JPH05281054A - Temperature detecting mechanism - Google Patents

Abstract

PURPOSE:To improve the accuracy of temperature detection by providing a temperature detecting mechanism with an output correcting means to correct a detected temperature based on the output of a temperature measuring element to a reasonable value according to dispersion in the accuracy of the temperature measuring element. CONSTITUTION:Standard voltage is applied to a series circuit composed of a thermister T and a resistance R, and the resultant data of A/D conversion of a voltage divided by both the components is compared with basic data to an influence temperature X deg.C stored in a table memory 3, and difference between the two data is stored in a fixed memory 4 as correcting data for the dispersion of temperature measuring elements. The voltage for the correcting data stored in the memory 4 is added to detected data through a data comparing section 2 to make the detected data coincide with a voltage value obtained by computation. After then, the data comparing section 2 determines temperature from in the table memory 3 on the basis of the voltage value after the above correction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detecting mechanism for detecting the temperature of an object to be measured by using a temperature measuring element such as a thermistor.

[0002]

2. Description of the Related Art For example, in a recording apparatus for recording an image using a thermal head, the recording density changes depending on the temperature of the thermal head. Therefore, the print pulse applied to the thermal head depends on the temperature of the thermal head. By controlling the pulse width, temperature control for uniformly controlling the recording density is executed.

As described above, for temperature control, a thermistor whose resistance value changes according to the temperature is widely used as a temperature measuring element for detecting the temperature of the controlled object.

An example of a temperature detecting circuit using this thermistor is shown in FIG.

In FIG. 4, a thermistor T and a resistor R are connected in series, the thermistor T is connected to the ground side, and the resistor R is connected to the power source side. The thermistor T is in close contact with or close to a controlled object. The temperature of the controlled object is then sensed.

Here, when the thermistor T having a characteristic that the resistance value decreases as the temperature rises is used, the voltage V at the interconnection end of the thermistor T and the resistance R becomes smaller as the temperature rises.

Therefore, the temperature of the controlled object can be detected by detecting the level of the voltage V.

[0008]

However, the temperature measuring element such as the thermistor T has variations due to accuracy of resistance value and accuracy of B constant. Further, the temperature measuring element such as the thermistor T and the resistance element for extracting an analog signal as a divided voltage signal from the reference voltage also have variations due to accuracy.

The result of A / D conversion of the analog signals from the elements having such variations varies depending on the individual elements, and temperatures having variations with respect to the reference temperature are detected. Therefore, the temperature that is higher or lower than the actual ambient temperature is detected, and the parameter for determining the energization time to the thermal head varies from product to product, resulting in different print quality for each product. Was occurring.

The present invention has been made in view of these points, and automatically corrects the output of the temperature measuring element to an appropriate value according to the variation in accuracy of the temperature measuring element such as the thermistor. An object of the present invention is to provide a temperature detection mechanism that can improve the accuracy of temperature detection.

[0011]

In order to achieve the above object, a temperature detecting mechanism of the present invention is a temperature detecting mechanism for detecting a temperature based on an output of a temperature measuring element. It is characterized by having an output correction means for correcting the detected temperature to an appropriate value in accordance with the variation in the accuracy of the temperature measuring element.

[0012]

According to the temperature detecting mechanism of the present invention, the output correcting means is capable of responding to variations in accuracy of temperature measuring elements such as thermistors.
Since the output of the temperature measuring element is automatically corrected to an appropriate value, the temperature detection accuracy can be improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In the embodiment of the present invention shown in FIG. 1, the thermistor T and the resistor R are connected in series, and the thermistor T is connected to the ground side and the resistor R is connected to the power source side. The thermistor T is arranged so as to be in close contact with or close to a controlled object such as a thermal head so that the temperature of the controlled object can be sensed. Further, between the thermistor T and the resistor R, an A / D converter 1 for converting the divided voltage by them into a digital value is arranged. This A / D
A data comparison unit 2 is connected to the conversion unit 1, and a table memory 3 and a non-volatile memory 4 are connected to the data comparison unit 2. In the table memory 3, reference data indicating a voltage value for each temperature, which is previously calculated, is stored. The non-volatile memory 4 is an EEP-ROM or NV-R.
Comprised of AM and the like, the correction data is stored and stored. The data comparison unit 2, the table memory 3, and the non-volatile memory 4 serve as an output correction unit that corrects the detected temperature to an appropriate value according to the variation in accuracy.

Next, the operation of this embodiment will be described.

In this embodiment, the correction data is input to the non-volatile memory 4 when the temperature detecting mechanism is manufactured.
This will be described with reference to the flowchart of FIG.

First, in step ST11, the environmental temperature X ° C. in the manufacturing process is input to the data comparison section 2 by an input means (not shown). Next, in step ST12,
Temperature detection and A / D conversion are performed. That is, a standard voltage is applied to a series circuit composed of a thermistor T which is a temperature measuring element and a resistor R, the voltage divided by the two is taken out as an analog signal, and this analog signal is A /
The D conversion unit 1 converts the digital value. Next, in step ST13, the data of the A / D conversion result is compared with the reference data stored and stored in the table memory 3 for the environmental temperature X ° C. Next, in step ST14, the difference between these two data is used as correction data for the dispersion of the temperature measuring elements, and the EEP-ROM and NV-RA are used.
It is stored in the nonvolatile memory 4 such as M. FIG. 3 is an output voltage / temperature characteristic diagram showing an example of occurrence of such a variation. An output voltage B based on a thermistor T and an output voltage C based on a resistor R with respect to a reference voltage A previously calculated. Do not match, and the difference from the reference voltage A is the voltage value for the correction data. The correction data obtained from this FIG. 3 is almost constant even if the temperature changes. This ends the automatic adjustment mode before product shipment.

In actual use by the user thereafter,
A / D conversion result data obtained by A / D converting the analog signal composed of the voltage detected by the thermistor T, which is a temperature measuring element, is stored and stored in the non-volatile memory 4. The voltage for the corrected data is
The voltage value obtained by calculation is matched with the calculated voltage value. Then, the data comparison unit 2 obtains the temperature from the data stored in the table memory 3 based on the corrected voltage value. As a result, the detected temperature has a value that exactly matches the actual environmental temperature. For example, with respect to the environmental temperature of 25 ° C., the standard data indicated by the line A in FIG.
Where 5V is required, the thermistor T shown in line B of FIG.
The detected voltage is 2.6V, but the nonvolatile memory 4
The difference between the two, which is the correction data in 0.1 V, is subtracted from 2.6 V by the data comparison unit 2, and the detected temperature of 25 ° C. is output from the temperature detection mechanism.

Therefore, according to this embodiment, the thermistor T
Even if there are variations in the temperature measuring elements such as the above, the variations in the temperature detection mechanism can be eliminated, and the printing quality for each product can be made more stable.

The present invention is not limited to the above embodiment, but can be modified as necessary. For example, if the manufacturing process environment is always kept constant,
The data stored and stored in the table memory is only the reference data for the environmental temperature, and the input of the environmental temperature in the automatic adjustment mode can be omitted.

Further, the data can be adjusted by inputting the data into the table memory with the switch of the operation panel.

[0022]

As described above, since the temperature detecting mechanism of the present invention is constructed and operates, the output of the temperature measuring element is corrected to an appropriate value according to the variation in accuracy of the temperature measuring element such as the thermistor. Since it has the output correction means for controlling the temperature, the accuracy of temperature detection can be improved. Therefore, in a plurality of printers and the like equipped with the mechanism of the present invention, it is possible to stabilize the print quality of each product more uniformly.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a temperature detecting mechanism of the present invention.

FIG. 2 is a flowchart showing setting of temperature correction data in this embodiment.

FIG. 3 is a temperature-output voltage characteristic diagram showing an example of a variation state.

FIG. 4 Conventional temperature detection circuit diagram

[Explanation of symbols]

 T thermistor R resistance V voltage 1 A / D conversion unit 2 data comparison unit 3 table memory 4 non-volatile memory

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // G01K 15/00 7267-2F

Claims (1)

[Claims] 1. A temperature detecting mechanism for detecting a temperature based on an output of a temperature measuring element, wherein a detected temperature based on an output of the temperature measuring element is corrected to an appropriate value according to a variation in accuracy of the temperature measuring element. A temperature detecting mechanism comprising: