JP2002368614A - Method of correcting conversion error of analog/digital converter and digital-to-analog converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for correcting conversion errors of an analog/ digital converter and a digital/analog converter, by which control with high accuracy can be conducted, without the need for storing data for error correction, in advance in a nonvolatile memory and without the need for an adjustment time at shipment. SOLUTION: A control unit for converting an analog signal into a digital signal as its control always corrects errors in the analog/digital converter 3 and the digital/analog converter 6, by using a difference between a digital signal resulting from converting a received analog signal by the digital/analog converter 6 and a digital signal, resulting from converting an analog signal, converted from the digital signal by the analog/digital converter 3 receiving an analog signal from the digital/analog converter 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an A / D converter and a method for correcting a conversion error of a D / A converter.

[0002]

2. Description of the Related Art Generally, an A / D converter and a D / A converter include a non-linear error and an offset error, and these errors affect control accuracy.

In order to achieve higher accuracy by reducing or eliminating errors in the A / D converter, Japanese Patent Application Laid-Open No.
In Japanese Patent No. 088166, as shown in FIG. 2, data for error correction prepared in advance is stored in a non-volatile memory 15 and the converted value is corrected by a correction calculation unit 16 based on the data. Then, a method of sending to the control unit 17 is adopted.

[0004]

However, in the conventional example, there is a problem that error correction data must be prepared in advance and stored in a non-volatile memory, and an adjustment time is required at the time of product shipment. Was.

Therefore, the present invention provides an A / D converter and a D / A converter capable of performing high-accuracy control without storing error correction data in a nonvolatile memory in advance or requiring adjustment time at the time of shipment. A method for correcting a converter conversion error is provided.

[0006]

According to the present invention, there is provided a control apparatus for converting an analog signal into a digital signal and controlling the value by converting an input analog signal into a digital signal by an A / D converter. After the digital signal is converted into an analog signal by the D / A converter, the difference between the digital signal and the value converted into the digital signal by the A / D converter is used to calculate the A / D.
The error of the converter and the D / A converter is always corrected.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a diagram showing an embodiment of a method for correcting a conversion error of an A / D converter and a D / A converter.

[0008] The control command 1 input as analog data is passed to the A / D converter 3 through the channel 1 of the multiplexer 2, and is output through the output switch 4 for the channel 1 of the A / D converter 3. The control command becomes 5. The control command 5 is input to the D / A converter 6, and the control command 7 for analog data is output.

Control command 7 output from D / A converter 6
Is the A / D converter 3 via the channel 2 of the multiplexer 2.
And the output becomes a control command 8 via the switch 4 for ch2. The switching cycle of the switch 4 varies depending on the control target and the system, but is switched to ch2, for example, every second only when correction is desired.

Since the difference between the control command 5 and the control command 8 corresponds to the sum of conversion errors between the A / D converter 3 and the D / A converter 6,
The value is added to the control command 5 as a control correction value 9 and is input to the control unit 11 as a control command 10. Note that the control commands 5 and 9 are retained in the memory while being disconnected from the switch 4.

The value output from the control unit 11 is converted into analog data by a D / A converter 12 and
Given to.

The above method eliminates the problem that error correction data is stored in a non-volatile memory in advance and that an adjustment time at the time of shipment is required.

Further, since error correction is always performed, not only offset error correction, but also non-linearity error can be corrected, so that high-accuracy control can be performed.

[0014]

As described above, according to the present invention, the error of the A / D converter and the D / A converter is always corrected, so that the error correction data is stored in the nonvolatile memory in advance or shipped. The problem that the time for adjusting the time is required is eliminated.

Further, since the error correction is always performed, not only the correction of the offset error but also the non-linear error can be corrected, so that there is an effect that the control can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Control command 2 ... Multiplexer 3 ... A / D converter 4 ... Switch 5 ... Control command 6 ... D / A converter 7 ... Control command 8 ... Control command 9 ... Control correction value 10 ... Control command 11 ... Control unit 12 ... D / A converter 13 ... Control target 14 ... A / D converter 15 ... Non-volatile Memory 16: Correction operation unit 17: Control unit

Claims (1)

[Claims] 1. A control device for converting an analog signal into a digital signal and controlling the digital signal by using an A / D converter to convert the input analog signal into a digital signal and a D / A converter A / D converting the analog signal to an analog signal, and always correcting an error between the A / D converter and the D / A converter by a difference from a value converted to a digital signal by the A / D converter. Converter and D
A method for correcting a conversion error of the / A converter.