JPH0688434B2 - Small printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a small printer, more specifically, a type wheel is rotated and paper is fed by a pulse motor.
The present invention relates to a small printer that completes one printing cycle by obtaining at least a printing process and a paper feeding process.

<Prior Art> Conventionally, a small printer of this type has an energization mode in which energization from a step motor to a step motor via a gear train is forwardly driven, as disclosed in JP-A-56-63471. The type wheel is driven and stopped depending on the energization mode to be stopped.

<Problems to be Solved by the Invention> Therefore, in the conventional structure, the step motor is energized in the energization mode so that the step motor is affected by the inertia even if the step motor is stopped. Is. When printing is performed in this state, the type wheel naturally vibrates, so the characters printed at each digit are scattered and the linearity (alignment) deteriorates.
Further, in order to improve this alignment, it is conceivable to wait for the above-mentioned vibration to stop before printing, but in this case, the printing speed cycle becomes very long. Further, if the vibration is large, there is a risk that a predetermined character to be tapped and the hammer do not engage with each other, resulting in a missing character or erroneous printing.

Further, in this structure, when the rotation of the step motor is stopped for printing, the energization mode is used for stopping with a long single pulse, so that it has a drawback that power consumption becomes large. .

The present invention has been made in view of such drawbacks,
An object of the invention is to provide a small printer which has high printing speed, excellent printing quality, high reliability, and low power consumption.

<Means for Solving the Problems> Therefore, in order to solve the above problems, a small printer of the present invention includes a rotatable type wheel having a type on the outer periphery, a step motor for rotationally driving the type wheel, and a step motor. Controlling circuit means, ratchet teeth formed on the type wheel or driven integrally with the type wheel to correspond to the type character, reverse rotation preventing means for engaging the ratchet tooth to prevent the type wheel from reversing, and the type character. The step motor is reversely rotated during the printing process, and the type wheel is stopped by the ratchet teeth and the reverse rotation preventing means contacting each other.

<Operation> According to the above configuration of the present invention, since the type wheel is stopped by contact between the ratchet teeth and the reverse rotation preventing means, the vibration when the type wheel is stopped is converged in a short time, and the type wheel is stopped. The position stabilizes in place.

<Embodiment> An embodiment of the present invention will be described with reference to FIGS. 1 to 9 using an example in which a type wheel is composed of a type sheet and a type sheet receiver.

1 is a perspective view, FIG. 2 is a side view, and FIG. 3 is a plan sectional view.

1 is a frame. Reference numeral 2 is a first print yoke, which is screwed to both ends of the frame 1. The first printing yoke 2 has long strip-shaped portions 201 and 202 at both ends, and has a U-shaped yoke portion 203 at the center. A second print yoke 3 is provided so as to cover the U-shaped portion. The second print yoke 3 has holes corresponding to the digits, and the print iron core 5 is caulked and attached to the hole 301. A print coil 4 is provided inside the U-shape of the first print yoke 2, a print iron core 5 is provided in a central hole of the print coil 4, and a print suction plate 7 is inserted into a recess 601 provided in the hammer 6. And are provided. When the printing coil 4 is energized, the printing suction plate 7 is sucked by the printing iron core 5 and moves. At this time, the hammer 6 also moves together with the print suction plate 7.

A type sheet 8 and a type sheet receiver 9 are rotatably arranged around the first print yoke 2. The type sheet receiver 9 has a hole 901 on its outer circumference, and the projection 801 provided on the type sheet 8 has a hole.
It's got into the 901.

One end of the type sheet receiver 9 is rotatably supported by the type bearing 10. The type bearing 10 is fixed to a long strip 201 at one end of the first printing yoke 2. The type sheet 8 is provided with a type 802 on the front surface and a protrusion 801 on the back side thereof. When the hammer 6 presses the protrusion 801, the type 802 protrudes and transfers ink to the printing paper 12 along the platen 11. 13 is an ink roll. A motor 14 is directly connected to one end of the type sheet receiver 9. The protrusion 902 of the type sheet receiver 9 is the motor 14
The rotation of the motor 14 is transmitted to the type sheet receiver 9 as it is, which is in the recess 151 of the outer case 15. The configuration of the motor 14 includes a motor coil frame 16, a motor yoke 17, and a motor magnet 1.
8, outer case 15, motor magnet yoke 20.
This is a so-called outer rotor type stepping motor. The motor coil frame 16 is fixed to the long strip 202 of the first print yoke 2 and also serves as a bearing for the outer case 15.
The motor coil frame 16 has two coils wound in two phases to form a total of four coils. When a predetermined pulse is applied to this coil, the outer case 15, the motor magnet 18, and the motor magnet yoke 20 are integrated. It is a rotating one. Outer case 15
A ratchet tooth 152 is provided on the outer periphery of the lever, engages with the reverse rotation stop lever 24, and rotates in the direction of arrow A.
It does not rotate in the direction of arrow B. (See FIG. 8). 22 is a paper feed rubber, and 23 is a paper feed gear. When the intermittent teeth 903 provided on the type sheet receiver 9 mesh with the paper feed gear 23, the paper feed rubber 22 rotates by a predetermined angle to feed the print paper 12 by a fixed amount.

Reference numeral 25 is a reset spring, which also serves as a mechanical contact point, and a reset pulse is output once per one rotation of the type sheet receiver 9 by a cam 904 provided on the type sheet receiver 9.

The character arrangement of the type sheet 8 is shown in FIG. Type sheet 8
Is expanded, the vertical axis indicates the character position,
The horizontal axis indicates digits. The characters are arranged in a staggered manner, and one hammer width has a width of two digits, and one hammer can control two digits. When the motor 14 rotates in the direction of the arrow A, the printing position 19 starts from "space-3", and sequentially goes to "even-1""odd-0""even-0". This relationship is shown in the time chart character position column of FIG.

The operation of the mechanism having the above configuration will be described.

First, the character sheet 8 has a character position of the space 3 at a position (printing position 19) facing the hammer 6.
Here, the motor 14 is energized to rotate in the direction of arrow A.
As for the energization mode of the motor 14, the four coils of the motor 14 are energized as shown in the time chart of FIG. This energization indicates a pulse state applied to the motor coil-the transistor connected to the motor coil-as shown in FIG. Numbers of motor energization form shown in time chart (Fig. 5)
The 915462A8 will be described. 9 is energization of the motor coil, 1 is energization of the motor coil, 5 is 4, 6 is
Means that 2, A, and 8 are respectively energized.

Here, in order for the motor 14 to rotate normally, the motor energization form 915462A8
It is sufficient to energize in this order. Further, the relationship between the energization mode of the motor 14 and the character position is as shown in FIG.
Excitation, and for even numbers, excitation of 5 makes a predetermined character come to the print position 19. When printing is performed at the print position 19 when a predetermined character is printed, the motor 14 is energized in the motor 14
Energize in the reverse direction. At this time, the motor 14 turns to the arrow B
Although it tries to rotate in the direction, the reverse rotation stop lever 24 and the ratchet teeth 152 come into contact with each other, and the motor 14 surely stops at a predetermined position. When the motor 14 is stopped and the print coil is energized, the hammer 6 pushes the projection 801 of the type sheet 8 and the type 8
02 can be printed on the printing paper 12. Do the same for each character position. When the character position not to be printed comes, the motor 14 continues to rotate in the arrow A direction.
When the character position reaches "even 11", the selective printing of the print characters ends. When the motor 14 is further rotated, the intermittent teeth 903 provided on the type sheet receiver 9 mesh with the paper feed gear 23 to feed the paper. A reset pulse is issued during this paper feeding.

Since this structure is directly connected to the motor 14 and the type sheet 8,
When the motor 14 is stopped for printing, the type sheet receiver 9 is also stopped immediately.

Further, when the motor 14 is stopped for printing, an energization mode is set so that the motor 14 is rotated in the reverse direction. At this time, the reverse rotation stop plate 24 and the ratchet teeth 152 are used to quickly stop the reverse movement of the motor 14 at a predetermined position. Therefore, the type sheet receiver 9 can also be stopped. As shown in FIG. 6, the movement of the motor 14 shown by the broken line in the prior art becomes the movement shown by the solid line, and the motor 14 stops for a short time t.

When the motor 14 is stopped for printing, an energization form that gives reverse rotation is performed.In the present invention, this energization form is continuously turned on and off, and the motor 14 consumes at this time. The average current is as shown in Fig. 7.
It is much smaller than the current value in the ON state (shown by the broken line).

<Effects of the Invention> As described above, according to the present invention, a rotatable type wheel having a type on the outer periphery, a step motor for rotationally driving the type wheel, a circuit means for controlling the step motor, and a type wheel. A ratchet tooth that is formed or is integrally driven with the type wheel and corresponds to the type character, a reverse rotation preventing means that engages with the ratchet tooth and makes it impossible to reverse the type wheel, and a printing means that engages with the type character and prints. Since the step motor rotates in the reverse direction during the printing process and the type wheel is stopped by contact between the ratchet teeth and the reverse rotation prevention means, the vibration of the type wheel is stopped in a short time, so the time to the printing process is shortened. The printing speed can be increased.

Further, since the printed characters can be accurately stopped with respect to the predetermined position of the printing means and the printing position, the linearity of the printed characters is very excellent and the printing quality is good, and the engagement position with the printing means is also good. Since it is accurate, it is possible to provide a printer with extremely high reliability without missing characters, erroneous printing, or deformation of characters.

Furthermore, the reverse rotation of the step motor changes the energization mode to
By repeating F, the power consumption can be reduced and the heat generation of the step motor can be suppressed, so that the characteristic deterioration of the step motor due to the heat generation can be suppressed.

Thus, the practical effect of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is a side sectional view,
FIG. 3 is a plan view. FIG. 4 is a developed view of the arrangement of characters on the type sheet according to the embodiment of the present invention. FIG. 5 is a time chart of the embodiment of the present invention. FIG. 6 is a diagram showing the movement of the motor according to the embodiment of the present invention. FIG. 7 is a diagram showing the amount of current consumed by the motor of the embodiment of the present invention. FIG. 8 is a view showing the ratchet teeth and the reverse rotation preventing means of the embodiment of the present invention. FIG. 9 is a diagram showing a circuit for driving the motor according to the embodiment of the present invention. 1 ... Frame, 2 ... 1st printing yoke 3, 2nd printing yoke, 4 ... Printing coil 5 ... Printing iron core, 6 ... Hammer 7 ... Printing suction plate, 8 ... Type sheet 9 ... Type sheet receiver, 10 ... Type bearing 11 … Platen, 12… Printing paper 13… Ink roll, 14… Motor 22… Paper feed rubber, 23… Paper feed gear 24… Reverse rotation stop lever 25… Reset spring 152… Ratchet teeth

Claims (1)

[Claims] 1. A rotatable type wheel having a type on the outer circumference, a step motor for rotating the type wheel, circuit means for controlling the step motor, and a unit formed on the type wheel or integrated with the type wheel. Driven ratchet teeth corresponding to the type letters, reverse rotation preventing means for engaging the ratchet teeth to prevent the reverse rotation of the type wheel, and printing means for engaging the type letters for printing. A small-sized printer characterized in that the step motor rotates in the reverse direction during a printing process, and the type wheel is stopped by contact between the ratchet teeth and the reverse rotation preventing means.