JPH0151128B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a multi-pen recorder.

Recently, with the diversification of measurement purposes, pen recorders of this type have tended to have more pens and have diversified functions.Therefore, there is a trend towards incorporating microcomputers. Since a microcomputer is used in this way, it is necessary to digitize and process the input signal to be recorded. On the other hand, since a servo mechanism is used to drive the pen, it is also necessary to convert the calculation results by the microcomputer into analog quantities. Therefore, in order to record multiple input signals using different pens, an AD converter must be placed between the input end and the microcomputer for each input channel, and a DA converter must be placed between the microcomputer and the servo mechanism. There must be the same number of channels as there are channels between them. This results in disadvantages such as an increase in the number of uses and an increase in manufacturing costs.

An object of the present invention is to simplify the configuration by reducing the number of converters used during multi-channel recording.

This invention calculates the deviation from the analog value of the previous input signal each time one input signal is given to each channel, AD converts this, stores it in the arithmetic processing unit, and adds this deviation to the previous input signal. is digitally added (including subtraction) to obtain the digital value of the current input signal, and the next time a new signal is given, this value is further converted to an analog quantity and used as the new input signal as described above. It is characterized in that it is used to find the deviation from the servo mechanism and is also applied to the servo mechanism, thereby driving the pen. According to this, only one AD conversion and DA conversion element is required even for multi-channels.

Embodiments of the invention will be described with reference to the drawings. 1a
-1n are input terminals, and the input signals applied thereto are amplified by preamplifiers 2a to 2n to become input signals _X1 to _Xo , which are applied to the multiplexer 3. 4 is a microcomputer that constitutes an arithmetic processing unit, which includes a central processing unit 5, an output port for input switching, an output port 7 for sample and hold control, a memory (ROM) 8 for executing each program, and a calculation result. memory (RAM) 9 for storing, AD converter 10, DA converter 11,
It is composed of a clock oscillator 12, an output port 13 for controlling a step motor, and the like. 14 is a data bus. According to a program predetermined by the memory 8, each of the input signals X ₁ to X _o is sequentially taken into the multiplexer 3 and sequentially output from there. This output is given to comparator 15.
Here, the digital amount of the previous input signal is outputted from the DA converter 11, and the deviation thereof is outputted from the comparator 15.

To explain this in detail, assume that the input signal I in a certain channel changes over time as shown in FIG. Here, the magnitude of the input signal at a certain time to _{-1 is} x _o-1 , the magnitude of the input signal at time to which time Δt has elapsed from then _{is x o ,} and the magnitude of the input signal at time Δt is If the difference is Δx, then the relationship x _o = x _o-1 + Δx holds true. Therefore, as shown in the figure, the analog value of the previous input signal _xo-1 is output from the DA converter 11, and this is used as the input for the current input signal _xo .
If negative feedback is given to the AD converter 10, the AD converter 10
The input becomes the deviation Δx. This deviation Δx is taken into the central processing unit 5, and is added to the previous input signal.
Add x _o-1 and set it as the current input signal x _o , which is
It is supplied to the DA converter 11 and stored in the memory 9 for calculation on the next input signal. This calculation is then executed for each input signal of each channel.

Note that the resolution of the AD converter 10 may be lower than that of the DA converter 11 here.
For example, when converting DA converter 11 to 12 bits, AD
Converter 10 may be 8 bits, for example.
This is because the sampling period Δt is sufficiently short,
This is because the amount of change Δx in the input signal during this period is also considered to be sufficiently small, so the number of bits may be small. Therefore, an inexpensive AD converter 10 can be used.

The output from the DA converter 11 is sent to sample and hold circuits 15, which are provided in the same number as channels.
One of channels a to 15n is held in response to a signal from output port 7. Each of the hold values ya to yn is given to each of the position servo mechanisms 16a to 16n. As a result, according to each hold value, the pens 17a to 1
7n are each driven. On the other hand, the recording paper 18 is driven by a feeding motor 19 (step motor). The rotational speed of the motor 19 is determined by the frequency of the pulses applied thereto, and these pulses are obtained by dividing the pulses from the clock oscillator 12 to a desired frequency by the central processing unit 5. This pulse is applied to the motor 19 from the output port 13 via the driver 20.

As detailed above, according to the present invention, when multiple inputs are given and each input is recorded,
Even if digital calculations are used, AD, DA
It is not necessary to install both converters for each channel, which has the effect of simplifying the configuration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a curve diagram of input signals for explaining the operation. 1a to 1n...Input terminal, 3...Multiplexer, 4...Arithmetic processing unit, 8...Memory, 9...
Memory, 10...AD converter, 11...DA converter, 15a to 15n...sample hold circuit,
16a-16n...Position servo mechanism, 17a-1
7n...pen, 18...recording paper.

Claims (1)

[Claims] 1. In a multi-pen recorder that records multiple input signals on recording paper using each pen, there is a multiplexer that takes each of the input signals as input and sequentially switches and outputs the input signals, and a multiplexer that outputs the same input signal as the previous input signal of the same channel as the output of the multiplexer. An AD converter that receives as input the deviation from the analog value of the input signal;
an arithmetic processing device that calculates the currently given input signal by calculating the output of the AD converter and the previously given input signal; A DA converter that converts the signal into an analog value for calculating the deviation, a sample hold circuit that holds the converted value of the DA converter for each channel, and a hold value of the sample hold circuit. A multi-pen recorder comprising a servo mechanism that drives corresponding pens.