JPH0550669A - Paper feeder for printer - Google Patents

Abstract

PURPOSE:To provide a paper feeder for a printer having high interchangeability which can change the minimum feed pitch of paper only by selecting an exchange gear to be installed in a power transmission route. CONSTITUTION:A plurality of change gears 9, 10 of different pitch circles are coaxially arranged in a power transmission path between a paper feed part 3 and a motor 6 to be integratedly freely rotatively provided and besides, a transmission gear 5 having an axial core in parallel with rotary axial cores of the change hears 9, 10 is freely rotatively provided. A plurality of kinds of change gears 13, 14 having a first teeth part 15 of an equal pitch circle to be mated with this transmission gear 5 and a second teeth part 16 or 17 to be mated with either of change gears 13, 14 are provided, and a bearing part 12 holding freely rotatively those change gears 13, 14 is arranged at a specific position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding device for a printer.

[0002]

2. Description of the Related Art Conventionally, there is a sheet feeding device of a printer that decelerates the rotation of a step motor by a plurality of gears and transmits it to a sheet feeding portion such as a platen or a tractor. The minimum sheet feed pitch corresponds to the rotation angle of one step of the step motor. In a dot printer, the number of pins (wires) of the print head varies depending on the degree of print quality requirement, and the paper feed pitch also varies depending on the number of pins of the print head. For example, using a 9-pin print head,
When printing on the forward path of the print head and then feeding the paper by a length equivalent to one half of the pin arrangement pitch and printing on the return path, set the minimum feed pitch of the paper to 1/144 inch and set the pin to two. When using a 24-pin print head that is arranged in a zigzag pattern in rows, the minimum feed pitch of paper is 1 /
There is a printer with a specification of 180 inches.

[0003]

Conventionally, a printer equipped with a 9-pin print head and a printer equipped with a 24-pin print head have different speed reduction ratios between a step motor and a paper feeding unit, and therefore power consumption is reduced. The gear pitch circles, the number of teeth, the number of gears, the gear arrangement position, etc. in the transmission path are different. As a result, the positions of the studs holding the gears and the bearings also differ. Therefore, for each printer equipped with a print head having a different number of pins, the frame holding these studs and bearings must be replaced, which complicates production management and raises the cost.

[0004]

SUMMARY OF THE INVENTION According to the present invention, in a paper feeding device of a printer for transmitting the rotation of a motor to a paper feeding portion in contact with paper, a pitch circle is provided in a power transmission path between the paper feeding portion and the motor. Of different transmission gears are coaxially arranged to be integrally rotatable, and a transmission gear having an axis parallel to the rotation axis of these transmission gears is also rotatably provided and meshed with the transmission gears. A plurality of types of exchange gears each having a first tooth portion having the same pitch circle and a second tooth portion having a different pitch circle and meshed with one of the transmission gears, and rotating these exchange gears. A bearing portion, which is freely held, is arranged at a fixed position having an axis parallel to the rotation axis of the transmission gear and the rotation axis of the transmission gear.

[0005]

By selecting an exchange gear to be mounted on the bearing, the first gear can be always meshed with the common transmission gear and the transmission gear meshed with the second gear can be changed. Different exchange gears can be mounted on a common bearing, which allows the minimum rotation angle of the paper feed section (minimum feed pitch of paper) to be changed simply by selecting the exchange gear to be mounted on the bearing. It is possible to rationalize production management by increasing the number of compatible parts between printers having different minimum feed pitches of paper.

[0006]

An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the bearing 2 fixed to the frame 1
A shaft portion 4 of a platen 3 which is a paper feeding portion is rotatably supported on the shaft portion 4, and a transmission gear 5 (platen gear) is fixedly fitted to the shaft portion 4. A drive gear 7 is directly connected to a step motor 6 which is a motor fixed to the frame 1, and an input gear 8 meshed with the drive gear 7 and a plurality of transmission gears 9 and 10 having different pitch circles are integrally formed. It is formed and rotatably held by the stud 11. The stud 11 and the other stud 12 that is a bearing portion are erected on the frame 1 with an axis parallel to the rotational axis of the transmission gear 5.

Therefore, a plurality of types of exchange gears 13 and 14 selectively mounted on the stud 12 are provided. One exchange gear 13 is a two-stage gear having a first tooth portion 15 meshed with the transmission gear 5 and a second tooth portion 16 meshed with the speed change gear 9, and the other exchange gear 14
Is a two-stage gear having a first tooth portion 15 meshed with the transmission gear 5 and a second tooth portion 17 meshed with the transmission gear 10. Further, an annular groove 19 for fixing the retaining ring 18 is formed at the tips of the studs 11 and 12.

Here, the individual gears 5, 7, 8, 9, 1
Table 1 shows the pitch circles Φ of 0, 13, and 14 and the number of teeth Z.

[0009]

[Table 1]

In such a structure, when the 9-pin print head is mounted, the exchange gear 13 is fitted to the stud 12. In this state, as shown in FIG.
Is transmitted in the order of the input gear 8, the transmission gear 9, the second tooth portion 16, the first tooth portion 15, the transmission gear 5, and the platen 3. Therefore, the reduction ratio is 1/1 depending on the number of teeth in Table 1.
It becomes 5.2. Here, when the step angle of the step motor 6 is 7.5 ° and the diameter of the platen 3 is 40 mm, the sheet feed pitch when the step motor 6 rotates one step is 1/144 inch.

When a 24-pin print head is mounted, a replacement gear 14 is fitted on the stud 12. In this state, as shown in FIG. 3, the rotation of the drive gear 7 is caused by the input gear 8, the transmission gear 10, the second tooth portion 17, the first tooth portion 15,
The transmission gear 5 and the platen 3 are transmitted in this order. Therefore, the reduction ratio is 1/19 depending on the number of teeth in Table 1, and the paper feed pitch is 1/180 inch when the step motor 6 rotates one step.

As described above, by selecting the exchange gears 13 and 14 to be fitted to the stud 12, the first tooth portion 1
5 can be always meshed with the common transmission gear 5, and the transmission gears 9, 10 meshed with the second tooth portion 16 or 17 can be changed, and different exchange gears 13, 14 can be fitted to the common stud 12. Therefore, the minimum rotation angle of the platen 3 (minimum feed pitch of the paper) can be obtained only by selecting the exchange gears 13 and 14 that are fitted to the stud 12.
Can be changed. Therefore, even if the printer has a different minimum feed pitch of paper, the frame 1 and the exchange gear 1
Gears 5, 7, 8, 9, 10 other than 3, 14 can be used in common, which can streamline production management and reduce costs.

Although the input gear 8 and the speed change gears 9 and 10 are integrally formed, the same purpose can be achieved by fixing them independently to the rotating shaft instead of the stud 11.

[0014]

According to the present invention, in a paper feeding device of a printer for transmitting the rotation of a motor to a paper feeding portion contacting a paper, a plurality of different pitch circles are provided in a power transmission path between the paper feeding portion and the motor. The transmission gears are coaxially arranged so as to be integrally rotatable, and a transmission gear having an axis parallel to the rotation shaft center of these transmission gears is also provided rotatably, and a pitch circle meshed with the transmission gears is provided. A plurality of types of exchange gears having equal first tooth portions and second tooth portions each having a different pitch circle and meshed with one of the transmission gears are provided, and these exchange gears are rotatably held. Since the bearing portion is arranged at a fixed position having an axis parallel to the rotation axis of the transmission gear and the rotation axis of the transmission gear, the first gear is selected by selecting the replacement gear to be mounted on the bearing. The department always shares a common transmission It is possible to change the speed change gear that meshes with the second gear and also to change the transmission gear that is meshed with the second tooth.Also, different exchange gears can be mounted on the common bearing part. The minimum rotation angle of the paper feed section (minimum paper feed pitch) can be changed simply by changing the number of parts. Therefore, the number of compatible parts between printers with different paper feed pitches can be increased to streamline production management. Therefore, there is an effect that the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view.

FIG. 2 is a front view showing a power transmission path in a printer equipped with a 9-pin print head.

FIG. 3 is a front view showing a power transmission path in a printer equipped with a 24-pin print head.

[Explanation of symbols]

 3 Paper Feeding Part 5 Transmission Gear 6 Motor 9,10 Speed Change Gear 13,14 Exchange Gear 15 First Tooth Part 16,17 Second Tooth Part

Claims (1)

[Claims] 1. A paper feeding device of a printer for transmitting the rotation of a motor to a paper feeding portion that contacts a paper, wherein a plurality of speed change gears having different pitch circles are coaxial in a power transmission path between the paper feeding portion and the motor. A transmission gear having an axis parallel to the rotation axis of these speed change gears is rotatably provided and arranged on the upper side so as to be integrally rotatable, and a first gear with an equal pitch circle meshed with the transmission gear. Providing a plurality of types of exchange gears each having a tooth portion and a second tooth portion whose pitch circle is changed and meshes with one of the transmission gears,
A sheet feeding device for a printer, characterized in that a bearing portion for rotatably holding these exchange gears is arranged at a fixed position having an axis parallel to the rotational axis of the transmission gear and the rotational axis of the transmission gear. .