JPH0340714B2 - - 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 energy-mechanical energy exchange 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 printing wire driving electromagnets, increasing the printing speed directly relates to an increase in the size of the device and an increase in 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 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 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 adsorption tip 9, which has a printing spring 8 fixed thereto, with an air space 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 is m, the spring constant of the printing spring 8 is k, and the reciprocating member 15 and the spring 16 are Regarding the vibration system composed of, the movable mass M and the spring constant K
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 composed of a reciprocating member 15 and a spring 16. It is continuously driven at the resonance frequency of the vibration system. 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, which is attached to a guide shaft 8 so as to be able to reciprocate parallel to the printing surface of the printing paper 6, and is driven by a drive pulley by a motor 19. 20a, 20b, drive wire rope 21
Driven through. The carriage 17 includes a light emitting element 22a and a light receiving element 2 arranged facing each other.
2b is fixed, and between the light emitting element 22a and the light receiving element 22b, a strip 24 having a transparent slit 23 corresponding to the position where the printing wire 3 is to be driven is attached to the guide shaft 18.
is placed parallel to. 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 selection drive circuit 26 to have a time delay with respect to the operation timing of the drive circuit 25. Further, the selection control circuit 27 is 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 operates the return electromagnet 14 to drive the reciprocating member 15 in the direction of the return position, and the magnet 1 is moved in the deformed state of the printing spring 8 as shown in FIG.
Move it to the position held by 0. Furthermore, 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 energized again by the drive circuit 25.
Continuous printing is performed by the above continuous operations. The electric energy given by the selection coil 12 in this embodiment is consumed only for canceling the holding force generated by the closed magnetic circuit including the magnet 10, and unlike the conventional example described above, the electric energy provided by the selection coil 12 is This is extremely small compared to the electrical energy required to generate the suction force to move the printing member at high speed. As a result, the magnetic circuit can be made smaller. In addition, since the adsorption 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 magnet 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. Here, the return electromagnet 14 in this embodiment can be operated continuously at approximately constant intervals. Therefore, the return electromagnet 14 is connected to the printing wire 3.
By driving at the resonance frequency of the vibration system composed of the printing spring 8 and the printing spring 8, it is possible to reduce the load fluctuation of the vibration system on the return electromagnet 14 due to a change in the number of printing wires 3 to be printed. Therefore, there is no need for a complicated electric circuit configuration for controlling the input electric energy of the return electromagnet 14 according to the number of printing wires 3 to be printed. This is because the vibration system composed of the printing wire 3 and the printing spring 8 is driven at the resonance point, which means that it is possible to operate with the smallest driving force when driving with a predetermined amplitude. This is because the driving force that operates the vibration system made up of the printing wire 3 and the printing spring 8 is extremely small compared to the driving force that drives the returning electromagnet 14 alone, so that fluctuations in the driving force of the returning electromagnet 14 are It is possible to keep it small. By setting the vibration system shown in this example,
The return electromagnet 14 can always be driven in a resonant state against fluctuations in the vibration system due to 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 resonance frequency of all the vibration systems driven by the return electromagnet 14 is: By substituting K/M=k/m from the above-mentioned condition f _i = f _M and rearranging, f _T = f _M = f _i = f _d is obtained, and regardless of the number of prints n, the vibration system The resonant frequency f _T 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. In addition, the timing for energizing the selection coil 12 for performing a selection operation is determined by adjusting the timing for energizing the selection coil 12 for the selection operation with respect to the operation timing for driving 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. Furthermore, 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. Print quality can be improved with less pitch deviation. 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 controls the operation of the return electromagnet 14 and the energization of the selection coil 12. 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 detecting device 22 and the reference pulse. Note that the present invention can also be implemented in a printing device such as a line printing device that operates multiple printing hammers selectively at high speed. As described above, according to the present invention, by setting the vibration system, the electro-mechanical conversion efficiency of the return electromagnet can be significantly improved, and reduction in power consumption and size can be realized. In addition, regardless of the number of printing wires, the resonance frequency fluctuation of the entire vibration system is extremely small, so the phase shift between the electrical input of the return electromagnet and the displacement of the reciprocating member is kept small, improving the reliability of selection operation and improving printing quality. It also has the excellent advantage of improving performance.

[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, 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 perform printing by impact force at the printing position, and when the printing members are at the return position, they are deformed and held, and the distortion a first spring that uses energy to apply a driving force to the printing member from the return position to the printing position; a reciprocating member that is reciprocable; a second spring that elastically supports the reciprocating member; It has a driving means that applies a driving force to continuously reciprocate the member at a predetermined period, and a selection driving means that selectively releases the holding of the first spring corresponding to the printing member to be subjected to impact printing, A printing device characterized in that the driving frequency of the reciprocating member is made substantially equal to the resonance frequency of a vibration system constituted by the printing member and the first spring. 2. The ratio of the movable mass to the spring constant in the vibration system composed of the printing member and the first spring, and the ratio of the movable mass to the spring constant of the vibration system composed of the reciprocating member and the second spring. 2. The printing device according to claim 1, wherein the printing device has substantially the same number of characters.