JPH0540619Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a DC control voltage correction method suitable for electronic equipment that performs various adjustments using DC control voltage.

<Prior art> For example, various image adjustments such as brightness and contrast in video equipment such as television receivers, etc.
Generally, digital data output from a microcomputer in response to a remote control operation by a viewer (user) is converted into a pulse width modulation (PWM) signal by a D/A conversion circuit, and this pulse width modulation signal is processed by a filter circuit. The DC voltage is converted into a DC voltage, and the IC to be controlled, such as the video adjustment circuit, is controlled by the DC voltage.

By the way, this controlled IC has variations in characteristics, so in order to correct them and perform optimal control, the manufacturer adjusts the DC control voltage using a correction volume etc. at the time of factory shipment. Corrections are being made.

FIG. 2 is a block diagram showing an example of such a conventional correction method. In the figure, 1 is a microcomputer, 2 is a 6-bit open-drain type D/A conversion circuit that outputs digital data from microcomputer 1 as a corresponding pulse width modulation signal, and 3 is for correcting the DC control voltage. 4 is an impedance conversion circuit; 5 is a filter circuit that converts the pulse width modulation signal clamped with a DC voltage adjusted by the correction volume 3 into a DC control voltage; 6 is a DC current from the filter circuit 5; This is a controlled IC such as a video adjustment circuit that is controlled by a control voltage.

Conventionally, in order to correct variations in the characteristics of the controlled IC 6 and enable optimal control, the DC control voltage has been corrected in the following manner at the time of shipment from the manufacturer's factory.

First, set the pulse width modulation output of the D/A conversion circuit 2 to the center value, that is, 32/64 (=2 ⁶ ) in this example, by operating a specific key on the remote control, etc. The DC control voltage applied to the controlled IC 6 is adjusted by the correction volume 3 so that the image becomes a clear image. That is, the DC control voltage is corrected by adjusting the clamp voltage of the pulse width modulation signal using the correction volume 3.

However, with such conventional correction methods,
To make adjustments when the set is almost finished,
It is necessary to be able to adjust it from the outside, and it is necessary to devise a mounting point for the correction volume. Also, since the correction volume 3 is not used by the user, it is installed in a place that is difficult for the user to access. There are some drawbacks, such as difficulty in making adjustments.

<Purpose of the invention> The present invention has been made in view of the above-mentioned points, and an object thereof is to provide a DC control voltage correction method that is easy to adjust.

<Structure of the invention> In order to achieve the above-mentioned purpose, the present invention calculates the appropriate median value of the DC control voltage for a controlled circuit in which various adjustments are made using the DC control voltage.
A device for pre-compensating controlled circuits according to variations in characteristics between products, which includes a control circuit that outputs digital data corresponding to the DC control voltage applied to the controlled equipment, and digital data from this control circuit. converting means to convert the voltage into a DC control voltage and applying it to the controlled circuit, the converting means comprising:
The following includes a D/A conversion circuit that converts digital data output from a control circuit into a pulse width modulation signal, and a filter circuit that converts the pulse width modulation signal of this D/A conversion circuit into a DC control voltage. Adopt the composition. That is, the present invention includes an output means for inputting a specific correction signal for adjusting the DC control voltage to a median value, and outputting correction data corresponding to the correction signal input; Based on the correction data from
variable means for varying the clamp voltage of the pulse width modulation signal output from the D/A conversion circuit of the conversion means; and a variable means corresponding to the clamp voltage after being corrected based on the correction data output from the output means. It has a storage means for storing digital data.

<Examples> Examples of the present invention will be described below with reference to drawings.
Explain in detail. FIG. 1 is a block diagram of one embodiment of the present invention, and parts corresponding to the conventional example of FIG. 2 are given the same reference numerals. This example is a television receiver.

The microcomputer 7 as a control circuit is
As in the past, corresponding digital data is output to the D/A conversion circuit 2 in response to operation signals from the viewer's remote control operation or key operation on the main body. The conversion means 8 that converts this digital data into a DC control voltage includes a 6-bit D/A conversion circuit 2 that converts the digital data from the microcomputer 7 into a pulse width modulation signal, and a 6-bit D/A conversion circuit 2 that converts the digital data from the microcomputer 7 into a pulse width modulation signal. It is equipped with a filter circuit 5 that converts a pulse width modulation signal into a DC control voltage and supplies it to a controlled IC 6 such as a video adjustment circuit.

In this embodiment, the following configuration is adopted to enable the manufacturer to easily correct the DC control voltage in order to enable optimal control according to the variation in characteristics of the controlled IC 6.

That is, the microcomputer 7 serves as an output means for outputting digital data corresponding to a correction signal for correcting the DC control voltage, and the desired digital data after correction among the digital data from the microcomputer 7 is used. A nonvolatile memory 9 that stores data, and a clamp as a variable means that varies the DC control voltage output from the filter circuit 5 based on digital data of the microcomputer 7 or digital data read from the nonvolatile memory 9. The circuit 10 is provided.

As an output means, the microcomputer 7 outputs digital data to the clamp circuit 10 in accordance with a correction signal from a remote control 14 dedicated to the manufacturer, for example, when the manufacturer corrects the DC control voltage at the time of factory shipment. That is, when this microcomputer 7 receives a remote control signal, it determines whether the remote control signal is from the user or the manufacturer, and if it is from the user, it performs the same processing as before, and if it is from the manufacturer, it performs the same processing as before. , outputs digital data corresponding to the correction signal to the clamp circuit 10.

The clamp circuit 10 is
A 6-bit D/A converter circuit 11 converts digital data from the input to a pulse width modulated signal.
It consists of a filter circuit 12 which converts the pulse width modulated signal of the A conversion circuit 11 into a DC voltage, an impedance conversion circuit 13, a diode D, and a capacitor C which cuts the DC component of the output of the D/A conversion circuit 2. This clamp circuit 10 clamps the pulse width modulated signal from the D/A conversion circuit 2 with a clamp voltage according to the digital data, thereby correcting the DC control voltage given to the controlled IC 6.

Next, the operation when correcting the DC control voltage in the above embodiment will be explained. This correction is performed by the manufacturer at the time of factory shipment. First, the pulse width modulation output of the D/A conversion circuit 2 is set to the center value, that is, in this example, using the manufacturer's exclusive remote control 14 or the like.
32/64 (=2 ⁶ ), and in this state, operate the remote control 14 to provide a correction signal to the microcomputer 7 so as to obtain an optimal image. As a result, the microcomputer 7 outputs digital data according to the correction signal to the clamp circuit 10, and the clamp voltage of the pulse width modulation signal of the D/A conversion circuit 2 is varied to correct the DC control voltage. . When the optimum image is obtained by operating the remote controller 14, the correction ends, and the digital data at that time is stored in the non-volatile memory 9 by a predetermined remote control signal. It is clamped with a clamp voltage corresponding to the data.

Therefore, in the user, the pulse width modulation signal of the D/A conversion circuit 2 is clamped with the clamp voltage corresponding to the digital data of the nonvolatile memory 9. The operation by the user is the same as in the conventional case, and by operating the remote control or the keys on the main unit, the corresponding digital data is output from the microcomputer 7 to the D/A conversion circuit 2, and the D/A conversion circuit 2 converts the data. The signal is converted into a pulse width modulation signal, clamped with a clamp voltage corresponding to the digital data in the nonvolatile memory 9, and further converted into a DC control voltage by the filter circuit 5 and applied to the controlled IC 6.

In the above embodiment, a television receiver was described, but the present invention can be similarly applied to other video equipment and audio equipment.

<Effects of the invention> As described above, according to the invention, for controlled circuits in which various adjustments are made using DC control voltage, the factory standard so that the DC control voltage is
It is now possible for the manufacturer to adjust the median value electronically using a remote control, etc.
Adjustment work becomes easier, and the correction volume and the like of the conventional example become unnecessary.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention;
The figure is a block diagram of a conventional example. 7...Microcomputer (output means), 8
...Conversion means, 9...Nonvolatile memory, 10...
clamp circuit.

Claims (1)

[Claims for Utility Model Registration] Regarding the controlled circuit 6 in which various adjustments are made using the DC control voltage, the appropriate median value of the DC control voltage is set according to the variation in characteristics of each product of the controlled circuit. A device for pre-correction, which includes a control circuit 7 that outputs digital data corresponding to the DC control voltage applied to the controlled equipment 6, and a control circuit 7 that converts the digital data from the control circuit 7 into the DC control voltage. The conversion means 8 includes a D/A conversion circuit 2 that converts digital data outputted from the control circuit 7 into a pulse width modulation signal, and this D/A conversion circuit. a filter circuit 5 for converting the pulse width modulation signal of No. 2 into a DC control voltage, a specific correction signal for adjusting the median value of the DC control voltage is input, and in accordance with this correction signal input, an output means 7 for outputting correction data corresponding to this, and a clamp voltage of a pulse width modulation signal outputted from the D/A conversion circuit 2 of the conversion means 8 based on the correction data from the output means 7; and a storage means 9 for storing digital data corresponding to the clamp voltage corrected based on the correction data output from the output means 7. Control voltage correction device.