JP2539666Y2 - Control structure of dot print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a control structure of a dot print head in a wire dot impact printer.

[Conventional technology]

FIG. 6 is a side sectional view showing a conventional example of the structure of this type of dot print head, which is of a spring charge type.

In FIG. 1, reference numeral 1 denotes a base, and a permanent magnet 2, a base plate 3, and a spacer 4 are sequentially stacked on an end of the base 1,
A leaf spring 7 and a yoke 8 are sandwiched between the spacer 4 and the guide frame 5 via a clamp 6 in a cantilever manner.

Reference numeral 9 denotes a core provided on the base 1 and reference numeral 10 denotes a coil wound around the core. An electromagnet 11 is formed by the core 9 and the coil 10.

Reference numeral 12 denotes a cover for protecting a current-carrying substrate 13 for wiring the coil 10.

An electromagnet is provided on the flexible portion of the leaf spring 7 adjacent to the yoke 8.
Armature 14 facing 11 core 9 is attached,
A print wire 15 is attached to the tip of the armature 14, and is guided to the platen side by a wire guide 16 fixed to the guide frame 5.

Here, the base plate 3, the spacer 4,
A magnetic circuit is formed to return to the permanent magnet 2 again through the yoke 8, the armature 14, the core 9 and the base, and the armature 14 is attracted to the core 9 together with the leaf spring 7 by the magnetic circuit and is in a biased state.

In this biased state, the coil 10 is energized to
When the magnet 11 is excited (hereinafter referred to as a drive) to generate a magnetic flux in the direction opposite to the magnetic circuit, the armature 14 is released from the core 9, the strain energy stored in the leaf spring 7 is released, and the leaf spring 7 is released. Is restored, the printing wire 15 attached to the tip of the armature 14 protrudes from the wire guide 16, and the printing is performed by pressing the ink ribbon and the printing medium (not shown) against the platen.

A plurality of these printing elements are radially arranged to form a dot print head.

In the above configuration, the excitation time of the electromagnet 11 (hereinafter referred to as drive time) is an important factor that greatly affects characteristics such as print quality, print speed, and print efficiency.

FIG. 7 is a waveform diagram showing the relationship between the drive time and the print wire displacement.
(B) shows the case of a short drive time, and (c) shows the case of a long drive time.

In the case of the standard drive time shown in FIG.
Immediately after release, voltage is applied.After that, the current is held down by the inductance of the coil 10 until just before printing to prevent re-attraction, the breaking current is cut off immediately before printing, and the repulsion force during printing is reduced. Is attracted again by the attraction force of the permanent magnet 2.

When the drive time is short as shown in FIG. 7 (b), the printing speed is reduced and the printing power is weakened.

Further, as shown in FIG. 7 (c), if the drive time is too long, the re-suction force after printing is disturbed, and the return time is delayed.

In other words, the drive time has an optimum value according to changes in conditions such as the wire stroke to the print medium, drive voltage, the number of simultaneous prints, coil temperature, etc., and characteristic variations for each print element. There is a printable drive range that does not exist.

Therefore, in the conventional example of the above-described configuration, a change in the condition is limited by incorporating an approximate correction circuit for the drive time for some of the changes.

[Problems to be solved by the invention]

However, according to the conventional technology having the above-described configuration, since the conventional technology only responds to a condition change within a predetermined allowable range,
The correction function does not work with respect to an object deviating from this, and there is a problem that the correction is limited.

Further, it is hardly possible to cope with a change in the wire stroke due to a change in the thickness of the print medium or the like, which results in missing prints or trapped prints.

In addition, there is a problem that the device becomes expensive because a drive time approximation correction circuit is incorporated.

Furthermore, when the repetition speed is high and the rebound that occurs during re-suction during the previous printing is affected, the printing operation changes variously even under the same conditions. Or hinder speeding up.

In view of the above problems, the present invention obtains a configuration that always maintains an optimum drive time for each element, improves print quality, print speed, and print power, and achieves high print quality, high-speed printing, and low print quality. It is an object to realize a noise dot print head.

[Means for solving the problem]

In order to achieve the above object, the present invention provides an armature that is attracted by a permanent magnet to attract an armature to deflect a leaf spring, and the attracted magnetic flux is canceled by a demagnetizing magnetic flux by an electromagnet to release the armature. In the control structure of the dot print head that drives the print wire fixed to the surface, in the displacement direction of the armature, an electrode integrally formed as a pattern on the detection substrate so as to face each armature with a minute space therebetween, and the operation of the armature A detection circuit for detecting the suction and release of all operation printing wires individually based on a change in the capacitance of the electrode at each printing occasion; and, during printing, the excitation time of the electromagnet by the operation of the armature detected by the detection circuit. And set a drive circuit to control the drive time for each print wire and each print opportunity. When the coil is energized and the armature begins to displace, the electrodes on the detection board detect the change in capacitance and send a displacement signal to the detection circuit, which compares the displacement signal with the detection level. When the detection level is reached, a release detection signal is output, and the drive circuit stops energizing the coil with this release detection signal, releases the armature, and performs printing.

[Operation] In the present invention having the above structure, the armature is attracted by the permanent magnet to attract the armature to deflect the leaf spring, and the electromagnet is excited to generate a demagnetizing magnetic flux to cancel the attracting magnetic flux to release the armature. This drives the print wire attached to the tip of the armature.

At that time, the detection circuit detects the suction and release of all operation printing wires individually at each printing opportunity from the change in the capacitance of the electrode due to the displacement amount of the armature, and at the time of printing, the detection of the armature detected by this detection circuit The excitation time of the electromagnet is determined based on the amount of displacement, and the drive time is controlled by a drive circuit for each print wire and each print opportunity.

〔Example〕

 Embodiments will be described below with reference to the drawings.

 FIG. 1 is a side sectional view showing one embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a base, and a permanent magnet 2, a base plate 3, and a spacer 4 are sequentially stacked on an end of the base 1,
A leaf spring 7 and a yoke 8 are sandwiched between the spacer 4 and the guide frame 5 via a clamp 6 in a cantilever manner.

Reference numeral 9 denotes a core provided on the base 1 and reference numeral 10 denotes a coil wound around the core. An electromagnet 11 is formed by the core 9 and the coil 10.

Reference numeral 12 denotes a cover that protects a current-carrying substrate 13 for wiring the coil 10.

An armature 14 facing the core 9 of the electromagnet 11 is attached to the flexible portion of the leaf spring 7 adjacent to the yoke 8, and a print wire 15 is attached to a tip of the armature 14 and is fixed to the guide frame 5. Wire guide 16
Is guided to a platen side (not shown).

Reference numeral 17 denotes a detection board provided between the guide frame 5 and the yoke 8, and reference numeral 18 denotes a fixed pole provided on the detection board 17, and the fixed pole 18 faces the armature 14 by opening a narrow space. And has a certain value of capacitance.

This value is determined according to the gap between the fixed pole 18 and the armature 14, and when the armature 14 is displaced in the printing operation, the capacitance also changes.By observing this change, the printing wire 15 fixed to the armature 14 is observed. You can know the operation.

FIG. 2 is a plan view showing the detection board 17, in which a 9-pin head is shown as an example.

The number of the fixed poles 18 is the same as the number of the armatures 14, that is, the number corresponding to the number of elements is integrally formed as a pattern on the detection substrate 17, and the signal lines 19 independent of each fixed pole 18 are formed.
However, it has a structure in which an armature displacement detection circuit described later is connected via a connector (not shown).

Reference numeral 20 denotes a connector portion of the signal line 19, and reference numeral 21 denotes an exposed common line, which comes into contact with the yoke 8 and conducts with each armature 14. Reference numeral 22 denotes a connector portion, and the signal line 19 of the fixed pole 18 passes through the back surface of the detection board 17 and is electrically connected to the front surface by the connector portion 22.

FIG. 3 is a perspective view showing the operation of the armature 14 in the present embodiment, wherein a solid line indicates a suction state, and a dashed line indicates a released state.

The axis M is the center of rotation of the armature 14, and the fixed pole
18 is arranged inside this axis M.

FIG. 4 is a block diagram showing the control system of the present embodiment, and FIG. 5 is a time chart showing the operation of the control system.

4, reference numeral 23 denotes a dot print head having the structure shown in FIG. 1, reference numeral 24 denotes a detection circuit for detecting the amount of displacement of the armature 14 from a change in the capacitance of the fixed pole 18, and reference numeral 25 denotes the detection circuit.
A drive circuit for controlling the drive of the electromagnet 11 of each element of the dot print head 23 in accordance with the amount of displacement of the armature 14 detected by the reference numeral 24.
3 is a control unit for controlling the operation of each mechanism.

S ₁ is a print signal output from the control unit 26 to the drive circuit 25, S ₂ is a drive output output from the drive circuit 25 to the coil 10 of the dot print head 23, and S ₃ is a dot print head 23
Is a displacement signal input to the detection circuit 24 from the fixed pole 18 in the inside, and this displacement signal S ₃ is a release detection signal S ₄
And is converted into printing detecting signal S ₅ and input to the drive circuit 25.

The operation of the present embodiment having the above configuration will be described below with reference to FIG.

Note that the principle of the printing operation by the suction and release of the armature 14 is the same as that of the related art, and thus the description is omitted.

The energization of the coil 10 is started by the print signal S1, and the energization signal S2
Is output, and when the armature 14 starts to be displaced, the fixed pole 18 of the detection board 17 detects a change in the capacitance, and the displacement signal S3
To the detection circuit 24.

The detection circuit 24 transmits the displacement signal S3 as a displacement waveform (sensor output) as shown in the figure, compares it with the detection level a, and outputs a release detection signal S4 when the detection level a is reached.

The drive circuit 25 stops supplying power to the coil 10 in response to the release detection signal S4, releases the armature 14, and enters a state in which current due to inductance is held.

Next, when the peak detection or the differential output S6 (velocity waveform) of the displacement reaches the detection level b, printing is detected, the current is forcibly cut off by the drive circuit 25 by the print detection signal S5, and the regenerative current holding signal S7 The coil 10 holds a positive current.

As a result, the print signal S1 is transmitted from the control unit 26 to the drive circuit 25.
The armature changes constantly depending on the conditions at that time while the actual drive time is constantly transmitted
Correction of extension and shortening is sequentially performed according to the displacement amount of 14, and the optimal drive time can be always maintained for each element.

In addition, the structure of the dot print head of this embodiment can use the conventional structure as it is, and only by adding one detection substrate,
Easy to implement.

In this embodiment, the number of boards for connection is increased to two. However, a flexible cable or the like may be used to integrate the board internally, or the detection circuit 24 and the drive circuit 25 may be printed by dot printing. The number of connection wirings provided in the head 23 may be reduced.

Further, the present invention has been described with respect to a spring-charge type dot print head. However, the present invention can also be applied to a clapper type which performs printing by the attraction of an electromagnet.

[Effect of the invention]

As described in detail above, according to the present invention, the armature is attracted by the permanent magnet to attract the armature to deflect the leaf spring, and the attracted magnetic flux is canceled by the demagnetizing magnetic flux by the electromagnet to release the armature. In a dot print head that drives a print wire while being fixed to the tip of an armature, an amount of displacement of the armature is detected from an electrode facing a small space in a displacement direction of the armature and a change in capacitance of the electrode. A detection circuit and a drive circuit for determining the drive time of the electromagnet in accordance with the displacement of the armature detected by the detection circuit at the time of printing are provided. And printing can be performed while correcting the drive time in accordance with the detection.

This makes it possible to maintain the optimal drive time for each element at all times, improving print displacement, printing speed and printing power, and realizing a high-quality, high-speed printing and low-noise dot print head. There is an effect of doing.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing one embodiment of the present invention, FIG. 2 is a plan view of a main part of the embodiment, FIG. 3 is a perspective view of a main part of the embodiment,
4 is a block diagram showing the control system of the embodiment, FIG. 5 is a time chart showing the operation of the control system, FIG. 6 is a sectional side view of the conventional example, and FIG. 7 is drive time and print wire displacement. FIG. 6 is a waveform chart showing the relationship of FIG. 2 ... permanent magnet, 7 ... leaf spring 9 ... core, 10 ... coil 11 ... electromagnet, 14 ... armature 15 ... printed wire, 17 ... detection board 18 ... fixed pole, 24 ... detection Circuit 25 Drive circuit 26 Control unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Hideaki Ishimizu 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Tomohiro Komori 1-7-12 Toranomon, Minato-ku, Tokyo No. Oki Electric Industry Co., Ltd. (56) References JP-A-59-2864 (JP, A) JP-A-61-81610 (JP, A)

Claims (1)

(57) [Scope of request for utility model registration] An armature is attracted by a magnetic flux attracted by a permanent magnet to deflect a leaf spring, and the attracted magnetic flux is canceled by a demagnetizing magnetic flux by an electromagnet to release the armature, whereby a printing wire fixed to the tip of the armature. In the control structure of the dot print head that drives the electrodes, an electrode integrally molded as a pattern on the detection substrate so that each armature faces each other with a minute space in the direction of armature displacement, A detection circuit for detecting the suction and release of all operation printing wires individually at each printing occasion based on a change in capacity; and, during printing, determining the excitation time of the electromagnet by the operation of the armature detected by the detection circuit. For each print wire,
A drive circuit that controls the drive time for each printing opportunity is provided.When the coil is energized and the armature starts displacing, the electrodes on the detection board detect the change in capacitance and the displacement signal is sent to the detection circuit. The displacement signal is compared with the detection level by the detection circuit, and when the detection level is reached, a release detection signal is output, and the drive circuit stops energizing the coil with this release detection signal, releases the armature, and prints. A dot print head control structure.