JPH0619048Y2 - Data recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a data recording device having an auto-zero means.

<Prior Art> An auto-zero means is used to automatically correct an offset error of a circuit in a data recording device or the like.
When this auto-zero technique is used for a scanner circuit that switches inputs in a data recording device, if auto-zero is performed for each channel, there is a problem that one cycle takes a long time.

<Problems to be Solved by the Invention> The present invention has been made to solve such problems, and it is an object of the present invention to provide an auto-zero circuit capable of speeding up even when applied to a scanner circuit for switching inputs. It is intended.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the present invention performs auto-zero on the first channel of one cycle, and corrects the gain corresponding to the gain on the other channels by the calculation of the microprocessor. It is configured to do the above. Hereinafter, embodiments will be described in detail with reference to the drawings.

<Embodiment> FIG. 1 is a connection diagram of an embodiment of the device according to the present invention. In the figure, 1 is an input terminal, and in the figure, 1 to 6 channels are shown. Reference numeral 2 is a scanner for switching the input, and each contact is connected to the input terminal 1, respectively. Reference numeral 3 denotes a changeover switch having contacts a and b. The contact a is connected to each H (high) side terminal of the input terminal 1, and the contact b is connected to each L (low) side terminal. L-side terminal and contact b in changeover switch 3
Are connected to a common potential COM. 4 is an operational amplifier 4
1, a resistance element 42, and a plurality of switches 43a to 43n
It is an amplifier circuit composed of. The changeover switch 3 is connected to one input terminal of the operational amplifier 41. The resistance element 42 is connected to the output terminal of the operational amplifier 41 and the common potential COM.
The switches 43a to 43n are connected between the other input terminal of the operational amplifier 4 and each voltage dividing point of the resistance element 42. When the switches 43a to 43n are closed, the voltage dividing resistors are connected to the feedback circuit of the operational amplifier 41 in accordance with the closed switch, whereby the gain of the amplifier circuit 4 changes to Aa to An (Aa. <Ab ... <
An). Reference numeral 5 indicates the offset voltage of the operational amplifier 41.

Reference numeral 6 is an analog / digital converter, 7 is a microprocessor, and the output terminal of the amplifier circuit 4 is connected to the microprocessor 7 via the analog / digital converter 6. The microprocessor 7 includes the scanner-2, the changeover switch 3 and the switches 43a to 4 in the amplifier circuit 4.
In addition to controlling the switching operation of 3n, control for outputting a measurement signal corresponding to the input signal applied to the input terminal 1 is performed. The operation of the data recording device having such a configuration will be described below.

First, the changeover switch 3 by the microprocessor 7
To the contact b side, and the switch 4 in the amplifier circuit 4
The switches 43n are closed so that the amplifier circuits 3a to 43n have the highest gain An. At this time, the amplifier circuit 4
The value of the offset (denoted as X) on the circuit including is stored in the memory provided in the microprocessor 7.
Next, the changeover switch 3 is closed to the contact a side, the 1ch contact of the scanner-2 is closed, and the switches 43a to 43n in the amplifier circuit 4 become the gain (for example, Aa) measured by the gain of the amplifier circuit 4. Thus, the switch 43a is closed. As a result, the input signal is multiplied by Aa in the amplifier circuit 4, and the output multiplied by Aa is converted into a digital signal by the analog / digital converter 6 to generate a micro signal.
It is stored in the memory of the processor 7.

Next, when measuring 2 ch or less, even if the gain of the amplifier circuit 4 is changed (for example, when the switch 43b is closed and the gain is changed to Ab), the changeover switch 3 remains closed on the contact a side and Measure. The input signal of 2ch is multiplied by Ab, converted into a digital signal, and stored in the memory of the microprocessor 7. Hereinafter, similarly, the gain is changed for each input channel, and the measurement is performed up to 6 channels. When the input measurement of 6ch is completed in this way, the microprocessor 7 performs the following correction calculation,
The error due to the offset 5 is corrected.

When the measurement channel is 1ch, the output of the analog / digital converter 6- (Aa / An) .X ... (1) When the measurement channel is 2ch, the output of the analog / digital converter 6- (Ab / An) .X ... (2) Similarly, when the number of measurement channels is 6 ch. Output of analog-digital converter 6- (Af / An) .X ... (3) As is clear from (1) to (3), After measuring the offset value with the maximum gain An of the amplifier circuit 4, the microprocessor 7 calculates the ratio of the offset value to the actual measurement gain A, and the calculated value is the analog digital value which is the actual measurement value. Since it is configured to subtract from the output of the converter, even if different gain settings are made for each input channel, the correction offset is measured once at the maximum gain. If only the measurement is performed, the offset error for all channels can be automatically corrected.

<Effects of the Present Invention> As described above, according to the present invention, in the multi-channel data acquisition device, it is not necessary to perform the auto-zero for each input channel, and the data acquisition device having the input means speeded up by that much is provided. Obtainable.

[Brief description of drawings]

FIG. 1 is a connection diagram of an embodiment of a data recording device according to the present invention. 1 ... Input terminal, 2 ... Scanner, 3 ... Changeover switch, 4 ... Gain variable amplifier, 6 ... Analog-digital converter, 7 ... Microprocessor.

Claims (1)

[Scope of utility model registration request] 1. A multipoint data recording device, wherein multichannel inputs are converted into digital signals through a variable gain amplifying circuit and then taken into a microprocessor for measurement. Is set to the maximum value An and the input terminal of this amplifier circuit is connected to a common potential point to obtain the value X of the digital signal at that time. Based on this value X, the micro A multi-point data recording device having an auto-zero means for removing offset error by performing the following correction calculation in the processor. Digital signal value- (A / An) · X, where A: gain of the amplifier circuit at the time of measurement