JPH09309200A - Ink jet image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet image forming apparatus for rapidly cooling a printing head or ink by a relatively simple structure and not requiring a printing interrupting time for cooling. SOLUTION: Side panels 34, 36 are fixed to both ends of a guide rail 16 and a fan 38 is fixed to the part on the extension in the moving direction of a heat conductive member 32 of the side panel 34 and a suction and discharge port 40 is formed to the part on the extension in the moving direction of the head conductive member 32 of the side plate 32. The fan 38 is rotated and air streams are generated in the direction shown by an arrow C within the moving region of the heat conductive member 32 to cool the heat conductive member 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet type image forming apparatus for forming an image on a recording medium such as recording paper by ejecting ink from the print head while reciprocating a carriage having a print head in a predetermined direction. Regarding

[0002]

2. Description of the Related Art As one of output devices of computers and workstations, there is known an ink jet type image forming apparatus which forms an image on recording paper by discharging ink. This inkjet type image forming apparatus is, for example,
A print head having a plurality of discharge nozzles for discharging ink, a carriage mounted with the print head and reciprocating in a predetermined direction, and a transport device for transporting recording paper in a direction orthogonal to the predetermined direction are provided. ing. When forming an image on a recording sheet, the recording sheet being conveyed by the conveying device is temporarily stopped, and the carriage is reciprocated in the above-described predetermined direction to form an image forming area of the recording sheet on which the image is formed. The ink is ejected from the ejection nozzles to the portion located at the position (1) to form (print) an image for one band, and then the recording paper is conveyed for a predetermined length to the portion newly located in the image forming area. The operation of forming an image for a band is repeated.

Generally, the above-mentioned plurality of ejection nozzles are formed on a silicon plate (or glass plate), and a heating element (ejection heater) for ejecting ink from each ejection nozzle is formed in the vicinity of each ejection nozzle. ing. The print head also includes an aluminum base plate adjacent to the silicon plate that reinforces the silicon plate. In the print head having such a configuration, about half of the area of the heat generating element is in contact with the silicon plate, so that the heat of the heat generating element is heated by the silicon every time the heat generating element is heated and ink is ejected from the ejection nozzle. It is transmitted to the plate, and as a result, the temperature of the print head and ink rises.

When the temperature of the ink changes, the viscosity of the ink changes. Since the viscosity of the ink affects the flow resistance when the ink is ejected from the ejection nozzles, if the viscosity of the ink changes, the amount of the ejected ink changes, resulting in uneven image density. Further, when the temperature of the ink rises to near the boiling point of the ink, bubbles are generated in the ink, and due to the bubbles, the ink cannot be supplied to the ejection nozzle, and the ink cannot be ejected. Further, the heat may destroy the print head.

Therefore, when the temperature of the print head exceeds a predetermined temperature, printing is stopped and the temperature of the print head is lowered in order to prevent uneven image density and inability to eject ink.
There is also a device in which a carriage is provided with a cooling fan to forcibly cool the print head.

[0006]

However, in the cooling for stopping the printing, the temperature drop of the heated print head is slow, and it takes time to cool the print head to an appropriate temperature.
There is a problem that it takes a long time to complete printing. Further, when a cooling fan is provided on the scanning carriage, there is a problem that the carriage becomes large in size and has a complicated structure, although the print stop time for cooling is not required.

In view of the above circumstances, the present invention provides an ink jet system image forming apparatus that cools a print head and ink quickly with a relatively simple structure and does not require a discontinuation time for cooling until printing is completed. With the goal.

[0008]

SUMMARY OF THE INVENTION To achieve the above object, an ink jet image forming apparatus of the present invention comprises a print head for ejecting ink, and a carriage carrying the print head and reciprocating in a predetermined direction. And an ink jet system image forming apparatus for forming an image on a recording medium by ejecting ink from the print head while reciprocating the carriage in the predetermined direction.
A heat conducting member, which is fixed to the carriage so as to come into contact with the print head and moves together with the carriage, and through which heat of the print head is conducted. It is characterized in that it is provided with an air flow generating means.

Here, (3) the ink jet type image forming apparatus comprises a duct in which the heat conducting member moves, and (4) the air flow generating means generates an air flow inside the duct. It is preferable.

(5) It is preferable that the heat conducting member has a plurality of plate-shaped portions extending in the predetermined direction. Further, (6) the inkjet type image forming apparatus includes a carriage position detecting means for detecting the position of the carriage, and (7) the airflow generating means is based on the position of the carriage detected by the carriage position detecting means. It is preferable that the velocity or direction of the generated airflow be changed.

Furthermore, (8) the ink jet type image forming apparatus comprises a print head temperature detecting means for detecting the temperature of the print head, and (9) the air flow generating means,
It is preferable to change the velocity or direction of the generated air flow based on the temperature of the print head detected by the print head temperature detecting means.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ink jet type image forming apparatus according to the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is a perspective view showing a first embodiment of an ink jet type image forming apparatus of the present invention.

The ink jet type image forming apparatus 10 is
A platen 14 is provided on which the recording paper 12 conveyed in the direction of arrow A by a conveying device (not shown) is placed. Above the platen 14, parallel to the platen 14, 2
A book guide rail 16 is arranged. The guide rail 16 can be freely moved in the arrow B direction (which is an example of the predetermined direction referred to in the present invention and is a direction orthogonal to the arrow A direction) by a belt 20 and a carriage drive motor 22 that are wound around a pulley 18. A carriage 24 that reciprocates is fixed. A print head 30 having a plurality of ejection nozzles 42 (see FIG. 3) for ejecting the ink 26 is mounted on the carriage 24. A heat conducting member 32 made of aluminum is fixed to the carriage 24. When the print head 30 is mounted on the carriage 24, the heat conducting member 3 is fixed.
2 abuts on the heat-conducting aluminum base plate 48 of the print head directly or via a heat-conducting rubber. Therefore, the heat of the print head 30 is conducted to the heat conducting member 32. Further, the heat conducting member 32 has five plate-shaped portions 32a extending in the arrow B direction and substantially parallel to each other.

At both ends of the guide rail 16, side plates 34, 36 are fixed which spread in a direction orthogonal to the arrow B direction. A fan (which is an example of the airflow generating means according to the present invention) 38 is fixed to a portion of the side plate 34 that is an extension of the heat conducting member 32 in the moving direction. On the other hand, an intake / exhaust port 40 is formed in a portion of the side plate 36, which is an extension of the heat conducting member 32 in the moving direction. When the fan 38 is normally or reversely rotated, air is sucked or exhausted from the intake / exhaust port 40, so that the direction of the arrow C (the direction substantially parallel to the direction of the arrow B) is within the moving region of the heat conducting member 32. Airflow is generated.

The structure of the print head 30 will be described with reference to FIGS.

FIG. 2 is a side view showing the carriage shown in FIG. 1, and FIG. 3 is a sectional view showing the vicinity of the discharge nozzle of the print head shown in FIG.

The print head 30 includes a plurality of ejection nozzles 42.
And a silicon substrate 44 on which is formed. In the vicinity of each ejection nozzle 42, the ink 26
A discharge heater 46 for discharging is formed. Also,
The print head 30 includes an aluminum base plate 48 that is adjacent to the silicon substrate 44 and reinforces the silicon substrate 44. When the print head 30 is mounted on the carriage 24, the heat conductive member 32 contacts the base plate 48 via the rubber 50 having high heat conductivity. Therefore, every time the ejection heater 46 is heated to eject ink from the ejection nozzle 42, the heat of the ejection heater 46 is transferred to the silicon substrate 44, the base plate 48, and the rubber 50, and further to the heat conducting member 32. .

In forming an image on the recording paper 12, the recording paper 12 is placed on the platen 14 and the recording paper 1
2 is sandwiched by a conveyance roller (not shown) and a pinch roller (not shown), and the conveyance roller is rotated by a motor (not shown) and conveyed in the direction of arrow A. Chart paper 1
2 is temporarily stopped on the platen 14, the carriage 24 is reciprocated in the direction of the arrow B, and ink is ejected from the ejection nozzle based on the image signal carrying image information transmitted to the print head 30. Then, an image is formed on the recording paper 12.

When an image is formed on the recording paper 12 in this way, as described above, the temperature of the print head 30 rises and the temperature of the heat conducting member 32 also rises. So fan 3
When 8 is rotated to generate an air flow, the heat conducting member 32 reciprocates while receiving this air flow. As a result, the heat conducting member 32 is cooled, and as a result, the print head 30 is also cooled. Since the heat conducting member 32 has the plurality of plate-shaped portions 32a, it is efficiently cooled by the air flow.

In this way, by rotating the fan 38, the print head and ink can be quickly cooled,
The viscosity of the ink can be maintained within a certain range. As a result,
It is possible to obtain a high-quality image by eliminating the unevenness of the image density without interrupting the printing by providing the cooling time. Further, it is possible to prevent ink ejection failure and print head destruction. Further, since the fan 38 is fixed to the side plate 34,
The configuration is simpler than fixing the fan to the carriage 24. The direction of the air flow by the fan 38 is indicated by the arrow C.
Either direction is acceptable. Further, although one fan 38 is used here, the speed of the airflow impinging on the heat conducting member 32 can be increased by providing two fans with the intake / exhaust ports 40, so that the print head can be operated more quickly. The temperature can be lowered.

[Second Embodiment] Referring to FIG. 4, a second embodiment of the ink jet image forming apparatus of the present invention will be described.

FIG. 4 is a perspective view showing a second embodiment of the ink jet type image forming apparatus of the present invention. In FIG. 4, the same components as those of FIG. 1 are designated by the same reference numerals.

The feature of the second embodiment is that a duct 60 for connecting the fan 38 and the intake / exhaust port 40 is provided. An opening 62 extending in the direction of arrow B is formed in the duct 60. The connecting portion 51 between the carriage 24 and the heat conducting member 52 penetrates through the opening 62, and the heat conducting member 52 reciprocates inside the duct 60.

By thus providing the duct 60 and reciprocally moving the heat conducting member 52 inside the duct 60, the air flow generated by the fan 38 can be made to flow through the plate portion 5 more than in the case of the first embodiment.
The print head 30 can be cooled more quickly by efficiently contacting the print head 2a. Further, since the flying ink droplets 26 are not affected by the turbulence of the air flow, the air volume can be set so as to maximize the cooling efficiency without considering the printing deviation. In addition,
The direction of the air flow by the fan 38 may be either in the direction of arrow C. Also, here, the fan 38 is set to 1
However, by providing a fan at the intake / exhaust port 40 and using two fans, the speed of the airflow impinging on the heat conducting member 52 can be increased, so that the temperature of the print head can be lowered more quickly.

[Third Embodiment] Referring to FIG. 5, a third embodiment of the ink jet type image forming apparatus of the present invention will be described.

FIG. 5 is a perspective view showing a third embodiment of the ink jet type image forming apparatus of the present invention. In FIG. 5, the same components as those of FIG. 4 are designated by the same reference numerals.

A feature of the third embodiment is that a linear scale 70 for detecting the position of the carriage 24 is installed in parallel with the guide rail 16, and a position sensor (not shown) is provided on the carriage 24, and a linear scale is provided. The point is that the position of the carriage 24 is detected by the scale 70 and the position sensor, and the velocity and direction of the air flow are changed based on the position and the moving direction of the carriage 24.

When the fan 38 is rotated to generate an air flow to cool the heat conducting member 52, the speed and direction of the air flow are changed based on the position and moving direction of the carriage 24.
An example of this will be described with reference to FIG.

FIG. 6 is a schematic diagram showing the relationship between the position and moving direction of the carriage and the velocity and direction of the air flow.

In FIG. 6, the arrows from D1 to D6 represent the speed and direction of the air flow generated by the fan 38, and the larger the number of arrows, the faster the speed of the air flow. The arrows from E1 to E6 indicate the air flow that is sucked and exhausted at the intake / exhaust port 40, and the larger the number of arrows, the faster the speed of the air flow. Further, arrows F and G indicate the moving direction of the carriage 24.

As described above, the position and the moving direction of the carriage 24 are detected by the linear scale 70 and the position sensor, and when the carriage 24 moves in the direction of the arrow F and approaches the fan 38, the arrows D1 to D3. Generate an air flow in the direction indicated by. On the other hand, the carriage 24 has an arrow G
When moving in the direction and moving away from the fan 38,
An airflow is generated in the directions indicated by arrows D4 to D6. At this time, the rotation speed of the fan 38 is maximized when the distance between the carriage 24 and the fan 38 is maximum, and the carriage 24 uses the speed of the airflow near the heat conduction member as a reference. 38, the rotation speed of the fan 38 is decreased according to the distance to the fan 38, and the rotation speed of the fan 38 is increased according to the distance from the fan 38. The airflow velocity generated by the fan 38 is continuously changed so that becomes the reference value. That is, even if the distance between the carriage 24 and the fan 38 changes, the velocity of the airflow flowing near the heat conducting member 52 is made constant.

In this way, the air flow is generated in the direction opposite to the moving direction of the carriage 24, and the carriage 24
If the velocity of the air flow generated by the fan 38 is continuously changed according to the distance between the fan 38 and the fan 38, the moving heat conducting member 5
Since the wind speed in the vicinity of 2 can be made almost constant, the print head 30
Can be cooled stably.

[Fourth Embodiment] Referring to FIG. 5 again, a fourth embodiment of the ink jet type image forming apparatus of the present invention will be described.

The feature of the fourth embodiment resides in that the direction of the air flow generated by the fan 38 is constant, and the relative velocity of the air flow near the heat conducting member is constant.

As described above, the linear scale 70 and the position sensor detect the position and moving direction of the carriage 24, and the carriage 24 moves in the direction of arrow F to move the fan 3
When approaching 8, the airflow is generated in the directions indicated by arrows D1 to D3.

In the third embodiment, when the carriage 24 moves in the direction of the arrow G and moves away from the fan 38, the airflow is generated in the directions indicated by the arrows D4 to D6, but in the fourth embodiment, the arrow D4. To D6 to generate an air flow in the opposite direction. That is, the fan 38
The direction of the air flow that is generated is constant. This is fan 3
While the carriage 24 is moving in a direction away from 8, the airflow velocity from the fan 38 becomes the weakest at the position farthest from the fan 38. Therefore, the airflow velocity at that time is used as a reference regardless of the position and the moving direction of the carriage 24. , Set the relative speed to the same value as the reference value. That is, when the carriage 24 is moving in the G direction, the rotation speed of the fan 38 is lower than that at the reference when the carriage 24 is close to the fan 38, and the rotation speed of the fan 24 is further reduced when the carriage 24 is moving in the F direction. By lowering it, the velocity of the air flow generated by the fan 38 is continuously changed so that the relative velocity of the air flow hitting the heat conducting member 52 becomes constant.

In this way, the carriage 24 is replaced by the fan 38.
The speed of the airflow generated by the fan 38 is continuously changed according to the distance between the carriage 24 and the fan 38 by adding the moving speed of the carriage to the speed of the airflow generated when moving away from the carriage 24 and the airflow. When the relative speed of the print head 30 is constant, the speed of the airflow in the vicinity of the moving heat conducting member 52 becomes substantially constant, so that the print head 30 can be cooled stably. Furthermore, since the direction of the air flow generated by the fan 38 is made constant, the control of the fan 38 can be simplified without requiring the forward and reverse rotation of the fan 38, as compared with the case of the third embodiment.
A commonly used DC type fan can be used.

[Fifth Embodiment] Referring to FIG. 7, a fifth embodiment of the ink jet type image forming apparatus of the present invention will be described.

FIG. 7 is a perspective view showing a fifth embodiment of the ink jet type image forming apparatus of the present invention. In FIG. 7, the same components as those of FIG. 5 are designated by the same reference numerals.

The feature of the fifth embodiment is that fans 38 and 80 are provided at both ends of the duct 60. Fans 38,8
When 0 is rotated to generate the airflow and cool the heat conducting member 52, the direction of the airflow is changed based on the moving direction of the carriage 24. An example of this will be described with reference to FIG.

FIG. 8 is a schematic diagram showing the relationship between the moving direction of the carriage 24 and the direction of the air flow.

In FIG. 8, the arrows D7 and D8 indicate the directions of the air flows generated by the fans 38 and 80. Further, arrows F and G indicate the moving direction of the carriage 24.

As described above, the position and the moving direction of the carriage 24 are detected by the linear scale 70 and the position sensor, the carriage 24 moves in the direction of the arrow G, and the fan 8 moves.
When approaching 0, an air flow is generated in the direction of arrow D7. On the other hand, when the carriage 24 moves in the direction of arrow F and approaches the fan 38, an airflow is generated in the direction of arrow D8.

In this way, the fan 3 is attached to both ends of the duct 60.
8 and 80 are provided, air is sucked and exhausted using the two fans 38 and 80, and an airflow is generated in a direction opposite to the moving direction of the carriage 24. The velocity of the air stream hitting 52 can be increased. As a result, the print head 3 is
The temperature of 0 drops rapidly, and a high cooling function can be obtained.

[Sixth Embodiment] Referring to FIG. 9, a sixth embodiment of the ink jet type image forming apparatus of the present invention will be described.

FIG. 9 is a perspective view showing a sixth embodiment of the ink jet type image forming apparatus of the present invention. In FIG.
The same components as those of FIG. 4 are designated by the same reference numerals.

The feature of the sixth embodiment is that a diode temperature sensor (which is an example of the print head temperature detecting means referred to in the present invention) 90 is disposed inside the print head 30, and the print head is detected by the diode temperature sensor 90. The point is that the speed or direction of the air flow generated by the fan 38 is changed based on the temperature.

When the fan 38 is rotated to generate an air flow to cool the heat conducting member 52, the print head temperature detected by the diode temperature sensor 90 is within a predetermined temperature range (for example, T1 = 50 ° C. to T2 = 80 ° C.). If the difference between the maximum value T2 and the print head temperature is larger, the speed of the generated air flow is increased. Further, when the print head temperature is within the above predetermined temperature range or lower than the minimum value T1, the fan 38 is stopped.

As described above, by rotating or stopping the fan 38 based on the temperature of the print head 30, it is possible to prevent the print head 30 from being over-cooled, and it is possible to perform fine temperature control. The head temperature can be maintained within an appropriate temperature range. Furthermore, when the print head temperature is close to the temperature suitable for printing, the rotation speed of the fan 38 can be decreased to reduce the speed of the airflow, and the fan 38 can be stopped. Since the direction of the air flow can be changed according to the moving direction of the carriage 24, the power consumption and noise of the fan 38 can be reduced.

[0051]

As described above, according to the ink jet type image forming apparatus of the present invention, the print head can be cooled by cooling the heat conducting member by generating the air flow by the air flow generating means, which is relatively simple. The structure can cool the print head and ink quickly. Therefore, it is not necessary to stop printing and cool the print head, so that an image can be formed at high speed.

Here, in the case where the ink jet type image forming apparatus has a duct in which the heat conducting member moves, and the air flow generating means generates an air flow inside the duct. Since the airflow generated by the airflow generation means is guided by the duct to cool the heat conducting member, the print head can be cooled more quickly.

When the heat conducting member has a plurality of plate-shaped portions extending in the predetermined direction, the heat conducting member is efficiently cooled, so that the cooling head can be cooled more quickly.

Further, the ink jet type image forming apparatus is provided with a carriage position detecting means for detecting the position of the carriage, and the air flow generating means is based on the position of the carriage detected by the carriage position detecting means. , If the velocity or direction of the generated airflow is changed, the velocity of the airflow can be continuously changed according to the distance between the carriage and the airflow generation means. Since the velocity of the air flow can be made almost constant, the print head can be cooled stably.

Furthermore, the ink jet type image forming apparatus is provided with a print head temperature detecting means for detecting the temperature of the print head, and the air flow generating means is the print head detected by the print head temperature detecting means. If the speed or direction of the generated airflow is to be changed based on the temperature of the print head, the air flow generating means can be activated or stopped depending on the temperature of the print head. It prevents overcooling, enables fine temperature control, and maintains the temperature of the print head during printing within an appropriate temperature range.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of an inkjet type image forming apparatus of the present invention.

FIG. 2 is a side view showing the carriage shown in FIG.

3 is a cross-sectional view showing the vicinity of a discharge nozzle of the print head of FIG.

FIG. 4 is a perspective view showing a second embodiment of an inkjet type image forming apparatus of the present invention.

FIG. 5 is a perspective view showing a third embodiment of an inkjet type image forming apparatus of the present invention.

FIG. 6 is a schematic diagram showing the relationship between the position and movement direction of the carriage and the velocity and direction of the air flow in the third embodiment.

FIG. 7 is a perspective view showing a fifth embodiment of an inkjet type image forming apparatus of the present invention.

FIG. 8 is a schematic diagram showing the relationship between the moving direction of the carriage and the direction of the air flow.

FIG. 9 is a perspective view showing a sixth embodiment of the inkjet image forming apparatus of the present invention.

[Explanation of symbols]

 10 Inkjet image forming apparatus 12 Recording paper 24 Carriage 30 Print head 32,52 Heat conduction member 38,80 Fan 60 Duct 90 Diode temperature sensor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobumori Shimizu 6-3-3, Shimorenjaku, Mitaka City, Tokyo Inside the Copier Corporation (72) Inventor Kenji Nagata 6-3-3, Shimorenjaku, Mitaka City, Tokyo (72) Inventor Hirokazu Ikegami 6-3-3 Shimorenjaku, Mitaka City, Tokyo

Claims (5)

[Claims] 1. A print head that ejects ink, and a carriage that mounts the print head and reciprocates in a predetermined direction, and ejects ink from the print head while reciprocating the carriage in the predetermined direction. In an inkjet type image forming apparatus for forming an image on a recording medium, a heat conduction member fixed to the carriage so as to abut the print head and moving together with the carriage, the heat conduction member for conducting heat of the print head, An ink jet image forming apparatus comprising: an air flow generating unit that generates an air flow in the predetermined direction within a moving region of a heat conducting member. 2. The ink jet image forming according to claim 1, wherein the heat conducting member includes a duct that moves inside, and the air flow generating means generates an air flow inside the duct. apparatus. 3. The inkjet image forming apparatus according to claim 1, wherein the heat conducting member has a plurality of plate-shaped portions extending in the predetermined direction. 4. A carriage position detecting means for detecting the position of the carriage, wherein the air flow generating means changes the speed or direction of the air flow generated based on the position of the carriage detected by the carriage position detecting means. The inkjet image forming apparatus according to claim 1, wherein the image forming apparatus is an inkjet image forming apparatus. 5. A print head temperature detecting means for detecting the temperature of the print head, wherein the air flow generating means generates a speed of an air flow based on the temperature of the print head detected by the print head temperature detecting means. 4. The inkjet image forming apparatus according to claim 1, wherein the direction is changed.