JPH0331590B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paper feeding mechanism for a reversible printer.

In the paper feed mechanism in conventional printers, the first
Paper feed roller 1 and drive wheel 5 as shown in the example in the figure.
In addition, when the paper feed roller 1 is to be reversed by providing a transmission wheel 4 and a drive transmission wheel 3, the rotation of the drive wheel 5 is normally directly controlled by the paper feed roller 2.
By energizing the solenoid 8, the switching lever 7 is actuated to combine the transmission wheel 4 with the drive transmission wheel 3 to reverse the paper feed roller, and the mechanism requires a large number of parts. The disadvantage was that it required a large space, and the solenoid required a strong magnetic force, making it expensive.

It is an object of the present invention to provide a reversible paper feeding mechanism that does not require any shafts other than the drive shaft, reduces the number of parts, fits the mechanism in a small space, and provides a reversible paper feeding mechanism.

The present invention is characterized by a paper feeding mechanism for a printer that feeds recording paper forward and backward, including a drive shaft that rotates in one direction, an internal gear fixed to the drive shaft, and a rotatable gear mounted on the drive shaft. a composite gear that is rotatably mounted on the drive shaft and has teeth formed on a large diameter portion and a small diameter portion, respectively; teeth formed on the outer periphery and a shaft formed on the side surface. and a ratchet rotatable on the small diameter portion of the composite gear, and a ratchet wheel rotatably mounted on the shaft of the ratchet wheel and constantly meshing with the internal gear and the teeth formed on the small diameter portion. a planetary gear, a clutch spring member having one end locked to the compound gear and the other end to the paper feed roller, and first and second clutch spring members disposed opposite to the compound gear and the ratchet wheel, respectively. the composite gear or the paper feed roller has an engaging portion that engages with the paper feed roller or the composite gear with play, and the first and second trigger means When the compound gear and the ratchet are in a disengaged state,
The composite gear operates the clutch spring member through the internal gear, the planetary gear, and the pawl, and the clutch spring member rotates the paper feed roller in one direction, and the second trigger means operates the pawl. When engaged with the wheel, the compound gear is configured to rotate the paper feed roller in the other direction by engagement of the engagement portion via the internal gear and the planetary gear.

The present invention will be explained based on the drawings.
In FIG. 3, a rotatable paper feed roller 17 and a compound gear 11 are attached to a drive shaft 10, and a clutch spring 18 is installed inside the drive shaft 10 through the shaft 10. Note that the paper feed roller 17 and the composite gear 11 are each embedded with the tips of a spring 18 and connected to each other. The internal gear 9 is fixed to a drive shaft 10, and a planetary gear 20 is installed between the internal gear 9 and the composite gear 11. The planetary gear 20 is mounted on a pawl gear 12 rotatable around the compound gear 11. The pawl 13 normally regulates the position of the compound gear 11 so that the paper feed roller 17 is rotated by one tooth of the compound gear 11 by the solenoid 16. The pawl 14 is in a standby position and is not engaged with the gear 12. Also hook 21
is provided for the purpose of rotating the paper feed roller 17 and preventing the clutch spring 18 from becoming too loose. The paper press roller 19 is the paper feed roller 1
It is mounted on the drive shaft 7 in a manner that it is pressed in the direction of the drive shaft 10.

In the case of the paper feeding mechanism as described above, it can be accommodated in a small space on the drive shaft 10 on the side of the paper feeding roller, and a small and reversible paper feeding mechanism can be obtained.

The operation of the present invention will be described in detail below based on embodiments.

In this paper feed mechanism, when the paper feed roller 17 rotates in the same direction as the shaft 10 and normally feeds paper, the spring 18 is loosened when the pawl 13 is engaged with the gear 11. As a result, the paper feed roller 17 is stationary and the drive shaft is in an idling state. At this time, the claw 14 is on standby and does not mesh with the gear 12, and the planetary gear 20 and the claw gear 12 are in a free state. Next, the solenoid 16 is energized to disengage the pawl 13 and the composite gear 11. In this state, the pawl 14 and the pawl gear 12 are not engaged,
When the internal gear 9 rotates as the drive shaft 10 rotates, the compound gear 11 also rotates due to friction, tightening the clutch spring 18 to the drive shaft 10, and the rotation of the drive shaft 10 is transmitted to the paper feed roller 17. . At this time, if the energization to the solenoid 16 is controlled in accordance with one tooth of the compound gear 11,
The paper feed roller 17 can be rotated by teeth.

Next, during reverse rotation, the solenoid 15 is first energized and the pawl 14 engages with the gear 12, so that the gear 12 is fixed at a fixed position, and the internal gear 9 rotates in the opposite direction via the planetary gear 20. and is transmitted to the composite gear 11. At this time, since a rotational force is applied in the direction in which the spring 18 is loosened, the drive shaft 10 becomes idle, and the composite gear 11 begins to rotate in the reverse direction, and the hook 21 causes the paper feed roller to also rotate in the reverse direction.

As explained above, the present invention is simpler, has fewer parts, and is more compact than conventional mechanisms by attaching a paper feed reversal mechanism to the side of the paper feed roller on a single drive shaft. This also has the effect that paper feeding can be reversed extremely quickly due to the structure that uses planetary gears.

[Brief explanation of drawings]

FIG. 1 shows a reversing mechanism in a conventional paper feeding mechanism. 1...Paper feed roller, 2...Paper press roller, 3
... Drive transmission vehicle, 4... Transmission vehicle, 5... Drive vehicle, 6
...Double return spring, 7...Switching lever, 8...Solenoid. FIG. 2 is a cross-sectional view of a reversing mechanism showing an embodiment of the present invention. FIG. 3 is a sectional view from the front. 9...Internal gear wheel, 10...Drive shaft, 11...Compound gear, 12...Claw gear, 13, 14...Claw, 1
5, 16...Solenoid, 17...Paper feed roller, 18...Clutch spring, 19...Paper press roller, 20...Planetary gear, 21...Hook, 22,
23...Return spring.

Claims (1)

[Scope of Claims] 1. A paper feeding mechanism for a printer that feeds recording paper forward and backward, comprising a drive shaft that rotates in one direction, an internal gear fixed to the drive shaft, and a rotatable gear mounted on the drive shaft. a paper feed roller mounted thereon; a compound gear rotatably mounted on the drive shaft and having teeth formed on a large diameter portion and a small diameter portion; a ratchet wheel that is rotatable on the small diameter portion of the composite gear; and a ratchet wheel that is rotatably mounted on the shaft of the ratchet wheel and is constantly meshed with the internal gear and the tooth portion formed on the small diameter portion. a clutch spring member having one end locked to the composite gear and the other end locked to the paper feed roller, and first and second clutch spring members disposed opposite to the composite gear and the ratchet, respectively. the composite gear or the paper feed roller has an engaging portion that engages with the paper feed roller or the composite gear with play; and the first and second trigger means. is in a state of disengagement with the compound gear and the ratchet wheel, respectively,
The composite gear operates the clutch spring member through the internal gear, the planetary gear, and the pawl, and the clutch spring member rotates the paper feed roller in one direction, and the second trigger means operates the pawl. When in engagement with a wheel, the compound gear is configured to rotate the paper feed roller in the other direction by engagement of the engagement portion via the internal gear and the planetary gear. Printer paper feed mechanism.