JPH07101334B2 - Electromagnetic drive circuit for magnetic panel - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electromagnet drive circuit for a magnetic panel.

[Conventional technology]

In order to display information consisting of a set of dots on the magnetic panel, as shown in FIG. 4, the printing head 2 having a large number of electromagnets is moved along the magnetic panel 1 in the direction of the arrow while selectively driving the electromagnets. There has been proposed a magnetic display device that performs the display.

More specifically, at least one transparent magnetic panel 1 is used. A dispersion liquid (usually white) in which magnetic particles (usually black) are dispersed and held between two substrates. Is formed by sealing.

In addition, the electromagnet has a plurality of groups (for example, 6 groups).
The electromagnet drive circuit 3 shown in detail in FIG. 5 is provided for each group. The electromagnet drive circuit 3 connects the electromagnet coils H1 to H96 provided with the reverse current prevention diode 4 to the vertical and horizontal anode lines 5 and cathode lines 6, respectively, and the anode lines 5 are connected to the power source Vc.
Anode line drive switching element SX1 to be connected to c
Connect to SX6 respectively, and connect each cathode line 6 to cathode line drive switching devices SY1 to SY16.
A scan signal is input to X1 to SX6, and a data signal is input to the elements SY1 to SY16.

When the electromagnet is selectively driven to apply the display magnetic field, the magnetic particles to which the magnetic field is applied migrate and are collected from one substrate side to the other transparent substrate side, and the color of the magnetic particles and the dispersion liquid are dispersed. Information consisting of a set of dots can be displayed by the difference in color contrast.

By the way, a characteristic of the dispersion liquid used in the magnetic panel 1 is that it holds magnetic particles and prevents their sedimentation.
Therefore, it is usual that a thickening agent is added to the dispersion liquid to increase the yield value of the dispersion liquid. In such a magnetic panel, if some of the magnetic particles that have been subjected to a magnetic force cannot be migrated and are retained in the dispersion liquid, the display becomes thin and blurred. For this reason, at least most of the electromagnets that do dot display on the magnetic panel further migrate the magnetic particles held in the dispersion liquid without being able to migrate, so that the current value gradually decreases after passing a current of a predetermined current value. A current waveform that

[Problems to be solved by the invention]

However, the above-mentioned electromagnet drive circuit 3 includes the electromagnet coils H1 ...
Since the exciting current flowing through H96 is controlled only by using SX1 to SY16, the flyback current from the electromagnet does not recirculate regardless of the opening order of the above elements, and as shown in FIG. The current value flowing through the electromagnet coils H1 to H96 is only large during the excitation time t, and the current value after the excitation time t cannot be gradually decreased. For this reason, the magnetic particles in the magnetic panel 1 cannot be sufficiently migrated, and the printed information has a defect that the printed information has a thin feeling and the contour portion of the information is blurred. On the other hand, the printing quality of each electromagnet is improved by increasing the excitation time, but the printing speed becomes slow.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electromagnet drive circuit that improves the above-mentioned drawbacks and can obtain high quality printing without sacrificing the printing speed.

[Means for solving problems]

In the present invention, an electromagnet coil provided with a diode for preventing reverse current is connected to each vertical and horizontal anode line and each cathode line, and one end of each anode line is connected to an anode line drive switching element connected to a power source. The other end of the anode line is connected to the grounded reverse diode, the one end of each cathode line is connected to the grounded cathode line drive switching element, and the other end of each cathode line is connected to the forward diode connecting the power supply. Connected to each other, a scan signal is input to the anode line drive switching element, one data signal is input to the cathode line drive switching element using two types of data signals with different timings, and the other data signal is input to the cathode line drive switching element. Data signal is sent to the remaining cathode line drive switching element. When the electromagnet coil (A) to be excited next is excited from the excited electromagnet coil (A), only one of the anode line drive switching element and the cathode line drive switching element for the electromagnet coil (A) is input. When is closed, the flyback current generated from the electromagnet coil (A) recirculates.

[Action]

In the present invention, the other end of each anode line is connected to a grounded reverse diode, the other end of each cathode line is connected to a forward diode connected to a power supply, and a scan signal is input to the anode line drive switching element. ,
Electromagnetic coil excited by inputting every other data signal to the cathode line drive switching element using two types of data signals with different timings and inputting the other data signal to the other cathode line drive switching elements When the electromagnet coil (B) to be energized next from (A) is energized, if either one of the anode line drive switching element and the cathode line drive switching element for the electromagnet coil (A) is closed, The flyback current generated from the electromagnet coil (A) recirculates to gradually reduce the current value of the electromagnet coil (A) after being excited.

〔Example〕

Hereinafter, the present invention will be specifically described based on an embodiment shown in the drawings.

The electromagnet drive circuit 7 shown in FIG. 1 is similar to the conventional electromagnet drive circuit 3 in that it has a diode 4 for preventing reverse current, electromagnet coils H1 to H96, anode line 5, cathode line 6, elements SX1 to SX6, and elements SY1 to SY16. However, the other end of each anode line 5 is connected to the grounded forward diodes DX1 to DX6.
And the other end of each cathode line 6 is connected to the power source Vc.
Connected to the reverse diodes DY1 to DY16 which are connected to c.

Next, driving will be described.

The scan signal and the data signal are input to the elements SX1 to SX6 and the elements SY1 to SY16, respectively.

In this embodiment, it is assumed that the data signals D1 and D2 are used, the data signal D1 is input to every other cathode line drive switching element, and the data signal D2 is input to the remaining cathode line drive switching elements. There is.

In the example of FIG. 2, the scan signals S1, S2, and S3 are input to the elements SX1, SX2, and SX3, respectively, but the data signal D1 is input to the elements SY1 and SY3, and the data signal D2 is input to the element SY2. I will.

At the timing t1, the element SX1 is closed and the element S
Since Y1 and SY3 are closed, the drive current flows from the power supply Vcc to the electromagnet coils H1 and H13, and the electromagnet coils H1 and H13 are excited.

Next, at timing t2, the data signal D1 opens the elements SY1 and SY3, and the data signal D2 opens the elements.
SY2 closes. Then, the drive current flows from the power supply Vcc to the electromagnet coil H7, and the electromagnet coil H7 is excited.

At this time, since the element SX1 for the electromagnet coils H1 and H13 is closed, the electric energy stored in the electromagnet coils H1 and H13 becomes a flyback current, and the electromagnet coil H1 →
It flows through the path of diode DY1 → element SX1, electromagnet coil H13 → diode DY3 → element SX1.

In the state of the timing t3, the element SY2 remains closed and the element SX2 is closed, so that the drive current flows from the power supply Vcc to the electromagnet coil H8 and the electromagnet coil H8 is excited.

At this time, since the element SY2 for the electromagnet coil H7 is closed, the electric energy stored in the electromagnet coil H7 becomes a flyback current, and the electromagnet coil H7 → element SY2 →
It flows through the path of the diode DX1.

Next, at the timing t4, the data signal D2 opens the element SY2, and the data signal D1 opens the elements SY1 and SY.
3 closes. Then, the drive current flows from the power supply Vcc to the electromagnet coils H2 and H14, and the electromagnet coils H2 and H14 are excited.

At this time, since the element SX2 for the electromagnet coil H8 is closed, the electric energy stored in the electromagnet coil H8 becomes a flyback current, and the electromagnet coil H8 → diode
It flows through the path from DY2 to element SX2.

In this way, when the electromagnet coil (A) to be excited next is excited from the excited electromagnet coil (A), either the anode line drive switching element or the cathode line drive switching element for the electromagnet coil (A) is closed. At this time, the flyback current generated from the electromagnet coil (A) recirculates. Thus, when the flyback current flows back from the electromagnet coil, the potential difference seen from each electromagnet becomes almost zero, and as shown in FIG. 3, the current that sharply rises during the time t due to the excitation gradually decreases, The excitation of the electromagnet coil is continued during the time Δt.

〔The invention's effect〕

As described above, according to the present invention, the other end of each anode line is connected to a reverse diode that is grounded, and the other end of each cathode line is connected to a forward diode that is connected to a power source. A scan signal is input to the switching element, and one data signal is input to the cathode line driving switching element using two types of data signals having different timings, and the other data signal is input to the remaining cathode line driving switching. One of an anode line driving switching element and a cathode line driving switching element for the electromagnet coil (A) when the electromagnet coil (A) to be excited next is excited from the excited electromagnet coil (A) When only is closed, the flyback current generated from the electromagnet coil (A) Since reflux, the current value after excitation of the electromagnet coil can gradually reduce, without sacrificing print speed, those capable of performing clear high-quality printing on the magnetic panel compared to the prior art.

[Brief description of drawings]

FIG. 1 is a circuit diagram in which a part of the circuit of the present invention is omitted, FIG. 2 is a time chart, FIG. 3 is a current waveform diagram, FIG. 4 is a schematic explanatory diagram of a magnetic display device, and FIG. FIG. 4 is a circuit diagram of a conventional circuit in FIG. 4, and FIG. 6 is a current waveform diagram. 1 ... Magnetic panel, 2 ... Printing head, 4 ... Reverse current prevention diode, H1 to H96 ... Electromagnetic coil, 5 ... Anode line, 6 ... Cathode line, 7 ... Electromagnet drive circuit, SX1 ... SX6 …… Anode line drive switching element, SY1 to SY96 …… Cathode line drive switching element, DY1 to DY16 …… forward diode, DX1 to DX6 …… reverse diode.

Claims (1)

[Claims] 1. An electromagnet coil provided with a diode for preventing reverse current is connected to each vertical and horizontal anode line and each cathode line, and one end of each anode line is connected to an anode line drive switching element connected to a power source. The other end of each anode line is connected to a grounded reverse diode, the one end of each cathode line is connected to a grounded cathode line drive switching element, and the other end of each cathode line is connected to the power source. The scan signal is input to the anode line driving switching element, and one of the data signals is input to the cathode line driving switching element using two types of data signals with different timings, and the other is input to the other. Data signal of the remaining cathode line drive switching One of an anode line driving switching element and a cathode line driving switching element for the electromagnet coil (A) when the electromagnet coil (A) to be excited next is excited from the excited electromagnet coil (A) A flyback current generated from the electromagnet coil (A) flows back when only one is closed.