JP2721882B2 - Print head for inkjet printing equipment - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a printhead for an ink jet printing apparatus, and in particular, to a character or numeric character or other symbol on a surface which ejects a small drop of ink and passes through the printhead. The invention relates to a printhead of the type having a plurality of jet orifices arranged to form a matrix for printing such as. For this type of printhead, see U.S. Pat.
No. 5,350, No. 4,378,564, No. 4,542,386, No. 4,4
Nos. 50,375, 4,555,719 and 4,576,111. For cross-reference, there is U.S. Pat. No. 4,792,817, filed Apr. 14, 1986, assigned to the same applicant as this application, and the invention of this application is an improvement on the above-mentioned U.S. application. is there. SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved printhead of the type described above, which is relatively simple, compact and integrally formed with ink jet orifices relatively closely spaced for printing relatively small characters. To provide a print head having an ink jet orifice structure which is improved, and to provide a print head capable of performing an ink jet print which forms a character which is reliable and accurate and is operated. It is an object to provide a printhead that has relatively few moving parts, can be manufactured at a relatively low cost, and can be easily disassembled when cleaning is required. It is a further object of the present invention to provide a printhead that can be adjusted to compensate for variations in tolerances or to provide accurate control of ink droplets. SUMMARY OF THE INVENTION A printhead of the present invention includes a body having a recess on a back surface. A plurality of bosses extend from the bottom of the recess, and an orifice extends through each boss. A flexible membrane is provided over the recess to form a chamber for the ink supplied from the pressurized ink source. The membrane is adapted to engage the rear end of the boss to close the rear end of the orifice. The boss and orifice are arranged in a matrix with a small spacing. Means are provided at the rear end of each boss to press and hold the membrane and to selectively release the membrane so that it can be released from the boss so that drops of ink can be sent from the chamber to the orifice. ing. The means includes an elongate member for each boss, the member having an inner end aligned with each corresponding boss, and thus arranged to form a proximity array corresponding to the matrix described above. ing. Means provided at the outer end of each of the elongated members operate through the members to release the membrane. These release means are larger than the distance between the bosses,
Cannot align with boss. Accordingly, the release means are arranged in an outwardly diverging diffusion array, with the elongate member extending from a proximal array at its inner end to release means located on the diffusion array. In a first embodiment of the invention, said elongated member is an air tube and said release means is a valve. Each valve is supplied with pressurized air. When the valves are not energized, air is supplied to the tubes and the pressure holds the membrane against the respective boss. When the valve is activated, the supply of air to the air tube is temporarily stopped, and the membrane is temporarily released, allowing ink drops to pass from the chamber to the orifice. In a second embodiment, the elongate member is a flexible wire having a head for pressing against the membrane, and the release means is a solenoid. When energized, the solenoids temporarily pull the wire and respective heads away from the membrane, releasing the membrane and allowing ink drops to pass from the chamber to the orifice. Other objects and features of the present invention will be more or less apparent, but will now be described. [Description of Embodiments] Hereinafter, description will be made with reference to the drawings, in which the same reference numerals indicate the same parts. A first embodiment of a printhead for an ink jet printing apparatus constructed in accordance with the principles of the present invention is shown generally at 20 in FIGS. Generally speaking, the print head 20 has a front surface 24 and a rear surface.
26. As best seen in FIG. 6, a recess 28 is formed in the back surface 26 of the body 22. A flexible membrane 30 covers the recess 28 to form a chamber 32 for ink supplied to the chamber 32 from a pressure source 34. As can be seen in FIG. 6, a plurality of posts or bosses 36 extend through the chamber 32 from the bottom of the recess 28.
Penetrate each boss 36, from the rear end of the boss to the front of the main body 22
An orifice 38 extends to 24. As best seen in FIG. 2, the membrane 30 is adapted to contact the rear end of the boss 36 to close the rear end of the orifice 38. The orifices 38 are spaced closely together and selectively eject droplets of ink from the chamber 32 through the orifice 38 onto a target surface proximate to and spaced apart from the front surface 24. Thus, for example, they are arranged so as to form a matrix for non-contact printing of a pattern of data forming a character such as an alphabet. The printhead 20 further includes a membrane to prevent ink from flowing from the chamber 32 through the orifice 38.
Pressing 30 against the rear end of the boss 36, and also selectively releasing the membrane 30 away from the rear end of the selected boss 36,
Means are also provided for allowing ink droplets to be delivered from the chamber 32 through each orifice 38. Generally speaking, this means is provided one for each boss, extends rearward from the membrane 30 and has a front end at each boss 36.
A plurality of relatively elongate members 40 adapted to be substantially aligned. The elongate members 40 are thus arranged in close proximity to one another, each inner end of which forms a closely spaced array corresponding to a matrix of orifices 38. Release means 42 provided at the outer end of each member 40 act via each corresponding member 40 to release the membrane 30 from the respective boss 36 so that drops of ink from the chamber 32 pass through the respective orifices 38. To be released. Since this release means 42 is larger than the mutual spacing of the boss 36 and the orifice 38, it is too large to arrange all the release means 42 in direct alignment with the boss 36. Therefore, the release means 42 is the boss
The elongated members 40 are arranged in an array (extended spacing arrangement) that extends outward with respect to 36, and the elongate members 40 are located relatively close in their inner ends. The array extends from the array to release means 42 forming an outwardly extending array. More specifically, the print head 20 includes a frame 44 and a cover 46. In FIG. 1, a part of the cover 46 is shown removed. The frame 44 has a U-shaped bracket 48 for mounting the main body 22. Preferably, body 22 is formed of Delrin, acetyl homopolymer, or other suitable material. The orifice 38 can be formed using a laser or by drilling. As best seen in FIG. 6, recess 28 in body 22 has a relatively deep portion 50 adjacent each boss. An insert 52 is arranged in the recess 28 of the main body 22.
The insert 52 has a hole 54 for receiving each boss 36 and forming a space 56 adjacent to each boss 36. Also insert
52 has at least one, and preferably two, inlet holes 58 and 60 communicating with a supply of ink. The insert 52 and the recess 28 form a passage 62 between the inlet holes 58 and 60 and the space 56 around each boss 36. In the preferred embodiment, this passage 62 is formed by the deep portion 50 of the recess 28, but instead, a groove is provided in the insert 52 that extends between the inlet holes 58, 60 and each hole 54. It may be provided. The flexible film 30 has a thickness of about 0.3810 to 0.762 mm (about 0.015 to
(0.03 inch) of ethylene propylene copolymer or other suitable sheet of flexible material by stamping or stamping. As shown in FIG. 5, membrane 30 has holes 64 aligned with inlet holes 58 and 60, respectively.
66. A rear plate 68 having a front surface 70 and a rear surface 72 is engaged with the body 22, with the membrane 30 disposed therebetween. Rear plate 68 and body 22
Are fixed by screws 74. The front 70 of this rear plate 68
Has a central recessed area 76 for receiving the membrane 30. A hole 78 aligned with each boss 36 is provided in the back plate 68. Each hole 78
Is surrounded by a raised rim 80, the front of which engages the membrane 30 and inserts the membrane 30
The chamber is pressed against the main body 22 to form a chamber 82 aligned with each boss 36 after the membrane 30. From the rear surface 72 of the rear plate 68, a sleeve 84 extends in alignment with each hole 78. Through the rear plate 68, holes 64 and 66 in the membrane 30 and holes 58 in the insert 52
Aligned with 60, holes 86 and 88 extend. Rear of rear plate 68
Sleeves 90 and 92 extend from 72 holes 86 and 88. In this first embodiment, the elongate member 40 is an air tube.
Consists of 94. The inner end of the air tube 94 is covered by a sleeve 84. The outer end of the air tube 94 is connected to the release means 42. In the first embodiment, the release means
42 comprises an electrically operated pneumatic valve 96. Each valve 96 is provided with an electrical lead 98 such that between a deactivated position where the first port 100 is coupled to the common port 102 and an energized position where the second port 104 is coupled to the common port 102. Works with A tube 106 extends from each common port 102 to block
It is connected to the sleeve 108 passing through the sleeve 110. The first port 100 of each valve 96 is connected to a source of pressurized air, so that when the valve 96 is in its deactivated position, pressurized air is passed through the valve 96 through the air line 94. And then membrane 30
Is supplied to the chamber 82 after the. A tube 114 is overlaid on a sleeve 116 extending from each of the first ports 100 from the rear surface of the block 110. Each sleeve 116 has a block 11
It is in contact with the chamber 118 provided at 0. Chiyamba 11
8 is supplied with pressurized air by two hoses 120 and 122 connected to both sides of the block 110 and communicating with the chamber 118. The other ends of the hoses 120 and 122 are connected to an air hose 126 via a T-shaped connector 124. Air hose 126 is connected to connector 1
It extends to 28. Hose 130 extended to pressurized air source
Are connected over the connector 128. The second port 104 of the valve 96 is open to the atmosphere, and thus, when the valve 96 is in the biased position, the air line 94 and thus the membrane 30 is open.
Afterwards the chamber 82 communicates with the atmosphere. Lead 98 of valve 96 extends to plug 132 and plug 1
A pin (not shown) provided on the board 134 is inserted into the 32. These pins are connected to cable 140 by wires (not shown). Cable 140 is
It extends to a controller that generates the appropriate signals to produce the desired character. The ink supply 34 includes a hose 142 connected over the sleeve 90. Hose 142 has restriction valve 14
4 and a filter 146 are provided. The hose 142 is connected to a coupling 148 provided after the frame 44. A hose 150 is connected to the sleeve 92 so as to cover it, and extends rearward. The hose 150 is connected to a coupling 152 provided after the frame 44. A source of pressurized ink can be connected to couplings 148 and 152. Ink is supplied from an ink source and passes through a coupling 148, a hose 142, a filter 146, a restriction valve 144, and an inlet hole 86. From there, the ink passes through a passage 62 to a space 56 adjacent each boss 36. Air is supplied from an air source through hoses 130, 126 to a T-connector 126, from where it is routed through hoses 120 and 122 to a chamber 118 in block 110. Air sleeve
It is passed through 116 to hose 114 and to port 100 of valve 96. When valve 96 is deactivated, air travels through valve 96 to common port 102 and through tube 106, sleeve 108 to tube 9
Proceed to 4. From there, air is directed to the chamber 82, where air pressure acts on the back of the membrane 30 to press the membrane 30 against the rear end of the boss 36 and close the orifice 38. The air pressure is in the range of about 0.38665-0.5624 Kg / cm ² (about 5.5-8 psi). The ink pressure is in the range of about ^{2 to} 6 psi. During the initial setup,
Pressure to a predetermined value, for example, ink pressure of about 0.2109 kg / cm ³ (3p
si), set the air pressure to about 0.4921Kg / cm ² (7psi). Next, the apparatus is operated and adjusted so as to obtain the required print quality. The ink pressure is adjusted to obtain the required dot size, and the air pressure is adjusted to obtain a clear print. If the air pressure is too low, extra dots are formed, and if the air pressure is too high, dots in some of the characters may not be formed.
The air pressure must be adjusted for each ink pressure within the above two limits. To form the character, the controller sends appropriate signals through cables 140 to pins on board 134. These signals are routed through plug 132 to the appropriate valve 96 lead to temporarily energize that valve. When valve 96 is energized, air flows into port 100 and common port 102
And the port 104 is connected to the common port 102. To this end, the pressure in the chamber 82 is vented from the port 104 and the membrane 30 can return to the rear, so that the ink in the space 56 around each boss 36 can be ejected from the orifice 38. . 8 to 10 show a second embodiment of the print head for ink jet printing according to the present invention.
Printhead 200 is similar to printhead 20, and similar parts are indicated using the same reference numerals. However, the elongated member 40 and release means 42 of the printhead 200 are different from the air tube 94 and valve 96 of the printhead 20. In this second preferred embodiment, each member 40 is
Head part (head-shaped part) 2 slidably arranged in the hole 204 inside
02. The dimensions and position of the head 202
On the back of the membrane 30 and press it against the boss 36 to close the orifice 38. Wire 206
Extend rearward from each head 202. The head 202 is larger than the wire. Each of the wires 206 is slidably mounted within the sleeve 208. Sleeve 208
The front end is locked to a support block 210, and the rear end is locked to a block 212. Release means 42 includes a solenoid 214 connected to the controller by a lead 216. Each of the wires 206 is connected to one plunger (not shown) of the solenoid. A threaded projection 216 extends from the rear of each solenoid and is fixed to a vertical plate 218 by, for example, a nut 220. A coil spring 222 is inserted between each of the plates 218 and the associated rear of the solenoid 214. Tightening the nut 220 allows the solenoid to be pulled back against the force of the spring 222, while the nut 220
Is released, the solenoid is pushed forward by the spring 222. By adjusting the position of each head (head) 202, it is possible to apply a pressing force to the film as a preload and to compensate for variations in tolerance. When the solenoid is adjusted backward, the corresponding head also moves backward. Similarly,
As the solenoid is adjusted forward, the corresponding head is also adjusted forward. Each solenoid includes a spring that biases the plunger and wire forward with respect to the solenoid.
Due to the preload described above, the top gives pressure to the membrane,
When the pressure is relieved, the film is deflected away from the boss, and the pressurized ink mechanically helps the film to move away from the boss. The amount of preload at each head can be adjusted independently of each other, and by the ability to electrically control the energizing time of the solenoid, the amount of liquid to be ejected and hence the droplets The size can be controlled. To form the character, the controller supplies appropriate signals to appropriate solenoids 214 via leads 215.
The solenoid 214 is momentarily energized by a signal and the plunger pulls the wire 206 and the leading end 202 backward to disengage the membrane 30 so that the membrane 30 turns back and
Ink can be ejected from a space 56 around the boss 36 through a selected orifice. From the above description, it will be understood that the objects of the present invention have been achieved and other advantageous effects can be obtained. Also, without departing from the scope of the invention, various modifications can be made to the above-described structure,
All matters described in the above description and in the accompanying drawings are mere examples, and the present invention is not limited thereto.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing a first embodiment of a print head for an ink jet printing apparatus made in accordance with the principle of the present invention, with a part of a cover removed, and FIG. 1 Orifice of print head, body,
FIG. 3 is an enlarged front view of a print head with a cover attached, FIG. 4 is an enlarged front view of the print head, showing a rear plate, a membrane, an insert, and a main body. FIG. 5 is an exploded perspective view showing a main body, an insert, a membrane, and a back plate of the print head, FIG. 6 is a rear view showing a recess and a boss of the main body, and FIG. FIG. 8 is a front view of a block with a part removed to show the inside, FIG. 8 is a sectional view of an orifice portion of a second embodiment of a print head for an ink jet printing apparatus made in accordance with the principle of the present invention; FIG. 9 is a plan view of a print head according to the second embodiment, and FIG. 10 is a side view of the print head according to the second embodiment. 22 ... body, 30 ... membrane, 36 ... boss, 38 ... orifice, 40 (94, 206) ... elongated member, 42 (96, 214) ...
Release means.

Claims (1)

(57) [Claims] When the direction toward the target surface is the forward direction and the direction away from the target surface is the rear direction, the front surface, the back surface, the recess formed on the back surface, and the pressurized ink are supplied to the recess. A body having at least one inlet for forming a chamber for the pressurized ink supplied from the pressurized ink supply, the flexible membrane covering the recess. Are provided with a plurality of bosses extending rearward from the bottom of the recess through the chamber, and extend through the respective bosses from rear ends of the plurality of bosses to the front surface of the main body. A plurality of orifices are provided, and the membrane is made of one sheet of a flexible material covering the recess, and is pressed against the rear ends of all of the plurality of bosses to form the rear ends of the plurality of orifices. Can be closed Wherein the plurality of bosses through which the orifice penetrates selectively pass ink drops from the chamber through the orifice onto the target surface passing close to and away from the front surface of the body. Are arranged in a matrix at a small interval from each other so as to contactlessly print a pattern of data forming a character such as an alphabet on the target surface by ejecting the bosses; Holding the membrane against the pressure to prevent ink from flowing from the chamber through the plurality of orifices and curling away from the rear end of a selected one of the bosses. Selectively release the membrane to allow access from the chamber through the orifice passing through the selected boss. Means extending from the back of the membrane to the back thereof, the means comprising a plurality of tubular or wire-shaped shapes provided one for each of the bosses. An elongate member, the membrane-side ends of the elongate member being substantially aligned with the respective bosses, so that the membrane-side ends are arranged in a closely spaced array corresponding to the matrix. A plurality of elongate members, and a plurality of release means respectively provided at ends of the elongate members remote from the membrane, each of which selectively acts via a corresponding elongate member, A plurality of membranes are released from the corresponding bosses so that the membrane can be turned back away from the corresponding bosses to allow drops of ink to be delivered from the chamber through the corresponding orifices. And each release means is greater than the spacing of the plurality of bosses in a direction transverse to the corresponding elongate member, and all of the plurality of release means are coupled to the plurality of bosses. Further, the plurality of release means are arranged in an array with an interval that is enlarged as compared with the interval between the plurality of bosses, and the plurality of elongate members are not arranged in direct alignment. A printhead for an ink jet printing device that extends from the narrowly spaced array at the membrane end to the plurality of release means in the enlargedly spaced array; 2. After the flexible membrane, there is provided an auxiliary body having a plurality of air chambers, one for each of the bosses, each aligned with a respective boss; Comprises a plurality of air pipes, wherein the plurality of release means comprises a plurality of electrically operated valves, and the valves are supplied with pressurized air from an air supply source. When pressurized, the pressurized air is supplied to the corresponding air chamber to hold the film in a pressed state against the rear end of the corresponding boss, and also corresponds when temporarily biased. The air chamber is vented to release the membrane from the trailing end of the corresponding boss so that a drop of ink is ejected through the corresponding orifice onto the target surface. Inkjet described in Print heads for printing machines. 3. The plurality of elongated members include a plurality of flexible wires, and each of the wires has a leading end at the end on the membrane side for pressing the membrane against the rear end of the corresponding boss. The plurality of releasing means comprises a plurality of solenoids, and each of the solenoids, when temporarily energized, separates the leading end of the corresponding wire from the membrane and passes through the corresponding orifice. Causing the drops of ink to be ejected onto the target surface; and moving the plurality of wires in a direction toward the film so that the film is moved by the leading ends of the plurality of bosses. The printhead for an inkjet printing apparatus according to claim 1, further comprising means for biasing the plurality of wires so as to be pressed against a rear end of the printhead. 4. When the direction toward the target surface is defined as the front direction and the direction away from the target surface is defined as the rear direction, a front surface, a back surface, a recess provided on the back surface, and a plurality extending rearward from the bottom of the recess. A plurality of bosses each having an orifice extending from a rear end of the plurality of bosses to the front surface; and a plurality of bosses arranged in the recess and accommodating each of the bosses. An insert having a plurality of holes and forming a plurality of spaces respectively adjacent to the respective bosses, further having an ink receiving hole for receiving ink from a pressurized ink supply source, and cooperating with the main body. An insert for forming a passage between the ink receiving hole and the space adjacent to the boss; and covering the recess provided on the rear surface of the main body; A flexible film made of one sheet of a flexible material having holes aligned with the ink receiving holes; and a front surface and a back surface, wherein the film is sandwiched between the body and the body. The fixed rear plate, furthermore, a hole through which the ink flows in alignment with the hole in the film and the ink receiving hole in the insert, and a plurality of biasing holes aligned with each of the bosses, A rear plate having: a space provided adjacent to the boss, the space being adjacent to the boss, and being provided in correspondence with each of the plurality of urging holes; Means for interrupting communication between said orifices passing through said orifice, said ink being released from said space adjacent to said corresponding boss and through said corresponding orifice onto said target surface when said membrane is released. Means to make the droplets be ejected And a print head for an ink jet printing apparatus, comprising: 5. The means for releasably pressing the membrane includes a plurality of air chambers respectively provided at ends of the biasing holes closer to the membrane, and a plurality of air chambers extending from the biasing holes, respectively. A plurality of air pipes communicating with each other, and a plurality of electrically operated valves respectively provided at ends of the air pipes. Each of the valves is pressurized from a pressurized air supply source. When air is supplied and the valve is deenergized, pressurized air is supplied to the corresponding air chamber to hold the membrane against the rear end of the corresponding boss; When temporarily energized, the corresponding air chamber is vented to release the membrane from the rear end of the corresponding boss, and a drop of ink is ejected onto the target surface through the corresponding orifice. Configured to be The print head for an inkjet printing apparatus according to claim 4, wherein 6. The means for releasably pressing the film is a plurality of flexible wires provided respectively corresponding to the biasing holes, and the wire corresponding to the end of the wire closer to the film, A plurality of wires each having a leading portion for pressing the film against the rear end of the boss; and a plurality of solenoids provided at ends of the wire farther from the film, each of which is temporarily biased. A plurality of solenoids that, when performed, cause the head of the corresponding wire to separate from the membrane so that drops of ink are ejected onto the target surface through the corresponding orifice; and 5. The ink jet printing of claim 4, comprising means for biasing toward the membrane to press the membrane against the rear ends of the plurality of bosses by the leading ends of the plurality of wires. Dress Use print head.