The invention relates to a driver chip and more particularly to a device for driving a multiple segment electroluminescent (EL) device.
Presently, the change of the dark-and-light status of each segment of an EL independently is controlled by a corresponding transistor, that is to say, the number of transistors increases in proportion to that of the EL. Therefore, in a multiple segment EL, a large number of transistors are required to control the dark-and-light status of the EL, which may increase the area of the circuit board for controlling the EL, and make the design of a circuit board complex and the cost higher. In addition, displaying an EL with different dark-and-light scale is generally controlled by increasing or decreasing the input voltage of a power supply circuit of the EL, or by controlling the frequency of an oscillating circuit in the power supply circuit of the EL. Accordingly, the driving circuit board should comprise the power supply circuit, which further increases the area of the circuit board. On the other hand, it is inconvenient for the user to have to be familiar with the driving method of an EL and the design procedures of a power supply circuit, in order to achieve a proper design of a driving circuit board of an EL.
Accordingly, the present invention is directed to a driver chip for a multiple segments EL that may downsize the driving circuit board, and thus make it more simple and easier to design a circuit for an EL to display information.
In order to achieve the above objects, the present invention provides an integrated circuit (IC) driver chip for a multiple segment EL device.
An EL display-data-control block (DCB) inputs display data and a display pulse into an EL and then dynamically delivering said display data according to a data locking pulse.
A display-segment-driver block (SDB) receives the display data from said DCB and then drives the EL to display information in real-time.
An EL driver chip is provided as mentioned above, wherein said driver chip further comprises a power supply control block for controlling the dark-and-light status of said EL.
An EL driver chip is provided as mentioned above, wherein said power supply control block comprises a step-up transformer, a transistor, and an oscillating circuit, said oscillating circuit outputs control signals of different frequency to the step-up transformer through said transistor, and accordingly, the step-up transformer outputs different power supplies to the EL.
An EL driver chip is provided as mentioned above, wherein said driver chip is connected to a power supply control block and said power supply control block comprises a step-up transformer and an oscillating circuit in which said oscillating circuit outputs control signals of different frequency to the step-up transformer through the-driver chip. And accordingly, the step-up transformer outputs different power supplies to the EL.
An EL driver chip is provided as mentioned above, wherein the step-up transformer is a DC-AC step-up circuit as an integrated circuit.
An EL driver chip is provided as mentioned above, wherein the electronic component parameter of said power supply control block is used to change the power supply for the EL, and therefore, to change the intensity of the EL indirectly.
An EL driver chip is provided as mentioned above, wherein said EL display-data-control block (DCB) is a shift register and said shift register comprises at least the first group of carry flip-flops and the second group of carry flip-flops. The output pins of the first group of carry flip-flops are connected with the input pins of the second group of carry flip-flops.
An EL driver chip is provided as mentioned above, wherein said display-segment-driver block (SDB) comprises a plurality of transistors connected to the output pins of said shift registers, collectors of said transistors connected to the EL.
An EL driver chip is provided as mentioned above, wherein said transistors are a plurality of NPN transistors, the base of which is connected to the output pin of said shift register through a resistor and connected in parallel to the emitter and grounded through another resistor.
An EL driver chip is provided as mentioned above, wherein said transistors are a plurality of NPN transistors, the emitter of which is connected to the output pin of said shift register and the base connected to a DC voltage through a resistor.
An EL driver chip is provided as mentioned above, wherein said transistors are a plurality of PNP transistors, the base of which is connected to the output pin of said shift register and the emitter connected to a DC voltage through a resistor.
An EL driver chip is provided as mentioned above, wherein said transistors are a plurality of PNP transistors the emitter of which is connected to the output pin of said shift register and the base grounded through a resistance and connected to a DC voltage through another resistance.
An EL driver chip is provided as mentioned above, wherein said driver chip may control the dark-and-light status of the EL by changing the display cycle time of the EL data.
The present invention further provides an EL display device comprising: a single-chip microprocessor for outputting EL display information; at least one EL driver chip, connected to said single-chip microprocessor, for receiving the EL display information and outputting the EL display driving information; a power supply circuit, connected to the EL driver chip, for supplying an EL display power supply; and at least one multiple segments EL connected to the EL driver chip and the power supply circuit, for displaying the display information with respect to said EL display driving information.
An EL display device is provided as mentioned above, wherein, said at least one driver chip is connected in cascade with each other for driving said EL.
An advantage of the present invention is to provide a novel EL driver chip, wherein the transistors for controlling the dark-and-light status of an EL is integrated into one driver chip to reduce the number of transistors required for a driving circuit and thus greatly reduces the area of the driving circuit board. The EL driver chip provided also integrates an oscillating circuit into an EL power supply control circuit which can further reduce the area of the circuit board.
At the same time, since several functions of conventional driving circuits are integrated into the driver chip and complex conventional circuits are encapsulated in one chip, it is easy for a user to design and use a powerful EL driver chip without much expertise.
The driver chip provided also integrates a multi-bit shift register inside. Said register provides a standard data transmission interface protocol to obtain a cascade-connection, to set the data content for an EL to display, and to obtain a cascade-connection which makes it easy and flexible to display the data content of the EL. In addition, when a plurality of EL driver chips are cascade-connected, these chips can be combined into one driver chip for the digital display of a multiple segments EL.
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying figures, in which:
As shown in
Pin 1, P1 is connected to an external step-up transformer,
Pin 2, P2 is for the EL display data input,
Pin 3, P3 is for the EL display data input pulse,
Pin 4, P4 is for the EL display data input reset signal,
Pin 5, P5 is for the first digital data locking pulse of the EL display data,
Pin 6, P6 is for the second digital data locking pulse of the EL display data,
Pin 7, P7 is for the third digital data locking pulse of the EL display data,
Pin 8, P8 is for the half digital data locking pulse of the EL display data,
Pin 9, P9 to pin 15, P15 are for the first digital data bit of the EL display data,
Pin 16, P16 to pin 22, P22 are for the second digital data bit of the EL display data,
Pin 23, P23, is a grounded pin of the driver chip,
Pin 24, P24 to pin 30, P30 are for the third digital data bit of the EL display data,
Pin 31, P31 to pin 34, P34 are for the half digital data bit of the EL display data,
Pin 35, P35 is for the cascade-connected EL display data output,
Pin 36, P36 is for an external EL power supply circuit or an external power supply chip,
Pin 37, P37 is a non-function pin,
Pin 38, P38 to pin 39, P39 are for the frequency control of an oscillating circuit configured inside the driver chip,
Pin 40, P40 is for the working power supply of the driver chip.
It is obvious from this drawing that the oscillating circuit 2, register 3, and transistors 4 are all encapsulated in one driver chip 10.
In the oscillating circuit 2, as shown in
In addition, another embodiment for changing the dark-and-light level of the EL is shown in
In the multi-bit shift register 3 shown in
The driver chip, as shown in
The principle for controlling the EL display by changing the conductive condition of a plurality of transistors is that, when the light emitting status of an EL is required to be changed, the data output pin which is locked in the shift register 3 inside the driver chip is set to be logical 1. And since the output pin of the shift register is connected to the bases of NPN transistors, bases of said transistors are also set to be logical 1. Additionally, the biased voltage difference between the base and the emitters of the transistors allows the electric current to flow from the output pin of the shift register 3 into the bases of the transistors to make the transistors on, and the EL circuit is grounded through the transistors. According to this principle, there is a circuit connected to the ground that makes the EL turn into the light emitting status. Contrarily, when the data locked in the inner shift register 3 of the driver chip is set to be logic zero, the bases of NPN transistors is also set to be logic zero and the bias voltage is not generated between the bases and emitters of the transistors, which makes the transistors off and the EL turn into the dark status as the circuit is cut off. As shown in
Although the present invention has been described in connection with the preferred embodiments with reference to the accompanying figures, the preferred embodiments are intended not to limit the invention, and all the equivalent transformation may be made according to content of the description and accompanying figures of the present invention, such as replacing the power supply step-up transformer with other DC-AC step up circuits in an integrated circuit. We may also use either N-Channel or P-Channel field effect transistor to replace the current bipolar transistors to achieve controlling the EL segments. In both cases we may achieve the same effect, without departing from the scope and spirit of the invention.
Number | Date | Country | Kind |
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02 1 57176 | Dec 2002 | CN | national |
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Number | Date | Country | |
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20040113868 A1 | Jun 2004 | US |