JPH0713495A - Terminal device to be personally carried - Google Patents

Abstract

PURPOSE:To prevent the degradation in display quality, malfunction of electronic parts and low-temp. destruction by a low temp. by mounting temp. sensors on a printed circuit board, laying exothermic sheets on the rear surface of a liquid crystal display and the front surface or rear surface of the printed circuit board and allowing the exothermic sheets to generate heat or insulate heat according to a temp. change, thereby maintaining a preset temp. CONSTITUTION:The first temp. sensor part of the first temp. sensor 7 mounted on the printed circuit board 2 makes the same operation as the operation of the first temp. sensor 6 mounted on the same surface as the surface of the liquid crystal display LCD. Namely, The analog output of the temp. sensor 7 is converted by an A/D converter which is not shown in Fig. to a digital signal. A CPU 3 executes temp. control of the second exothermic sheet 5 in accordance with this signal. The discrimination reference temp. of this sensor is different from that of the temp. sensor 6. The second temp. sensor part of the second temp. sensor 7 directly controls the power source input of the exothermic sheet 5 without sending its output signal to the CPU 3, thereby warming up the circuit board even in the case of the power source off of the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to all electronic equipment used in a low temperature environment, and more particularly to a liquid crystal display so-called LCD (Liquid Crystal Display, hereinafter simply referred to as "LC").
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[0002]

2. Description of the Related Art In the prior art, for example, temperature countermeasures for a notebook computer and the like are only high temperature countermeasures for fans and heat sinks, but not low temperature countermeasures.

[0003]

The LCD used in the above-mentioned notebook personal computer or the like has a slow response speed when the temperature is lowered, and the display quality is deteriorated. Also, when the temperature drops to a few tens of degrees below the freezing point, the electronic components may malfunction and eventually even be destroyed. In view of this problem, an object of the present invention is to provide a personal portable terminal device that is resistant to temperature changes.

[0004]

In order to solve this problem, according to the present invention, a temperature sensor is mounted on a printed circuit board on which an LCD frame and electronic parts are mounted, and the LCD is further mounted.
A thin sheet-shaped heat generating sheet with a power source is laid on the back side of the LCD and the front or back of the printed circuit board, and the temperature sensor monitors the surface temperature of the LCD and the temperature of the printed circuit board. The personal portable terminal device keeps a preset temperature by turning on or off the power source to heat or heat-insulate the heat generating sheet.

[0005]

According to the present invention by the above means, quality deterioration due to temperature decrease of LCD is prevented, and malfunction and destruction of electronic parts at low temperature are prevented, so that high quality and high reliability are achieved. An existing personal mobile terminal device can be realized.

[0006]

Embodiments of the present invention will be sequentially described below with reference to the drawings.

FIG. 1 is a block diagram showing an electric circuit configuration in an embodiment of the present invention. Each block of this configuration diagram will be described. 1 is an LCD. Due to the physical properties of liquid crystal, it has a property that the response speed to an electric signal becomes low at low temperature. Reference numeral 2 is a printed circuit board on which electronic components of this apparatus are mounted. Reference numeral 3 denotes a CPU mounted on the printed circuit board 2. Reference numeral 4 is a first heat generating sheet attached to the LCD 1, and 5 is a second heat generating sheet attached to the printed circuit board 2. 6 is an LCD frame 11 which is on the same surface as the LCD 1.
It is the first temperature sensor mounted on top. A second temperature sensor 7 is attached to the printed board 2. Reference numeral 8 denotes a power source for the present apparatus, which is a power source for all electronic components and a heat source for the heat generating sheets 4 and 7. However, in addition to the power source 8, a further power source is provided,
It is also desirable to keep all of the electronic components on the LCD 1 and the printed circuit board 2 under temperature control even when the device itself is off.

Next, the specific operation of the apparatus will be described with reference to the circuit configuration diagram of FIG. 1 and the perspective conceptual diagram of FIG. The first temperature sensor 6 outputs an absolute temperature as a voltage, and although not shown, its analog signal is converted into a digital signal by an A / D converter. The CPU 3 inputs the digital signal and detects the temperature of the LCD 1. Celsius 1
When 0 degree is used as the criterion for the temperature control of the LCD 1, when the temperature reaches 10 degrees Celsius or less, the first heat generating sheet 4
Turn on the switch [ON] to warm LCD1. Even if the ambient temperature drops by this operation, the temperature of the LCD 1 does not drop below 10 degrees Celsius, and as a result, the display response speed does not drop and a certain level of display quality can be maintained. However,
When the temperature of the LCD 1 becomes higher than the set value, the switch is automatically turned off, and in the low temperature environment, the switch is repeatedly turned on or off though the cycle is long.

By setting the judgment reference temperature variably, the set temperature can be adjusted by observing the actual reaction speed of the LCD 1.

The second temperature sensor 7 is composed of two types of temperature sensors. The first temperature sensor section of the second temperature sensor 7 operates in the same manner as the first temperature sensor 6. That is, the analog output of the temperature sensor 7 is converted into a digital signal by an A / D converter (not shown), and the CPU 3 controls the temperature of the second heat generating sheet 7 based on the signal.
The difference from the first temperature sensor 6 is that the determination reference temperature is set differently. By setting the lower limit temperature of the operation guarantee temperature of the electronic component as the judgment reference temperature, malfunction of the electronic component due to low temperature is prevented. In the present invention, the judgment reference temperature is set to -10 degrees Celsius to guarantee the operation of the device in cold regions.

The second temperature sensor portion of the second temperature sensor 7 differs from the above-mentioned temperature sensor 4 and the like in that the output signal is C
The power input of the heat generating sheet 5 is directly controlled without sending it to the PU 3. That is, the outputs of the temperature sensors 6 and 7 are compared with a certain voltage [not shown], and the heating sheets 4 and 5 are turned on or off based on the result. If this control unit is operated by a battery different from the power source 8, even if the power of the device is turned off, if the temperature of the device is lowered due to the temperature decrease around the device, the heat generating sheets 4 and 5 are The switch can be turned on to heat the board. As shown in FIG. 2B, the determination reference temperature for the ON or OFF control of the heat generating sheets 4 and 5 at this time is set to the lower limit temperature of the guaranteed storage temperature of the electronic component, so that the power is turned off. Then, when the temperature of the device is lowered to around the dangerous temperature, the heat generating sheets 4 and 5 are turned on to warm the electronic components mounted on the substrate and prevent the low temperature destruction. Since the lower limit temperature of the guaranteed storage temperature of an electronic component is usually about -40 degrees Celsius, the outputs of the temperature sensors 6 and 7 at this temperature are used as reference voltages for comparison, and the heat generating sheets 4 and 5 are controlled. As described above, the two heat generating sheets 4 and 5 are based on the three kinds of temperatures.
By controlling the temperature, it is possible to prevent a decrease in the reaction speed of the LCD 1 due to a low temperature, and it is possible to prevent malfunction and low temperature destruction of electronic components due to a low temperature.

[0012]

As described above, according to the present invention, it is possible to prevent the deterioration of the display quality of LCD due to low temperature, the malfunction of electronic parts and the destruction at low temperature, and to realize a personal portable terminal device of high quality and high reliability, and to carry out this type of portable device. It is possible to achieve a particular effect that the display speed and the useful life of the terminal device are significantly improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electric circuit configuration according to an embodiment of the present invention.

FIG. 2A is a perspective conceptual view showing a three-dimensional structure in one embodiment of the present invention. FIG. 2B is an explanatory view of a reference temperature for setting a sensor sensing temperature.

[Explanation of symbols]

 1 LCD 2 Printed circuit board 3 CPU 4,5 Heat generating sheet 6,7 Temperature sensor 8 Power supply 11 LCD frame

Claims (2)

[Claims] 1. A personal portable terminal device comprising a display device and a printed circuit board on which an LCD and electronic components are mounted and printed and arranged side by side. The temperature sensor is provided on the same surface as the display surface of the LCD. A heat generating sheet that forms a thin sheet-like heat generating part having a power source on the back surface of the LCD, temperature change detecting means for detecting a temperature change of the display surface of the LCD detected by a temperature sensor, and temperature change by the temperature change detecting means. Means for keeping the LCD at the set temperature by turning on or off the power source to heat the heat generating sheet based on the information of 1. 2. The personal portable terminal device according to claim 1, wherein a temperature sensor is provided on the printed circuit board, a heat generating sheet is formed on the front surface or the back surface of the printed circuit board and has a thin sheet-like heat generating portion, and the temperature sensor detects the temperature. A temperature change detecting means for detecting a temperature change of the printed circuit board, and a means for keeping the printed circuit board at the set temperature by turning on or off the power source based on the information of the temperature change to heat the heat generating sheet. A personal portable terminal device characterized by: