Title of Invention

A LIQUID CRYSTAL DISPLAY FOR A VEHICLE

Abstract A liquid crystal display for a vehicle comprising: a liquid crystal display panel; a circuit board for mounting circuit elements including a liquid crystal driver; a temperature sensor mounted directly on the circuit board for detecting an ambient temperature of the circuit board; and a control circuit, mounted on the circuit board, for controlling liquid crystal drive voltage based on the ambient temperature detected by the temperature sensor, the liquid crystal display panel and the circuit board being placed one upon the other in a meter housing having a substantially closed space therein with a predetermined space therebetween, wherein the display further comprises a heat collection panel exposed to surround the screen of the liquid crystal display panel, said heat collection panel divides an inside space of the meter housing where said temperature sensor and said liquid crystal display are mounted, and causes the ambient temperature of said temperature sensor to follow a temperature change of said liquid crystal display panel.
Full Text FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
COMPLETE SPECIFICATION
[See Section 10]
"LIQUID CRYSTAL DISPLAY FOR VEHICLE"
HONDA GIKEN KOGYO KABUSHIKI KAISHA, a corporation of Japan, 1-1, Minamiaoyama 2-chome, Minato-ku, Tokyo, Japan
The following specification particularly describes the nature of the invention and the manner in which it is to be performed :-


[Detailed Description of the Invention]
[0001]
[Field of the Invention]
The present invention relates to a liquid crystal display for vehicle and, particularly, to a liquid crystal display for vehicle which adjusts liquid crystal drive voltage based on the temperature of a liquid crystal display panel so that the contrast of the liquid crystal display panel becomes optimum.

[0002]
[Prior Art]
In a liquid crystal display, the contrast of a liquid crystal display panel changes according to an ambient temperature environment even if liquid crystal drive voltage remains the same. Then, Japanese Laid-Open Patent Application No. 10-31204 proposes a liquid crystal display which automatically adjusts liquid crystal drive voltage based on the temperature of the liquid crystal panel detected by a temperature sensor such as a thermistor.
[0003]
That is, the contrast of liquid crystals has correlation with temperature and drive voltage must be reduced as the temperature of the liquid crystals becomes higher in order to keep a large difference in brightness between the time when liquid crystals are on in a transparent state and the time when the liquid crystals are off in a non-transparent state, that is, high contrast of the liquid crystals. Therefore, in the above prior art, the ambient temperature of the liquid crystals is detected by a temperature sensor and a temperature compensation circuit is provided to increase drive voltage when the ambient temperature drops and conversely reduce drive voltage when the"ambient temperature rises.
[0004]
[Problem to Be Solved by the Invention]
In the above prior art, the temperature of a liquid crystal display panel is represented by the detection temperature of a temperature sensor for detecting the inside

temperature of a housing. However, in a liquid crystal display which is often exposed to direct rays of the sun as when it is employed as the meter panel of a motorcycle, there is a temperature difference between the ambient temperature of the inside of the housing and the actual temperature of the liquid crystal display panel, thereby making it difficult to apply the optimum liquid crystal drive voltage. To solve this technical problem, a technology for mounting a temperature sensor to a liquid crystal display panel is also proposed.
[0005]
However, when the temperature sensor is mounted to the liquid crystal display panel, an electrode for connecting this temperature sensor to a circuit board are newly required, thereby causing technical problems such as an increase in the number of parts or a complicated production process.
[0006]
It is an object of the present invention to provide a liquid crystal display for vehicle panel which can control liquid crystal drive voltage accurately without mounting a temperature sensor to a liquid crystal display panel.
[0007]
[Means for Solving the Problem]
To attain the above object, according to the present invention, there is provided a liquid crystal display for vehicle comprising a liquid crystal display panel, a circuit board mounting circuit elements including a liquid crystal driver, a temperature sensor mounted on the circuit board, and a control circuit, mounted on the circuit board, for

controlling liquid crystal drive voltage based on the detection temperature of the temperature sensor, the liquid crystal display panel and the circuit board being arranged parallel to each other with a predetermined space therebetween in a meter housing, wherein the display further comprises ah exposed heat collecting panel arranged to surround the screen of the liquid crystal display panel. [0008]
According to the above feature, when the temperature of the liquid crystal display panel is increased by exposure to sunlight, the inside, of the apparatus is heated by the heat collection panel to keep the difference between the ambient temperature in the housing detected by the temperature sensor and the actual temperature of the liquid crystal display panel substantially constant. Therefore, since the temperature of the liquid crystal display panel can be judged accurately based on the detection temperature of the temperature sensor in a high temperature environment in which the appropriate range of liquid crystal drive voltage is narrow, drive voltage can be controlled to the optimum value based on the detection temperature of the temperature sensor.

The present invention relates to a liquid crystal display for a vehicle comprising: a liquid crystal display panel; a circuit board for mounting circuit elements including a liquid crystal driver; a temperature sensor mounted directly on the circuit board for detecting an ambient temperature of the circuit board; and a control circuit, mounted on the circuit board, for controlling liquid crystal drive voltage based on the ambient temperature detected by the temperature sensor, the liquid crystal display panel and the circuit board being placed one upon the other in a meter housing having a substantiafly closed space therein with a predetermined space therebetween, wherein the display further comprises a heat collection panel exposed to surround the screen of the liquid crystal display panel, said heat collection panel divides an inside space of the meter housing where said temperature sensor and said liquid crystal display are mounted, and causes the ambient temperature of said temperature sensor to follow a temperature change of said liquid crystal display panel. Detailed Description of the Preferred Embodiments
Preferred embodiments of the liquid crystal display for vehicle according to the present invention will be described in detail with reference to the accompanying drawings.

[Brief Description of the Drawings]
[Fig. 1] This is a front view of a liquid crystal display
for vehicle according to the present invention.
[Fig. 2] This is a sectional view cut on line A-A of Fig. 1.
[Fig. 3] This is a diagram showing the relationship between the temperature Tq of a liquid crystal display panel and temperature T detected by a temperature sensor when a heat collection panel is not provided.
[Fig. 4] This is a diagram showing the relationship between the temperature Tq of the liquid crystal display panel and temperature T detected by the temperature sensor when the heat collection panel is provided.
[Fig. 5] This is a block diagram of the control circuit of the liquid crystal display for vehicle.
[Fig. 6] This is a block diagram showing the constitution of the essential section of Fig. 5 functionally.
[Fig. 7] This is a diagram showing the' relationship. between the temperature of the liquid crystal display panel and liquid crystal drive voltage.
[Fig. 8] This is a front view of the key section of a motorcycle provided with the liquid crystal display for vehicle of the present invention. [0010] Fig. 8 is a front view of the essential section of a

motorcycle provided with the liquid crystal display 1 for vehicle of the present invention. The liquid crystal display 1 for vehicle is mounted to a center portion of a handlebar 61 and winkers 37L and 37R are arranged on right and left sides of the handlebar 61 such that they project from the handlebar 61. On the right side of the vehicle body of a leg shield 62 is arranged a power switch 38 which can be operated by a power key.
[0011]
A brake lever 39 for front wheels is provided on the right grip 61R of the handlebar 61 and a brake lever 36 for rear wheels is provided on the left grip 61L. Mirrors 46L and 46R are provided on left and right sides of the handlebar 61.
[0012]
Fig. 1 is a front view of the liquid crystal display 1 for vehicle and Fig. 2 is a sectional view cut on line A-A of Fig. 1. Since the liquid crystal display 1 for vehicle of this embodiment is mounted to a vehicle in such a manner that it is inclined at an angle 6 in a longitudinal direction, the sectional view of Fig. 2 is inclined at the angle 0 .
[0013]
In this embodiment, an opaque support case 2 0 and a transparent case cover 21 constitute a housing and both are fixed to each other at three locations by screws 31, 32 and 33. In the housing, a liquid crystal display panel 10 containing liquid crystals sealed up between two glass sheets 10a and 10b is held by a liquid crystal holder 16. Process data such as vehicle speed, engine speed, water temperature and the

amount of the residual fuel are displayed on this liquid crystal display panel 10 . A heat collection panel 11 having an opening 12 for exposing the screen of the liquid crystal display panel 10 is placed on the exposed side of the liquid crystal display panel 10 to surround the screen of the liquid crystal display panel 10.
[0014]
The above heat collection panel 11 comprises an opaque resin panel 11a and an ^diabatic cushion material lib mounted on the rear side of the panel 11a to surround the above opening 12. Therefore, the opaque resin panel 11a which is directly exposed to rays of the sun passing through the case cover 21 and the liquid crystal display panel 10 are in contact with each other through the above adiabatic cushion material lib. Since the above heat collection panel 11 is arranged such that it divides the inside space of the meter housing, the temperature change rates of the both spaces become equal to each other.
[0015]
The above liquid crystal holder 16 is placed upright on the circuit board 17 by its leg portions 14 and 18. An illumination LED 15 is placed upright on the circuit board 17 and the end of the light emitting portion of the LED 15 is exposed outward from the opening formed in the heat collection panel 11. Circuit elements guch as an LCD driver for driving the liquid crystal display panel 10, LED driver (not shown) for driving the illumination LED 15, temperature sensor 51 for detecting the ambient temperature of the circuit board 17 and

temperature detection circuit (not shown) for controlling the above LCD driver based pn temperature information detected by the above temperature sensor 51 are mounted on the above circuit board 17. The above liquid crystal display panel 10 and the circuit board 17 are electrically connected by an electrode 52.
[0016]
Figs. 3 and 4 shPW the actual temperature (Tq) of the above liquid crystal display panel 10 and the internal ambient temperature (T) detected by the above temperature sensor 51 when the above heat collection panel 11 is not provided (Fig. 3) and when the panel H is provided (Fig. 4). [0017]
At night before a time to or in the shade, the temperature Tq of the liquid crystal display panel and the detection temperature T are almost equal to each other. In contrast to this, when pseudo sunlight begins to be irradiated at a time tO, the difference betveen the temperature Tq of the liquid crystal display panel a^d the detection temperature T becomes larger along the passage of time as shown in Fig. 3 without the heat collection paJiel 11. Therefore, there is a big difference between the temperature difference ATI at a time tl and the temperature difference AT2 at a time t2.
[0018]
In contrast to this, since the detection temperature T of the temperature sensor 51 rises in the same manner as the temperature Tq of the liquid crystal display panel as shown in Fig. 4 when the heat collection panel 11 is provided, the

difference between the both temperatures remains almost the same regardless of the passage of time. That is, the temperature difference ATI at a time tl and the temperature difference AT2 at a time t2 are almost equal to each other.
[0019]
Consequently, when the heat collection panel 11 is provided to surround tl*e liquid crystal display panel 10, the actual temperature Tq of the liquid crystal display panel 10 can be judged accurately simply by adding a compensation temperature ATadd equivalent to the above temperature difference ATI (= temperature difference AT2) to the detection temperature T of the temperature sensor 51.
[0020]
Further, as air warmed by heat generated by the heat collection panel and circuit elements is convected upward in the housing, the ambient temperature of an upper portion has higher follow-up properties to the temperature rise of the liquid crystal display panel 10 than the ambient temperature of a lower portion. SiAce the temperature sensor is placed at a high position while the liquid crystal display for vehicle is properly mounted on a vehicle in the above described embodiment, the folloW-up properties of the detection temperature T to the temperature change of the liquid crystal display panel 10 are improved.
[0021]
Fig. 5 is a block diagram of the control circuit of the above liquid crystal display 1 for vehicle, wherein the same reference numerals as above denote the same or corresponding

parts.
[0022]
An LCD driver 53 supplies a liquid crystal drive signal to the liquid crystal display panel (LCD) 10 in response to an instruction from a CPU 50. The LED driver 54 supplies an LED drive current to an LED 15 in response to an instruction from the CPU 50. A temperature detection circuit 56 converts the resistance value of the temperature sensor 51 (thermistor in this embodiment) into temperature information. The CPU 50 receives process data D such as vehicle speed and engine speed and outputs their segment data to the LCD driver 53. Control programs and reference values are stored in a ROM 55.
[0023]
Fig. 6 is a block diagram showing the constitution of the essential section of the above control circuit functionally, wherein the same reference numerals as above denote the same or corresponding parts.
[0024]
A function f(T) for controlling LCD drive voltage to an appropriate range based on the detection temperature T of the temperature sensor 51 is registered in the first storage portion 551 of the ROM 55. A compensation temperature ATadd equivalent to the difference between the temperature Tq of the liquid crystal display panel and the detection temperature T is registered in the second storage portion 552.
[0025]
The temperature compensation portion 502 of the CPU 50 outputs a switch signal Sch when the detection temperature T

reaches a predetermined reference temperature Tref (45*0 in this embodiment) . An adder 504 adds the detection temperature T of the temperature sensor 51 and the above compensation temperature ATadd. A switch portion 503 provides the detection temperature T to a drive voltage decision portion 501 when the switch signal Sch is not output from the above temperature compensation portion 502 and provides the total value (ATadd + T) of the compensation temperature ATadd stored in the second storage portion 552 and the detection temperature T to the drive voltage decision portion 501 when the switch signal Sch is output.
[0026]
A decoder 505 converts the process data D into a segment signal to supply it to the LCD driver 53. The drive voltage decision portion 501 determines LCD drive voltage based on the above function f (T) and temperature information provided from the above switch portion 503 to control the LCD driver 53.
[0027]
In this constitution, when the detection temperature T of the temperature sensor 51 does not exceed the reference temperature Tref (45"C), the detection temperature T is selected by the switch portion 503. Therefore, the drive voltage decision portion 501 determines LCD drive voltage based on the function f(T) and the detection temperature T.
[0028]
In contrast to this, when the detection temperature T of the temperature sensor 51 exceeds the reference temperature Tref, the addition portion 504 is selected by the switch portion

503. Therefore, the drive voltage decision portion 501 determines LCD drive voltage based on the function f(T) and the total temperature (ATadd + T).
[0029]
Fig. 7 is a diagram showing the relationship between the temperature Tq of the liquid crystal display panel and LCD drive voltage in this embodiment.
[0030]
The liquid crystal display panel 10 is blackened when its LCD drive voltage exceeds an appropriate range and whitened when the LCD drive voltage falls below the appropriate range. Although the upper limit voltage Vmax and the lower limit voltage Vmin of the appropriate range fall as the temperature rises, since the reduction rate of the upper limit voltage Vmax is larger than the reduction rate of the lower limit voltage Vmin, the appropriate range of the LCD drive voltage narrows as the temperature of liquid crystals increases.
[0031]
In contrast to this, as the detection temperature T can represent the temperature Tq of the liquid crystal display panel accurately until the detection temperature T of the temperature sensor 51 exceeds 45^3 in this embodiment as shown in Fig. 4, the LCD drive voltage can be set to an almost intermediate level of the appropriate range based on the above function f(T) and the detection temperature T.
[0032]
As the total value (T + ATadd) of the detection temperature T and the compensation temperature ATadd can

represent the temperature Tq of-the liquid crystal display panel accurately when the detection temperature exceeds 45°C, the LCD drive voltage can be set to an almost intermediate level of the appropriate range based on the above function f(T) and the total value (T + ATadd) .
[0033]
According to the present invention, the following effects are obtained.
(1) The heat collection panel is provided to surround the liquid crystal display panel so that the detection temperature T of the temperature sensor rises, keeping a constant temperature difference from the temperature Tq of the liquid crystal display panel when the temperature Tq of the liquid crystal display panel is increased by exposure to direct rays of the sun. Therefore, simply by adding the above temperature difference to the detection temperature T, the temperature Tq of the liquid crystal display panel can be judged accurately based on the detection temperature T of the temperature sensor.
(2) Since the temperature sensor is installed at a high position while the liquid crystal display for vehicle is properly mounted slant to a vehicle, the follow-up properties of the detection temperature T to a change in the temperature Tq of the liquid crystal display panel improve. Therefore, the temperature Tq of the liquid crystal display panel can be judged more accurately based on the detection temperature T of the temperature sensor.

[Explanation of Reference Numerals] 10 ... liquid crystal display panel, 10a, 10b . . . glass sheet, 11 . . . heat collection panel, 11a ... opaque resin panel, lib .. adiabatic cushion material, 12 .. opening, 15 . . . illumination LED, 16 . . . liquid crystal holder, 17 . . . circuit board, 20 . . . support case, 21 ... transparent case cover, 31, 3.2, 33 ... screw, 51 ... temperature sensor, 52 ... electrode

WE CLAIM:
1. A liquid crystal display for a vehicle comprising:
a liquid crystal display panel;
a circuit board for mounting circuit elements including a liquid crystal driver;
a temperature sensor mounted directly on the circuit board for detecting an ambient temperature of the circuit board; and a control circuit, mounted on the circuit board, for controlling liquid crystal drive voltage based on the ambient temperature detected by the temperature sensor,
the liquid crystal display panel and the circuit board being placed
one upon the other in a meter housing having a substantially
closed space therein with a predetermined space therebetween,
wherein the display further comprises a heat collection panel
exposed to surround the of the liquid crystal display panel,
said heat collection panel divides an inside space of the meter housing where said temperature sensor and said liquid crystal display are mounted, and causes the ambient temperature of said temperature sensor to follow a temperature change of said liquid crystal display panel.
2. The liquid crystal display for a vehicle as claimed in claim 1, wherein the heat collection panel is mounted to the liquid crystal display panel through an adiabatic member.
3. The liquid crystal display for a vehicle as claimed in claim 1, wherein the circuit board is inclined when the liquid crystal display for vehicle is properly mounted to a vehicle and the temperature sensor is installed at a high position above the inclined circuit board.
4. The liquid crystal display for vehicle as claimed in claim 1, wherein the control circuit further comprises:

a function storage portion for storing a function representing the relationship between the temperature of the liquid crystal display panel and the optimum drive voltage;
a compensation temperature storage portion for storing a compensation temperature for compensating for a difference between the detection temperature of the temperature sensor and the temperature of the liquid crystal display panel; and a drive voltage decision portion for determining LCD drive voltage based on the function and the temperature of the liquid crystal display panel,
the drive voltage decision portion represents the temperature of the liquid crystal display panel by the detection temperature until the detection temperature exceeds a predetermined reference temperature, and represents the temperature of the liquid crystal display panel by the total of the detection temperature and the compensation temperature when the detection temperature exceeds the reference temperature.
5. A liquid crystal display for a vehicle substantially as herein described with reference to and as illustrated in the accompanying drawings.
Dated 20th day of February, 2002.
[RAJAN AILAVADI]
Of Remfry & Sagar
Attorney for the applicants

Documents:

165-mum-2002-abstract(25-6-2007).pdf

165-mum-2002-cancelled pages(12-5-2006).pdf

165-mum-2002-claims(granted)-(25-6-2007).pdf

165-mum-2002-correspondence(25-6-2007).pdf

165-mum-2002-correspondence(ipo)(3-10-2007).pdf

165-mum-2002-drawing(25-6-2007).pdf

165-mum-2002-form 1(20-2-2002).pdf

165-mum-2002-form 1(25-6-2007).pdf

165-mum-2002-form 18(24-1-2006).pdf

165-mum-2002-form 2(granted)-(25-6-2007).pdf

165-mum-2002-form 3(2-4-2004).pdf

165-mum-2002-form 3(20-2-2002).pdf

165-mum-2002-form 3(25-6-2007).pdf

165-mum-2002-form 5(20-2-2002).pdf

165-mum-2002-petition under rule 137(25-6-2007).pdf

165-mum-2002-petition under rule 138(25-6-2007).pdf

165-mum-2002-power of authority(10-5-2002).pdf

165-mum-2002-power of authority(25-6-2007).pdf

abstract1.jpg


Patent Number 210404
Indian Patent Application Number 165/MUM/2002
PG Journal Number 41/2007
Publication Date 12-Oct-2007
Grant Date 03-Oct-2007
Date of Filing 20-Feb-2002
Name of Patentee HONDA GIKEN KOGYO KABUSHIKI KAISHA
Applicant Address 1-1, Minamiaoyama 2-Chome, Mainato-Ku, Tokyo
Inventors:
# Inventor's Name Inventor's Address
1 KAZUHIKO MORI AND ATSUSHI HATAYAMA C/O Kabushiki Kaisha Honda Gijutsu Kenkyusho, 4-1, Chuo 1-Chome, Wako-shi, Saitama,
PCT International Classification Number G02F1/1333
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2001-063430 2001-03-07 Japan