JP3134975B2 - Brightness synthesis circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminance synthesizing circuit for adjusting luminance when displaying waveforms input from a plurality of channels.

[0002]

2. Description of the Related Art Conventionally, when displaying a plurality of waveforms while displaying a gradation of luminance, video signals output from respective waveform memories are simply compared with each other. Among the video signals to be displayed, the one with the highest luminance is displayed as the luminance of the same pixel (display dot) on the screen.

[0003]

For this reason, for example, as shown in FIG. 4, in the portion where the waveforms overlap, the state of only the waveform having the highest luminance among the waveforms is displayed on the screen. At the same time, there is a problem that the state of the waveform is not known for the other portions that overlap. It is an object of the present invention to solve such a problem and to realize a luminance synthesizing circuit capable of displaying that waveforms overlap with a simple configuration.

[0004]

According to the present invention, a plurality of waveform memories for storing display data based on a plurality of input waveforms, and video signals output from the plurality of waveform memories represent the luminance of each waveform. A plurality of brightness setting registers for superimposing data, a maximum brightness detection circuit for detecting a maximum brightness among outputs from the plurality of brightness setting registers, and a video signal output from the waveform memory. An overlapping number counting means for calculating how many outputs from the waveform memories are simultaneously displayed on the screen, an upper limiter for determining an upper limit of the output from the overlapping number counting means, and an upper limiter. Final addition means for adding the output of the maximum luminance detector and the output of
A digital-to-analog converter for digital-to-analog conversion of the output from the final addition means.

[0005]

[Function] To calculate how many waveforms are overlapped and displayed on the same pixel, and add the data to the maximum luminance to obtain the luminance at the pixel (display dot). Can be displayed.

[0006]

FIG. 1 is a block diagram of an embodiment of the present invention.
In the figure, reference numerals 11 to 1n denote waveform memories which store display data of waveforms of respective channels. Reference numerals 21 to 2n denote luminance setting registers, which are means for superimposing luminance gradation data on each waveform data. Specifically, as shown in FIG. 2, a register 211 for holding a signal from a CPU (a so-called microprocessor), and each waveform memory 11 to 1n for each bit of the output of the register 211.
And ANDs 2121 to 215 for outputting a logical product with the video signal output from the FB. For example, if the display is turned on (displayed) when the video signal is at the H level, the content stored in the register 211 is output as it is.

Reference numeral 30 denotes a maximum luminance detecting means for comparing data output from the luminance setting registers 21 to 2n and detecting the maximum luminance among them. The specific configuration is
The output of the luminance setting registers 21 and 22 and the output of the luminance setting registers 23 and 24 are compared by a combination of a digital comparator and a selection output means, and a large value is output. Out of the data output from the brightness setting registers 21 to 2n.

Reference numeral 40 denotes an overlap number counting means for comparing the outputs of the waveform memories 11 to 1n and counting how many overlapping waveforms are displayed on the same pixel. Specifically, of the outputs of the waveform memories 11 to 1n, H
Count how many levels you have. By adding the outputs of the waveform memories 11 and 12 to the outputs of the waveform memories 13 and 14, respectively, the number of H-level outputs is finally detected. Reference numeral 50 denotes an upper limiter which determines the upper limit of the output of the overlap number counting means 40. Numeral 60 denotes a final adding means for adding the digital output of the maximum luminance detecting means 30 and the digital output of the overlapping number counting means 40. Reference numeral 70 denotes a D / A converter,
The output of 0 is converted to an analog signal.

The operation in such a configuration will be described. First, it is assumed that the operation of the present invention is updated as a whole every time data for display dots is output. In other words, the operation is performed for each display dot clock pulse.
For example, it is assumed that at the timing of a certain display dot, only the outputs of the waveform memories 11 and 12 are at the H level. At this time, the contents of the luminance setting registers 21 and 22 are compared, and the larger value is the digital output of the maximum luminance detecting means 30.

On the other hand, at this time, since the outputs of the waveform memories 11 and 12 are at the H level, the output of the overlap number counting means 40 is [10] (binary number) ("2" in decimal number). The upper limiter 50 sets an upper limit because if the remaining displays overlap, the display in that portion becomes too bright. For example, set the upper limit value to [11] (binary number) ("3" in decimal number)
In this case, since a value smaller than the upper limit value [11] is input, the upper limiter 50
Is the output of the overlap number counting means 40 [1
0] is output as it is. If the output of the overlapping number counting means 40 is [100] (binary number) or the like, the output of the upper limiter 50 is the upper limit value [11].

The final addition means 60 adds [10] which is the output of the upper limiter 50 to the digital output of the maximum luminance detection means 30 and outputs the result. The digital value output from the final addition means 60 is converted into an analog voltage value, and becomes a video output such as a CRT. In the case of a CRT or the like, the ON / OFF of the video signal determines whether or not display is performed on the display dot, and the brightness is determined by the voltage value of the video signal. Therefore, as shown in FIG. 3, in the overlapping portion, the output of the overlap number counting means 40 is added as data to the data of the maximum brightness detecting means 30, so that the brightness increases.

Conventionally, the display does not often have a function of determining whether or not the displays overlap each other, and the means considered have been based on complicated arithmetic processing. , And it was considered that a huge cost and a circuit scale were required.

[0013]

As described above in detail, according to the present invention, since each waveform memory output is used, a luminance synthesizing circuit capable of performing luminance display even with overlapping display waveforms with a simple configuration is provided. realizable.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a partial configuration diagram of an embodiment of the present invention.

FIG. 3 is an explanatory diagram of an operation of the present invention.

FIG. 4 is an explanatory diagram of an operation of a conventional example.

[Explanation of symbols]

 11-1n Waveform memory 21-2n Brightness setting register 30 Maximum brightness detecting means 40 Overlapping number counting means 50 Upper limiter 60 Final adding means 70 D / A converter

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01R 13/00-13/42 G09G 5/36 510 G09G 5/36 520 G09G 1/00 G09G 5/10 H04N 5/57

Claims (1)

(57) [Claims] A plurality of waveform memories for storing display data based on a plurality of input waveforms, and a plurality of video signals output from the plurality of waveform memories for superimposing data representing luminance for each waveform on the video signals. A brightness setting register, a maximum brightness detection circuit for detecting the maximum brightness of the outputs from the plurality of brightness setting registers, and a video signal output from the waveform memory, and simultaneously inputting a number of waveform memories. Number counting means for calculating whether or not the output is displayed on the screen; an upper limiter for setting an upper limit of the output from the overlapping number counting means; an output from the upper limiter and the maximum brightness detector And a digital / analog converter for performing digital / analog conversion on the output from the final addition means. A luminance synthesizing circuit characterized in that: