JPH08331404A - Voltage generating method, voltage generating circuit and monitoring device - Google Patents

Abstract

PURPOSE: To use a little storage capacity for a storage part and to provide an inexpensive voltage generating circuit by reading data, for which curved line approximation is performed to a required voltage waveform, from the storage part, operating linearly approximated data and reproducing the waveform. CONSTITUTION: The waveform data of curved line approximation, with which a parabolic wave voltage to be generated can be approximated by a little waveform data, are stored in a memory part 10 corresponding to a control value for controlling the contour of a display image. The waveform data of curved line approximation read from the memory 10 are inputted to a CPU 11. The output signal of a control value designating part 12 for designating the control value for controlling the contour of the display image is inputted to the CPU 11. The waveform data of linear approximation operated by the CPU 11 corresponding to the fetched waveform data of curved line approximation are inputted to a D/A converter 13. The D/A converter 13 converts the input signal to an analog amount and generates the parabolic wave voltage and afterwards, it is inputted to a monitoring device 14 for displaying the image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage generating method, a voltage generating circuit and a monitor device.

[0002]

2. Description of the Related Art On a monitor of a personal computer or a television receiver, a pincushion distortion in which the horizontal width changes in the vertical direction as shown by the broken line in the display image of the CRT 100 shown in FIG. In order to correct this pincushion distortion
A built-in parabolic wave voltage generation circuit for generating a vertical parabolic wave voltage V _P as shown in FIG.

FIG. 15 is a block diagram of a conventional vertical parabolic wave voltage generating circuit for generating a parabolic wave voltage by a digital signal. The memory 1 stores waveform data that linearly approximates a vertical parabolic wave voltage (hereinafter referred to as a parabolic wave voltage) to be generated. When linearly approximating one parabolic wave voltage, the waveform data for linear approximation requires 512 words. If there are 100 types of parabolic voltage waveforms, waveform data that linearly approximates each parabolic voltage is required. Therefore, the memory 1 is a data table having 512 words in the horizontal direction and 100 rows in the vertical direction as shown in FIG.

Further, the data table stores waveform data of 512 words which is linearly approximated in association with the adjustment value for adjusting the contour of the display image. The waveform data read from the memory 1 is input to the CPU 2. An output signal of the contour adjusting unit 3 that specifies an adjustment value for adjusting the contour of the display image is input to the CPU 2. The linear approximation waveform data read from the memory 1 corresponding to the specified adjustment value is input to the digital / analog converter 4. The digital / analog converter 4 converts the input digital signal into an analog voltage to generate an analog parabolic wave voltage, and the generated parabolic wave voltage is input to the monitor device 5.

Next, the operation of the parabolic wave voltage generating circuit will be described with reference to the flowchart of FIG. 17 showing the control contents of the CPU 2. When the user performs the correction of the contour of the display image, that is, the correction of the pincushion distortion of the display image and specifies the adjustment value, the CPU 2 takes in the designated adjustment value for adjusting the contour of the display image (S1). The adjustment value designated here is set to "2" (S2). The signal of the adjusted value is input to CPU 2 and CP
U 2 outputs the address signal corresponding to the specified adjustment value and outputs the linear approximation waveform data corresponding to the adjustment value “2” of the data table of FIG. 15 from the area of the adjustment value “2” of the data table. Reads and loads 512 words of waveform data (S3).

Then, the CPU 2 inputs the taken-in 512-word waveform data to the digital / analog converter 4 (S4). Then, the digital / analog converter 4 performs digital / analog conversion on the input digital signal of the linearly approximated waveform data to generate an analog parabola wave voltage, which is input to the monitor device 5. Thereby, the pincushion distortion of the display image is corrected.

[0007]

The memory for storing the linear approximation waveform data of the parabolic wave voltage to be generated as described above is (512 words x 100 rows) x 2 bytes.
There is a problem that a storage capacity of (here, 1 word is 2 bytes) is required, and an expensive memory must be used for the parabola wave voltage generation circuit. In view of such a problem, it is an object of the present invention to provide a voltage generation method, a voltage generation circuit, and a monitor device that can use a storage unit having a small storage capacity.

[0008]

According to a first aspect of the present invention, there is provided a method for generating a voltage having a desired waveform by a digital signal, wherein waveform data is stored in a storage section storing waveform data that approximates the voltage to be generated by a curve. Is read out, and the waveform data of a linear approximation of the voltage to be generated is calculated from the read waveform data, and the calculated waveform data is digital-to-analog converted to generate an analog voltage.

A voltage generating circuit according to a second aspect of the present invention is a voltage generating circuit for generating a voltage of a required waveform by a digital signal, a storage section for storing waveform data that approximates a voltage to be generated by a curve, and waveform data from the storage section. Is provided, a calculating means for calculating waveform data for linear approximation based on the read waveform data, and a digital / analog converter for digital / analog converting the calculated linear approximation waveform data.

A monitor device according to a third aspect of the present invention includes the voltage generating circuit according to the second aspect.

[0011]

According to the first aspect of the present invention, the waveform data for approximating the voltage to be generated is stored in the storage unit having a storage capacity of, for example, 5 words × 100 rows × 2 bytes. The linear approximation waveform data of the voltage to be generated is calculated based on the curve approximation waveform data read from the storage unit. When a digital signal of the calculated linear approximation waveform data is converted from digital to analog, an analog voltage is generated. When storing waveform data that linearly approximates the voltage to be generated, the storage capacity of the storage unit is, for example, 512 words × 100 rows × 2 bytes. Thereby, a storage unit having a small storage capacity can be used.

According to the second aspect of the present invention, the storage unit stores the waveform data that approximates the voltage to be generated by the curve. The number of waveform data which approximates the voltage to be generated by the curve approximation is small, the number of waveform data is smaller than the number of the waveform data which approximates the straight line, and the storage unit does not need a large storage capacity. The curve-approximated waveform data is read from the storage unit, and the linear-approximated waveform data is calculated based on the read waveform data. When the digital signal of the calculated linear approximation waveform data is converted from digital to analog, an analog voltage is generated. Thereby, a storage unit having a small storage capacity can be used.

According to the third aspect of the invention, the linear approximation waveform data is calculated based on the waveform data that approximates the voltage to be generated by the curve. Calculated linear approximation waveform data is digital /
The display state of the display image is controlled by the analog voltage obtained by analog conversion. Thereby, the display state of the display image can be adjusted.

[0014]

The present invention will be described in detail below with reference to the drawings showing the embodiments thereof. FIG. 1 is a block diagram showing the configuration of a voltage generating circuit according to the present invention. In the memory 10, waveform data of a curve approximation capable of approximating the parabolic wave voltage to be generated with a small number of waveform data is shown in FIG.
The data table of the row is stored in association with the adjustment value for adjusting the contour of the display image. The curve approximation waveform data read from the memory 10 is input to the CPU 11.

An output signal of the adjustment value designating section 12 for designating an adjustment value for adjusting the contour of the display image is inputted to the CPU 11. CPU
The linear approximation waveform data calculated from the curve approximation waveform data captured by 11 is a digital / analog converter.
Input to 13. The digital / analog converter 13 converts a digital signal of the input waveform data into an analog signal to generate an analog parabola wave voltage. The parabolic wave voltage output from the digital / analog converter 13 is a monitor device for displaying an image.
Input to 14.

FIG. 3 is a conceptual diagram when the parabolic wave voltage to be generated is linearly approximated, and when linearly approximated, as shown in FIG. 3, basically, one point in the X coordinate direction is used for the Y coordinate. Waveform data for one point in the direction is needed. By the way, since the parabolic wave voltage has many curved portions, when performing the known cubic spline interpolation, for example, five points a, b, c, as shown in the conceptual diagram of the curve approximation shown in FIG.
By using the waveform data of d and e, it is possible to reproduce a curve that approximates the parabolic wave voltage in the same manner.

That is, the curve can be approximated with a small amount of coordinate information by performing the curve approximation. Therefore, as described above, it is sufficient to store the waveform data of 5 words for one parabola wave voltage in the data table of the memory 10. The same waveform data is stored for each of the 100 types of parabola voltage. Therefore, (5
X 100) x 2 bytes (1 word is assumed to be 2 bytes in this example), so memory 10 stores 512 words x 100 rows x when storing linear approximation waveform data.
An inexpensive memory having a very small storage capacity can be used as compared with the case of requiring 2 bytes.

Next, the operation of the voltage generating circuit thus constructed will be described with reference to the flowchart of FIG. 5 showing the control contents of the CPU 11. When the user performs an operation to correct the contour of the display image, that is, the pincushion distortion of the display image, the CPU 11
Takes in the adjustment value specified by the operation (S1). The adjustment value specified here is set to "2" (S2). The signal of the adjustment value “2” is input to the CPU 11, and the CPU 11 inputs the address signal corresponding to the specified adjustment value to the memory 10, and the memory 10
The curve approximation waveform data corresponding to the adjustment value “2” is read out from the data table shown in FIG.

That is, curve-fitting waveform data of 5 words is read from the area of the adjustment value "2" in the data table. Then, the CPU 11 calculates the waveform data of the curve by a known cubic spline curve interpolation method based on the read waveform data (S4). Subsequently, based on the calculated curve waveform data, the linear approximation waveform data of the Y coordinate corresponding to the X coordinate of 512 points is calculated (S5). Subsequently, the calculated linear approximation waveform data is input to the digital / analog converter 13 as in the conventional case (S6). Then, the digital / analog converter 13 converts the input digital signal of the waveform data into an analog voltage and outputs the analog parabola wave voltage. When this parabola wave voltage is input to the monitor device 14, the contour of the display image on the monitor device 14 is adjusted by the parabola wave voltage and the contour display image corresponding to the designated adjustment value “2” is displayed.

Conventionally, since waveform data for linearly approximating the parabolic wave voltage is stored in the memory, it is necessary to use a memory having an extremely large storage capacity. It suffices to store the waveform data of No. 3 in the memory, and an inexpensive memory with extremely small storage capacity can be used. As a result, the cost of the parabolic wave voltage generation circuit can be reduced.

FIG. 6 is a block diagram showing the configuration of another embodiment of the voltage generating circuit according to the present invention. This FIG. 6 is configured to generate a sawtooth voltage that corrects vertical linearity. In the memory 10A, the waveform data for one cycle of the curve approximation that can approximate the sine wave voltage to be generated with a small number of waveform data is stored in a data table of 8 words in the horizontal direction and 100 rows in the vertical direction as shown in FIG. , And is stored in association with an adjustment value for adjusting the vertical linearity of the display image. Memory 10
The sinusoidal curve approximation waveform data read from A is CPU1.
Input to 1.

The output signal of the adjustment value designating section 12 for designating the adjustment value for adjusting the vertical linearity of the display image is inputted to the CPU 11. The sine wave linear approximation waveform data calculated from the curve approximation waveform data read from the memory 10A and fetched by the CPU 11 is input to the digital / analog converter 13A. The memory 10B stores the waveform data for one cycle of the sawtooth wave voltage that should be generated in the same cycle as the sine wave voltage. The waveform data of the sawtooth voltage read by the CPU 11 and read from the memory 10B is input to the digital / analog converter 13B. The digital / analog converter 13A converts the input digital signal of the sine wave waveform data into an analog signal to generate an analog sine wave voltage. The digital / analog converter 13B is adapted to convert the digital signal of the input sawtooth wave waveform data into an analog signal to generate an analog sawtooth wave voltage.

The sine wave voltage output from the digital / analog converter 13A and the sawtooth wave voltage output from the digital / analog converter 13B are input to the waveform synthesizer 16. The waveform synthesizing unit 16 is configured to output a corrected sawtooth wave voltage by synthesizing the input sine wave voltage and the sawtooth wave voltage, and is output from the waveform synthesizing unit 16.
The corrected sawtooth wave voltage is applied to the monitor device 14 that displays an image.
Is input to a vertical circuit (not shown).

FIG. 8 is a block diagram showing the configuration of the waveform synthesizer 16. The output side of the digital / analog converter 13A the negative input terminal of the operational amplifier OA ₁ and gathered the resistor R ₁ - is connected to. Negative input terminal-and output terminal of operational amplifier OA ₁
A parallel circuit of a capacitor C ₁ and a resistor R ₂ is interposed between the OP and OP. The output terminal OP of the operational amplifier OA ₁ is a capacitor C
₂ and a resistor R ₃ are connected in series to connect to the positive input terminal + of the operational amplifier OA ₂ .

On the output side of the digital / analog converter 13B, the resistor R _{4 is connected} to meet the negative input terminal of the operational amplifier OA _3.
Connected to A parallel circuit of a capacitor C ₃ and a resistor R ₅ is provided between the negative input terminal − of the operational amplifier OA ₃ and the output terminal OP, and the negative input terminal − is connected to the positive input terminal + of the operational amplifier OA _1. . The positive input terminal + of the operational amplifier OA ₃ is grounded, and the output terminal OP meets the resistor R ₆ and the operational amplifier OA ₂
Connected to the positive input terminal + of. The negative input terminal − of the operational amplifier OA ₂ is connected to its output terminal OP and is connected to a vertical circuit (not shown) of the monitor device 14.

FIG. 9 is a conceptual diagram when a sine wave voltage to be generated is approximated to a curve. As shown in Fig. 9, the sine wave is positive,
Total of 4 points on each negative side 8 points j, k, l, m, o, p, q,
A curve approximating a sine wave voltage can be reproduced by using the waveform data of r. That is, by approximating the curve, the curve can be approximated with a small amount of coordinate information as in the case of the parabolic wave voltage as described above. Therefore, the data table of the memory 10A only needs to store the waveform data of 8 words for one sine wave voltage. Also in the data table
The same waveform data is stored for each of the 100 types of sine wave voltage.

Therefore, the memory 10A has (8 × 100) × 2
Since it is sufficient to store data of 1 byte (here, 1 word is 2 bytes), the memory 10A stores 512 words x 100 when storing linear approximation waveform data as described above.
Inexpensive memory having a very small storage capacity can be used as compared with the case of requiring 2 rows x 2 bytes.

Next, the operation of the voltage generating circuit thus constructed will be described with reference to the flowchart of FIG. 10 showing the control contents of the CPU. When the user performs an operation to correct the vertical linearity of the display image, the CPU 11 takes in the adjustment value designated by the operation (S11). The adjustment value specified here is set to "2" (S12). The signal of the adjustment value “2” is input to the CPU 11, the CPU 11 inputs the address signal corresponding to the specified adjustment value to the memory 10A, and the adjustment value “2” is input from the data table of the memory 10A shown in FIG. The curve approximation waveform data corresponding to “” is read and loaded (S13). That is, the waveform data of the four-word curve approximation is read from the area of the adjustment value “2” in the data table.

Subsequently, based on the waveform data read by the CPU 11, the waveform data of the curve is calculated by a known cubic spline curve interpolation method (S14). Then, based on the calculated waveform data of the curve, the linear approximation waveform data of the Y coordinate corresponding to the 512 points of the X coordinate is calculated (S15).
Then, the calculated linear approximation waveform data is input to the digital / analog converter 13A as in the conventional case (S16). Then, the CPU 11 inputs the same address signal as the address signal input to the memory 10A to the memory 10B, reads the waveform data of the sawtooth wave from the memory 10B, and loads it (S17). Then, the waveform data of the captured sawtooth wave is input to the digital / analog converter 13B (S18).

Then, the digital / analog converter
The data 13A is the digital of the input sine wave waveform data.
The signal is converted to an analog voltage and the analog voltage shown in Fig. 11 (a) is displayed.
Sine wave voltage V_AIs output. Also digital / analog
Converter 13B converts the input sawtooth waveform data.
The digital signal is converted to an analog voltage and shown in Figure 11 (b).
Analog sawtooth voltage V_BIs output. These electricity
Both pressures are input to the waveform synthesizer 16 and the operational amplifier OA₁,
OA₃After being individually amplified by the operational amplifier OA ₂By
The sine wave voltage and sawtooth wave voltage are combined and shown in Fig. 11 (c).
Sawtooth voltage V corrected by sinusoidal voltage_COccurs
Output. The corrected sawtooth wave voltage V_CIs a sine wave
Voltage V_AWave with large voltage change at the time corresponding to half cycle
It has a shape.

When the sawtooth voltage V _C thus corrected is input to a vertical circuit (not shown) of the monitor device 14, the linearity of the display image on the monitor device 14 is corrected by the corrected sawtooth voltage. Then, when an uncorrected sawtooth wave voltage is input, as shown in FIG. 12 (a), the spacing between the scanning lines L becomes large near the vertical center of the display image on the CRT 100 due to the influence of the stray magnetic field. The linearity deteriorates because the vertical linearity is corrected according to the specified adjustment value “2” as shown in FIG. 12 (b) and the interval between the scanning lines L becomes constant.
An image with good vertical linearity will be displayed.

As in the case of generating the parabolic wave voltage, the waveform data that approximates the sine wave to the curve may be stored in the memory when the sine wave voltage is generated. In this case also, the storage capacity is extremely small. An inexpensive memory can be used, and the cost of the voltage generating circuit that generates the corrected sawtooth wave voltage can be reduced. Further, although the waveform data of the curve approximation used in this embodiment is 5 words or 8 words and the point of the X coordinate is 512, it goes without saying that this is an example.

[0033]

As described in detail above, according to the first invention, the curve approximation waveform data of the voltage to be generated is stored in the storage unit, and the linear approximation waveform is read based on the curve approximation waveform data read from the storage unit. Since the data is calculated to generate the voltage, it is possible to inexpensively generate the voltage by using a storage unit having a small storage capacity.

According to the second aspect of the present invention, since the waveform data of the curve approximation of the voltage to be generated is stored in the storage unit, the amount of the waveform data for the curve approximation of the voltage to be generated is small, and an inexpensive storage unit having a small storage capacity is provided. The present invention has excellent effects such that it can be used and can provide an inexpensive voltage generation circuit.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a voltage generating circuit according to the present invention.

FIG. 2 is a conceptual diagram of a data table of a memory.

FIG. 3 is a conceptual diagram when a parabolic wave voltage is linearly approximated.

FIG. 4 is a conceptual diagram when a parabola voltage is approximated to a curve.

FIG. 5 is a flowchart showing the control contents of the CPU.

FIG. 6 is a block diagram showing the configuration of another embodiment of the voltage generating circuit according to the present invention.

FIG. 7 is a conceptual diagram of a data table of a memory.

FIG. 8 is a block diagram showing a configuration of a waveform synthesizer.

FIG. 9 is a conceptual diagram when a sine wave voltage is approximated to a curve.

FIG. 10 is a flowchart showing the control contents of the CPU.

FIG. 11 is a waveform diagram of a sine wave, a sawtooth wave, and a corrected sawtooth wave.

FIG. 12 is an explanatory diagram of a display state of a display image.

FIG. 13 is an explanatory diagram of pincushion distortion of a display image.

FIG. 14 is a waveform diagram of a vertical parabola voltage.

FIG. 15 is a block diagram of a conventional parabola wave voltage generation circuit.

FIG. 16 is a conceptual diagram of a memory data table.

FIG. 17 is a flowchart showing the control contents of the CPU.

[Explanation of symbols]

 10 Memory 11 CPU 12 Adjustment value specification block 13 Digital / analog converter 16 Waveform synthesis block

Claims (3)

[Claims] 1. In a method of generating a voltage having a required waveform by a digital signal, waveform data is read from a storage unit that stores waveform data that approximates the voltage to be generated by a curve, and a straight line of the voltage to be generated by the read waveform data. A voltage generation method characterized in that approximate waveform data is calculated, and the calculated waveform data is digital-to-analog converted to generate an analog voltage. 2. A voltage generating circuit for generating a voltage of a desired waveform by a digital signal, a storage unit for storing waveform data that approximates a voltage to be generated by a curve, a unit for reading the waveform data from the storage unit, and the read waveform. A voltage generating circuit comprising: a calculating unit for calculating waveform data for linear approximation based on data; and a digital / analog conversion unit for performing digital / analog conversion on the calculated linear approximation waveform data. 3. A monitor device comprising the voltage generating circuit according to claim 2.