JPH07213073A - Brightness adjusting method of inverter-device display part - Google Patents

Abstract

PURPOSE:To provide a brightness adjusting method in which the brightness of an inverter-device display part made of a liquid-crystal display element is always almost constant irrespective of the operating state of an inverter device or irrespective of a change in the outside temperature. CONSTITUTION:The A/D-converter signal of a power-element temperature by a temperature sensor or of a temperature detection signal near it is read out by a CPU. In succession, the temperature of a liquid-crystal display element constituting a display part is operated according to a temperature-estimation operation program which is composed of a distance variable and of a time variable which contains a peculiar time constant. In succession, an applied voltage to the display element (LCD) is computed on the basis of an estimated and operated liquid-crystal-element temperature. In succession, the applied voltage which has been computed is given, as its output-voltage instruction value, to an electronic variable resistor as an application-voltage adjustment means to the LCD. The applied voltage is prescribed by a functional relationship which is reduced at a prescribed grade with increase in the estimated element temperature from a reference voltage at the reference temperature of, e.g. the liquid-crystal display element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for automatically adjusting the brightness of a display unit of an inverter device, which is composed of a liquid crystal display device, in response to temperature changes.

[0002]

2. Description of the Related Art Conventionally, the brightness of an inverter device display section composed of a liquid crystal display element is changed when the brightness of the display section changes under the influence of the outside air temperature or the temperature fluctuation caused by the internal heat generated by the operation of the apparatus itself. As a brightness adjusting method, there is known a method in which the voltage applied to the liquid crystal display element is changed through manual operation of the voltage applying means by an operator to correct the brightness to be considered appropriate by the operator himself.

[0003]

The temperature of the liquid crystal display element forming the display unit of the inverter device depends on the outside air temperature around the inverter device and the self-heating amount of the internal storage function element which changes depending on the operating state of the inverter device. It changes depending on the internal temperature of the device that is affected. Therefore, the brightness of the display unit of the inverter device formed by the liquid crystal display element having a sensitive temperature characteristic with respect to the brightness frequently and irregularly changes depending on the outside air temperature or the operating state of the inverter device.

The above-mentioned fluctuation of the brightness of the display portion is annoying to the operator of the apparatus, and the brightness correction work by the manual operation is troublesome. In view of the above, it is an object of the present invention to provide a brightness adjusting method for automatically correcting a brightness variation caused by a temperature change of a liquid crystal display element constituting an inverter device display section by adjusting a voltage applied to the liquid crystal display element. Is.

[0005]

In order to achieve the above object, in the method for adjusting the brightness of an inverter device display section according to the present invention, 1) According to claim 1, the brightness adjustment of the inverter device display section comprising a liquid crystal display element is performed. In the method, the brightness of the display section is adjusted by automatically adjusting the applied voltage of the liquid crystal display element according to the temperature change of the liquid crystal display element itself.

2) According to a second aspect, in the brightness adjusting method for an inverter device display section according to the first aspect, an estimation calculation is performed from a detection signal of a temperature sensor provided at an arbitrary position inside the inverter device according to a predetermined calculation program. The temperature thus obtained is used as the required liquid crystal display element temperature. 3) According to claim 3, in the brightness adjusting method for an inverter device display section according to claim 1, the voltage applied to the liquid crystal display element is set to a predetermined value from a reference voltage at a reference temperature of the display element as the element temperature increases. It shall be specified by the functional relationship that is reduced by the gradient.

4) According to a fourth aspect of the present invention, in the brightness adjusting method of the inverter device display section according to the second aspect, the detection signal of the temperature sensor for brightness adjustment of the display section is an inverter section switching element housed in the inverter apparatus. The detection signal of the temperature sensor provided for the thermal protection of various functional elements such as is shared.

[0008]

In general, the liquid crystal display device functions by controlling the electric field between the electrodes, but at the same time, it has a sensitive temperature characteristic with respect to its brightness. The present invention relates to automatic correction of luminance fluctuation due to temperature change of an inverter device display section composed of a liquid crystal display element. 1) According to claim 1, voltage applied between electrodes according to temperature change of the liquid crystal display element. Is automatically adjusted.

2) According to a second aspect, the temperature of the liquid crystal display element that defines the voltage applied between the electrodes is estimated from a detection signal of a temperature sensor provided at an arbitrary position inside the inverter device according to a predetermined calculation program. It is something that is calculated. 3) According to claim 3, the voltage applied to the liquid crystal display element is defined by a functional relationship in which the voltage is reduced from the reference voltage at the reference temperature of the display element with a predetermined gradient as the estimated element temperature is increased. Is.

4) According to a fourth aspect of the present invention, the detection signal of the temperature sensor for adjusting the brightness of the display section is the temperature provided for thermal protection of various functional elements such as the switching element of the inverter section housed in the inverter device. The sensor detection signal is shared.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the flow chart shown in FIG. 2 and 3 are an example of a front view and a side sectional view of the inverter device, respectively. First, an outline of the board surface of the inverter device and the arrangement of the devices in the board will be described with reference to FIGS. 2 and 3. In FIG. 2, 1 is an inverter device, 2 is an operation panel which includes various operation keys and a display unit and which is attached to the panel surface of the inverter device 1, and 3 is a display unit which is attached to the operation panel 2 and is a liquid crystal display element (LC).
D). Further, in FIG. 3, reference numeral 4 is a control board, 5 is a power element mounting plate on which a switching power element of the inverter unit is mounted, and 6 is a temperature sensor for heat protection of the power element.

FIG. 3 shows an example of the mutual positional relationship between the display unit 3 and the temperature sensor 6, and this positional relationship is not fixed. Further, generally, most of the heat generated in the inverter device 1 is generated in the power element of the inverter part. Therefore, the temperature of each place in the inverter device 1 including the temperature in the display part is peculiar to the temperature of the power element. It can be considered to change with a positional and temporal relationship. The temperature of the power element itself fluctuates based on the outside air temperature of the inverter device 1.

In accordance with the above, the present invention is to automatically adjust the voltage applied to the liquid crystal display element constituting the display unit 3 in accordance with the temperature of this element by the temperature estimation calculation program shown in the flow chart of FIG. Regarding the detection of the element temperature, the detection signal of the temperature sensor 6 for heat protection is shared as an input signal of the arithmetic program shown in the above flow chart without providing a dedicated temperature sensor. The detection signal of the temperature sensor 6 is assumed to have been A / D converted as an input signal of the heat protection arithmetic circuit of the power element.

Here, in the flow chart of FIG.
First, the power element temperature by the temperature sensor 6 or the A / D converted signal of the temperature detection signal in the vicinity thereof is read into the CPU, and subsequently, the temperature of the liquid crystal display element forming the display unit 3 includes a distance variable and a peculiar time constant. It is calculated according to a temperature estimation calculation program consisting of time variables, and then the voltage applied to this liquid crystal display element (LCD) is calculated based on the estimated temperature of the liquid crystal display element, and subsequently as means for adjusting the voltage applied to the LCD. The calculated applied voltage is given to the electronic volume as the output voltage command value.

The applied voltage calculation program defines, for example, the applied voltage from a reference voltage at the reference temperature of the liquid crystal display element by a functional relationship in which the estimated element temperature is increased and is decreased by a predetermined gradient. Is.

[0016]

According to the present invention, with respect to the brightness adjustment of the inverter device display section composed of the liquid crystal display element, the applied voltage is automatically adjusted according to the temperature change of the liquid crystal display element itself according to claim 1, and According to the second aspect, the temperature of the liquid crystal display element is estimated and calculated according to a predetermined calculation program from the detection signal of the temperature sensor installed at an arbitrary position inside the inverter device, and the voltage applied to the liquid crystal display element is calculated according to the third aspect. It is defined by a functional relationship in which a reference voltage at a reference temperature of a display element is reduced by a predetermined gradient as the temperature of the liquid crystal display element increases, and the detection signal of the brightness adjusting temperature sensor according to claim 4 is the inverter. Detection of temperature sensor provided for thermal protection of various functional elements such as inverter switching elements housed in the equipment By sharing the signal, the brightness of an inverter device display section composed of a liquid crystal display element having a sensitive temperature characteristic with respect to the brightness can be improved even if the ambient temperature or the operating state of the inverter device fluctuates. It is possible to always maintain a substantially constant desired state without newly installing a correction temperature sensor, and the operator can avoid the troublesome brightness correction work.

[Brief description of drawings]

FIG. 1 is a flowchart of a temperature estimation calculation program showing an embodiment of the present invention.

FIG. 2 is a front view of the inverter device.

FIG. 3 is a side sectional view of the inverter device.

[Explanation of symbols]

 1 Inverter device 2 Operation panel 3 Display (LCD) 4 Control board 5 Power element mounting plate 6 Temperature sensor

Claims (4)

[Claims] 1. A method for adjusting the brightness of an inverter device display section comprising a liquid crystal display element, wherein the brightness of the display section is adjusted by automatically adjusting the applied voltage according to the temperature change of the liquid crystal display element. A method for adjusting the brightness of an inverter device display unit, comprising: 2. The method for adjusting the brightness of an inverter device display unit according to claim 1, wherein the temperature is estimated from a detection signal of a temperature sensor provided at an arbitrary position inside the inverter device according to a predetermined calculation program. The method for adjusting the brightness of the display unit of the inverter device is characterized in that the temperature of the liquid crystal display element is set. 3. The brightness adjusting method for an inverter device display unit according to claim 1, wherein a voltage applied to said liquid crystal display element is changed from a reference voltage at a reference temperature of said display element to a predetermined gradient as said element temperature increases. The brightness adjustment method of the inverter device display section is characterized by being defined by a functional relationship that is reduced by 4. The method for adjusting the brightness of an inverter device display section according to claim 2, wherein the detection signal of the temperature sensor for brightness adjustment of the display section is a functional element such as an inverter section switching element housed in the inverter apparatus. A method for adjusting the brightness of an inverter device display section, wherein a detection signal of a temperature sensor provided for thermal protection of the same is shared.