JPH0365558B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive circuit for a dot matrix type fluorescent display tube that displays numbers, characters, figures, etc.

Fluorescent display devices display images by causing electrons emitted from a heated filament-shaped cathode to collide with an anode that has a phosphor coated on its top surface, and they emit light in a good color and can be driven at low voltages. It has advantages such as low power consumption and is often used as display devices in various electronic devices. In this, a plurality of anodes each having a phosphor layer coated on the upper surface are arranged in a matrix, and the anodes for each row are led out to the row wiring, and are arranged facing the anodes of each column. The so-called dot matrix display device, in which control electrodes are led out to column wirings and anodes located at the intersections of selected row and column wirings emit light, has become increasingly popular with the diversification of information handled by various electronic devices. Therefore, there is a demand for higher resolution, and progress is being made to increase the density of display dots.

Two problems need to be resolved in order to promote this higher density. One of these is that as the density of each anode increases, the distance between each control electrode becomes narrower, so the negative electric field created by the control electrode facing the anode that is to emit light and the adjacent control electrode leads from the cathode to the anode. The problem is that the path of electrons is bent, resulting in a blank area at the end of the anode. The second problem is that the number of anodes increases,
In order to reduce the number of external terminals, the display method is as follows.
Generally, a dynamic drive method is used, but in this case the number of control electrodes is also increased, so the proportion of the period during which each control electrode is selected in one display cycle, the so-called duty factor, becomes smaller. It is a point. In other words, the scan pulse width per control electrode becomes narrower, and the luminance of light emitted from the anode decreases, so it is necessary to increase the driving voltage to compensate for the decreased brightness, and even though low-voltage driving should be possible, This would undermine the merits of the fluorescent display.

Therefore, the present inventors have proposed a fluorescent display device in Japanese Patent Application No. 56-86785 which can eliminate the above-mentioned drawbacks. That is, FIG. 1 is a schematic diagram showing the electrode connection structure of a fluorescent display device proposed by the present inventors, and numeral 1 in the figure indicates a fluorescent display tube.
In this fluorescent display tube 1, m×n dot-shaped anodes a (a ₁₁ to a _no ) are arranged in a matrix of m rows and n columns, and each anode a arranged in the same row is Every two pieces are connected in common. That is, three wiring conductors C ₁ , C ₂ , C ₃ are formed for each row, and the first wiring conductor C ₁ has a sequence of (3n-2) (where n is a positive integer). The anodes a ₁₁ , a ₁₄ , a ₁₇ ... at the positions represented by are connected, and the second wiring conductor
C ₂ has a (3n-1) sequence (where n is a positive integer)
Anodes a ₁₂ , _{a 15} , a ₁₈ . a ₁₃ ,
a ₁₆ , a ₁₉ ... are connected. Further, above the anode a, for example, mesh-shaped control electrodes G (G ₁ , G _{2 .} . . G _k ) are stretched and arranged facing the anode a, and each control electrode G is connected to the above-mentioned wiring. Conductor C ₁ , C ₂ ,
One control electrode G is provided along the direction perpendicular to C ₃ , that is, along the row direction of the anodes a, so as to cover each of the two rows of anodes a. Therefore, the number of control electrodes G is set to 1/2 of the number of anode rows. 2 is an anode drive circuit that applies a display signal to the anode a, and 3 is a control electrode drive circuit that applies a scanning signal to the control electrode G.

Therefore, in the above-mentioned wiring structure, the control electrode drive circuit 3 scans the adjacent control electrodes G simultaneously and while shifting them one by one.
G ₁ and G ₂ , G ₂ and G ₃ ...G _k-1 and G _k (The control electrodes G ₁ and G _k located at both ends are driven independently,
Alternatively, drive the control electrodes G ₁ and G _k simultaneously,
The anodes a of the first row and the nth row may be scanned simultaneously. ), and in synchronization with this, the anode drive circuit 2 applies display signals to two rows of anodes a located on the inside facing the control electrodes G scanned at the same time to perform display.

The above-mentioned fluorescent display tube is of the anode triple matrix type as described above, and the number of anode conductors C ₁ , C ₂ , C ₃ is three times that of a normal matrix type fluorescent display tube, but on the other hand, the control electrode G (Scanning side) The number can be cut in half.
And by adopting the above-mentioned driving method,
Display duty factor (the emitting time of one pixel in the time required to scan one screen)
can be doubled compared to the conventional method. This means that with the same amplitude of anode voltage, almost twice the brightness can be obtained, and if the brightness is the same,
This shows that it is possible to lower the anode voltage.

Furthermore, this anode triple matrix method is not affected by the electric field of adjacent control electrodes, so even if the distance between the anodes is narrowed, the phenomenon of overlapping the display does not occur and high quality display can be achieved. It will be done.

By the way, as an example of the above-mentioned fluorescent display tube, FIG. 2 shows an example of a drive circuit when the number of anode rows is 8, that is, the anode a has 8 vertical dots, and the anodes a ₁₂ ,
Consider the case where column a ₁₃ is to be displayed.

In this case, the control electrodes G ₁ and G ₂ are simultaneously selected by the control electrode drive circuit 3, and in synchronization with this, the anodes a ₁₂ and a ₁₃ located in the inner row of the control electrodes G ₁ and G ₂ are selected. A display signal for controlling lighting and non-lighting is applied to the wiring conductors C ₂ and C ₃ that are connected to each other. On the other hand, in this case, the anodes a ₁₁ and a ₁₄ located in the outer row facing the control electrodes G ₁ and G ₂ need to be kept in a non-lighted state.

Therefore, it is necessary to apply a non-lighting signal to the wiring conductor C ₁ at the same time as applying a display signal to the wiring conductors C ₂ and C ₃ . That is, each row of wiring conductors
It is necessary to apply a control signal to all C ₁ , C ₂ , and C ₃ at the same time, and when displaying 8 vertical dots on anode a, a signal of 8 × 3 = 24 bits is sent from the anode drive circuit 2 to the fluorescent display. It is necessary to supply it to the pipe 1 side at the same time. This is now connected from the drive circuit 2 side to the fluorescent display tube 1.
If we consider the case where a display signal is sent serially, the incoming display signal is first converted into a parallel signal by a shift register _SR1 , and then stored in a temporary storage circuit _M1 (formed by a D-type flip-flop, for example). Functionally, this is called a latch circuit (hereinafter referred to as a latch).

Next, the parallel signal converted by shift register SR ₂ is input to latch M ₂ , and then the parallel signal converted by shift register SR ₃ is input to latch M ₃ .
It is necessary to transfer them sequentially.

However, since the above-mentioned operation needs to be performed within the display blanking period of the fluorescent display tube 1, in cases where there are a large number of display dots, for example, it is impossible to transfer the signal within the display blanking period. There will be cases where this happens.

This invention has been made to solve the above-mentioned drawbacks. That is, even if the number of display dots in one row increases, the display signal can be easily transferred within the display blanking period of the fluorescent display tube. It is an object of the present invention to provide a drive circuit for a fluorescent display tube that does not require a long blanking period for signal transfer and can increase the duty factor.

Therefore, in order to achieve this object, a driving circuit for a fluorescent display tube according to the present invention includes a plurality of anodes coated with a phosphor layer and arranged in a matrix.
Sequence of (3n-2) in each row (n: positive integer)
Anodes at positions represented by the sequence (3n-1) (n: a positive integer), and anodes at positions represented by the sequence (3n) (n: a positive integer) are connected to each other in common, and control electrodes are arranged in each row facing every two rows of anodes, and the two adjacent control electrodes are simultaneously and sequentially connected one by one. In a drive circuit for a fluorescent display tube that selectively scans while shifting the control electrodes and applies display signals to anodes in adjacent rows of the two selected control electrodes, within a display period of the fluorescent display time tube, A first stage temporary storage circuit section stores a display signal to be displayed next, and a first stage temporary storage circuit section stores a display signal to be displayed next.
A second stage temporary memory receives a display signal directly transferred from the temporary memory circuit section of the second stage and applies the display signal to the anodes of the adjacent rows facing the two selected control electrodes. and, during the display period of the fluorescent display tube, give a non-lighting signal to the first stage temporary storage circuit part as necessary, and give a strobe signal for storing a display signal to be displayed next. Then, during the display blanking period, a strobe signal that causes the display signal held in the first stage temporary storage circuit section to be transferred to the second stage temporary storage circuit section is sent to the second stage temporary storage circuit section. It is characterized by comprising a display control section that provides information to the circuit section.

The present invention will be explained below with reference to illustrated embodiments.

FIG. 3 is a configuration diagram showing an embodiment of a drive circuit for a fluorescent display tube according to the present invention, and FIG. 4 is a timing chart for explaining the display operation of the embodiment.

Reference numeral 1 in FIG. 3 is a fluorescent display tube, and this fluorescent display tube has the same structure and function as the fluorescent display tubes shown in FIGS. 1 and 2. Reference numeral 3 in the figure is a drive circuit for the control electrodes, and as shown in FIGS. 1 and 2, the control electrodes G (for example, G ₁ G ₂ , G ₂ G ₃ , etc.) at the same time, and select this selection one after the other.
The structure is such that it can be moved and scanned while shifting each element one by one.

Next, the drive circuit section 20 for driving the anodes, which is the main part of the present invention, will be constructed in the same manner as shown in FIG. This will be explained in detail with reference to FIG.

The display signal S for one screen is stored in advance in this drive circuit section 20, or the display signal S is generated by a display signal forming section 18 that forms a display signal according to a control signal from a control device (not shown).
The structure is such that bits are sent in parallel.
(However, if the display signal is a serial input, a circuit for converting it into a parallel signal using a shift register is required as in the case of FIG. 2 described above.) In other words, the corresponding wiring for each row of anodes a on the fluorescent display tube 1 side An 8-bit display signal is introduced from the display signal forming section 18 by combining the display signals to be input into the conductors C ₁ , C ₂ , and C ₃ as a group.

Therefore, the drive circuit section 20 includes a temporary storage circuit 11 that temporarily stores signals to be introduced into the wiring conductors C1 of each row of the fluorescent display tube ₁ , and a temporary storage circuit 11 that temporarily stores signals to be introduced into the wiring conductors _C2 of each row. The first stage is composed of a temporary memory circuit 12 for temporarily storing the signal and a temporary memory circuit 13 (hereinafter referred to as latches 11, 12, 13) for temporarily storing the signal to be introduced into the wiring conductor _C3 of each row. It consists of a memory circuit section (hereinafter referred to as a latch circuit section) and temporary memory circuits 21, 22, 23 (hereinafter referred to as latches 21, 22, 23) into which each output of this first stage latch circuit section is introduced. It includes a second stage temporary storage circuit section (hereinafter referred to as a latch circuit section).

Then, the latch circuit section in the first stage locks each latch 11 by the strobe signals E ₁ , E ₂ , and E ₃ .
.about.13 are enabled to latch and temporarily store the applied display signal.

Furthermore, latches 21 to 23 constituting the second stage latch circuit section are brought into a latchable state by the simultaneously applied strobe signal _E0 , and store the outputs of latches 11 to 13, respectively.

On the other hand, each of the latches 11 to 13 has a clear terminal, and a clear signal is applied to each latch.
The memory contents are cleared to zero by CL ₁ , CL ₂ , and CL ₃ to form a non-lighting signal for the fluorescent display tube 1 .

Further, 31, 32, 33 are the latch 2
The outputs of 1, 22, and 23 are inputted separately to drivers that respectively drive the wiring conductors C ₁ , C ₂ , and C ₃ of each row of the anode a.

19 forms the strobe signals E ₁₁ , E ₁₂ , E ₁₃ and E ₀ and the clear signals CL ₁ , CL ₂ and CL ₃ , and also instructs the display signal forming section 18 to send out the display signal S and the drive circuit 3. This is a display control unit that generates a scanning timing signal.

Next, the operation of the above configuration will be explained with reference to FIGS. 3 and 4.

First, the control electrodes G are G ₁ , G ₂ , G ₃ . . . in FIG.
As shown by the waveforms . . . , adjacent control electrodes are simultaneously scanned by the control electrode drive circuit 3 and sequentially shifted one by one. In this case, the first
The control electrode G ₁ in the column does not have an adjacent control electrode on its left side, so it can be selected alone, or it can be selected as a control electrode arranged in the rightmost column (not shown).
G is selected at the same time as _k .

However, first, the anode a of the first row of the fluorescent display tube 1 is
(a ₁₁ , a ₂₁ ... a _n1 ), when the display signal S input from the display signal forming unit 18 to the wiring conductor C ₁ of each row is applied, before the scanning signal is applied to the control electrode G ₁ . Then, as shown in FIG. 4 _E11 , a strobe signal _E11 is applied from the display control section 19 to the latch 11 and latched.

In this case, simultaneously with the control electrode _G1 , the control electrode _Gk arranged in the rightmost column (not shown) of the fluorescent display tube 1 is also selectively scanned, and the anode in the rightmost column connected to the wiring conductor _C3 is also selectively scanned. When displaying is desired, a strobe signal _E13 is also applied to the latch ₁₃ , as shown by the broken line in FIG. 4E13.

On the other hand, when the anodes a in the first row are lit, the anodes a (a ₁₂ , a ₂₂ , . . . a _n2 ) in the second row must be kept in a non-lighted state. Therefore, following the strobe signal _E11 , the display control section 19 applies a clear signal _CL2 to the latch ₁₂ , as shown in FIG. 4, to reset the contents of the latch 12 to zero. put.

When the display blanking period ends and a control signal is applied to the control electrode _G1 as shown in FIG. 4 _G1 , the _display control unit 19 Applying _the strobe signal _E0 to the latches 21 to 23 as shown in FIG. 4E0,
The memory contents of latches 11 to 13 are transferred at once.

As a result, all the display signals to be supplied to the row of anodes a ₁₁ to a _n1 facing the selected control electrode G ₁ are stored in the latch 21, and the non-lighting signal is stored in the row of anodes a ₁₂ to a _n2 . This means that the signal is stored and is applied to the wiring conductors C ₁ and C ₂ in each row via the drivers 31 and 32. Then, as shown in FIG. ₄ C1 to _C3, lighting and non-lighting of each anode of the fluorescent display tube 1 is controlled.

On the other hand, the next display signal S is prepared in the latches 11 to 13 within the display period T _D1 by the control electrode _G1 . In this operation, during the display period T _D1 , the stored contents of the latch 11 are first reset to zero by the clear signal CL ₁ as shown in FIG. 4 CL ₁ , and then the strobe signal E ₁₂ shown in FIG. 4 E ₁₂ is reset to zero. Latch 1
2 is the display signal S to be given to the wiring conductor _C2 of each row.
to remember. Finally, as shown in FIG. 4 _E13 , the latch 13 is turned into a latchable state by the strobe signal _E13 , and the display signal S to be applied to the wiring conductor _C3 of each row is stored.

Since this storage operation is performed separately and independently from the display period T _D1 , it does not affect the display operation by the control electrode _G1 in any way.

After the end of the display period T _D1 , a display blanking period (T in G ₁ to _{G 3} in Figure 4) is started to prevent the display from becoming heavy due to a delay in the fall time of the drive signal for the control electrode G or anode a. _B1 to T _B3, etc.), the second row anode a (a ₁₂ to a _n2 ) and the third row anode a of the fluorescent display tube 1
In order to put the anodes a (a ₁₃ to a _n3 ) in the column into the display state,
As shown in FIG. 4 G ₁ and G ₂ , control signals are simultaneously applied to the control electrodes G ₁ and G ₂ . At the same time, in synchronization with the rising edge _r2 of this control signal, a strobe signal _E0 is applied from the _display control section 19 to the latches 21 to 23 as shown in FIG. The signal is transferred and the drivers 31-3
3, each wiring conductor C ₁ to _{C 3} is connected to C 1 to C ₃ in FIG.
It will be driven and displayed as shown in _C3 .

On the other hand, the display period T _D2 by these control electrodes G ₁ and G ₂
Within this period, the display signal S to be applied to each wiring conductor C ₁ and C ₂ during the display period T _D3 due to the simultaneous scanning of the next control electrodes D ₂ and D ₃ is controlled by the strobe signals E ₁₁ and E ₁₂ and the clear signal CL ₃ . Latches 11 to 13 will be prepared.

Thus, the above-mentioned operations are sequentially repeated, and the two adjacent control electrodes G of the fluorescent display tube 1 are simultaneously controlled.
Display is performed by selectively scanning the anodes while shifting them one by one, and by applying display signals to adjacent anode rows of the anode rows facing the selected control electrode.

Moreover, in this case, as mentioned above, during the display period, the display signal to be displayed next is prepared in advance in the latch circuit section of the first stage, and this display signal is generated using the blanking time peculiar to the fluorescent display tube. Since the display signal is directly transferred to the second stage latch circuit, transfer of the display signal becomes extremely easy.

That is, since it is not necessary to transfer the display signal S from the display signal forming section 18 within the display blanking period, even if the number of bits of the display signal S increases, the blanking period is not necessary for data transfer. There's no need to take it long. Therefore, it is possible to keep the duty factor large, and the brightness can be improved, and if the brightness is kept constant, it is possible to lower the anode voltage.

By the way, in the above-mentioned embodiment, in order to apply a non-lighting signal to the row of outer anodes a facing the two selectively scanned control electrodes G, it is necessary to clear the memory contents of the first stage latch circuit section. A zero signal is generated by this, and thereby the lighting of the required row of anodes a is prohibited.

However, as a method of forming this non-lighting signal, a display signal S having always data "0" is created in advance in the display signal forming section 18, and the wiring conductors C ₁ to C to be in a non-lighting state are This "0" data may be transferred to the first stage latches 11 to 13 corresponding to latches ₃ along with other display signals S.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without changing the gist thereof.

As explained above, according to the present invention, the anode drive circuit is provided with two stages of temporary storage circuit sections, a front stage and a rear stage, and both storage circuit sections are controlled by the display control section at a timing specific to the fluorescent display tube. By doing so, the next display signal is prepared in advance by inputting the next display signal into the temporary storage circuit section of the first stage within the display period of the fluorescent display tube, and the next display signal is input to the temporary storage circuit section of the first stage within the display period of the fluorescent display tube. Since the display signal of the temporary memory circuit of the eye is directly transferred to the second stage temporary memory circuit, it does not take time to transfer the display signal when displaying on the fluorescent display tube. Even when displaying a large number of display dots, the display signal can be easily transferred.In other words, there is no need to take a long display blanking period to transfer the display signal as in the past, which reduces the amount of time required. It has the excellent effect of enlarging the Teifu Acta.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the electrode connection structure of a triple anode matrix type fluorescent display tube, which is the object of the present invention. FIG. 2 is a configuration diagram showing an example of a conventional anode drive circuit. FIG. 4, a configuration diagram showing an embodiment of a drive circuit for a fluorescent display tube according to the invention, is a timing chart for explaining the display operation of the embodiment. a... Anode, G... Control electrode, C ₁ to C ₃ ... Wiring conductor, 1... Fluorescent display tube, 20... Anode drive circuit section, 11, 12, 13... First stage temporary Temporary memory circuits forming the memory circuit section, 21, 22, 23
...A temporary memory circuit forming the second stage temporary memory circuit section.

Claims (1)

[Scope of Claims] 1. Of a large number of anodes coated with phosphor layers and arranged in a matrix, the anodes at positions represented by the sequence (3n-2) (n: positive integer) in each row, ( The anodes at positions represented by the sequence (n: positive integer) of 3n-1) and the anodes at positions represented by the sequence (n: positive integer) of (3n) are each commonly connected, and 2 of the anode
Control electrodes are separately arranged facing the anode rows in each row, and the two adjacent control electrodes are simultaneously connected to each other.
and a drive circuit for a fluorescent display tube that performs selective scanning while sequentially shifting one control electrode at a time, and applies display signals to anodes in adjacent rows of the two selected control electrodes; A first-stage temporary storage circuit section that stores a display signal to be displayed next within a period, and a display directly transferred from this first-stage temporary storage circuit section within the next display blanking period. a second-stage temporary memory circuit unit that receives a signal and applies a display signal to anodes in adjacent rows facing the two selected control electrodes; , gives a non-lighting signal to the first stage temporary storage circuit section as needed, and also gives a strobe signal for storing the display signal to be displayed next, and furthermore, within the next display blanking period, and a display control unit that supplies the second stage temporary storage circuit with a strobe signal that causes the display signal held by the second stage temporary storage circuit to be transferred to the second stage temporary storage circuit. Features a fluorescent display tube drive circuit.