JPH0333510B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a printing device that drives a plurality of printing hammers and printing wires such as a line type and a wire dot type among impact type printing devices, and an object of the present invention is to reduce the size, speed, and power consumption of the printing mechanism. It is something to do. Various types of impact printing devices are known, and generally an electromagnet is used to drive a printing member such as a printing hammer or a printing wire.
Taking a wire dot type printing device as an example, a structure as shown in FIG. 1 is generally used. It includes a printing wire 3 and an armature 4 that are driven in the direction of the platen 2 by a plurality of printing wire driving electromagnets 1 arranged radially. 3, characters, symbols, etc. are printed on printing paper 6 via an ink ribbon 5. This method is extremely widely used due to its characteristics such as the relatively high operating speed of the electromagnet and the simple structure. However, electromagnets have poor electrical-to-mechanical energy conversion efficiency and require a relatively large amount of electrical energy for printing. As a result, it is necessary to increase the capacity of the electromagnet drive circuit and power supply, resulting in high costs and an increase in the size of the device itself. Therefore, in such a structure having a plurality of print wire driving electromagnets, increasing the printing speed is directly related to an increase in the size of the device and power consumption. Although a detailed explanation will be omitted regarding line-type printing devices, they have similar problems as long as they have a plurality of driving electromagnets. Currently, as printing speeds are increasing, there is an increasing demand for the development of compact, low power consumption printing devices that can solve these drawbacks. The present invention realizes a printing device that satisfies these demands. The configuration of the present invention will be explained below based on the drawings showing one embodiment thereof. FIG. 2 is a sectional view showing a printing state of a first embodiment in which the present invention is applied to a wire dot type printing device, and FIG. 3 is a sectional view similarly showing a non-printing state. In FIG. 2, the printing wire 3 is supported at one end by a bearing 7 and fixed at the other end by a printing spring 8 so as to be able to reciprocate in a direction substantially perpendicular to the printing paper 6. The printing spring 8 is made of a magnetic material, has a suction tip 9 fixed on the opposite side to the fixed printing wire 3 as described above, and has its base end fixedly supported by the wire housing 11 together with the magnet 10. On one end surface of the magnet 10, there is an L-shaped yoke 1 made of a magnetic material and having a selection coil 12 wound around a part thereof.
3 is fixed, and the distal end surface of the yoke 13 faces the suction chip 9 fixed to the printing spring 8 with a gap therebetween. When energized, the return electromagnet 14 drives a reciprocating member 15 fixed to its movable iron core to return the printing wire 3 to the return position as shown in FIG. It is reset by 16. Regarding the vibration system constituted by the printing wire 3 and the printing spring 8, the movable mass of the printing wire 3 and the printing spring 8 is m, the spring constant of the printing spring 8 is k, and the reciprocating member 15 and Regarding the vibration system constituted by the spring 16, when the movable mass M and the spring constant K are set, the movable mass and spring constant of each vibration system are set so as to satisfy the following condition: k/m=K/M. , and the return electromagnet 14 is continuously driven at the resonance frequency of a vibration system constituted by a reciprocating member 15 and a spring 16. Furthermore, the reciprocating member 15 has an engaging portion at its tip, and as shown in FIG. The spring 8 is deformed and the printing wire 3 is simultaneously moved toward the return position. Further, as shown in FIG. 4, the wire housing 11 is fixed to a carriage 17, and the carriage 17 is attached to a guide shaft 18 so as to be able to reciprocate in parallel with the printing surface of the printing paper 6, and a drive pulley is driven by a motor 19. 20a, 20b, and are driven via a drive wire rope 21. In the carriage 17,
A position detection device 22 consisting of a light emitting element 22a and a light receiving element 22b arranged opposite to each other is fixed,
In the gap between the light emitting element 22a and the light receiving element 22b,
A strip 24 with a transparent slit 23 corresponding to the position in which the printing wire 3 is to be driven is arranged parallel to the guide shaft 18. In FIG. 5, the return electromagnet 4 is connected to the drive circuit 2.
5 is energized, and the selection coil 12 is energized by the selection drive circuit 26. Furthermore, it has a selection control circuit 27 that causes the operation timing of the selected drive circuit 26 to have a time delay with respect to the operation timing of the drive circuit 25. Also, the return electromagnet 14
It has a drive control circuit 28 that increases or decreases the voltage input to the return electromagnet 14 in accordance with the number of printed printing wires 3 during operation. Further, the selection control circuit 27 and the drive control circuit 28 are controlled by timing signals from the print control circuit 29 and the position detection device 22. Next, its operation will be explained. In the initial state, the printing spring 8 is held in a deformed state by the holding force of the magnet 10. Further, when the carriage 17 is driven at a predetermined speed by the motor 19 and the position detection device 22 detects that the printing wire 3 has come to the position where it should be driven and issues a timing signal, this timing signal causes the drive circuit 25 to and the drive control circuit 28 is the return electromagnet 1
4 to drive the reciprocating member 15 in the direction of the return position, and move the printing spring 8 to a position where it is held by the magnet 10 in a deformed state as shown in FIG. At this time, when returning the reciprocating member 5, the drive control circuit 28 controls the load fluctuation according to the number of printing wires 3 that are not held by the magnet 10 (i.e., the number of printing wires 3 used in the previous printing). In order to compensate, the input voltage of the return electromagnet 14 is controlled according to the number. Further, the reciprocating member 15 operates with a time delay relative to the timing signal due to a phase difference caused by the movable mass, the spring constant of the spring 16, viscous resistance, and the like. Therefore, the printing wire 3 is returned to the return position with a predetermined time delay including a phase difference from the timing signal.
Then, the selection drive circuit 26 energizes a predetermined coil of the selection coil 12 in a direction to cancel the magnetic flux of the magnet 10 at a timing delayed by a predetermined time from the timing signal by the selection control circuit 27. As a result, the holding force of the magnet 10 is canceled out, and the predetermined printing spring 8 is released from its restraint and drives the printing wire 3 toward the platen 2 to perform printing. In addition,
At this time, the return electromagnet 14 is in a non-energized state, and the reciprocating member 15 is held against the platen 2 by the spring 16.
is being driven in the direction of After printing is completed, the return electromagnet 14 is connected to the drive control circuit 28 and the drive circuit 2 again.
It is energized by 5. Continuous printing is performed by the above continuous operations. The electric energy given by the selection coil 12 in this embodiment is consumed only to cancel the holding force generated by the closed magnetic circuit including the magnet 10, and unlike the conventional example described above, printing is performed using a magnetic circuit with an air gap. This is extremely small compared to the electrical energy required to generate the suction force to move the member at high speed. As a result, the magnetic circuit can be made smaller. In addition, since the suction chip 9, printing spring 8, magnet 10, and yoke 13 form a closed magnetic path,
It has good magnetic efficiency and allows the magnetic circuit to be miniaturized. Furthermore, by using an alnico magnetic material for the magnet 10 and a high magnetic permeability material such as permalloy for the yoke 13, the holding force of the magnet 10 can be canceled out with low power consumption. As a result, the drive circuit and power supply can be made smaller and have lower capacity, resulting in lower costs. Furthermore, whereas the conventional electromagnet 1 (FIG. 1) must operate in response to a print signal, the return electromagnet 14 in this embodiment can be operated continuously at approximately constant intervals. . Therefore, by setting the vibration system shown in this embodiment, the return electromagnet 14 can always be driven in a resonant state against fluctuations in the vibration system caused by changes in the number of printing wires 3 to be printed. . This is because the resonance frequency of the vibration system composed of the printing wire 3 and the printing spring 8 is

The resonance frequency of the vibration system composed of the reciprocating member 15 and the spring 16 is expressed by [Formula].

If it is expressed by [Formula] and the number of printing wires to be printed is n, then the resonant frequency of all the vibration systems driven by the return electromagnet 14 is:

[Formula] By substituting K/M=k/m from the above condition f _i =f _M and sorting it out, f _T = f _M = f _i = f _d is obtained, regardless of the number of prints n. The resonant frequency f _T of the vibration system coincides with the driving frequency f _d . Therefore, the mechanical work efficiency is extremely good, and the power consumed by the return electromagnet 14 can be small. Furthermore, fluctuations in the phase difference between the electrical input of the return electromagnet 14 and the displacement of the reciprocating member 15 are also reduced, and the reliability of the printing operation is also improved. Furthermore, this effect can also be obtained by increasing or decreasing the input current value or the input current energization time of the return electromagnet 14 by the drive control circuit 28 in accordance with the number of printing wires 3 as in the present embodiment. In addition, with respect to the operation timing for driving the return electromagnet 14, the timing for energizing the selection coil 12 for performing the selection operation is set by adjusting the timing for energizing the selection coil 12 for the return electromagnet 14.
By delaying by a predetermined time including the phase difference between the excitation force and the amplitude, the reliability of the selection operation of the printing wire 3 can be improved. Further, the motor 19 drives the carriage 17 at a predetermined speed, and at this time, the timing signal issued by the position detection device 22 operates the return electromagnet 14 and energizes the selection coil 12, so the constant speed of the carriage 17 allows printing. There is less pitch deviation and printing quality can be improved. This effect, as shown in FIG. 6, has a reference oscillation circuit 30 that continuously emits a reference pulse at a predetermined period, and the timing of this reference pulse causes the return electromagnet 14 to operate and the selection coil 12 to be energized. The same result can also be obtained by driving the motor 19 by a motor control circuit 31 for synchronizing the pulses continuously emitted by the position detection device 22 and the reference pulse. Note that the present invention can also be applied to a printing device that selectively operates a plurality of printing hammers at high speed, such as a line-type printing device of the present invention. As described above, according to the present invention, by using the drive control circuit, the drive means can cope with load fluctuations caused by changes in the number of printing wires during operation of the return electromagnet.
It is driven with a constant amplitude, and as a result, the reliability of the selection operation by the selection drive means is improved, and the printing quality is also improved.Also, since the printing wire is controlled according to the number of printing wires, it does not consume more energy than necessary. It has the excellent advantages of low power consumption and miniaturization.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a printing head showing a conventional example of a wire dot printing device, FIGS. 2 and 3 are sectional views of a wire dot printing head showing an operating state of an embodiment of the present invention, and FIG. 5 is a schematic diagram of the appearance of the printing device, and FIG. 5 is a system block diagram of the printing device.
FIG. 6 is a system block diagram of a printing device showing a second embodiment of the present invention. 3... Printing wire, 8... Printing spring, 9...
Adsorption chip, 10...Magnet, 12...Selection coil, 13...Yoke, 14...Returning electromagnet, 15...Reciprocating member, 16...Spring, 17...
Carriage, 19...Motor, 22...Position detection device, 25...Drive circuit, 26...Selection drive circuit, 27...Selection control circuit, 28...Drive control circuit, 29...Print control circuit, 30... Reference oscillation circuit, 31...Motor control circuit.

Claims (1)

[Scope of Claims] 1. A plurality of printing members that can reciprocate between a printing position and a return position and print by impact force at the printing position, and a plurality of printing members that are continuously driven at a predetermined period to drive the printing members back and forth. a driving means that operates; and a selection driving means that holds only the printing members that should not be printed in response to a printing signal when the plurality of printing members are in the return position, and does not transmit the driving force of the driving means to the printing members. and, in order to return the printing members that have been selectively driven in the printing position direction by the selection driving means a substantially constant distance from the printing position to the return position, the driving is performed according to the number of the moving printing members. A printing device characterized by comprising a drive control means for increasing or decreasing the power of the means. 2. An electro-mechanical converter is used as the drive means, and the drive control means increases or decreases the input electric energy of the electro-mechanical converter according to the number of printing members selectively operated by the selective drive means. A printing device according to claim 1. 3. The driving means is composed of a vibration means consisting of an electromagnet that drives in one direction when energized and a spring that returns in the opposite direction when not energized, and the drive control means controls the number of printing members selectively operated by the selective driving means. 3. The printing device according to claim 1, wherein the energization time of the electromagnet is increased or decreased depending on the time.