CN114407543B - Paper feeding mechanism for double-sided printing function of ink-jet printer - Google Patents

Abstract

The invention relates to a paper feeding mechanism used for the double-sided printing function of an inkjet printer, which includes a printing channel, a turning channel and a paper ejection channel arranged in the printer. There is a nozzle on one side of the printing channel, and a double-sided paper ejection entrance, a double-sided printing outlet, and a double-sided printing inlet are arranged in sequence on the printing channel. The double-sided paper ejection entrance is upstream of the nozzle, and the double-sided printing outlet and the double-sided printing inlet are are located downstream of the nozzle. The inlet of the flipping channel is connected to the double-sided printing inlet, the outlet of the flipping channel is connected to the double-sided printing outlet, the double-sided printing inlet is provided with a first switch, the double-sided printing outlet is provided with a second switch, and the entrance of the paper return channel is connected to the double-sided printing outlet. The double-sided paper exit entrance is connected, the exit of the paper exit channel is connected with the exit of the printing channel, and a third switch is provided at the double-sided paper exit entrance. A flipping channel is added in the printer to flip the paper, thereby increasing the double-sided printing speed.

Description

A paper feeding mechanism for double-sided printing function of inkjet printer

Technical field

The present invention relates to the field of printing, and in particular, to a paper feeding mechanism used for the double-sided printing function of an inkjet printer.

Background technique

When the printer performs double-sided printing, it is often necessary to manually turn the paper over and then put it into the printing entrance for printing. Existing double-sided printing requires the paper to pass through the printing paper path twice, and the paper needs to be processed once. Flip, the entire flip process requires multiple sets of pickup rollers to complete, and the double-sided printing speed is slow.

Contents of the invention

(1) Technical problems to be solved

The invention provides a paper feeding mechanism for the double-sided printing function of an inkjet printer, aiming to solve the technical problem of slow double-sided printing speed of paper in the prior art.

(2) Technical solutions

In order to solve the above problems, the present invention provides a paper feeding mechanism for the double-sided printing function of an inkjet printer. The paper feeding mechanism includes a printing channel, a turning channel and a paper ejecting channel provided in the printer;

A nozzle is provided on one side of the printing channel; along the entrance of the printing channel to the outlet of the printing channel, a double-sided paper ejection entrance, a double-sided printing outlet and a double-sided printing entrance are sequentially provided on the printing channel. The double-sided paper ejection inlet is located upstream of the nozzle, and the double-sided printing outlet and the double-sided printing inlet are located downstream of the nozzle;

The inlet of the flipping channel is connected to the double-sided printing inlet, and the outlet of the flipping channel is connected to the double-sided printing outlet. A first switch is provided at the double-sided printing inlet, and the first switch can control The turning channel and the double-sided printing inlet are connected and connected, and the printing channel is connected and controlled; a second switch is provided at the double-sided printing outlet, and the second switch can control the turning channel and the double-sided printing outlet. The on-off of the double-sided printing outlet and the on-off control of the printing channel;

The entrance of the paper exit channel is connected to the double-sided paper exit entrance, and the outlet of the paper exit channel is connected to the exit of the printing channel; a third switch is provided at the double-sided paper exit entrance, and the third switch is provided at the double-sided paper exit entrance. The three switches can control the opening and closing of the paper exit channel and the double-sided paper exit entrance, and control the opening and closing of the printing channel.

Preferably, the printing channel, the turning channel and the paper exit channel are provided with multiple pairs of paper feeding roller groups;

The paper feeding roller group on the printing channel can drive paper along the entrance of the printing channel to the exit of the printing channel;

The paper feeding roller group on the turning channel and the paper exit channel can drive the paper from the entrance of the turning channel to the exit of the turning channel, and then enter the paper exit channel through the printing channel.

Preferably, on the printing channel, the paper feeding roller group upstream of the nozzle and adjacent to the nozzle is the first paper feeding roller group, and the paper feeding roller group downstream of the nozzle and adjacent to the nozzle is the first paper feeding roller group. The second paper feeding roller group; the double-sided printing outlet is located between the second paper feeding roller group of the nozzle, and the double-sided paper exit entrance is located between the first paper feeding roller group and the nozzle .

Preferably, the paper feeding roller group includes a driving roller and a driven roller arranged opposite each other. The driving roller and the driven roller are both rotatably installed in the printer. The driving roller is connected to the output shaft of the motor. The driving roller can rotate under the driving of the motor, and the printing channel, the turning channel and the paper exit channel are all located between the driving roller and the driven roller, and the paper can pass through the driving roller and the driven roller. The area between the driven rollers.

Preferably, the flipping channel includes a first flipping paper path, a second flipping paper path and a third flipping paper path, the first flipping paper path is connected to the double-sided printing inlet, and the third flipping paper path is connected to the double-sided printing inlet. The double-sided printing outlet is connected, and the second flipping paper path is used to connect the first flipping paper path and the third flipping paper path;

The paper exit path includes a first paper exit path, a second paper exit path, and a third paper exit path. The first paper exit path is connected to the outlet of the printing channel, and the third paper exit path is connected to the exit of the printing channel. The paper path is connected to the double-sided paper exit entrance, and the second paper exit path is used to connect the first paper exit path and the third paper exit path;

The paper feeding roller group on the first turning paper path and the first paper exiting paper path share one driving roller; the second turning paper path and the second paper exiting paper path are connected to the first paper feeding roller group. The paper feeding roller groups on the opposite paths of the two turning paper paths share one driving roller.

Preferably, a negative pressure plate is provided on the side of the printing channel opposite to the nozzle, and the negative pressure plate can absorb paper.

Preferably, the turning channel is U-shaped.

Preferably, a first switch is rotatably provided at the double-sided printing entrance, and the first switch has two states:

When the first switch is in the first state, the double-sided printing inlet and the inlet of the flip channel are in a closed state, and the first switch does not block the printing channel;

When the first switch is in the second state, the double-sided printing inlet and the inlet of the flip channel are in a connected state, and the first switch can block the printing channel.

Preferably, a second switch is rotatably provided at the double-sided printing outlet, and the second switch has two states:

When the second switch is in the first state, the double-sided printing outlet and the outlet of the flip channel are in a closed state, and the second switch does not block the printing channel;

When the second switch is in the second state, the double-sided printing outlet and the outlet of the flip channel are in a connected state, and the second switch can block the printing channel.

Preferably, a third switch is rotatably provided at the double-sided paper exit entrance, and the third switch has two states:

When the third switch is in the first state, the entrance to the paper exit channel and the double-sided paper exit entrance are in a closed state, and the third switch does not block the printing channel;

When the third switch is in the second state, the entrance of the paper exit channel and the double-sided paper exit entrance are in a connected state, and the third opening can block the printing channel.

(3) Beneficial effects

The invention adds a flipping channel in the printer to flip the paper, so that the reverse side of the paper passes from the downstream side of the nozzle and then to the upstream side of the nozzle, and then prints on the reverse side of the paper, which is different from the existing The paper is flipped through the pickup roller, which improves the flipping efficiency and double-sided printing speed, allowing the paper to quickly complete double-sided printing in the printer.

Description of the drawings

Figure 1 is a schematic structural diagram of the first switch, the second switch and the third switch in the paper feeding mechanism of the present invention when they are all in the first state;

Figure 2 is an enlarged view of Figure 1 at A;

Figure 3 is a schematic structural diagram of the first switch, the second switch and the third switch in the paper feeding mechanism of the present invention when they are all in the second state;

Figure 4 is an enlarged view of Figure 3 at B.

[Explanation of reference symbols]

1: printing channel; 11: double-sided paper ejection entrance; 12: double-sided printing exit; 13: double-sided printing entrance; 14: first switch; 141: first profile; 142: second profile; 15: second switch ;16: The third switch; 2: Flip channel; 21: The first flip paper path; 22: The second flip paper path; 23: The third flip paper path; 3: Paper ejection channel; 31: The first paper ejection path ;32: The second paper exit path; 33: The third paper exit path; 4: Print head; 5: Paper feeding roller group; 51: Driving roller; 52: Driven roller; 53: First paper feeding roller group; 54: Second paper feeding roller group; 6: Negative pressure plate;

Implementation

In order to better explain the present invention and facilitate understanding, the present invention will be described in detail below through specific embodiments in conjunction with the accompanying drawings.

It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiment of the present invention are only used to explain the relationship between components in a specific posture (as shown in the drawings). Relative positional relationship, movement conditions, etc., if the specific posture changes, the directional indication will also change accordingly.

In addition, descriptions such as "first", "second", etc. in the present invention are for descriptive purposes only and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

In the present invention, unless otherwise clearly stated and limited, the terms "connection", "fixing", etc. should be understood in a broad sense. For example, "fixing" can be a fixed connection, a detachable connection, or an integral body; It can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two elements or an interactive relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

As shown in FIGS. 1 to 4 , the present invention provides a paper feeding mechanism for double-sided printing of an inkjet printer. The paper feeding mechanism includes: a printing channel 1 , a turning channel 2 and a paper exit channel 3 . A nozzle 4 is provided on one side of the printing channel 1. Along the entrance of the printing channel 1 to the exit of the printing channel 1, the printing channel 1 is provided with a double-sided paper ejection entrance 11, a double-sided printing outlet 12 and a double-sided printing entrance 13. The double-sided paper exit inlet 11 is located upstream of the nozzle 4 , and the double-sided printing outlet 12 and the double-sided printing inlet 13 are located downstream of the nozzle 4 . The upstream side of the nozzle 4 is the side of the nozzle 4 facing the outlet of the printing channel 1, and the downstream side of the nozzle 4 is the side of the nozzle 4 facing the outlet of the printing channel 1. The inlet of the flipping channel 2 is connected to the double-sided printing inlet 13, and the outlet of the flipping channel 2 is connected to the double-sided printing outlet 12. A first switch 14 is provided at the double-sided printing inlet 13. The first switch 14 can control the flipping channel 2 and the double-sided printing inlet 13. The second switch 15 is provided at the double-sided printing outlet 12, and the second switch 15 can control the opening and closing of the flipping channel 2 and the double-sided printing outlet 12 and control printing. Channel 1 is on and off. The entrance of the paper exit channel 3 is connected to the double-sided paper exit entrance 11, and the exit of the paper exit channel 3 is connected to the exit of the printing channel 1; a third switch 16 is provided at the double-sided paper exit entrance 11, and the third switch 16 can control the exit. The paper channel 3 is connected to the double-sided paper exit entrance 11 and the printing channel 1 is controlled to be connected. In the preferred embodiment, the first switch 14, the second switch 15 and the third switch 16 are all rotatably installed in the printer, and the first switch 14, the second switch 15 and the third switch 16 are individually connected to a control motor. connected, the control motor can control the rotation of the first switch 14, the second switch 15 and the third switch 16. By controlling the rotation of the first switch 14, the second switch 15 and the third switch 16, the printing channel 1 and the flipping channel can be controlled. 2 and the connection between paper exit channels 3.

As shown in Figure 1, in the single-sided printing state, the first switch 14 controls the flipping channel 2 and the double-sided printing inlet 13 to be closed, and the second switch 15 controls the flipping channel 2 and the double-sided printing outlet 12 to be closed. , the third switch 16 controls the paper exit channel 3 and the double-sided paper exit entrance 11 to be closed; the paper directly enters the printing channel 1 from the entrance of the printing channel 1, and then passes under the nozzle 4 to complete printing, and finally exits from the printing channel 1 exit.

As shown in Figure 3, in the double-sided printing state, the paper first enters the printing channel 1 from the entrance of the printing channel 1, then enters the bottom of the nozzle 4 from the upstream of the nozzle 4, and then to the downstream of the nozzle 4. The front side of the paper is printed. ; When the paper passes through the double-sided printing inlet 13, the first switch 14 controls the flipping channel 2 and the double-sided printing inlet 13 to be connected, and closes and blocks the printing channel 1. The second switch 15 controls the flipping channel 2 and the double-sided printing outlet. 12 is in the connected state, the paper passes through the flip channel 2, and then enters the printing channel 1 from the double-sided printing outlet 12. At this time, the reverse side of the paper faces the nozzle 4, and the paper enters the bottom of the nozzle 4 from the downstream of the nozzle 4, and then to the nozzle 4 upstream, and finally enters the paper exit channel 3 under the control of the third switch 16, and then exits from the exit of the printing channel 1 to complete double-sided printing.

From the above analysis, it can be seen that the flip channel 2 is used to flip the paper, so that the reverse side of the paper passes from the downstream side of the nozzle 4 and then reaches the upstream side of the nozzle 4, and then prints the reverse side of the paper. This is different from The existing paper is turned over through the pick-up roller, which improves the turning efficiency and the double-sided printing speed. The paper that has been printed on the reverse side enters the paper ejection channel 3 to complete the paper ejection, and then completes the double-sided printing. The invention adds a turning channel 2 and a paper ejection channel 3 in the printer, so that the paper can quickly complete double-sided printing in the printer.

Further, multiple pairs of paper feeding roller groups 5 are provided on the printing channel 1, the turning channel 2, and the paper exit channel 3. The paper feeding roller group 5 on the printing channel 1 can drive the paper along the entrance of the printing channel 1 to the exit of the printing channel 1 . The paper feeding roller group 5 on the turning channel 2 and the paper exit channel 3 can drive the paper from the entrance of the turning channel 2 to the exit of the turning channel 2, and then from the entrance of the paper exit channel 3 to the exit of the paper exit channel 3 through the printing channel 1 . The paper feeding roller group 5 includes a driving roller 51 and a driven roller 52. The printing channel 1, the turning channel 2 and the paper exit channel 3 are all located between the driving roller 51 and the driven roller 52. The driving roller 51 and the driven roller 52 are both It is rotatably installed in the printer. The driving roller 51 is connected to the motor. The motor can drive the driving roller 51 to rotate. The paper can pass through the area between the driving roller 51 and the driven roller 52 and the driving roller 51 can drive the paper to move. In the present invention, the motor drives the driving roller 51 to rotate and then drives the paper to move in a set direction. In the present invention, the paper feeding roller group 5 only needs to rotate in one direction and does not need to change the direction of rotation to achieve double-sided printing. The service life of the paper feeding roller group 5 and the motor is improved, and the speed of double-sided printing is also accelerated.

In a preferred embodiment, as shown in Figures 1 and 3, the turning channel includes a first turning paper path 21, a second turning paper path 22, and a third turning paper path 23. The first turning paper path 21 is connected with double-sided printing. The inlet is connected, the third flipping paper path 23 is connected with the double-sided printing outlet, and the second flipping paper path 22 is used to connect the first flipping paper path 21 and the third flipping paper path 23 . The paper exit path includes a first paper exit path 31, a second paper exit path 32, and a third paper exit path 33. The first paper exit path 31 is connected to the outlet of the printing channel, and the third paper exit path 33 is connected to the outlet of the printing channel. The double-sided paper exit entrance is connected, and the second paper exit path 32 is used to connect the first paper exit path 31 and the third paper exit path 33 . The paper feeding roller group on the first turning paper path 21 and the first paper exiting paper path 31 share a driving roller; the second turning paper path 22 and the second paper exiting paper path 32 are on the opposite path to the second turning paper path 22 The paper feed roller group shares a driving roller. As shown in Figures 1 and 3, the moving directions of the paper in the first turning paper path 21, the first paper exiting path 31, the second turning paper path 22 and the second paper exiting path 32 are opposite, so the first turning paper The paper feeding roller group on the paper path 21 and the first paper exiting paper path 31 can share a driving roller, and the paper feeding roller group on the second turning paper path 22 and the second paper exiting paper path 32 can share a driving roller. By setting The shared driving roller reduces the usage of the driving roller. Through reasonable power distribution, the number of motors is effectively reduced and the cost is reduced.

Furthermore, on the printing channel 1, the paper feeding roller group 5 upstream of the nozzle 4 and adjacent to the nozzle 4 is the first paper feeding roller group 53, and the paper feeding roller group 5 downstream of the nozzle 4 and adjacent to the nozzle 4 is the third paper feeding roller group 5. Two paper feeding roller groups 54; the double-sided printing outlet 12 is located between the second paper feeding roller group 54 of the nozzle 4, and the double-sided paper exit entrance 11 is located between the first paper feeding roller group 53 and the nozzle 4. That is, during double-sided printing, when the paper is at the exit of the flipping channel 2, the paper can enter the printing channel 1 driven by the paper feeding roller group 5 on the flipping channel 2, pass through the nozzle 4, and then enter the paper exit channel 3. This process There is no need to drive the paper feeding roller group 5 on the printing channel 1, and the paper feeding roller group 5 on the printing channel 1 does not need to be reversed, ensuring that during the entire double-sided printing process, the paper feeding roller group 5 only needs to rotate in one direction. There is no need to change the direction of rotation, which ensures that the motor connected to the driving roller 51 does not need to change the direction of rotation, which increases the service life of the motor and paper feed roller set 5 and improves the efficiency of double-sided printing.

In a preferred embodiment, a negative pressure plate 6 is provided on the side of the printing channel 1 opposite to the nozzle 4, and the negative pressure plate 6 can absorb paper. By adsorbing the paper through the negative pressure plate 6, the nozzle 4 can better perform inkjet printing on the paper, thereby improving the printing effect. The flip channel 2 is U-shaped. The paper will be deflected after passing through the turning channel 2. When the paper moves from the entrance of the printing channel 1 to the exit of the printing channel 1, the front side of the paper faces the nozzle 4. When the paper passes through the flip channel 2 and enters the printing channel 1 from the double-sided printing outlet 12, then moves to the double-sided paper exit entrance 11 and enters the double-sided paper exit channel 3 from the double-sided paper exit entrance 11, the paper moves along the double-sided path in the printing channel 1 When the printing outlet 12 moves to the double-sided paper exit entrance 11, the reverse side of the paper faces the nozzle 4, thereby enabling the paper feeding mechanism provided by the present invention to quickly complete double-sided printing.

Finally, a first switch 14 is rotatably provided at the double-sided printing inlet 13, and the first switch 14 has two states. When the first switch 14 is in the first state, the double-sided printing inlet 13 and the inlet of the flip channel 2 are closed, and the first switch 14 does not block the printing channel 1; when the first switch 14 is in the second state, the double-sided printing inlet 13 and the inlet of the flip channel 2 are closed. The printing inlet 13 and the inlet of the flip channel 2 are in a connected state, and the first switch 14 can block the printing channel 1 .

A second switch 15 is rotatably provided at the double-sided printing outlet 12, and the second switch 15 has two states. When the second switch 15 is in the first state, the double-sided printing outlet 12 and the outlet of the flip channel 2 are closed, and the second switch 15 does not block the printing channel 1; when the second switch 15 is in the second state, the double-sided printing outlet 12 and the outlet of the flip channel 2 are closed. The printing outlet 12 and the outlet of the flip channel 2 are in a connected state, and the second switch 15 can block the printing channel 1 .

A third switch 16 is rotatably provided at the double-sided paper exit entrance 11, and the third switch 16 has two states. When the third switch 16 is in the first state, the entrance of the paper exit channel 3 and the double-sided paper exit entrance 11 are in a closed state, and the third switch 16 does not block the printing channel 1; when the third switch 16 is in the second state, The entrance of the paper exit channel 3 and the double-sided paper exit entrance 11 are connected, and the third opening can block the printing channel 1 .

In a preferred embodiment, the working principle of the first switch may be: the first switch includes a first profile 141 and a second profile 142. As shown in Figure 2, when the first switch rotates in the first state, the first switch The double-sided printing entrance can be blocked, and the paper can pass through the first printing entrance along the first contour 141; as shown in Figure 4, when the first switch is rotated in the second state, the first switch can block the printing channel, and The paper from the entrance of the printing channel can pass through the double-sided printing entrance and enter the turning channel under the guidance of the second profile 142 . Similarly, the working principles of the second switch and the third switch are similar to the working principles of the first switch, and will not be described in detail here.

When printing on one side:

As shown in Figure 1, the first switch 14, the second switch 15 and the third switch 16 are all in the first state. At this time, the paper moves directly from the entrance of the printing channel 1 to the exit of the printing channel 1, completing the single Surface printing.

When printing on both sides:

The second switch 15 and the third switch 16 are both in the first state, and the paper moves along the printing channel 1 from the exit of the printing channel 1 toward the exit of the printing channel 1;

As shown in Figure 3, when the paper moves between the double-sided printing outlet 12 and the double-sided printing inlet 13, the first switch 14, the second switch 15 and the third switch 16 are all in the second state. At this time, the paper passes through the double-sided printing outlet 12 and the double-sided printing inlet 13. The side printing entrance 13 enters the flip channel 2, and then along the flip channel 2 from the double-sided printing outlet 12 into the printing channel 1, then along the printing channel 1 from the double-sided paper exit entrance 11 into the paper exit channel 3, and finally the paper flows along the paper exit channel 3 Enter the printing channel 1 from the exit of the paper exit channel 3 and exit from the exit of the printing channel 1 to complete double-sided printing.

It should be understood that the above description of specific embodiments of the present invention is only to illustrate the technical route and characteristics of the present invention, and its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. However, the present invention It is not limited to the specific embodiment described above. All changes or modifications made within the scope of the claims of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. The paper feeding mechanism for the double-sided printing function of the ink-jet printer is characterized by comprising a printing channel, a turnover channel and a paper returning channel which are arranged in the printer;

a spray head is arranged on one side of the printing channel; the printing device comprises a nozzle, a printing channel, a double-sided paper outlet, a double-sided printing inlet, a double-sided paper outlet and a double-sided printing inlet, wherein the printing channel is sequentially arranged from the inlet of the printing channel to the outlet of the printing channel;

the inlet of the turnover channel is connected with the double-sided printing inlet, the outlet of the turnover channel is connected with the double-sided printing outlet, a first switch is arranged at the double-sided printing inlet, and the first switch can control the on-off of the turnover channel and the double-sided printing inlet and control the on-off of the printing channel; the second switch is arranged at the double-sided printing outlet and can control the on-off of the turnover channel and the double-sided printing outlet and control the on-off of the printing channel;

an inlet of the paper returning channel is connected with the double-sided paper returning inlet, and an outlet of the paper returning channel is connected with an outlet of the printing channel; a third switch is arranged at the double-sided paper returning inlet and can control the on-off of the paper returning channel and the double-sided paper returning inlet and the on-off of the printing channel;

the printing channel, the overturning channel and the paper returning channel are provided with a plurality of pairs of paper feeding roller groups;

the paper feeding roller group on the printing channel can drive paper to enter from the inlet of the printing channel to the outlet of the printing channel;

the paper feeding roller groups on the turnover channel and the paper returning channel can drive paper to enter the paper returning channel through the printing channel from the inlet of the turnover channel to the outlet of the turnover channel; the paper feed roller group only needs to rotate towards one direction, and double-sided printing can be realized without changing the rotation direction;

on the printing channel, a paper feed roller group adjacent to the spray head at the upstream of the spray head is a first paper feed roller group, and a paper feed roller group adjacent to the spray head at the downstream of the spray head is a second paper feed roller group; the double-sided printing outlet is positioned between the spray head and the second paper feeding roller group, and the double-sided paper withdrawing inlet is positioned between the first paper feeding roller group and the spray head.

2. The paper feed mechanism for a duplex printing function of an inkjet printer according to claim 1, wherein the paper feed roller group includes a driving roller and a driven roller which are disposed opposite to each other, the driving roller and the driven roller are both rotatably installed in the printer, the driving roller is connected to an output shaft of a motor, the driving roller is rotatable by the motor, and the printing path, the reversing path, and the paper ejection path are all located between the driving roller and the driven roller, and paper can pass through an area between the driving roller and the driven roller.

3. The paper feed mechanism for the duplex printing function of an inkjet printer as claimed in claim 2, wherein:

the turnover channel comprises a first turnover paper channel, a second turnover paper channel and a third turnover paper channel, the first turnover paper channel is connected with the double-sided printing inlet, the third turnover paper channel is connected with the double-sided printing outlet, and the second turnover paper channel is used for connecting the first turnover paper channel and the third turnover paper channel;

the paper returning channel comprises a first paper returning channel, a second paper returning channel and a third paper returning channel, the first paper returning channel is connected with an outlet of the printing channel, the third paper returning channel is connected with the double-sided paper returning inlet, and the second paper returning channel is used for connecting the first paper returning channel and the third paper returning channel;

the paper feeding roller group on the first turnover paper path and the first paper returning path share one driving roller; the second reversing paper path and the paper feeding roller group on the path opposite to the second reversing paper path share one driving roller.

4. A sheet feeding mechanism for a duplex printing function of an ink jet printer according to any one of claims 1 to 3, wherein a negative pressure plate is provided on a side of the printing path opposite to the head, the negative pressure plate being capable of sucking a sheet of paper.

5. A paper feed mechanism for a duplex printing function of an ink jet printer according to any one of claims 1 to 3, wherein the flipping path is U-shaped.

6. A paper feed mechanism for a duplex printing function of an inkjet printer according to any one of claims 1 to 3, wherein the duplex printing inlet is rotatably provided with a first switch having two states:

when the first switch is in a first state, the double-sided printing inlet and the inlet of the turnover channel are in a closed state, and the first switch does not block the printing channel;

when the first switch is in the second state, the double-sided printing inlet and the inlet of the turnover channel are in a communication state, and the first switch can block the printing channel.

7. A paper feed mechanism for a duplex printing function of an inkjet printer according to any one of claims 1 to 3, wherein a second switch is rotatably provided at the duplex printing outlet, the second switch having two states:

when the second switch is in a first state, the double-sided printing outlet and the outlet of the turnover channel are in a closed state, and the second switch does not block the printing channel;

when the second switch is in a second state, the double-sided printing outlet and the outlet of the turnover channel are in a communication state, and the second switch can block the printing channel.

8. A paper feed mechanism for a duplex printing function of an inkjet printer according to any one of claims 1 to 3, wherein a third switch is rotatably provided at the duplex paper exit, the third switch having two states:

when the third switch is in a first state, the inlet of the paper returning channel and the double-sided paper returning inlet are in a closed state, and the third switch does not block the printing channel;

when the third switch is in the second state, the inlet of the paper ejecting passage and the double-sided paper ejecting inlet are in a communication state, and the third switch can block the printing passage.