JPH09106264A - Driving circuit for fluorescent display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the driving circuit of a flourescent display device capable of improving yield and also capable of reducing a cost price by reducing number of manufacturing processes. SOLUTION: Shift register circuits 1 successively shifting display data every light emitting element 51 and latch circuits 2 holding outputs from these shift register circuits 1 and outputting them to respective light emitting elements 51 are provided in this circuit. After the display data to respective light emitting elements 51 are made to be inputted from a serial input SI in serial data and they are made to be successively shifted by a clock signal CLK to be shifted until corresponding light emitting elements 51, the outputs of the shift register circuits 1 are held in latch circuits 2 by a latch signal LAT as display data and then outputted to respective light emitting elements 51.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving circuit of a fluorescent display device which displays characters and symbols by using a phosphor, and more particularly, a fluorescent device formed by integrally forming light emitting elements in a dot matrix on a semiconductor integrated substrate. The present invention relates to a drive circuit of a display device.

[0002]

2. Description of the Related Art Generally, in this type of fluorescent display device, a phosphor layer is formed on a part of a semiconductor chip having a semiconductor integrated circuit for drive control, and a large number of light emitting elements are provided in a dot matrix form. By driving, various characters and symbols are displayed. FIG. 4 is an explanatory view showing a general fluorescent display device (cross section), in which 41 is a semiconductor chip (semiconductor substrate), 42 is a phosphor (anode), 43 is a grid, and 44 is a filament (cathode). , 45 is a bonding wire for electrically connecting the terminal portion 46 of the semiconductor chip 41 and the wiring pattern 47 of the glass substrate (anode substrate) 48, and 49 is a windshield.

FIG. 5 is a circuit diagram showing a display portion of a general fluorescent display device. Reference numeral 51 is a light emitting element (display dot) composed of a phosphor 42 and a transistor 52 for driving the phosphor, and 53 is each light emitting element. A memory which is provided for each 51 and stores display data indicating light emission ON / OFF in each light emitting element 51, 54 and 55 are control signals for selecting a predetermined memory 53 and writing the display data, and 56 is a filament 44 It is a driving power supply for driving. The transistor 52 is turned on / off based on the display data stored in the memory 53, and in response to the turn-on, the fluorescent substance 42 becomes a cathode voltage, and the thermoelectrons emitted from the filament 44 are fluorescently emitted through the grid 43. It collides with the body 42 and emits light.

Conventionally, as a circuit for driving such a fluorescent display device, the circuit corresponding to each light emitting element 51 is
A memory for storing display data indicating ON / OFF of light emission is provided at the intersection of the XY addresses, and each light emitting element 51 is driven based on the display data stored in these memories (for example, , JP-A-60-48
090 publication).

FIG. 6 is an explanatory view showing a conventional drive circuit, and particularly shows a driver in which light emitting elements are arranged in a 16 × 16 dot matrix. In the figure,
Reference numeral 61 is an X address decoder that decodes 4-bit X addresses X0 to X3, and 62 is a 4-bit Y address Y0.
Is a light emitting element, 53 is a memory, 54 is an X-direction address selection control signal, and 55 is an X-direction address selection control signal.

An X address and a Y address input by binary information from the outside are decoded by an X address decoder 61 and a Y address decoder 62, respectively, and one of address selection control signals 54 and 55 corresponding to the input address is output. To do. In response to this, the memory 53 existing at the intersecting position is selected, the stored content is rewritten based on the display data (not shown) of the light emitting element 51 input from the outside, and the stored content is based on the stored content. Therefore, the light emitting element 51 is driven.

[0007]

Therefore, in such a conventional drive circuit for a fluorescent display device, by inputting an XY address, the memory 53 corresponding to a desired light emitting element 51 is selected to display display data. Since it is rewritten, X ^1/2 + Y ^1/2 address lines are required on the semiconductor chip 41, which complicates the manufacturing process of the semiconductor chip, lowers the yield, and increases the price. there were. On the other hand, when this semiconductor chip is incorporated into a fluorescent display device, the wiring pattern 47 (mainly an Al-based thin film) formed on the glass substrate 48 (see FIG. 4) and the terminal portion 46 of the semiconductor chip 41 are electrically connected. Need to be connected to.

Generally, wire bonding 45 is used as this connection method. However, the number of wire bondings increases as the number of address lines increases, which causes an increase in the number of manufacturing steps and a decrease in yield. However, the use of relatively expensive wire materials has caused a rise in prices. The present invention is to solve such a problem, and by reducing the address lines, it is possible to reduce the manufacturing man-hours and improve the yield, and to provide a drive circuit of a fluorescent display device that can reduce the price. It is intended to be provided.

[0009]

In order to achieve such an object, a driving circuit of a fluorescent display device according to the present invention is provided for each light emitting element, and display data corresponding to each light emitting element is predetermined. A shift register circuit that sequentially shifts based on a clock signal is provided for each light emitting element, and the output from the corresponding shift register circuit is held as individual display data and output to the light emitting element based on a predetermined latch signal. And a latch circuit. Therefore, the display data is sequentially shifted by the respective shift register circuits, shifted to the shift register circuits of the corresponding light emitting elements, then held by the latch circuit, and output as individual display data to the light emitting elements.

The shift register circuit is composed of a bidirectional shift register circuit which switches the shift direction of display data based on a predetermined shift direction selection signal. Therefore, the shift direction of the display data in the shift register circuit is switched based on the shift direction selection signal.

[0011]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a fluorescent display device according to an embodiment of the present invention, and particularly shows a 16 × 16 dot matrix driver. In the figure, reference numeral 1 is provided for each light emitting element 51 (# 1 to # 256) connected in series, and the display data corresponding to each light emitting element 51 is provided with a shift direction selection signal L / R based on a clock signal CLK. The bidirectional shift register circuit 2 for sequentially shifting in the direction shown is a latch circuit provided for each light emitting element 51 and holding and outputting the output from the shift register circuit 1 based on the latch signal LAT.

Next, the operation of the present invention will be described with reference to FIG. The shift direction selection signal L / R for selecting the shift direction of the display data in the shift register circuit 1 is “H”.
In case of level, each light emitting element # 1, # 2 ...
The display data of 6 is, in order from the light emitting element # 256,
It is input from the serial input SI. These display data are output based on the clock signal CLK.
The shift register circuits 1 corresponding to 1, # 2, ...

After each display data is shifted to the corresponding shift register circuit 1, the latch signal LAT is generated.
Is input, and the display data output from each shift register circuit 1 at that time is held and output by each latch circuit 2. As a result, the display data held and output by the latch circuit 2 is input to each light emitting element 51, and the transistor 52 (see FIG. 5) in the light emitting element 51 is driven in response to this, and the display data to the phosphor 42 is supplied. The supply of the anode voltage is controlled, and the display corresponding to each display data is output.

Thus, for each light emitting element 51, the shift register circuit 1 for sequentially shifting the display data and the latch circuit 2 for holding and outputting the output from these shift register circuits 1 to the light emitting element 51 are provided.
Since the display data for each light emitting element 51 is inputted as serial data, a plurality of X elements can be input as in the conventional case.
The number of signal lines on the semiconductor chip and the number of signal lines to be supplied to the semiconductor chip is reduced as compared with the case where the Y address is input to the semiconductor chip, the manufacturing process of the semiconductor chip is simplified, and the wire bonding is performed. It is possible to reduce the number, improve the yield, and reduce the price.

On the other hand, the shift direction selection signal L / R is "L".
In the case of the level, contrary to the above, each light emitting element #
The display data of # 1,..., # 256 is input from the serial output S0 in order from the light emitting element # 1. These display data are sequentially shifted by the shift register circuits 1 of the light emitting elements # 256, # 255, ... # 1 based on the clock signal CLK.

After each display data is shifted to the corresponding shift register circuit 1, the latch signal LAT is generated.
Is input, and the display data output from each shift register circuit 1 at that time is held and output by each latch circuit 2. As a result, the display data held and output by the latch circuit 2 is input to each light emitting element 51, and the transistor 52 (see FIG. 5) in the light emitting element 51 is driven in response to this, and the display data to the phosphor 42 is supplied. The supply of the anode voltage is controlled, and the display corresponding to each display data is output.

FIG. 2 is an explanatory diagram showing an example of use of a 16 × 16 dot matrix driver, and particularly shows a case where the driver is arranged in an upside down direction and used. In the figure, 21, 22 ..., 25, 26 ... are 16 × 1
The driver is a 6-dot matrix driver,
22 .. are arranged in the forward direction so that the light emitting element # 1 is in the upper left position, and the drivers 25, 26 .. are arranged in the up and down directions so that the light emitting element # 1 is in the lower right position. .

In this, in each driver, the terminal portion is concentrated on one side portion, and the other side portion is arranged in close contact with an adjacent driver. As a result, a larger continuous display area can be obtained, and a more expressive graphic display is performed instead of a character or a graphic of a limited size. As described above, when the display data is input from the serial input SI regardless of the installation direction when the driver is installed upside down and is used upside down, as shown in FIG. The direction display is output.

In FIG. 3, (a) shows the display data input from the serial input SI arranged in the forward direction,
(B) is arranged upside down and receives display data from the serial input SI, and (c) is arranged upside down and receives display data from the serial output SO.
A driver of 4 × 4 dot matrix is shown as an example.

In FIG. 3A, the shift direction selection signal L /
R is at “H” level and display data is serial input S
"10001000111111000" is input in the order of the light emitting elements # 16, # 15 ... # 2, # 1 from I. Here, "1" indicates that the display is on, "0" indicates that the display is off, and the shaded area indicates the light emitting element 51 that is emitting light.
Is shown.

Here, display data "10001000111" similar to that shown in FIG.
When 11000 ”is input from the serial input SI, as shown in FIG. 3B, the symbol of FIG.
The design rotated by 0 ° is displayed. In this case, in order to display the same symbol as that of FIG. 3A, it is necessary to convert the display data by reversing the input order of the display data.

On the other hand, as shown in FIG. 3C, the shift direction selection signal L / R is set to the "L" level for the driver in the upside down direction, and the display data is output from the serial output SO to the light emitting element # 16. When "10001000111111000" is input in the order of # 15 ... # 2, # 1, the symbols in the same direction as in FIG. 3 (a) described above are displayed and output, and the same display data as in FIG. 3 (a). It is possible to display the same symbol by using.

Therefore, in FIG. 2 described above, the shift direction control signal L / R of "H" level is supplied to the lower drivers 21, 22, ..., And the light emitting elements # 256, # are supplied from the data input DAT-L. Display data is input in the order of 255 ... # 2, # 1, input to the serial input SI of the driver 21, and sequentially shifted based on the clock signal CLK-L. Further, the display data is sequentially input from the serial output SO of the driver 21 to the serial input SI of the driver 22, and when the display data is shifted to all the light emitting elements 51 of the drivers 21, 22 ... -L is input, the output of each shift register circuit 1 is held by the latch circuit 2 as display data, and is output to the light emitting element 51.

On the other hand, the upper drivers 25, 26, ...
・ Conversely to, "L" level shift direction control signal L / R
, And display data in the same order as the lower drivers 21, 22, ... Are input from the data input DAT-U,
It is input to the serial output SO of the driver 25 and sequentially shifted based on the clock signal CLK-U. further,
This display data is sequentially input from the serial input SI of the driver 25 to the serial output SO of the driver 26, and all the light emitting elements 51 of each driver 25, 26 ,.
Latch signal LAT- when the display data is shifted to
U is input, the output of each shift register circuit 1 is held as display data by the latch circuit 2, and is output to the light emitting element 51.

As described above, since the bidirectional shift register is provided for each light emitting element and the shift direction of the display data is switched according to the disposing direction of the driver, the driver is arranged in the upside down direction. Even if
The display data can be input in the same order as the drivers arranged in the forward direction, and there is no need to convert the display data according to the direction in which the drivers are arranged. It is also possible to arrange them.

[0026]

As described above, according to the present invention, the shift register circuit for sequentially shifting the display data corresponding to each light emitting element based on a predetermined clock signal, and the corresponding shift based on a predetermined latch signal. A latch circuit that holds the output from the register circuit as corresponding display data and outputs it to the light emitting element is provided for each light emitting element, and the display data is sequentially shifted by each shift register circuit, and the shift register of the corresponding light emitting element is provided. After the shift to the circuit, the data is held by the latch circuit and output as display data to each light emitting element. Therefore, as compared with the conventional technique of inputting a plurality of XY addresses to a semiconductor chip, Reduces the number of signal lines on the chip and the number of signal lines to be supplied to the semiconductor chip Are, together with the simplified manufacturing process of the semiconductor chip improves the yield reduces the number of wire bonding, it is possible to lower the price.

Further, as the shift register circuit, the bidirectional shift register circuit for switching the shift direction of the display data based on the predetermined shift direction selection signal is used.
The shift direction of the display data in the shift register circuit is switched based on the shift direction selection signal, and even if the driver including a predetermined number of light emitting elements is arranged in the upside-down direction, it is arranged in the forward direction. Display data can be input in the same order as the driver, there is no need to convert the display data according to the driver's arrangement direction, and it is possible to arrange each driver in the forward and reverse directions Becomes

[Brief description of the drawings]

FIG. 1 is a block diagram of a fluorescent display device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a usage example of a 16 × 16 dot matrix driver.

FIG. 3 is an explanatory diagram showing a relationship between a driver arrangement direction and display data.

FIG. 4 is an explanatory diagram showing a general fluorescent display device (cross section).

FIG. 5 is a circuit diagram showing a display section of a general fluorescent display device.

FIG. 6 is an explanatory diagram showing a drive circuit of a conventional fluorescent display device.

[Explanation of symbols]

1 ... Shift register circuit, 2 ... Latch circuit, 51 ... Light emitting element, SI ... Serial input, SO ... Serial output, L / R ... Shift direction selection signal, CLK ... Clock signal, LAT ... Latch signal.

Claims (2)

[Claims] 1. A large number of dot-matrix light emitting elements formed of a phosphor layer formed on a semiconductor chip, and by outputting individual display data to these light emitting elements, various characters, figures, etc. In a drive circuit of a fluorescent display device for displaying, a shift register circuit provided for each light emitting element and sequentially shifting display data corresponding to each light emitting element based on a predetermined clock signal, and for each light emitting element A driving circuit for a fluorescent display device, comprising: a latch circuit which is provided and holds an output from a corresponding shift register circuit as individual display data based on a predetermined latch signal and outputs the display data to a light emitting element. 2. The drive circuit for a fluorescent display device according to claim 1, wherein the shift register circuit comprises a bidirectional shift register circuit for switching a display data shift direction based on a predetermined shift direction selection signal. Driving circuit for a fluorescent display device.