JP3768545B2 - Sensor signal processing device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a sensor signal processing apparatus that processes an output signal of a sensor that detects physical information for the purpose of display or the like.
[0002]
[Prior art]
Modern electronic watches use sensors to measure constantly changing physical information such as pressure and temperature, such as atmospheric pressure and water pressure, in addition to the original timetable function, alarm, chrono and other commonly used functions. However, products with a sensor function for displaying via a signal processing circuit have been commercialized.
However, the electronic timepiece has a limited space for storing electronic circuit elements, and in order to reduce costs, elements such as variable resistors for adjusting amplification factor and offset can be used as much as possible. Only non-adjustment is desired. Furthermore, it is desirable that sensors with different specifications can be handled with the same hardware. The prior art related to the above constraint conditions will be described below.
[0003]
FIG. 2 shows an example of a conventional sensor signal processing apparatus used in a battery-driven electronic timepiece.
In FIG. 2, 1 is an atmospheric pressure sensor that outputs an atmospheric pressure signal S1 proportional to the atmospheric pressure P, 2 is a sensor driving circuit that is driven by passing a constant current through the atmospheric pressure sensor 1, and 3 is an amplification that amplifies the atmospheric pressure signal S1 using an operational amplifier. A circuit 4 is an A / D conversion circuit that A / D converts the amplified atmospheric pressure signal S1 ′ output from the amplification circuit 3 and outputs it as conversion data Dc, and 5 processes the conversion data Dc into sensor information data Dj. A sensor information data processing circuit for converting and outputting, a memory setting circuit 5a, an A memory 5b as a first memory, a B memory 5c as a second memory, a data selection circuit 5d, and a sensor characteristic equation calculation It is comprised by the microcomputer which is a means.
The memory setting circuit 5a outputs the conversion data Dc input from the A / D conversion circuit 4 to the terminal I from the terminal O1 or the terminal O2 according to the control signal S31 or S32 input from the outside to the terminals C1 and C2, respectively. The data is stored in the memory 5b or the B memory 5c.
When the conversion data Dc is output from the terminal O1 of the memory setting circuit 5a, the conversion data Dc is stored as memory data Da in the A memory 5b. When the conversion data Dc is output from the terminal O2, the conversion data Dc is stored in the B memory 5c as memory data Db. Note that the A memory 5b and the B memory are non-brightness generation memories, and when they are stored by the memory setting circuit 5a, their contents are retained even when the power is turned off.
The data selection circuit 5d uses the control signal input to the terminal C from the microcomputer 5e, or the conversion data Dc input to the terminal I1 or the memory data Da that is stored in the A memory 5b input to the terminal I2. Alternatively, the memory data Da, which is the storage content of the B memory 5c input to the terminal I3, is selectively output from the terminal O and supplied to the microcomputer 5e. The microcomputer 5e controls the terminal C of the data selection circuit 5d to read the memory data Da stored in the A memory 5b and the memory data Db stored in the B memory 5c from the terminal O of the data selection circuit 5d. the sensor characteristic equation to determine to output the sensor information signal Dj to the display device 6.
Reference numeral 6 denotes a display device that digitally displays an atmospheric pressure value based on sensor information data Dj output from the microcomputer 5e of the sensor information data processing circuit 5.
[0004]
The sensor signal processing apparatus having the above circuit configuration operates as follows.
When the atmospheric pressure sensor 1 is driven at a constant current by the sensor driving circuit 2, it outputs an atmospheric pressure signal S 1 proportional to the atmospheric pressure P applied to the atmospheric pressure sensor 1. The atmospheric pressure signal S1 is amplified by the amplifier circuit 3 to become a signal S1 ′, and this signal S1 ′ is further converted into digital conversion data Dc by the A / D conversion circuit 4. The digital conversion data Dc is converted into sensor information Dj by the sensor information data processing circuit. Here, how to calculate the sensor characteristic formula in the sensor information data processing circuit 5 will be described.
First, a certain atmospheric pressure P1 is applied to the atmospheric pressure sensor 1, and in this state, the control signal S31 is input from the outside to the terminal C1 of the memory setting circuit 5a, and the conversion data Dc output from the A / D conversion circuit 4 is stored in the A memory. Store in 5b. Next, an atmospheric pressure P2 different from the atmospheric pressure P1 is applied to the atmospheric pressure sensor 1, and in this state, the control signal S32 is input from the outside to the terminal C2 of the memory setting circuit 5a, and the conversion data Dc output from the A / D conversion circuit 4 is converted to B. Store in the memory 5c.
As shown in FIG. 3, the conversion data Dc at the atmospheric pressure P1 is stored in the A memory 5b as the memory data Da, and the conversion data Dc at the atmospheric pressure P2 is stored in the B memory 5c as the memory data Db. Become. In other words, the atmospheric pressure conversion characteristics obtained by integrating the characteristics of the atmospheric pressure sensor 1 and the characteristics of the amplifier circuit 3 are stored in the A memory 5b and the B memory 5c.
Next, calculation of the sensor characteristic formula by the microcomputer 5e will be described. The microcomputer 5e controls the terminal C of the data selection circuit 5d, and the memory data Da (conversion data Dc at the time of the atmospheric pressure P1) stored in the A memory 5b and the memory data Db stored in the B memory 5c. (Conversion data Dc at the time of atmospheric pressure P2) is read, α and β are calculated, and a sensor characteristic equation represented by the following equation 1 for determining the sensor information signal Dj is determined.
[0005]
[Expression 1]
Dj = α × Dc + β
α = (P2−P1) / (Db−Da)
β = P1−α × Da
[0006]
It should be noted that the determination of α and β in this sensor characteristic equation need only be performed once based on the memory data Da and Db stored in the non-brightness generation memory when the power is turned on.
Once the equation (1) of the sensor characteristic is determined, the converted data Dc is thereafter read into the microcomputer 5e via the data selection circuit 5d, and the sensor information signal Dj (representing the atmospheric pressure P) is represented by the equation (1). ) Is calculated.
When the digital conversion data Dc is input from the A / D conversion circuit 4 to the sensor information data processing circuit 5 having the sensor characteristic equation thus determined, the sensor information signal Dj calculated according to the sensor characteristic equation is converted into the microcomputer 5e. Is output from. The display device 6 displays an atmospheric pressure value (for example, 1013 hPa) based on the sensor information signal Dj.
[0007]
[Problems to be solved by the invention]
As described above, the sensor characteristic equation is calculated and determined for each sensor signal processing device so that it matches the characteristics of the atmospheric pressure sensor and the amplifier circuit. Can be done.
However, the sensor used actually has a large variation in sensitivity and offset, and the conventional sensor signal processing device is forced to adjust the sensor alone, non-standard ones are handled as defective, and the sensor completion yield is reduced. In consideration of variations in sensitivity and offset, the upper limit value Pmax of the atmospheric pressure to be measured does not exceed Dmax, which is the upper limit value of A / D conversion, or the lower limit value of the A / D conversion is also lower than the lower limit value Pmin of the atmospheric pressure to be measured. As shown in FIG. 4A, the amplification factor of the amplifier circuit 3 must be set as shown in FIG. 4A, and the offset must be set as shown in FIG. (A) As shown in (b), the dynamic range could not be used effectively, and it was difficult to increase the resolution per unit atmospheric pressure. Further, when using sensors with different specifications, it is necessary to reset the amplification factor and offset of the amplifier circuit 3 in accordance with the characteristics of each sensor, and it is difficult to cope with changes in specifications.
An object of the present invention is to provide a sensor signal processing apparatus that can eliminate the adjustment of the sensor alone and can handle different specification sensors with common hardware.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has the following configuration.
That is, a linear sensor that detects physical information;
A sensor driving circuit for driving the sensor;
An amplifier circuit for inputting and amplifying a sensor signal output from the sensor;
An A / D converter circuit for converting the amplified output value processed by the amplifier circuit into digital information;
A data processing circuit for creating sensor information data from digital information output from the A / D conversion circuit;
The data processing circuit includes a first memory and a second memory respectively storing two different digital information data output from the A / D conversion circuit;
Sensor characteristic equation calculating means for calculating a sensor characteristic equation based on two digital information data stored in the two memories,
In a sensor signal processing device for converting digital information data output from the A / D conversion circuit into sensor information data according to a sensor characteristic equation calculated by the sensor characteristic equation calculating means,
An amplification factor adjustment circuit configured by an amplification factor adjustment memory and an amplification factor switching circuit, and adjusting the amplification factor of the amplification circuit based on digital amplification factor adjustment data stored in the amplification factor adjustment memory;
Is constituted by the offset adjustment memory and offset adjustment D / A conversion circuit includes an offset adjusting circuit for adjusting, based on the digital offset adjustment data stored in the offset adjustment memory offset voltage of the amplifying circuit, the amplification factor adjusting circuit The sensor characteristic equation is calculated by the sensor characteristic equation calculating means after coarsely adjusting the amplification factor and the offset voltage value of the amplifier circuit using the offset adjusting circuit .
[0009]
【Example】
Embodiments of the present invention will be described below in detail with reference to the drawings.
Figure 1 shows one embodiment of a sensor signal processing apparatus according to the present invention, illustrated sensor signal processing apparatus herein are those designed to display the atmospheric pressure. The present invention will be described below with reference to this figure. In the figure, the same elements as those in FIG.
Reference numeral 7 denotes an offset adjustment circuit, which includes an offset adjustment memory 7a and an offset adjustment D / A conversion circuit 7b.
The offset adjustment memory 7a stores offset adjustment data Do represented by a digital value input from the outside, and outputs the offset adjustment data Do to the offset adjustment D / A converter 7b.
The offset adjustment D / A converter 7 b generates an offset adjustment signal So based on the offset adjustment data Do and supplies it to the amplifier 4.
Reference numeral 8 denotes an amplification factor adjustment circuit, which includes an amplification factor adjustment memory 8a and an amplification factor switching circuit 7b.
The amplification factor adjustment memory 8a stores digital amplification factor adjustment data Dg input from the outside, and outputs the amplification factor adjustment data Dg to the amplification factor switching circuit 8b.
The amplification factor switching circuit 8b generates an amplification factor adjustment signal Sg based on the amplification factor adjustment data Dg and supplies it to the amplification circuit 3. The amplifier circuit 3 switches the input of the operational amplifier or the feedback resistance value based on the amplification factor adjustment signal Sg, and determines the amplification factor.
The offset adjustment memory 7a and the amplification factor adjustment memory 8a is Futeruhatsu volatile memory, the contents of which are retained even when the power is turned off after storing the data.
[0010]
Next, the operation of the sensor signal processing apparatus according to the present invention having the above configuration will be described.
FIG. 5A shows a graph of the A / D conversion value when a barometric pressure sensor whose offset value is too large and sensitivity is too low is used. In the state of FIG. 5A, since the offset value is too large, the upper limit value Pmax to be measured exceeds the upper limit value Dmax of the measurement limit. For this reason, the desired measurement range cannot be obtained, and the sensitivity of the atmospheric pressure sensor 1 is too low, so that the weight per bit of the converted value Dc is too large and the measurement resolution becomes rough.
A procedure for adjusting the sensor signal processing apparatus will be described below. First, the atmospheric pressure P1 is added to the atmospheric pressure sensor 1, and in this state, an offset reduction pattern of the offset adjustment data Do is input from the outside to the offset adjustment memory 7a, and the offset adjustment signal So output from the offset adjustment D / A conversion circuit 7b is used. cut back. Then, the offset voltage value in the amplifier circuit 3 decreases, and the graph of the A / D conversion values at the atmospheric pressures P1 and P2 becomes as shown in FIG. Next, the atmospheric pressure P2 is applied to the atmospheric pressure sensor 1, and in this state, an amplification factor increase signal of the amplification factor adjustment data Dg is input from the outside to the amplification factor adjustment memory 8a, and the amplification factor adjustment signal output from the amplification factor switching circuit 8b. Increase Sg. Then, the amplification factor in the amplifier circuit 3 increases, and the graph of the A / D conversion values at the atmospheric pressures P1 and P2 is as shown in FIG.
[0011]
After roughly adjusting the sensor signal processing device as described above, the atmospheric pressure P1 is added to the atmospheric pressure sensor 1 as described in the prior art, and in this state, the control signal S31 is input from the outside to the terminal C1 of the memory setting circuit 5a. The conversion data Dc output from the A / D conversion circuit 4 is stored in the A memory 5b. Next, the atmospheric pressure P2 is applied to the atmospheric pressure sensor 1, and in this state, the control signal S32 is input from the outside to the terminal C2 of the memory setting circuit 5a, and the conversion data Dc output from the A / D conversion circuit 4 is stored in the B memory 5c. To do. The microcomputer 5e controls the terminal C of the data selection circuit 5d, and the memory data Da stored in the A memory 5b (conversion data Dc at the atmospheric pressure P1) and the memory data stored in the B memory 5c. Db (conversion data Dc at the time of atmospheric pressure P2) is read, α and β are calculated, and a sensor characteristic equation expressed by the following equation 1 for determining the sensor information signal Dj is determined. When the digital conversion data Dc is input from the A / D conversion circuit 4 to the sensor information data processing circuit 5 having the sensor characteristic formula thus determined, the sensor information signal Dj calculated according to the sensor characteristic formula is output from the microcomputer 5e. Is done. The display device 6 displays an atmospheric pressure value (for example, 1013 hPa) based on the sensor information signal Dj.
[0012]
【The invention's effect】
As is apparent from the above description, according to the present invention, by providing an offset adjustment circuit and an amplification factor adjustment circuit, even a sensor with large variations in sensitivity and offset does not require adjustment with a single sensor, and the sensor completion yield is improved. In addition, even when sensors with different specifications are used, it is possible to cope with common hardware, which has a great effect on simplification of the adjustment process and cost reduction.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram showing a sensor processing apparatus of the present invention.
FIG. 2 is a circuit block diagram showing a conventional sensor processing apparatus.
FIG. 3 is a graph showing A / D conversion values with respect to atmospheric pressure in a conventional example.
FIG. 4 is a graph showing A / D conversion values with respect to atmospheric pressure in a conventional example.
FIG. 5 is a graph showing A / D conversion values with respect to atmospheric pressure according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Barometric pressure sensor 2 Sensor drive circuit 3 Amplification circuit 4 A / D conversion circuit 6 Display apparatus 7 Offset adjustment circuit 8 Amplification rate adjustment circuit

Claims (1)

A linear sensor for detecting physical information;
A sensor driving circuit for driving the sensor;
An amplifier circuit for inputting and amplifying a sensor signal output from the sensor;
An A / D converter circuit for converting the amplified output value processed by the amplifier circuit into digital information;
A data processing circuit for creating sensor information data from digital information output from the A / D conversion circuit;
The data processing circuit includes a first memory and a second memory respectively storing two different digital information data output from the A / D conversion circuit;
Sensor characteristic equation calculating means for calculating a sensor characteristic equation based on two digital information data stored in the two memories,
In a sensor signal processing device for converting digital information data output from the A / D conversion circuit into sensor information data according to a sensor characteristic equation calculated by the sensor characteristic equation calculating means,
An amplification factor adjustment circuit configured by an amplification factor adjustment memory and an amplification factor switching circuit, and adjusting the amplification factor of the amplification circuit based on digital amplification factor adjustment data stored in the amplification factor adjustment memory;
Is constituted by the offset adjustment memory and offset adjustment D / A conversion circuit includes an offset adjusting circuit for adjusting, based on the digital offset adjustment data stored in the offset adjustment memory offset voltage of the amplifying circuit, the amplification factor adjusting circuit A sensor signal processing apparatus , wherein the sensor characteristic equation is calculated by the sensor characteristic equation calculating means after coarsely adjusting an amplification factor and an offset voltage value of the amplifier circuit using the offset adjusting circuit .

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