3
The comparison data of No. 5 is compared, and when the ADC output data becomes larger than the comparison data, the contact b of the switch 33 is turned on.

9 to 11 are waveform charts for explaining the operation of FIG. 8 in an analog manner. When the brightness data as shown in FIG. 9 is output from the ADC 31 and becomes larger than the value of the comparison data of the comparison data generation circuit 35 in the period of t1 to t2, the output of the comparator 34 becomes high level in this period and the switch is turned on. The contact b of 33 is turned on. This allows
The output of the replacement data generator 32 is sent to the output line 36 instead of the output of the ADC 31. It is possible to generate various replacement data from the replacement data generator 32. For example, when the replacement data and the comparison data are matched, the luminance data obtained by slicing FIG. 9 as shown in FIG. 10 can be sent out. it can. Further, by making the replacement data much lower than the comparison data, the brightness data as shown in FIG. 11 can be sent out.

With the configuration shown in FIG. 8, it is possible to suppress high-luminance display and emphasize and display the low-luminance portion. Note that the configuration is the same as that of FIG. 1 except for the data supply circuit 1b,
It is possible to obtain the same effect as that of FIG. In addition, FIG.
The data supply circuit 1 may be replaced by the data supply circuit 1b shown in FIG. 8 and the same operational effect as that shown in FIG. 6 can be obtained.

[0024]

MODIFICATION The present invention is not limited to the above-mentioned embodiments, and the following modifications are possible. (1) A solid-state image sensor other than CCD can be used as the image sensor 30. Further, by using a one-dimensional image sensor, it is possible to generate a relative scanning motion between the subject and the image sensor to sequentially generate data corresponding to the address of the display frame memory 2. (2) It is possible to provide a plurality of units corresponding to the comparator 34 of FIG. 8, compare with comparison data of different levels, respectively, and switch and send a plurality of replacement data. (3) By subtracting the data output from the data supply circuit so that the negative direction is on the bright side, the subtractor 14 can be configured using a simple adder. On the contrary, in the case of the second embodiment shown in FIG. 6, the adder can be configured by using a subtractor. Further, even when the negative direction is made brighter in the second embodiment of FIG. 6, the polarity of the data is inverted before the first adder 21 so that the positive direction becomes brighter. The adder of 1 and the second adder can be configured without using the subtractor.

[Brief description of drawings]

FIG. 1 is a block diagram showing a display circuit device according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram showing the input signal of FIG.

3 is a diagram showing in principle the writing of data in the frame memory of FIG.

FIG. 4 is a diagram showing a luminance change in the display of FIG.

FIG. 5 is a diagram showing a modification of luminance change in the display of FIG.

FIG. 6 is a block diagram showing a display circuit device of a second embodiment.

FIG. 7 is a block diagram showing a part of a display circuit device according to a third embodiment.

FIG. 8 is a block diagram showing a part of a display circuit device according to a fourth embodiment.

9 is a diagram showing an analog input of the comparator of FIG. 8. FIG.

10 is a diagram showing an analog signal of the output line of FIG.

FIG. 11 is a diagram showing in analog form the modification of the signal on the output line of FIG.

[Explanation of symbols]

 1 data supply circuit 2 frame memory 4 display 14 subtractor

Claims (7)

[Claims] 1. A frame memory having a plurality of addresses for storing image data including brightness information, image data supply means for supplying image data including brightness information to the frame memory, and the image from the frame memory. Read control means for repeatedly reading data at a predetermined cycle, and subtracting a predetermined value from the image data read from the frame memory, and subtracting to the same address as the address where the image data has been written so far. A display circuit device comprising: subtraction means for writing subsequent image data; and display means for obtaining a display corresponding to the image data read from the frame memory. 2. The display circuit device according to claim 1, wherein the subtraction means has means for changing a predetermined value to be subtracted. 3. The display circuit according to claim 1, further comprising an addition unit between the frame memory and the display unit for adding a predetermined addition value to an output of the frame memory. apparatus. 4. The first image data supplied from the image data supply means and the second image data obtained from the subtraction means.
Comparing means for comparing the magnitude of the first image data with the first image data obtained from the comparing means, and the first output in response to the first output indicating that the first image data is larger than the second image data. Image data is supplied to the frame memory, and the second image data is obtained in response to a second output indicating that the second image data obtained from the comparing means is larger than the first image data. The display circuit device according to claim 1, further comprising a data selector supplied to the frame memory. 5. The data supply means has an analog signal input terminal, an analog-digital converter connected to the input terminal, and a plurality of addresses corresponding to the XY plane, and the XY plane of the analog signal is provided. A frame memory for a buffer formed so as to write luminance data to an address corresponding to a display waveform, and an address to which the luminance data is to be written based on input data corresponding to the analog signal obtained from the analog-digital converter. A display circuit device comprising: a data write circuit that determines and writes the brightness data to the buffer memory. 6. The display circuit according to claim 1, wherein the data supply means includes a solid-state image sensor and an analog-digital converter connected to the solid-state image sensor. apparatus. 7. A comparator for comparing the input data supplied by the data supply means with predetermined comparison data,
7. A means for supplying replacement data in place of the input data during a period when the input data is larger than the predetermined comparison data, characterized in that: Display circuit device.