JPH04213493A - Fluorescent display device - Google Patents

Abstract

PURPOSE:To allow the varying and adjusting of the brightness of a fluorescent display tube with a simple input operation by selectively setting the duty cycles of the pulse signals to be impressed to the grids of the fluorescent display tube. CONSTITUTION:A brightness conversion table 7 for previously storing the various duty cycles determined by the pulse width and repetitive periods of the pulse signals impressed successively repetitively to the grids drawn out dividedly by every digit of the fluorescent display tube 2. Any one of the various duty cycles stored in this brightness conversion table 7 is selected by the key input of a keyboard 5 and the driving of the fluorescent display tube 2 is controlled according to the selected duty cycle.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent display device used as a character or numeric display device for audio equipment, home appliances, POS (point of sale) terminals, and the like.

0002

2. Description of the Related Art A fluorescent display tube consists of three components: a filament (directly heated oxide cathode), a grid, and an anode (a conductor coated with phosphor in a display pattern) in a vacuum container with a transparent field of view in at least one direction. An electron tube is equipped with various types of electrodes, and one of its drive methods is a dynamic drive method. This driving method involves sequentially and repeatedly applying a pulse signal to the grid drawn out for each digit of the fluorescent display tube, and applying pulse signals to the anode provided corresponding to each grid in accordance with the display data of the corresponding digit. This method displays numbers, characters, etc. by applying pulse signals. In this drive system, the luminance of the fluorescent display tube is determined by the duty cycle Du (=t
p/T).

Conventionally, therefore, the duty cycle Du of the pulse signal is fixedly set by software, and numbers, characters, etc. are displayed on a fluorescent display tube at a constant brightness.

0004

[Problems to be Solved by the Invention] As mentioned above, in conventional fluorescent display devices of this type, the brightness is fixed by software, so the standard duty cycle is uniquely determined by the manufacturer. Currently, they are shipped to users, and it is difficult for users to vary the brightness depending on the usage environment or operator's sense. For this reason, there have been problems such as making it difficult to see the displayed content and making it easy for the eyes to get tired.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a fluorescent display device in which the brightness of a fluorescent display tube can be variably adjusted by a simple input operation, and the operator can easily obtain the optimum display condition at any time.

[0006]

[Means for Solving the Problems] The present invention provides a fluorescent display device in which a fluorescent display tube is driven and controlled by a dynamic drive method, in which pulses are sequentially and repeatedly applied to terminals drawn out for each digit of the fluorescent display tube. a brightness conversion table storing various duty cycles determined by the pulse width and repetition period of the signal; a selection means for selecting one of the various duty cycles stored in the brightness conversion table; and a selection means for selecting one of the various duty cycles stored in the brightness conversion table; and display control means for controlling the pulse signal according to a set duty cycle.

[0007]

[Operation] With a fluorescent display device having such a configuration, when a table number is input to select one of the various duty cycles stored in the brightness conversion table, the duty cycle corresponding to the input table number is changed. is selected from the brightness conversion table. Then, a pulse signal is outputted according to the selected duty cycle to drive and control the fluorescent display tube. Therefore, by changing the duty cycle, the brightness of the fluorescent display tube can be adjusted to provide the optimum display for the operator.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a functional block diagram of this embodiment, in which a control circuit 1 consisting of a microcomputer, etc.
A dynamic drive circuit 3 that drives the fluorescent display tube 2 using a dynamic drive method, an external input interface 4 that receives display data such as numbers and characters input from an externally connected host computer or input device, etc., and various setting information etc. In addition to a keyboard 5 for input, a brightness setting memory 6 and a brightness conversion table 7 formed by RAM (random access memory) are connected.

FIG. 2 is a detailed diagram of the fluorescent display tube 2 and dynamic drive circuit 3, and shows the case of a seven-segment display tube with nine digits. The fluorescent display tube 2 includes a filament F and a grid 1G drawn out separately for each digit in a vacuum container 21 that is transparent in at least one direction.
9G, and anodes Pa to Pg, each having a conductor coated with phosphor arranged in a display pattern for each digit.

The dynamic drive circuit 3 includes a grid decoder driver 31 that applies a pulse signal as shown in A in FIG. 3 to each grid 1G to 9G based on the scan data D1 from the control circuit 1; An anode decoder driver 32 that applies a pulse signal as shown in FIG. 3B to each anode Pa to Pg according to segment data, each grid 1G to 9G, and each anode Pa
- Power supply 33 to Pg, Zener diode 34 for obtaining cut-off bias voltage applied to the center tap of filament transformer FT, each grid 1G to 9
It is composed of pull-down resistors Rg1 to Rg9, Rpa to Rpg, etc. inserted in order to quickly rise the pulse voltage waveform applied to G and each anode Pa to Pg.

As shown in FIG. 4, the brightness conversion table 7 is divided into grids 1G to 1G corresponding to a series of table numbers.
Pulse width tp (ms) of the pulse signal applied to 9G,
This is for presetting and storing the duty cycle Du (=tp/T) determined by the blanking time tb (ms) of the same pulse signal, the pulse width tp of the same pulse signal, and the repetition period T in multiple patterns. 9 in Figure 4
20 patterns are shown when the repetition period T is 20 (ms) in the fluorescent display tube 2 of the order of magnitude.

[0013] When the power is turned on, the control circuit 1 reads standard values (for example, duty cycle Du, pulse width tp, and blanking time tb of table number "10") from the luminance conversion table 7. The brightness settings are stored in the brightness setting memory 6. Thereafter, when display data is input via the external input interface, the scan data D1 is transmitted to the grid decoder driver 3 of the dynamic drive circuit 3 based on the stored contents of the brightness setting memory 6.
1, and also outputs segment data D2 corresponding to the display data to the anode decoder driver 32.
The program is controlled to output the data.

Further, when a table number is inputted using the keyboard 5 while the "setting" mode is selected, the brightness conversion table 7 is searched as shown in FIG.

If a table number matching the input table number exists, the duty cycle Du, pulse width tp, and blanking time tb corresponding to the table number are read out and stored in the brightness setting memory 6.
Rewrite the contents of. (Selection means) With this, after that,
When display data is input via the external input interface, scan data D1 is output to the grid decoder driver 31 of the dynamic drive circuit 3 based on the contents stored in the brightness setting memory 6, and the scan data D1 is outputted to the grid decoder driver 31 of the dynamic drive circuit 3. Segment data D2 is output to the anode decoder driver 32. (Display control means) In this embodiment configured as described above, various patterns preset in the brightness conversion table 7 can be displayed by simply selecting the "setting" mode and inputting an arbitrary table number from the keyboard 5. One of the duty cycle Du, pulse width tp, and blanking time tb is selected, and the display on the fluorescent display tube 2 is controlled based on the selected value. For example, if the duty cycle Du, pulse width tp, and blanking time tb corresponding to table number "1" are selected, the fluorescent display tube 2
The duty cycle Du of the pulse signal that is sequentially and repeatedly applied to each grid 1G to 9G is "1/30".
is the shortest, and the brightness is the lowest. On the other hand, the duty cycle Du corresponding to table number "20"
, when the pulse width tp and blanking time tb are selected, the duty cycle Du of the same pulse signal is "1".
/10'', which is the longest and has the highest brightness.

That is, the brightness of the fluorescent display tube 2 is changed by selecting one of various patterns preset in the brightness conversion table 7 by a simple key operation. In this case, key operations can be performed in a timely manner. Therefore, when the displayed content becomes difficult for the user to see due to the usage environment or the like or the operator's eyes tend to get tired, the brightness can be adjusted so as to obtain the optimum display for the operator.

In the above embodiment, the brightness conversion table 7
Although key input on the keyboard 5 is shown as a means for selecting one of the various duty cycles stored in the controller, the present invention is not limited to this. For example, a magnetic card reader may be connected to the control circuit 1 to select the desired duty cycle. It is also conceivable that a magnetic card with a table number magnetically recorded thereon is read by the card reader and selected. Further, the present invention can also be applied to a fluorescent display device using a light emitting diode instead of a grid. It goes without saying that various other modifications can be made without departing from the gist of the present invention.

[0018]

As described in detail above, according to the present invention, the brightness of the fluorescent display tube can be variably adjusted by a simple input operation, and the operator can easily obtain the optimal display condition at any time. A fluorescent display device that can improve business efficiency can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram functionally showing the configuration of an embodiment of the present invention.

FIG. 2 is a detailed diagram of the main parts of the dynamic drive circuit in the same embodiment.

FIG. 3 is a diagram of main signal waveforms of the dynamic drive circuit in the same embodiment.

FIG. 4 is a configuration diagram of a brightness management table in the same embodiment.

FIG. 5 is a flowchart showing brightness setting processing of the control circuit in the same embodiment.

[Explanation of symbols]

1... Control circuit, 2... Fluorescent display tube, 3... Dynamic control circuit, 4... External input interface, 5... Keyboard,
6... Brightness setting memory, 7... Brightness conversion table.

Claims (1)

[Claims] 1. In a fluorescent display device in which a fluorescent display tube is driven and controlled by a dynamic drive method, the pulse width and repetition period of a pulse signal that is sequentially and repeatedly applied to terminals drawn out separately for each digit of the fluorescent display tube. a brightness conversion table that stores in advance various duty cycles determined by the brightness conversion table; a selection means for selecting any one of the various duty cycles stored in the brightness conversion table; 1. A fluorescent display device comprising display control means for controlling a pulse signal.