JPH02196675A - small printer - Google Patents

Abstract

PURPOSE:To obtain a printer having a low noise by incorporating a ratchet gear and reverse preventing means inside the outer wall of a stepping motor to interrupt the noise generated by a reverse rotation stopping mechanism. CONSTITUTION:When a printing type is moved to a printing position 19, a motor 14 is energized in a direction for rotating reversely. In this case, the motor 14 tends to rotate in a direction of an arrow B, but the motor 14 is rapidly and effectively stopped at a predetermined position due to the contact of a reverse rotation preventing lever 24 with a ratchet gear 152. If a printing coil 4 is energized in a state that the motor 14 is stopped, hammer 6 pushes the protrusion 801 of a type sheet 8 thereby to print a printing sheet 12. A spring 27a for energizing a force for pressing the reverse rotation preventing lever 27, the ratchet gear 152 and a reverse rotation stopping lever to the ratchet gear is contained in the outer case 15 of the stepping motor 14 to interrupt a noise generated between the reverse rotation stopping lever 24 and the ratchet gear 152 from the exterior.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a small type printer mounted on a calculator or the like.

[Conventional technology]

Conventionally, in this type of printer, ratchet teeth and reverse rotation prevention means were provided outside the outer wall of the step motor, as disclosed in Japanese Patent Laid-Open No. 61-164865.

[Problem to be solved by the invention]

However, in the conventional technology, when the step motor is in the normal rotation state, the reverse stop lever climbs up the mountain of the ratchet teeth, then instantly flies through the air and hits the ratchet teeth again. At this time, a considerable amount of noise is generated. Also, when the step motor is stopped, the step motor is reversed and the reversal prevention lever is brought into contact with the ratchet teeth, which still generates noise. Furthermore, despite the constant noise generated, these mechanisms were open to the outside, and there was nothing to block the noise. As a result, there have been problems such as increased noise from the printer.

The present invention has been made to solve these drawbacks, and an object of the present invention is to provide a low-noise printer by blocking the noise generated by the reverse stop mechanism.

[Means to solve the problem]

The small printer of the present invention includes a type shaft having type characters on its outer periphery, a step motor for driving the type wheel, ratchet teeth provided in a portion directly or indirectly engaged with the type type shaft, and a step motor for driving the type wheel. In a small printer comprising a reverse rotation preventing means that engages with the ratchet teeth and makes it impossible for the type shaft to reverse, and a printing means that engages with the type wheel and prints, the step motor is stopped to perform printing. , wherein the ratchet teeth and the reverse rotation prevention means are built inside an outer wall of the step motor.

〔Example〕

FIG. 1, FIG. 2, and FIG. 3 are a perspective view, a side sectional view, and a plan sectional view, respectively, of the present invention.

1 is Freyno. A first printing yoke 2 is screwed to both ends of the frame 1. First printing yoke 2
has long strip portions 201 and 202 at both ends, and a yoke portion 203 in the center, which is U-shaped. A second printing yoke 3 is provided to cover this U-shaped portion. The second printing yoke 3 has holes corresponding to the digits, and holes 301
The printed core 5 is caulked and installed. A printing coil 4 is provided inside the U-shaped first printing yoke 2, and a printing core 5 is provided in a hole provided in the center of this printing coil 4.
and a print suction plate 7 inserted into a recess 601 provided in the hammer 6. When the printing coil 4 is energized, the printing suction plate 7 is attracted to 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 holder 9 are rotatably arranged around the first printing yoke 2. The type sheet holder 9 has a hole 901 on the outer periphery and a projection 80 provided on the type sheet 8.
1 has entered the hole 901.

One end of the type sheet support 9 is rotatably supported by a type bearing 10. The type bearing 10 is fixed to a long strip 201 at one end of the first print yoke 2. The type sheet 8 has type characters 802 on its surface and protrusions 801 on its back side.
This corresponds to

When the hammer 6 presses the protrusion 801, the type 802 protrudes and transfers ink to the printing paper 12 along the platen 11. 1
3 is an ink roll. A motor 14 is directly connected to one end of the type sheet holder 9.

The projection 902 of the type sheet holder 9 enters the recess 151 of the outer case 15 of the motor 14, and the rotation of the motor 14 is directly transmitted to the type sheet holder 9.

The motor 14 includes a motor coil frame 16, a motor yoke 17, a motor magnet 18, an outer case 15, an outer case cover 153, and a motor magnet yoke 20. This is a so-called outer rotor type step motor. The motor coil frame 16 is fixed to the long strip 202 of the first printing yoke 2, and also serves as a bearing for the outer case 15.

Two-phase coils are wound around the motor coil frame 16, resulting in a total of four coils.If a predetermined pulse of electricity is applied to these coils, the outer case 15, outer case lid 153,
The motor magnet 18 and the motor magnet yoke 2° rotate together. As shown in Fig. 8, the outer case 1
Ratchet teeth 152 are provided on the inner periphery of the first printing yoke 2, and the reverse stopper is rotatably attached to the rotating shaft 261 on the reverse stopper lever fixing base 26 fixed to the strip part 202 of the first printing yoke 2. The lever 24 rotates in the direction of arrow A, but is prevented from rotating in the direction of arrow B. Note that the reversal prevention lever 24 is always pressed against the ratchet tooth 152 side by the tension coil spring 27a. Also, this reverse stop lever fixing base 26
and reverse stop lever 24 and tension coil spring 27
A is surrounded by the outer case 5 and the outer case lid 153 also in the digit direction. 22 is a paper feed rubber, and 23 is a paper feed gear. Intermittent teeth 90 provided on the type sheet holder 9
3 meshes with the paper feed gear 23, the paper feed rubber 22 rotates by a predetermined angle and feeds the printed paper 12 by a certain amount.

Reference numeral 25 denotes a reset spring, which serves as a mechanical contact and is activated by a cam 904 provided on the type sheet holder 9.
A reset pulse is generated once per rotation.

The character arrangement of the type sheet 8 is shown in FIG. Type sheet 8
is expanded, the vertical axis shows the type position,
The horizontal axis shows the digits. The letters are arranged in a staggered manner, and one hammer width has the width of two digits, and one hammer 6 has the width of two digits.
It is now possible to control digits. When the motor 14 rotates in the direction of arrow A, the printing positions 19 start with "space 3" and are sequentially placed in the order of "even-", "odd QJr even 0". This relationship is expressed in the column of type position in the time chart of FIG.

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

First, the position of the type sheet 8 is such that the type position of space 3 is at the position opposite to the hammer 6 (print position!! 19). Here, the motor 14 is energized and rotated in the direction of arrow A. The mode of energization of the motor 14 is such that the four coils of the motor 14 are energized as shown in the time chart of FIG. This energization is carried out by inputting an applied pulse to the transistors 1 to 2 connected to the motor coils 1 to 2, as shown in FIG. Time chart (Figure 5)
The motor energization mode number 915462A8 shown in FIG. 9 is energizing the motor coil ■■, 1 is energizing the motor coil ■, 5 is ■■, 4 is ■, 6 is ■■, 2
means to energize ■, A to ■■, and 8 to ■, respectively.

Here, in order for the motor 14 to rotate normally (in the direction of arrow A), it is sufficient to energize the motors in the order of motor energization mode 915462A8. or,
The relationship between the energization mode of the motor 14 and the type position is as follows.
As shown in the figure, if the odd-numbered digits are excited by A and the even-numbered digits are excited by 5, a predetermined character is placed at the printing position 19. Printing position? When the characters to be printed come to 119, the energization mode of motor 4 is to energize the motor 14 in the reverse direction.

At this time, the motor 14 attempts to rotate in the direction of arrow B, but the motor 14 is quickly and reliably stopped at a predetermined position by the contact between the reverse stop lever 24 and the ratchet teeth 152. A series of behaviors of the motor 14 at this time is shown in FIG. When the printing coil is energized while the motor 14 is stopped, the hammer 6 presses the protrusion 801 of the type sheet 8 and prints the type 802 on the printing paper 12. A similar operation is performed for each character position to be printed. When the character position where printing is not performed is reached, the motor 14 continues to rotate in the direction of arrow A. Type position is r even 11
”, the selective printing of the printed characters 802 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.

Further, in this embodiment, a tension coil spring 27a is used to keep the reverse stopper lever 24 tilted toward the ratchet teeth 152, but as shown in FIG. 9, a torsion coil spring 27b is used. You can. Other options include leaf springs, compression springs, or other materials that utilize the elasticity of plastic parts, but any material may be used as long as it can apply the force that presses the anti-reverse lever 24 against the ratchet teeth 152. .

〔Effect of the invention〕

As described above, according to the present invention, the reverse prevention lever, the ratchet teeth, and the spring that biases the force that presses the reverse prevention lever against the ratchet teeth are housed in the outer case of the step motor. This allows the noise generated between the non-reverse lever and the ratchet teeth to be isolated from the outside, and when oil is applied between the non-reverse lever and the ratchet teeth, the surrounding area prevents the oil from entering. Since the printer lasts for a long time, the generated noise itself can be kept low, and the anti-reverse lever and ratchet teeth have good wear resistance, making it possible to provide a low-noise, long-life printer.

[Brief explanation of the drawing]

Figures 1 to 9 are views showing embodiments of the present invention. Figure 1 is a perspective view, Figure 2 is a side sectional view, Figure 3 is a plan sectional view, and Figure 4 is characters on a type sheet. Figure 5 is a time chart, Figure 6 is a diagram showing the movement of the motor, Figure 7 is a circuit diagram for driving the motor, Figure 8 is a side sectional view showing ratchet teeth and reverse rotation prevention means, FIG. 9 is a side sectional view showing ratchet teeth and reverse rotation prevention means in another embodiment. 1... Frame 2... First printing yoke 3...
Second printing yoke 4...Printing coil 5...Printing core
6. Hammer 7. Print suction plate 8.
Type sheet 9... Type sheet holder 10... Type bearing 1
1...Platen 12...Printing paper 13...Ink roll 14...Motor 22...Paper feed rubber 2
3.Paper feed gear 24..Reverse stop lever 25..Reset spring 26..Reverse stop lever fixing base and above Applicant: Seiko Epson Co., Ltd. Representative Patent Attorney Kizobe Suzuki (1 other person) Figure 6 Figure 7

Claims (1)

[Claims] a type wheel having type letters on its outer periphery, a step motor for driving the type wheel, ratchet teeth provided at a portion directly or indirectly engaged with the type wheel, and engaging with the ratchet teeth; In a small printer comprising a reversal prevention means that makes it impossible for the type wheel to reverse, and a printing means that engages with the type wheel to print, the printer stops the step motor and performs printing. A small printer characterized in that a prevention means is built inside an outer wall of the step motor.