JPH02277318A - D-a converter - Google Patents

Abstract

PURPOSE:To obtain an analog output always equal to each other for a measuring instrument with a different measuring range by providing an extraction means of a measuring range and a measuring value, a means operating a numerical data in response to the measured range data and an amplification means. CONSTITUTION:An interface section 3 converts digital data from a measuring instrument 2 into a voltage signal, which is transferred to a central control section 7. An arithmetic means 73 of the central control section 7 multiplies numeral data from a measuring value extraction means 72 with a multiple of 1/k so that the full scale of a D/A converter section 4 is coincident with the measuring range. The D/A converter section 4 converts the data into an analog signal, an amplifier 5 amplifies the signal at a multiple of (k) and an analog signal (b) is outputted from a multiplexer 6. Thus, the measuring instrument with a different measuring range can obtain an always equal analog output.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a DA converter that converts measurement data input from a measuring device such as a radiation thermometer into an analog signal and outputs the analog signal.

[Conventional technology]

Conventionally, the measured temperature data is measured using a radiation thermometer that measures the temperature of the object to be measured, converts the measured temperature into digital data, and sends it out. After converting the measured temperature data into an analog voltage using a D-A converter, this analog There are known devices in which the voltage is guided to a temperature control section such as an electric furnace to control the temperature, and the measured temperature is guided to a pen recorder or the like to be recorded.

However, when the measurement temperature is changed or the measurement target is changed, the measurement temperature range changes from 0°C to 1°C.
In some cases, it may be necessary to replace a radiation thermometer of 1,000°C to a radiation thermometer of 600°C to 3,000°C or a radiation thermometer of 1,000°C to 2,000°C.

Therefore, conventionally, a D/A converter having a D/A converting IC with a large number of input bits has been used so that temperature data measured by a radiation thermometer in any measurement range can be D/A converted. For example, in order to make the three types of radiation thermometers interchangeable, a DA conversion IC that can convert measured temperature data from 0° C. to 3000° C. into analog output has been used.

In addition, as a relatively new device, a D-A conversion IC with a relatively small number of input bits is used, and when measured temperature data is input from a radiation thermometer with a wide temperature range, the measured temperature data is D-A converted. There is a known method in which data is converted to fit within the number of input bits of a commercial IC, D-A conversion is performed, and then the data is returned to its original state by manual operation.

That is, in this device, a D-A conversion IC corresponding to a measurement temperature range of 0°C to 1000°C, for example,
When the measured temperature data of 2700℃ is sent from the radiation thermometer of 000℃, this measured temperature data is 1/3 9
Calculated at 00℃ and set at 900℃.
Enter.

Then, in order to triple the D-A converted analog output voltage by manual operation after identifying the type of radiation thermometer,
The amplification method was switched.

[Problem to be solved by the invention]

The above radiation thermometer with a wide measurement concentration range has a constant gain of D-
In a device connected to an A converter, it is necessary to increase the number of input bits of the DA conversion IC.

In other words, in order to convert the measured temperature data from a radiation thermometer of 0°C to 1000°C using a DA converter IC with a minimum resolution of 0.1°C, the number of input bits of the DA converter IC must be 14 bits. It would be nice to have one, but if you consider replacing it with a radiation thermometer with a temperature range of 600°C to 3000°C,
It is necessary to set the number of input bits to 15 so that it can correspond to 00°C.

Along with this, the cost of the DA conversion IC is 1-.

Similarly, the measurement temperature range is, for example, 0°C to 100°C.
Even when different radiation thermometers such as 0℃ and 1000℃ to 2000℃ are connected, it is possible to identify the type of radiation thermometer each time and adjust the analog output voltage manually. .

For this reason, the conventional latter device and the above device have a measurement temperature range of 0°C to 1000°C and 600°C to 3000°C.
, 1000 DEG C. to 2000 DEG C., or other radiation thermometers are being used, and switching adjustments are made each time, which poses a problem in that there is a risk of operational errors.

The present invention solves the above problem, and provides a D-A converter that always converts and outputs an analog voltage that matches the measured temperature even when radiation thermometers with different measurement temperature ranges are connected. With the goal.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a measurement range extraction means for extracting measurement range data from input digital data, and a measurement value extractor stage for extracting measurement value data from the digital data and converting it into numerical data. , a calculation means for multiplying the numerical data by 1/k in accordance with the measurement range data, and a D-A for converting the output signal from the calculation means into an analog signal.
It consists of a converting section and an amplifying means that multiplies the analog signal according to the measurement range data and outputs the multiplied signal.

In a second aspect of the present invention, there is provided a measurement range extraction means for extracting measurement range data from input digital data, a measurement value extraction means for extracting measurement value data from the digital data and converting it into numerical data, and a measurement range extraction means for extracting measurement range data from the digital data. a calculation means for subtracting a value corresponding to the data; a D-A converter for converting the output signal from the calculation means into an analog signal; and a bias signal corresponding to the measurement range data added to the analog signal, and output and addition means.

[Effect]

According to the D-A converter configured as described above, measurement range data and measurement value data are extracted from input digital data, and after the measurement value data is converted into numerical data, 1/ Multiplied by k. Then, the data multiplied by 1/k is converted into an analog signal, multiplied by k, and output.

Furthermore, measurement range data and measurement value data are extracted from the input digital data, and after the measurement value data is converted into numerical data, a value corresponding to the measurement range data is subtracted. The subtracted data is then converted to an analog signal, added with a bias signal, and output.

〔Example〕

FIG. 1 shows a block diagram of a first embodiment of a DA converter according to the present invention.

The DA converter 1 is connected to a measuring device 2 such as a radiation thermometer, and is composed of an interface section 3, a DA converter section 4, an amplifier 5, a multiplexer 6, and a central control section 7.

The interface section 3 is configured to comply with the R8232C interface standard, and converts the digital data from the measuring instrument 2 into voltage signals such as OV and 5V to represent "low" and "high" and performs central control. I am trying to forward it to Department 7.

Here, the digital data from the measuring device 2 will be explained. This digital data includes measurement range data and measurement value data consisting of ASCII code.

For example, if the digital data is “L50, OCR
", then "L" in the first word corresponds to the measurement range data, and "50.0" corresponds to the measurement value data measured by the measuring instrument 2. The above measurement range data corresponds to the measurement range data of the measuring instrument 2. It is set to correspond to the measurement range of the model, and if the model has a different measurement range, the measurement range data will be different.

Note that lIcR11 indicates the end of the data.

The DA converter 4 is composed of an IC or the like, and converts the output signal from the central controller 7 into an analog voltage signal (hereinafter referred to as an analog signal).

Further, the amplifier 5 and the multiplexer 6 constitute an amplifying means, and the amplifier 5 amplifies the analog signal from the DA converter 4 at a predetermined amplification factor. The multiplexer 6 is configured to output either the analog signal a directly input from the D-A converter 4 or the analog signal S input via the amplifier 5 based on a switching signal from the central control unit 7. It is something that can be switched.

The central control unit 7 includes a measurement area extraction means 71 and a measurement value extraction means 7.
2. It is composed of a calculation means 73 and a selection means 74.

The measurement area extraction means 71 extracts measurement area data from the digital data from the interface section 3. That is, in the case of the above-mentioned digital data "L 50.OCR", L II is extracted from this data.

The measured value extraction means 72 extracts measured value data from digital data and converts it into numerical data. That is, in the case of the above digital data, 50.0'' is extracted and this ASCII code is converted into numerical data of 50.0.

The calculation means 73 converts the D-A converter 4 based on the measurement range data.
The numerical data from the measured value extraction means 72 is multiplied by 1/k so that the full scale of the measured value matches the measurement range. That is, in order for the numerical data to fit within the number of input bits of the D/A converter 4,
．． I try to multiply it by 5. The selection means 74 sends a switching signal to the multiplexer 6 based on the signal from the measurement area extraction means 71.

Next, the operation of the D-A converter 1 having the above configuration will be explained using the flowchart shown in FIG. In this flowchart, the measuring device 2 is a radiation thermometer, and the D-A converter 1 is
The measurement temperature range of the radiation thermometer connected to the
The following description assumes that there are two types of data, 0° C. and 450° C. to 2000° C. (in the case of k=2), and that only numerical data corresponding to 0° C. to 1000° C. can be input to the D/A converter 4. Please note that due to the nature of the radiation thermometer's light receiving element, the measurement temperature range is 45
0℃~2000℃, but if you connect a radiation thermometer that outputs measurement data of 0℃~2000℃, the temperature will be 0℃~20℃.
It may be considered as 00°C.

First, when the power is turned on and the operation of the D-A converter 1 is started, the output of the D-A converter 4 is reset to OV in step S1, and the multiplexer 6 is set to OV in step S2.
It is switched to output the analog signal a from the converter 4.

Next, in step S3, the system waits until digital data from the measuring device 2 is received, and upon reception, measurement area data is extracted from the digital data.

In step S4, if this measurement range data is "'L" indicating that the measurement temperature range of the radiation thermometer is 0°C to iooo°C, in step S5 the measured value data extracted from the digital data is converted into numerical data. is converted to

Subsequently, in step S6, the multiplexer 6 is switched to the DA converter 4 side by a switching signal from the selection means 74, and further, in step S7, the numerical data is input to the DA converter 4 and converted into an analog signal a. The converted analog signal a is outputted via the multiplexer 6. After this, the process returns to step $3 and repeats the processing from step S3 onwards.

On the other hand, if the measurement range data in step S4 is "M" indicating that the measurement temperature range of the radiation thermometer is 450°C to 2000°C, the measured value data extracted from the digital data in step S8 is Converted to numerical data. In step S9, the multiplexer 6 is switched to the amplifier 5 side by the switching signal from the selection means 74.

Then, in step 810, the numerical data is calculated into numerical data with a compression slip of 1/2 so that it can be input to the D/A converter 4. The measured value data converted at this time is 22
Since the temperature is in the range of 5° C. to 1000° C., it can be input to the DA converter 4, where it is converted into an analog signal. This analog signal is amplified by an amplifier 5 with an amplification factor of 2, and the amplified analog signal is outputted from a multiplexer 6. After this, step S3 again
The process returns to step S3 and repeats the processing from step S3 onwards.

As described above, in this embodiment, if the measurement temperature range of the radiation thermometer is 0°C to iooo°C, the measured value data is converted to numerical data, and then directly converted to analog signal a and output. , the measurement temperature range of the radiation thermometer is 450℃~
If it is 2000℃, the numerical data is calculated by half, converted to an analog signal, and then amplified twice and output, so you can connect radiation thermometers with different measurement temperature ranges. Also, as the output of the DA converter 1, an analog voltage output can always be obtained with a constant gain with respect to the measured temperature.

In the above embodiment, two types of radiation thermometers are connected to the D-A converter 1. However, in order to correspond to the measurement temperature range of the radiation thermometer, a plurality of amplifiers 5 with different amplification factors are connected to the D-A converter 1. It is also possible to connect a plurality of radiation thermometers having different measurement temperature ranges by connecting them in parallel to the output side of the -A converter 4 and connecting the outputs of the amplifiers 5 to the multiplexer 6, respectively. In this case, the configuration is such that the output signal of the amplifier 5 corresponding to the type of radiation thermometer connected to the DA converter 1 is outputted via the multiplexer 6 in response to a switching signal from the selection means 74.

Further, in the above embodiment, the numerical data from the measured value extracting means 72 is reduced to 1/2, but it is possible to change the numerical data from the measured value extracting means 72 to 1/2, for example, from 600°C to 3000°C.
℃, calculate the above numerical data to 1/3. In this case, the range of the measured value data is 200° C. to 1000° C., which can be input to the DA converter 4. After converting it to an analog signal, it is amplified three times and output.

Next, a second embodiment of the DA converter according to the present invention will be described using FIG. 3. Note that in the figure, the same numbers as in FIG. 1 indicate the same items.

The DA converter 11 of this embodiment has an amplifier 51 having an amplification factor switching means 52 in place of the amplifier 5 and multiplexer 6, which are the amplification means of the first embodiment.

The amplifier 51 amplifies the analog signal from the DA converter 4 with an amplification factor set by the amplification factor switching means 52 and outputs the amplified signal.

The amplification factor switching means 52 switches the amplification factor of the amplifier 51 based on the switching signal from the selection means 74. For example, when the measuring instrument 2 is a radiation thermometer with a measurement temperature range of 0° C. to i ooo° C. , the amplification factor of the amplifier 51 is set to 1, and in the case of 450° C. to 2000° C., the amplification factor is switched and set to 2.

As described above, in the second embodiment, by switching the amplification factor of the amplifier 51, the output of the D-A converter 11 can be used even if radiation thermometers with different measurement temperature ranges are connected, as in the first embodiment. Analog voltage output can always be obtained with a constant gain for the measured temperature. Furthermore, this embodiment does not require the multiplexer 6, but instead consists of the amplifier 51, so the circuit configuration of the amplifying means can be simplified.

The amplification factor switching means 52 is configured so that a plurality of amplification factors can be set, and the amplification factor is switched to the amplification factor according to the type of radiation thermometer connected by a switching signal from the selection means 74, and the amplification factor is output from the amplifier 51. This makes it possible to accommodate multiple types of radiation thermometers with different measurement temperature ranges.

Next, a third embodiment of the D-A converter according to the present invention will be described using FIG. 4. Note that in the figure, the same numbers as in FIG. 1 indicate the same items.

In this embodiment, after the numerical data from the measured value extracting means 72 is subtracted by a value corresponding to the measurement range data in a sliding manner, the subtracted data is converted into an analog signal and a bias signal is added. .

That is, the D-A converter 12 of this embodiment has an addition system consisting of an adder 8, switches 81, 82, and clamping voltage 8I83 in place of the amplification means and arithmetic means 73 consisting of the amplifier 5 and multiplexer 6 of the first embodiment. and arithmetic means 731.

The adder 8 adds the analog voltage from the DA converter 4 and the voltage input via either one of the switches 81 and 82.

The switches 81 and 82 are turned on and off based on the switching signal from the selection means 74, so that when the switch 81 is on, the switch 82 is turned off, and when the switch 82 is on, the switch 81 is turned off. There is.

Additionally, an addition voltage source 83 that serves as a bias signal to the adder 8
The voltage 1 is set to a voltage corresponding to the subtraction valve in the calculation means 731. For example, in the case of the D-A converter 4 that can obtain an output voltage of Ov to 1V when a temperature of 0°C to 1000°C is input, if measurement data of 1000°C to 2000°C is input, Subtract ooo℃,
After D/△ conversion, the voltage corresponding to this 1000°C is 1
This is to add v.

For example, the calculation means 731 is configured such that the DA converter 12 is
When D-A conversion is possible in a temperature range of 1000°C and the measurable humidity range of the radiation thermometer connected to the DA converter 12 is from 0°C to 1000°C, the measured value extraction means 72 Output numerical data as is without calculating it. In addition, the calculation means 731 has a temperature range of 1000°C to 1000°C.
In the case of 2000°C, 1000°C is subtracted n from the numerical data from the measured value extraction means 72. In other words, if the numerical data is 1200℃, 200℃ after subtraction is D.
-A converter 4.

Next, the operation of the above configuration will be explained. In addition, D-A
The measurement temperature range of the radiation thermometer connected to the converter 12 is O
The explanation will be given assuming that there are two types of voltages: 0°C to 1000°C and 1000°C to 2000°C, and the DA converter 4 outputs an analog voltage of OV to 1v in response to a digital input of 0°C to 1000°C.

First, the measurable temperature range of the radiation thermometer is 0°C to 100°C.
In the case of 0° C., there is no need to convert the measured value data, and the calculation means 731 does not perform subtraction, so there is no need to apply a voltage to the adder 8. Therefore, the selection means 74
The switch 81 remains off and the switch 82 is set to be on due to the switching signal from the adder 8, so that the input terminals from the switches 81 and 82 of the adder 8
grounded through. As a result, the analog voltage signal from the [)-A converter 4 is output from the adder 8 as is without being changed.

On the other hand, when the temperature range is from ioooo°C to 2000°C, 1000°C is subtracted from the measured value data so that the data input to the DA converter 4 is from 0°C to 1000°C. Then, after D-A conversion, 1000℃
An analog voltage of 1 V is applied to the voltage. Then, the switching signal is switched and the switch 81 is turned on.
The switch 82 is turned off by the switching signal, and 1V, which is the voltage of the addition voltage source 83, is input to the adder 8 via the switch 81. As a result, after the numerical data subtracted by the calculation means 731 is converted into an analog voltage signal by the D-A converter 4, the adder 8 converts the numeric data into an analog voltage signal N83.
A voltage of 1V is added and output.

In this way, in the third embodiment, when the measurable temperature range of the radiation thermometer is from 0°C to 1000°C, the numerical data from the central control unit 7 is directly converted from D to A and output,
In the case of 1000° C. to 2000° C., the voltage of addition voltage #I83, which is the subtracted amount by calculation means 731, is added and output. Therefore, even if tliDA thermometers with different measurement temperature ranges, such as 1000°C to 2000°C, are connected, the D-
An analog voltage output always equal to the measured temperature can be obtained as the output of the A converter 12.

Note that the voltage of the addition voltage source 83 is not limited to 1V, and for example, the measurement temperature range is 1500°C to 2500°C.
1 when the radiation thermometer is connected to the D-A converter 12.
．． The voltage of the addition voltage source 83 is set to 1 so that 5V can be added.
．． It may be set to 5V.

Additionally, additional voltage sources 83 with different voltages are connected to the switches so as to correspond to the measurement temperature range of the radiation thermometer,
The radiation thermometers with different measurement temperature ranges are connected to the adder 8 through each switch, and the calculation means 731 subtracts the numerical data from the measurement value extraction means 72 so as to correspond to the measurement temperature range. It is also possible to connect multiple units.

In this case, the voltage of the addition voltage source 83 is 2V in addition to 1V.
V, 3V, etc., and the configuration is such that one of these voltages is input to the adder 8 via a switch. For example, when a radiation thermometer with a measurement temperature range of 2000° C. to 3000° C. is connected to the D-A converter 12, the numerical data from the measured value extraction means 72 is subtracted by 2000° C.
It is converted into an analog voltage signal by the DA converter 4, and further added with 2V from the addition voltage source 83 by the adder 8 and output.

Furthermore, the third embodiment is configured by combining the amplification means (amplifier 5 and multiplexer 6, or amplifier 51 and amplification factor switching means 52) explained in the first and second embodiments, and the temperature range of the radiation thermometer is When the temperature is 450°C to 2000°C, 600°C to 3000°C, etc., use an amplifying means to
In such cases, the calculation means 731, the adder 8, etc. may be used. Furthermore, in the case of 1000° C. to 3000° C., both of them may be used for output. In this case, first, from the measured value data, 1000℃
Subtract it to get data from 0°C to 2000°C, and then divide it by 1/2
The data is multiplied and converted into data from 0°C to 1000°C. Then, the resulting analog output of 1q is doubled and 1V, which is the analog output corresponding to 1000°C, is added.

〔Effect of the invention〕

The present invention automatically extracts measurement range data and measurement value data from input digital data, and then outputs an analog signal corresponding to the measurement value data based on the measurement range data. Even when a device is connected, an analog output equal to the measured value is always obtained, making it possible to perform processes such as temperature control accurately and easily, and to eliminate operational errors.

Furthermore, since a low-cost DA conversion IC can be used, the DA converter can be made smaller and lower in cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a first embodiment of the D-A converter according to the present invention, FIG. 2 is a flowchart showing the operation of the D-A converter according to the present invention, and FIG. 3 is a D-A converter according to the present invention. -A block diagram of a second embodiment of the A-to-A converter, and FIG. 4 is a block diagram of a third embodiment of the D-A converter according to the present invention. 1.11.12...D-A converter, 2...Measuring device,
3... Interface section, 4... D-A conversion section,
5゜51...Amplifier, 6...Multiplexer, 7.
. . . Central control unit, 8 . . . Adder, 52 . . . Amplification factor switching means, 71 . . . . selection means, 81. 82 . . . switch, 83 . . . addition voltage source. Patent applicant Minolta Camera Co., Ltd. Agent
Patent Attorney Etsushi Kotani Patent Attorney
1) Masamukai Patent Attorney Takao Ito

Claims (1)

[Claims] 1. Measurement area extraction means for extracting measurement area data from input digital data, measurement value extraction means for extracting measurement value data from the digital data and converting it into numerical data, and the measurement area data. a calculation means that multiplies the numerical data by 1/k in accordance with the measurement range data; a D/A converter that converts the output signal from the calculation means into an analog signal; A D/A converter consisting of an amplifying means for multiplying and outputting. 2. Measurement area extraction means for extracting measurement area data from input digital data, measurement value extraction means for extracting measurement value data from the digital data and converting it into numerical data, and corresponding to the measurement area data from the numerical data. an arithmetic means for subtracting by a value, a D/A converter for converting an output signal from the arithmetic means into an analog signal, and an addition means for adding a bias signal corresponding to the measurement range data to the analog signal and outputting the result. A D/A converter consisting of.