[0001] The present invention relates to an illuminating device for liquid crystal display
(LCD) timepieces and more particularly pertains to a neon lamp backlight device for
LCD timepieces such as alarm clocks and alarm watches.
[0002] Timepieces are daily necessities and are generally classified as analog or digital.
Analog timepieces available in the marketplace are usually equipped with luminous
devices so that the time as shown can be seen clearly in a dark environment. By pressing
a button, the user can turn on the light which illuminates the dial and the user can
then see clearly the time as indicated by the arms, but it is quite difficult to find
the timepiece and press the button in the dark. There are also timepieces available
in the marketplace showing time by light emitting diodes (LED) and the time as shown
is clearly visible in the dark. However, such a timepiece consumes high level of energy
and dry batteries cannot be used and alternating current (AC) is required, thus a
transformer has to be installed. If there is a blackout, the time of the timepiece
will have to be reset for use. Besides, LED timepieces are usually larger in size
and it is difficult to apply the same onto the increasingly compact electronic products.
Furthermore, graphics displayed by LED timepieces have lower resolution and so it
is commonly used to display only simple numerals or texts in monotonous style. As
a result, digital timepieces available in the marketplace are mainly those showing
time by LCD. LCD consumes less energy than LED, and is able to display graphics of
higher resolution. However, LCD is not luminous by itself and a light source is required
for displaying graphics.
[0003] If a LCD is not equipped with any backlight device, the user will have to rely on
ambient light to see the display on the screen, and the display is not visible in
the dark. Backlight devices can be installed at the back of the LCD screen. At present,
there are mainly three categories of backlight sources: electroluminescent lamps (EL),
cold cathode fluorescent lamps (CCFL), and LED. The light sources can shed light laterally
or vertically. The basic principle is to allow the light passing through the display
screen to display graphics. However, these backlight devices are susceptible of higher
production costs, complicated structure and more advanced manufacturing technology.
These devices also require the installation of transformers and consume more energy.
Therefore, they are only applicable to relatively high-end electronic products such
as electronic calculators and mobile phones, but not suitable for lower-end electronic
products such as alarm clocks and alarm watches.
[0004] In view of the aforesaid disadvantages now present in the prior art, the present
invention provides a neon lamp backlight device for LCD timepieces which does not
require any transformer and consumes low energy. It is simple in structure and susceptible
of a low manufacturing cost. It can also provide evenly-distributed, bright and various
color light sources. The neon lamp backlight device of the present invention is powered
by alternating current (AC), thus providing continuous illumination. It is easily
replaceable and simple and practical to use. The present invention uses an independent
power source and does not share its power supply with the LCD timepiece. Even if there
is any breakdown of power supply, the operation of the LCD timepiece will not be affected.
[0005] To attain this, the neon lamp backlight device for LCD timepieces of the present
invention is installed at the back of the LCD screen. It generally comprises a casing,
a printed circuit board, an electric wire, neon lamps, limiting resistors and a lens,
which is characterized in that the printed circuit board is installed at the inside
back of the casing, on which there is a hole for the electric wire to pass through
for connecting the printed circuit board to a power supply; one or more limiting resistors
and neon lamps are installed on the front surface of the printed circuit board; the
limiting resistors and the neon lamps are electrically connected to the printed circuit
board; and the lens is installed on the front of the casing.
[0006] The casing which is made of plastic material is in the shape of a bowl and is molded
into one piece by injection molding. The front area is larger than the back area.
It has a curved side surface, the inside of which can be covered by white paint or
reflective coating so as to achieve brighter and more evenly-distributed light sources.
[0007] The quantity of the neon lamps installed is in direct proportion to the size of the
area of the lens and the LCD screen.
[0008] The quantity of the limiting resistors installed is in direct proportion to the quantity
of the neon lamps installed.
[0009] The neon lamps are arranged in row or in column or in a matrix on the printed circuit
board.
[0010] The limiting resistors are arranged in row or in column or in a matrix on the printed
circuit board.
[0011] The neon lamps are neon glow lamps which emit orange glows. Each of the neon glow
lamps has a working current of 0.3mA to 1.5mA.
[0012] The neon lamps are fluorescent glow lamps which emit glows in green, blue or other
colors. Each of the fluorescent glow lamps has a working current of 0.4mA to 1.2mA.
[0013] At the front opening of the casing, there is a groove along the edge for positioning
the lens securely.
[0014] The lens is made of diffusing glass sheet or transparent diffusing plastic sheet
so as to cover the neon lamps to provide more evenly-distributed light sources.
[0015] The electric wire is connected to an electric plug. The electric plug is inserted
to an AC electric socket to supply electricity to the printed circuit board independently.
The present invention operates with a power source of alternating current at a voltage
of 100V to 130V, a frequency of 60 hertz and a power of 2W, or a power source of alternating
current at a voltage of 200V to 240V, a frequency of 50 hertz and a power of 2W.
[0016] The neon lamp backlight device for LCD timepieces is removably mounted at the back
of the LCD screen and can be replaced, if necessary.
- FIG. 1
- shows the schematic diagram of a LCD clock incorporating the neon lamp backlight device
of the present invention.
- FIG. 2
- shows the circuit diagram of the LCD clock incorporating the neon lamp backlight device
of the present invention.
- FIG. 3
- shows the vertical cross-sectional diagram of the neon lamp backlight device of the
present invention.
- FIG. 4
- shows the horizontal cross-sectional diagram of the neon lamp backlight device of
the present invention.
[0017] As illustrated in FIG. 1 to 4, the neon lamp backlight device of the present invention
is applied to a conventional digital alarm clock. The neon lamp backlight device of
the present invention is installed at the back of the LCD screen. It generally comprises
a casing 1, a printed circuit board 2, an electric wire 3, neon lamps 4, limiting
resistors 7 and a lens 5. The LCD screen 6 of the alarm clock is powered by dry batteries.
The neon lamp backlight device connects to an AC electric socket by the electric wire
3, and AC is used to power the printed board circuit 2. The casing 1 which is made
of plastic material is in the shape of a bowl and is molded into one piece by injection
molding. The front area is larger than the back area. It has a curved side surface,
the inside of which can be covered by white paint or reflective coating so as to achieve
brighter and more evenly-distributed light sources. The printed circuit board 2 is
installed at the inside back of the casing 1, on which there is a hole 11 for the
electric wire 3 to pass through for connecting the printed circuit board 2 to a power
supply. Five neon glow lamps 4 which emit orange glows are installed on the front
surface of the printed circuit board 2. The neon glow lamps 4 are arranged on the
printed circuit board 2 in a single file in H shape, and are electrically connected
to the printed circuit board 2. Five limiting resistors 7 are also installed on the
front surface of the printed circuit board 2, the quantity and the arrangement of
which are identical with those of the neon glow lamps 4, and are also electrically
connected to the printed circuit board 2. There is a groove 12 along the edge at the
front opening of the casing 1 to position the transparent diffusing plastic sheet
5 securely. The transparent diffusing plastic sheet 5 covers the neon glow lamps 4
to provide more evenly-distributed light sources.
[0018] After the circuit is connected, AC is supplied to the printed circuit board 2 through
the electric wire 3 and drives the neon glow lamps 4 to glow, and the glow passes
through the LCD screen 6. The neon lamp backlight device of the present invention
can provide light sources in the dark and the user can see the time or other graphics
or texts as shown on the LCD screen 6 at night.
List of reference numbers
[0019]
- 1
- casing
- 2
- circuit board
- 3
- electric wire
- 4
- neon lamps
- 5
- lens
- 6
- LCD screen
- 7
- imiting resistors
- 11
- hole
- 12
- groove
1. A neon lamp backlight device for LCD timepieces installed at the back of the LCD screen
which generally comprises a casing, a printed circuit board, an electric wire, neon
lamps, limiting resistors and a lens, which is characterized in that the printed circuit board is installed at the inside back of the casing, on which
there is a hole for the electric wire to pass through for connecting the printed circuit
board to a power supply, whereat one or more limiting resistors and neon lamps are
installed on the front surface of the printed circuit board; the limiting resistors
and the neon lamps are electrically connected to the printed circuit board, and the
lens is installed on the front of the casing.
2. The neon lamp backlight device for LCD timepieces according to claim 1, wherein the
neon lamp backlight device for LCD timepieces is removably mounted at the back of
the LCD screen and can be replaced.
3. The neon lamp backlight device for LCD timepieces according to claim 1, wherein the
casing which is made of plastic material is in the shape of a bowl and is molded into
one piece by injection molding; the front area of which is larger than the back area;
and it has a curved side surface, the inside of which is covered by white paint or
reflective coating.
4. The neon lamp backlight device for LCD timepieces according to claim 1, wherein the
quantity of the neon lamps installed is in direct proportion to the size of the area
of the lens and the LCD screen.
5. The neon lamp backlight device for LCD timepieces according to claim 1, wherein the
quantity of the limiting resistors installed is in direct proportion to the quantity
of the neon lamps installed.
6. The neon lamp backlight device for LCD timepieces according to claim 1 or 4, wherein
the neon lamps are arranged in row or in column or in a matrix on the printed circuit
board.
7. The neon lamp backlight device for LCD timepieces according to claim 1 or 5, wherein
the limiting resistors are arranged in row or in column or in a matrix on the printed
circuit board.
8. The neon lamp backlight device for LCD timepieces according to claim 1 or 4 or 5,
wherein the neon lamps are neon glow lamps which emit orange glows, whereat each of
the neon glow lamps has a working current of 0.3mA to 1.5mA.
9. The neon lamp backlight device for LCD timepieces according to claim 1 or 4 or 5,
wherein the neon lamps are fluorescent glow lamps which emit glows in green or blue
colour, whereat each of the fluorescent glow lamps has a working current of 0.4mA
to 1.2mA.
10. The neon lamp backlight device for LCD timepieces according to claim 1 or 3, wherein
there is a groove along the edge at the front opening of the casing for positioning
the lens securely, whereat the lens is made of diffusing glass sheet or transparent
diffusing plastic sheet.