JPH0957952A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer whose resolution is heightened without increasing the number of nozzles of a record head by switching an attaching angle of the record head on the way of going and returning of a carriage. SOLUTION: A guide axis 14 for holding a carriage 12 is of eccentric axis. An attaching angle of the carriage 12 varies between going and returning of a record head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer for ejecting ink from a recording head to print on a recording member, and more particularly to a means for improving resolution and printing quality.

[0002]

2. Description of the Related Art There are two types of conventional inkjet printers of this type.

1) For example, there is one disclosed in Japanese Unexamined Patent Publication No. 5-330182, in which the cam profile of a cam mechanism connected to the stepping motor is selected by rotating the stepping motor forward and backward, and recording is performed. By switching the transfer amount of the paper, it is possible to perform the normal transfer amount printing and the high resolution printing in which the transfer amount is minutely fed.

2) Also, as a method of increasing the high resolution, the resolution is increased by increasing the number of nozzles of the recording head.

[0005]

However, the above-mentioned prior art has the following drawbacks.

1) In the above-mentioned Japanese Patent Laid-Open No. 5-330182, as a drive source for switching the transfer amount of recording paper,
Since a stepping motor, which is a drive source capable of forward and reverse rotation, must be used, the motor alone is expensive, and at the same time, the control circuit is complicated and an expensive control circuit is required. Further, it is difficult to reduce the size and cost of the printer due to the complicated cam mechanism.

Next, regarding the high density of the recording head: 1) Since the number of nozzles of the recording head increases, the recording head becomes large and it is difficult to downsize the printer.

2) If the recording head is not increased in size, it is indispensable to reduce the size of parts constituting the head and to improve the accuracy, which causes drawbacks such as deterioration in reliability of the recording head and difficulty in cost reduction. ing.

The present invention has been made in order to solve such a drawback, and by changing the mounting angle of the recording head between the forward and backward passes of the carriage, high print quality,
The aim is to provide a reliable printer that is low in price and easy to control.

[0010]

SUMMARY OF THE INVENTION An ink jet printer according to the present invention is provided with a recording head for ejecting ink onto recording paper to perform a printing process, a carriage on which the recording head is mounted, and a reciprocating carriage. An inkjet provided with a drive mechanism is characterized by having a means for switching the mounting angle of the recording head and the carriage between the forward path and the backward path of the recording head.

A desirable mode for changing the mounting angle between the recording head and the carriage is that the guide shaft holding the carriage is an eccentric shaft, and cam guides are provided on both sides of the guide shaft. When the protrusion is pressed at both ends of the moving range of the carriage, the guide shaft is rotated and the mounting angle of the recording head and the carriage is switched.

As the switching means, a groove cam and a pin attached to the carriage may be additionally provided.

[0013]

According to the above construction of the present invention, the mounting angle of the recording head or the carriage changes depending on the forward path and the backward path of the recording head on which the printing process is performed. Since the ink liquid suitability ejected in the forward path and the ink liquid suitability ejected in the return path are printed on the recording paper sheet with a deviation of the mounting angle, it is twice as high as the number of nozzles of the recording head. The resolution is obtained.

[0014]

1 is an exploded view of an ink jet printer according to an embodiment of the present invention, and FIG.
FIG. 3 is a perspective view of the inkjet printer of FIG. The inkjet printer is composed of a printer body 10 and a paper feeding unit 50 as shown in the figure. The printer body 10 includes an ink cartridge 11 having a nozzle 11 a and an ink bag (not shown), and the inkjet cartridge 11 is attached to a carriage 12.

The carriage 12 is supported by a pair of guide shafts 14 provided on a frame 13 so as to be movable in its axial direction. A DC motor is provided as a motor 15 that is a drive source for driving the carriage 12, and is driven to rotate in a fixed direction. The rotation of the motor 15 is transmitted to the gear 16, and the gear 16 is driven to rotate the timing belt 19 by rotating the gear 17 and the drive wheel 18 engaged with the gear 16. This rotation causes the driven wheel 20 to rotate and the gear 21 connected thereto to rotate. A drive pin (see reference numeral 30 in FIG. 3) for reciprocating the carriage 12 is provided on the timing belt 19, and the carriage 12 is rotated by one direction of the timing belt 19.
Reciprocates. A gear 22 is engaged with a gear 21 on the driven wheel 20 side. The gear 22 is provided at one end of a transmission shaft 23, and a gear 24 is also provided at the other end. The rotation of the gear 22 supplies a drive source to the paper feeding unit 50 via the transmission shaft 23 and the gear 24. Also,
The printer body 10 is provided with an encoder 25 for detecting the rotation of the motor 15.
5 is directly connected to the rotary shaft. Further, in the printer body 10, as shown in the drawing, a control line 26 for driving a motor 15, a sensor (see reference numeral 31 in FIG. 4) or the like, or a control line 26 for extracting a signal, and a control for driving the recording head 11a. A control line 27 for inputting a signal is connected.

The paper feeding unit 50 is provided with a gear group 51 that engages with a gear 24 provided on the other end of the transmission shaft 23 of the printer body 10. The gear group 51 includes a pair of paper feeding rollers (see FIG. 3). Reference numeral 52, 53), and the inkjet cartridge 11 performs a printing process in a reciprocating path. Before returning to the home position, feed one line of inserted recording paper. The paper feeding unit 50 is fixed to the printer body 10 by being screwed to a guide surface 13a formed by bending the frame 13 of the printer body 10 upward at a right angle. FIG. 3 is a side sectional view of the inkjet printer of FIG. Although the motor 15 rotates only in a fixed direction, the carriage 12 needs to reciprocate. Therefore, the drive pin 30 is attached to the timing belt 19 as shown in the drawing, and the drive pin 30 is engaged with the carriage 12 to move. I have to. At that time, when the drive pin 30 is in the position of the solid line (upper part), the carriage 12 is moved from right to left, for example, and when the drive pin 30 is in the position of the two-dot chain line (lower part), the carriage 12 is moved from left to right. It shall be. Incidentally, this mechanism itself is already known and its details are omitted.

The paper feed unit 50 is provided with a pair of paper feed rollers 52 and 53 connected to a gear group 51.
The paper feed rollers 52 and 53 are rotated in opposite directions when the recording head 11a of the ink jet cartridge 11 finishes the printing process for one line and returns to the home position, and the recording paper is moved in the direction of the arrow 1 Lines are sent out.

FIG. 4 is a plan view of the ink jet printer of FIG. The sensor 31 has a U-shape, and the encoder 25 is inserted into its opening. The opening 25a provided along the circumferential direction of the "rotation of the encoder 25" allows light emitted from one end of the sensor 31 to be transmitted therethrough, thereby allowing the other end of the sensor 31 to pass through the opening 25a. The light is received, and the sensor 31 outputs a timing pulse accordingly and the rotation of the motor 15, that is, the carriage 1
The position of 2 is detected.

FIG. 5 is an explanatory view showing a mechanism for detecting the home position of the carriage 12 in the ink jet printer of FIG. A shield plate 33 for shielding the light emission from the sensor 31 is attached to the carriage 12. In the steady state, the sensor 31 receives light through the opening 25a of the rotary encoder 25 as the rotary encoder 25 rotates and outputs a timing pulse. However, when the carriage 12 reaches the home position, the shield plate 33 causes the optical path of the sensor 31 to pass. Shield. Since the shielding time is longer than in the case where the opening 25a of the rotary encoder 25 is used, the shielding plate 33 is detected by measuring the time, and it is understood that the carriage 12 has reached the home position.

The ink jet printer having the above-described structure has the motor 15 and the sensor 31 through the control line 26.
Control voltage and the like are supplied, and a control signal corresponding to the nozzle 11a mounted on the inkjet cartridge 11 is supplied via the control line 27. Then, the timing belt 19 is rotated by the rotational driving of the motor 15, and the drive pin 30 moves accordingly, and the drive pin 30 moves the carriage 12 along the guide shaft 14. At this time, ink is ejected from the nozzle 11a according to the control signal, and printing processing is performed. When the printing process for one line is completed, the driving force for feeding the paper is transmitted to the paper feeding unit 50 via the transmission shaft 22, and the paper feeding rollers 52 and 53 rotate, so that the recording paper is moved to the first position. Lines are sent out. The above operation is repeated for the number of print lines.

FIG. 6 is an explanatory view of the carriage mounting angle operation and the operation of the guide shaft 14. (A) is the state of the outward path in which the printing process is performed. The mounting angle is determined by the guide shaft position set at the home position, and desired printing is performed. Move the carriage 12 to the end of the outward path (b)
And the convex portion 12a of the carriage and the cam portion 1 of the guide shaft 14.
After the abutment of 4a, the guide shaft 14 is moved a predetermined amount by further moving the carriage (c) by pressing the carriage convex portion 12a, and the guide shaft portion 14b is transferred in the upward direction. The mounting angle a ° changes. When the carriage 12 is again moved in the return direction in this state and ink is ejected again, as described above, the proper ink liquid is printed on the recording paper with a mounting angle a ° offset from the proper ink liquid ejected in the forward direction. It It should be noted that the mounting angle a ° of the carriage 12 is an angle at which the ink liquid suitable for the return path is printed at a half pitch of the width c suitable for the ink liquid printed on the outward path, as shown in FIG. .

After that, when the carriage 12 is moved to the end point of the return path, the convex portion 12a of the carriage 12 comes into contact with the cam portion 14a of the guide shaft 14 and then the carriage 1 is slightly moved like the forward path.
Since the guide shaft shaft portion 14b is moved downward by moving 2, the mounting angle of the carriage 12 deviates from the return path by a ° and returns to the mounting angle of the carriage 12 in the forward path. Then, after feeding a predetermined amount of recording paper, the cycle is repeated as described above.

As described above, with the above-described structure, it is possible to obtain printing with a resolution twice as many as the number of recording head nozzles. Also a single D
A so-called cycle machine that rotates the C motor in one direction and performs a series of printing operation and paper feeding operation can be applied to an inkjet printer.

FIG. 7 is a view showing another embodiment, as seen from the paper feeding unit. A pin 80 is attached to the carriage 12, and a constant pressing force is applied by a leaf spring 90 or the like. The cam 81 has a groove cam 81a through which the pin 80 passes.

Carriage 1 in the case of the outward path as shown in FIG.
2, the carriage 12 is positioned by the groove cam on the upper stage, and ink droplets are ejected. At the end of the outward trip, the groove cam 8
The pin 80 moves to the lower stage of 1a. Similarly to the above, the mounting angle of the carriage is changed, and the ink droplets on the return path are ejected. After discharging, the pin 80 moves to the upper stage of the groove cam 81a,
Carriage mounting angle on the outward path.

[0026]

As described above, according to the present invention, by changing the mounting angle of the carriage, the ink droplets ejected in the forward path and the ink droplets ejected in the return path are not moved by the carriage. It is printed on recording paper with a deviation of the mounting angle. That is, the resolution is twice as high as the number of recording head nozzles. Therefore, the DC brush motor can be adopted without using an expensive stepping motor or its control circuit as a drive source for higher resolution. Further, it is not necessary to increase the number of nozzles to obtain high resolution. Therefore, it is possible to provide a simple, inexpensive, low power consumption, and highly efficient small inkjet printer.

Further, according to the present invention, since it is not necessary to increase the number of nozzles of the recording head, the recording head which is a consumable item can be provided at a low cost.

[Brief description of drawings]

FIG. 1 is an exploded view of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is a perspective view of the inkjet printer of FIG. 1 viewed from a motor side.

FIG. 3 is a side sectional view of the inkjet printer of FIG.

FIG. 4 is a plan view of the inkjet printer of FIG.

5 is an explanatory diagram showing a mechanism for detecting a home position of a carriage in the inkjet printer of FIG.

FIG. 6 is an explanatory diagram of a carriage operation of the inkjet printer of FIG.

FIG. 7 is an explanatory diagram of a carriage operation of an inkjet printer according to another embodiment.

8 is an explanatory diagram of a print sample of the inkjet printer of FIG.

[Explanation of symbols]

 10 Printer Body 11 Inkjet Cartridge 11a Nozzle 12 Carriage 12a Carriage Convex 13 Frame 13a Guide Surface of Frame 13 14 Guide Shaft 14a Guide Shaft Cam 14b Guide Shaft Shaft 15 Motor 16, 17 Gear 18 Drive Wheel 19 Timing Belt 20 Passive Wheel 21, 22 Gear 23 Transmission shaft 24 Gear 25 Encoder 25a Encoder 25 opening 26, 27 Control line 30 Drive pin 31 Sensor 33 Shield plate 50 Paper feed unit 51 Gear group 52, 53 Paper feed roller 80 Pin 81 Cam 81a Cam 81 Groove cam part

Claims (3)

[Claims] 1. An inkjet printer including a recording head for performing a printing process by causing ink to fly and adhere to a recording sheet, a carriage on which the recording head is mounted, and a drive mechanism for reciprocating the carriage. An ink jet printer having means for switching the mounting angle of the recording head and the carriage between the forward path and the backward path of the recording head. 2. The ink jet printer according to claim 1, wherein the guide shaft for positioning the carriage on the switching means is an eccentric shaft. 3. The ink jet printer according to claim 1, wherein the switching means is provided with a groove cam and a pin attached to the carriage.