JP2850614B2 - Ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet recording apparatus, and more particularly to an ink-jet recording apparatus in which ink held in an ink holder is heated and ejected onto recording paper to perform recording.

[0002]

2. Description of the Related Art Printers used as output devices of information equipment such as personal computers (personal computers) and word processors (word processors) are required to operate at high speed and have high print quality. Laser printers are becoming increasingly popular. However, laser printers contain many optical components,
Since the number of components is large, it is expensive, and thus it has not been used in ordinary households. In ordinary households, thermal transfer printers are generally used. The thermal transfer printer has the disadvantage that the printing cost is slow and the consumption of the ink ribbon is large, so that the running cost is high. For this reason, an ink jet printer has been attracting attention as being located between a laser printer and a thermal transfer printer, and as one of them, a bubble jet type ink jet printer has been rapidly entering the market.

[0003] Ink jet printers supply ink to fine nozzles arranged corresponding to vertical dot rows for forming characters, pressurize the ink held in the nozzles, and apply ink droplets to recording paper. The recording is performed by ejecting the ink.

The means for pressurizing the ink in the nozzle is roughly classified into a piezoelectric method and a bubble method. Among these, the former piezoelectric type is provided with a piezoelectric material in a part of the ink flow path as a means for pressurizing the ink, and is deformed by applying a voltage to the piezoelectric material. Generally, the volume of the passage is rapidly changed, and the ink is ejected by the change of the volume of the ink flow path. In the latter type, a heating source is provided in a part of the ink flow path, and the ink is heated by operating the heating source to generate bubbles (bubbles) in the ink. Ink is ejected.

[0005] In any of these methods, the ink is finally ejected by pressurizing the ink. However, since the bubble method has a simpler structure, the ink jet printer of the bubble method has recently become the mainstream. As a very small inkjet printer that can be used in notebook computers and the like, it is being marketed at a price range that can be purchased at ordinary homes.

[0006] As described above, an ink jet printer (ink jet recording apparatus) as a non-impact recording apparatus presses ink in an ink flow path by a piezoelectric method or a bubble method to eject ink from nozzles.
Ink droplets are made to adhere to recording paper to form dots, and a character is formed as an aggregate of dots. In a method in which ink is ejected from such a nozzle, the nozzle is liable to dry and clog, and thus lacks stability as a recording apparatus. As a method for solving this drawback, a vapor jet printing (VJT) method combining a perforated film and a thermal head has been proposed (see Japanese Patent Publication No. 60-71260).

[0007] The basic structure of a VJT type ink jet recording apparatus is as follows. Ink is poured into a perforated film provided with a large number of fine holes, and the perforated film is moved onto a thermal head. Is operated to rapidly heat the ink on the heating element, and the bubbles generated at this time cause the ink to be ejected from the fine holes of the perforated film.

FIG. 5 is a perspective view showing an example of the above-described conventional ink jet recording apparatus, FIG. 6 is a front view showing details of the perforated film of the example of FIG. 5, and FIG. 7 is a view of the example of FIG. Sectional view showing the state of ejection of ink from the perforated film,
FIG. 8 is a front view showing the state of forming the printing dots in the example of FIG.

In FIG. 5, a recording sheet 59 is mounted on a platen 58 and conveyed upward. This recording paper 59
The perforated film 51 arranged in front of and near the
It is formed in an endless tape shape by a polyimide resin, and runs leftward (in the direction of arrow FA). In the perforated film 51, a large number of fine small holes smaller than one of the dots constituting the print character are provided in a mesh shape.

That is, as shown in FIG. 6, a plurality of small holes 61 are provided in a perforated film 51, each of the small holes 61 has a diameter of several tens μm, and a space between adjacent small holes 61 (pitch). ) Is several tens of μm.

The perforated film 51 thus constructed
Is driven by a motor and a gear (both not shown), guided by guide rollers 53a to 53c, and
Travel in the direction. An ink tank 56 and an ink supply roller 52 are provided in the middle of the traveling path of the perforated film 51, and ink is supplied from these to small holes 61 provided in the perforated film 51 to be filled. A thermal head 55 is provided at a position facing the recording paper 59 in the middle of the traveling path of the perforated film 51. The perforated film 51 and its traveling system, the ink tank 56, the ink supply roller 52, and the thermal head 55 are mounted on a carriage 57, and the carriage 57 is moved in a direction opposite to the traveling direction FA of the perforated film 51 (arrow). (CA direction).

The ink jet type recording apparatus thus constructed operates the designated heating element of the thermal head 55 with respect to the perforated film 51 which is supplied with ink from the ink supply roller 52 and runs. When the small hole 61 corresponding to the heating element is heated by the heating, the ink filled in the small hole 61 is rapidly heated to generate a bubble, and the ink in the small hole 61 is ejected as an ink droplet by the bubble. Is done.

FIG. 7 is a cross-sectional view showing the state of ink ejection from the perforated film in the example of FIG. 5, and operates in the order of (a) to (c).

As shown in FIG. 7A, the ink 62 filled in the small holes 61 of the perforated film 51 which is in contact with the heat generating portion 63 of the thermal head 55 is heated by the heat generating portion 63. And bubble 6 as shown in FIG.
4 is generated. As this bubble 64 further develops, FIG.
The ink droplet 65 is ejected as shown in FIG. The ink droplets 65 fly toward the recording paper 59 (see FIG. 5) and adhere to the recording paper 59 to form dots to perform recording.

As shown in FIG. 8, the dot formation state on the recording paper 59 changes depending on the relative positions of the small holes 61 of the perforated film 51 and the heat generating portion 63 of the thermal head 55, as shown in FIG. When the positional relationship is as shown in a-1), as shown in FIG.
5, one print dot 66a is formed, and FIG.
In the case of the positional relationship as shown in (b-1), FIG.
As shown in 2), one print dot 66b is formed by the seven ink droplets 65.

In the VJT type ink jet recording apparatus using such an endless tape-shaped perforated film, it is necessary to run the perforated film and move the perforated film, the thermal head, and the ink supply mechanism. In particular, since a large space is required for the perforated film to run stably, there is a problem that the recording head becomes large and the whole running system of the perforated film becomes complicated.

In order to solve this problem, a disk-shaped perforated film (disc) is used (Japanese Patent Publication No. 61-2).
22754). In this type, a large number of fine net-like holes similar to an endless tape-shaped perforated film are provided around the outer periphery of a disk-shaped film and placed between the recording paper and the thermal head. Then, it is rotated about the center of the film as the center of rotation.

In the printing operation in this case, as in the case of the perforated film in the form of an endless tape, the ink filled in the small holes of the disk in contact with the heat generating portion of the thermal head is heated to generate bubbles, As a result, ink droplets are ejected, fly toward the recording paper, and adhere to the stamp surface of the recording paper to form dots, thereby performing recording. Therefore, the disc having the small holes plays the role of the endless tape-shaped perforated film, and the whole film system can be reduced in size.

[0019]

The conventional VJT type ink jet recording apparatus as described above uses an endless tape-shaped perforated film, a disc-shaped perforated film (disk), and the like. In each case, the heat generating portion is urged regardless of the positions of the small holes of the perforated film and the heat generating portion of the thermal head. Therefore, in order to ensure that the ink is always ejected and recorded, and that the result has no variation in print density, the size of the small hole provided in the perforated film should be larger than the size of one dot on the recording paper. It is necessary to make the size considerably small and further increase the installation density of the small holes so that one dot corresponds to a plurality of small holes.

For this purpose, the size of the small holes provided in the perforated film must be considerably small, and the interval (pitch) between adjacent small holes must be reduced. Since an appropriate amount of ink needs to be held, an appropriate thickness is required. Reducing the diameter of the small holes relative to the thickness of the perforated film has a processing limit, and reducing the pitch causes a problem in the strength of the perforated film. Therefore, for example, when a film having a thickness of 50 μm is used, the diameter of the small holes is limited to 25 μm and the pitch is limited to about 45 μm.

Therefore, 300 DPI (300 per inch)
In order to achieve the print quality of (dots), the size of one dot must be about 80 μm on one side. The limit is to correspond ~ 7 small holes,
There is a drawback that the print density varies greatly depending on the timing at which the heat generating portion of the thermal head is energized.

Further, in the case of constructing a line type printer (line printer), a perforated film feed mechanism becomes complicated and large-scale, so that it is extremely difficult to construct a line printer by an ink jet system. is there.

[0023]

According to the present invention, there is provided an ink jet recording apparatus comprising two rows of a plurality of small holes having substantially the same size as one dot forming a print character. A thin plate-shaped ink holding member having a row of small holes and provided in parallel with and near the recording paper;
Two ink holder support portions for holding the upper and lower ends, respectively , and the specified small holes of the small hole array provided between the two ink holder support portions and in contact with the ink holder. a thermal head having a heating portion for heating the, Louis ink supply part to supply ink to the pores of disposed adjacent to said thermal head wherein the ink holding member, the longitudinal direction the ink holding member a reciprocating mechanism for reciprocating the,
A fixed body disposed opposite to the recording sheet and fixed to a printer structure on which the ink holder, the ink supply unit, the thermal head, and the reciprocating mechanism are mounted. The heating section is energized in synchronization with the movement of the ink holding member, and the recording paper is synchronized with the reciprocating movement of the ink holding member.
It is designed to be moved dot by row.

[0024]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing a first embodiment of the present invention, FIG. 2 is a front view showing details of an ink holder, an ink supply section, and a thermal head of the embodiment of FIG. 1, and FIG. FIG. 7 is a cross-sectional view illustrating an operation of the ink holding member according to the first embodiment.

In FIG. 1, a thin plate (flat plate)
The ink holder 1 has a large number of small holes, the upper and lower ends of which are held by the ink holder support 2, and are disposed in parallel with and near the recording paper 9 mounted on the platen 8. The reciprocating mechanism 4 driven by the motor 3 performs a reciprocating motion in a vertical direction (arrow F direction). Behind the ink holder 1, a line type thermal head 5 is provided. Above and below the thermal head 5, ink supply units 6a and 6b are provided close to the ink holder 1. The ink holder 1, the thermal head 5, and the ink supply units 6a and 6b are mounted on a fixed body 7 together with the motor 3 and the reciprocating mechanism 4, and the fixed body 7 is fixed to a printer structure (not shown). I have. The recording paper 9 is conveyed by the platen 8 in the upward direction (the direction of arrow G).

As shown in FIG. 2, the ink holder 1 has two rows of small holes 12a and 12b in which a plurality of small holes are arranged in a row in the horizontal direction.
Both correspond to one dot line of a character string to be recorded on the recording paper 9, and are provided at vertically symmetric positions (distance A) with respect to the heat generating portion 13 provided at the center of the thermal head 5. Further, ink supply units 6a and 6b are provided at the positions of the small hole arrays 12a and 12b, respectively. The size of each of the small holes in the small hole arrays 12a and 12b is the same as one dot forming a print character. The upper and lower ends of the ink holding body 1 thus configured are held by the ink holding body supporting portion 2, and the small holes 12 a and 12 b are alternately positioned at the heat generating portion 13 of the thermal head 5 in the vertical direction (arrows). (F direction).

The operation of the ink holder 1 is shown in FIGS.
The operation is performed in the order shown in FIG.

That is, when the ink holder 1 is stationary,
The small hole rows 12a and 12b are vertically symmetric with respect to the center of the thermal head 5, as shown in FIG.
At that position, each small hole is filled with ink from the ink supply units 6a and 6b. Next, the state shown in (b) is reached, and the lower row of small holes 12b filled with ink comes to the position of the heat generating portion 13 at the center of the thermal head 5. When the heating unit 13 is urged in this state, as shown in FIG.
Ink droplets 14a are ejected from the heated small holes of the small hole array 12b. Next, when the ink holder 1 is moved downward to bring the small hole rows 12a and 12b into a vertically symmetric position with respect to the center of the thermal head 5 (the same state as the state shown in (a)), (d) As shown, the small hole array 12b comes to the position of the lower ink supply unit 6b, and
The small holes that have been emptied by discharging the ink droplets 14a of 2b are filled with ink again. Next, the ink holding body 1 is further moved downward, and as shown in FIG.
At the position of the heat generating portion 13 at the center of the thermal head 5. When the heat generating portion 13 of the thermal head 5 is urged again in this state, the ink droplets 14b are ejected from the heated small holes of the small hole array 12a as shown in FIG. After this,
The ink holder 1 is moved upward to the state shown in FIG.
Is discharged, and the small holes that have become empty are filled with ink again. By repeating this operation and moving the recording paper 9 upward by one dot line of the print row for a half cycle of the operation of the ink holding member 1, a desired character can be recorded.

As described above, the reciprocating movement of the ink holder 1 and the biasing of the thermal head 5 are synchronized, and a small hole having the same size as one dot of the print character corresponds to one dot line of the print character. Since characters can be recorded by discharging ink droplets to the part,
Unlike the prior art, it is not necessary to finely process the small holes at a high density, and a sufficient print density can be ensured.

As means for synchronizing the reciprocating movement of the ink holder 1 with the biasing of the thermal head 5, for example, a detection medium such as a magnetic marker is provided on the ink holder 1,
This is detected by using a magnetic mark sensor or the like, and when the row of small holes 12a or 12b of the ink holder 1 comes to the position of the heat generating portion 13 of the thermal head 5, the heat generating portion 13 is urged. , Can be perfectly synchronized.

FIG. 4 is a front view showing an ink holder according to a second embodiment of the present invention.

The ink holding member 21 of this embodiment has almost the same configuration as the ink holding member of FIG. 2, except that the relative positions of the small hole rows 24a and 24b are changed. That is, 2
The row of small holes 24a and 24b is
5 is provided at a vertically symmetrical position with respect to the horizontal center line of each heat generating portion 23 provided at the center of the ink holder 5 in FIG. The small hole row 24b on the side is shifted to the left by half (1 / 2P) of the interval (pitch) P between adjacent small holes with respect to the small hole row 24a on the upper side, and the recording paper 9 holds ink. A desired character is recorded by moving up by one dot line of the print row with respect to one cycle of the operation of the body 21.

With this configuration, the row of small holes 2
The interval (pitch) P between adjacent small holes of 4a and 24b
Can be reduced to two dots of the print character, so that the dot pitch of the print character can be reduced.
For example, by setting the pitch P between the small holes to 127 μm, a high-quality character of 400 DPI can be recorded.

The present invention is not limited to the embodiment described above. That is, in the above-described embodiment, the ink supply units are arranged at the upper and lower stationary points of the ink holder, but this is not necessarily necessary, and the ink supply units are provided at intermediate points of the reciprocation of the ink holder. be able to. By making the ink supply unit as close to the thermal head as possible or integrated with the thermal head, it is possible to reduce the amplitude of the reciprocating movement of the ink holder,
As a driving source of the ink holding member, not only a motor but also a piezoelectric actuator, an electromagnetic solenoid or the like can be used, so that the recording head can be further reduced in size. Further, the position of the small hole array on the ink holding member does not need to be vertically symmetrical with respect to the heat generating portion of the thermal head, and a magnetic marker and a magnetic mark sensor are provided to detect the small hole line position. By doing so, any position can be set within the amplitude of the reciprocating motion of the ink holding member.
Therefore, the number of the small hole rows is set to three or more, and the speed of the reciprocating motion of the ink holding body can be reduced, so that the degree of freedom in selecting an actuator as a driving source of the ink holding body can be widened.

FIG. 9 is a perspective view showing an ink holder and a thermal head according to a third embodiment of the present invention.

In the embodiment shown in FIG. 9, the row of small holes 34 is arranged obliquely with respect to the ink holder 31, and the row of small holes 34
9, the ink holder 31 is mounted obliquely so as to be perpendicular to the transport direction G, and the thermal head 35 is attached to the small hole array 34.
It is arranged at the position. By reciprocating the ink holding body 31 configured as described above in the direction of arrow FB (in a direction oblique to the transport direction G of the recording paper 39), the small hole array 34 is connected to the thermal head 35 and the ink supply unit ( (Not shown), the same operation and effect as the embodiment of FIG. 1 can be obtained.

FIG. 10 is a perspective view showing an ink holder and a thermal head according to a fourth embodiment of the present invention.

In the embodiment shown in FIG. 10, the row of small holes 44 is arranged obliquely with respect to the ink holder 41, and the ink holder 41 is arranged so as to be perpendicular to the transport direction G of the recording paper 49. Te are those of the ink holding member 41 so as to reciprocate in the arrow FC direction (the direction perpendicular to the transfer direction G of the recording sheet 4 9), Therefore, the small hole arrays 44, the conveyance of the recording sheet 49 It is oblique to the direction G. The thermal head 45, are disposed at the same position as the small hole arrays 4 4.
With this configuration, the small hole array 44 can be reciprocated between the thermal head 45 and the ink supply unit (not shown) as in the embodiment of FIG. since the small hole row 44 so that corresponds to the dot line of a plurality of rows, the data at the time of energizing the thermal head 45, the processed data so as to correspond thereto. With this configuration, the same operation and effect as in the embodiment of FIG. 1 can be obtained.

[0040]

As described above, according to the ink jet recording apparatus of the present invention, a thin plate-shaped (plate-shaped) ink holder is provided with a plurality of dots each having substantially the same size as one dot forming a printed character. A plurality of small hole rows in which small holes are arranged in a row in the horizontal direction are provided, and the small hole rows are reciprocated in front of the heat generating portion of the thermal head, and an ink supply portion is provided in proximity to the thermal head, and a thermal head is provided. The heat generating section is urged in synchronization with the movement of the ink holder, and the carriage on which the ink holder is mounted is synchronized with the reciprocating movement of the ink holder so that the recording paper is released.
By moving each dot by an amount, there is an effect that a line printer can be configured by an inkjet method. In addition, since it is not necessary to form minute holes in the ink carrier in close contact with each other, it is easy to manufacture, and it is possible to secure a sufficient print density and to reduce variations in print density.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a relationship among an ink holder, an ink supply unit, and a thermal head according to the embodiment of FIG.

FIG. 3 is a sectional view showing the operation of the ink holding member in the embodiment of FIG.

FIG. 4 is a front view showing a recording head according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing an example of a conventional ink jet recording apparatus.

FIG. 6 is a front view showing details of a perforated film in the example of FIG. 5;

FIG. 7 is a cross-sectional view showing a state of ink ejection from a perforated film in the example of FIG.

FIG. 8 is a front view showing a state of forming a printing dot in the example of FIG. 5;

FIG. 9 is a perspective view showing an ink holder and a thermal head according to a third embodiment of the present invention.

FIG. 10 is a perspective view showing an ink holder and a thermal head according to a fourth embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 ink holder 2 ink holder support 3 motor 4 reciprocating mechanism 5 thermal head 6a / 6b ink supply 7 fixing unit 8 platen 9 recording paper 12a / 12b small hole array 13 heat generator 14a / 14b ink drop 21 ink holding Body 22 Ink holder support part 23 Heat generating part 24a / 24b Small hole array 25 Thermal head 31 Ink holder 34 Small hole array 35 Thermal head 39 Recording paper 41 Ink holder 44 Small hole array 45 Thermal head 49 Recording paper 51 Perforated Film 52 Ink supply roller 53a-53c Guide roller 55 Thermal head 56 Ink tank 57 Carriage 58 Platen 59 Recording paper 61 Small hole 62 Ink 64 Bubble 65 Ink droplet 66a / 66b Print dot

Claims (2)

(57) [Claims] 1. A printing apparatus comprising two rows of small holes in which a plurality of small holes having substantially the same size as one dot forming a printing character are arranged in a row in a horizontal direction, and is provided in parallel with a recording paper. A thin plate-shaped ink holding member provided in
Two ink holder support portions for holding the upper and lower ends, respectively , and the specified small holes of the small hole array provided between the two ink holder support portions and in contact with the ink holder. a thermal head having a heating portion for heating the, Louis ink supply part to supply ink to the pores of disposed adjacent to said thermal head wherein the ink holding member, the longitudinal direction the ink holding member a reciprocating mechanism for reciprocating the,
An ink jet printer comprising: a stationary body that is disposed to face the recording sheet and is fixed to a printer structure on which the ink holder, the ink supply unit, the thermal head, and the reciprocating mechanism are mounted. Expression recording device. 2. A printing apparatus comprising two rows of small holes in which a plurality of small holes having substantially the same size as one dot forming a print character are arranged in a row in a horizontal direction, and is arranged in parallel with a recording paper. A thin plate-shaped ink holding member provided in
Two ink holder support portions for holding the upper and lower ends, respectively , and the specified small holes of the small hole array provided between the two ink holder support portions and in contact with the ink holder. a thermal head having a heating portion for heating the, Louis ink supply part to supply ink to the pores of disposed adjacent to said thermal head wherein the ink holding member, the longitudinal direction the ink holding member a reciprocating mechanism for reciprocating the,
A fixed body disposed opposite to the recording sheet and fixed to a printer structure on which the ink holder, the ink supply unit, the thermal head, and the reciprocating mechanism are mounted. The heating section is energized in synchronization with the movement of the ink holding member, and the recording paper is synchronized with the reciprocating movement of the ink holding member.
An ink jet recording apparatus characterized in that it is moved dot by row.