GB2124553A

GB2124553A - Ink supply for ink jet printer

Info

Publication number: GB2124553A
Application number: GB08317915A
Authority: GB
Inventors: Naohiro Oku; Masaaki Kuranishi; Masahiko Aiba; Hideyuki Miyake
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 1982-07-06
Filing date: 1983-07-01
Publication date: 1984-02-22
Also published as: CA1220377A; DE3324397A1; GB8317915D0; GB2124553B; JPS597056A

Abstract

An ink liquid supply system in an ink jet system printer of the charge amplitude controlling type includes a pump system for supplying ink liquid from an ink liquid reservoir to a nozzle. The pump system has a cylinder shaped wall 22 for defining a pump chamber 20, and a piezo element 23 attached to the outer surface of the cylinder shaped wall. When a pulse shaped drive signal is applied to the piezo element, the volume of the pump chamber is varied to achieve the pump function. <IMAGE>

Description

SPECIFICATION Ink liquid supply system in an ink jet system printer of the charge amplitude controlling type Background and summary of the invention The present invention relates to an ink liquid supply system in an ink jet system printer of the charge amplitude controlling type and, more particularly, to a pump system in an ink jet system printer for supplying ink liquid to a nozzle included in the ink jet system printer.

An ink jet system printer of the charge amplitude controlling type requires a small amount, constant flow rate pump system in order to ensure stable printing operation even when the ambient condition varies.

The conventional ink liquid supply system of the ink jet system printer of the charge amplitude controlling type includes a mechanical plunger pump of the constant flow rate type. However, the mechanical plunger pump does not ensure a stable constant flow rate supply when a small amount supply is conducted. Furthermore, the mechanical plunger pump occupies a considerably large size.

Accordingly, an object of the present invention is to provide a novel pump system suited for an ink liquid supply system in an ink jet system printer of the charge amplitude controlling type.

Another object of the present invention is to provide a pump system which ensures a constant flow rate supply in a small amount supply.

Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

To achieve the above objects, pursuant to an embodiment of the present invention, a pump chamber is disposed in an ink liquid supply system of an ink jet system printer of the charge amplitude controlling type. The pump chamber is cylinder shaped, and around which a piezo vibrator is secured. A pulse drive signal is applied to the piezo vibrator to vary the volume of the pump chamber. Ink liquid is introduced from a main tank into the pump chamber, and is developed to an accumulator which is connected to a nozzle via an electro-magnetic cross valve.

Brief description of the drawings The present invention will be better understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein: Figure 1 is a block diagram of an ink liquid supply system in an ink jet system printer of the charge amplitude controlling type, including an embodiment of a pump system of the present invention; Figure 2 is a partially sectional front view of the pump system included in the ink liquid supply system of Figure 1; and Figure 3 is a schematic perspective view of a piezo vibrator included in the pump system of Figure 2.

Description of the preferred embodiments An ink liquid supply system of an ink jet system printer of the charge amplitude controlling type includes a cartridge tank 1 removably secured to the ink liquid supply system. More specifically, the ink liquid supply system includes an ink outlet needle 2 for discharging the ink liquid from the cartridge tank 1, and an ink inlet needle 3 for introducing the ink liquid into the cartridge tank 1.

The ink outlet needle 2 and the ink inlet needle 3 are inserted into the cartridge tank 1 when the cartridge tank 1 is secured to the ink liquid supply system.

The ink liquid discharged from the cartridge tank 1 is introduced into a main tank 4. A pump system 6 of the present invention is connected to introduce the ink liquid from the main tank 4 via an ink inlet valve 5. The pump system 6 develops the ink liquid of a constant flow rate toward an accumulator 8 through an ink outlet valve 7. The accumulator 8 function to stabilize the static pressure of the ink liquid developed from the pump system 6.

The thus stabilized ink liquid is supplied from the accumulator 8 to a printer head 10 via an electro-magnetic cross valve 9. As is well known in the art, the printer head 10 includes a nozzle to which an electro-mechanical transducer (piezo vibrator) is attached in order to emit ink droplets at a given frequency. The printer head 10 further includes a charging tunnel for charging the ink droplets in accordance with a print information signal. The charged ink droplets are deflected while they pass between a pair of deflection electrodes which are also included in the printer head 1 0. The ink droplets not contributing to the actual printing operation are not charged nor deflected, and are directed to a beam gutter 11.

The ink liquid collected by the beam gutter 11 is returned to the cartridge tank 1 via a returning conduit 15.

When the actual printing operation is terminated, the pump system 6 is disabled, and the electro-magnetic cross valve 9 is switched to connect the printer head 10 to the returning conduit 1 5. The ink liquid disposed between the electro-magnetic cross valve 9 and the printer head 10 is forced to flow into the returning conduit 1 5 doe to the negative pressure created in the returning conduit 1 5. That is, when the printing operation is not conducted, the ink liquid does not remain in the nozzle portion of the printer head 1 0.

The ink liquid introduced into the returning conduit 1 5 is returned to the cartridge tank 1 by means of a suction pump 13. Valves 12 and 14 are associated with the suction pump 1 3.

The pump system 6 and the accumulator 8 are constructed as shown in Figure 2. In Figure 2, like elements corresponding to those of Figure 1 are indicated by like numerals.

The pump system 6 includes a pump chamber 20 surrounded by a cylinder shaped vibration pipe 22. At the bottom end of the pump chamber 20, a valve seat 25 is provided. An ink inlet passage 35 is formed through the valve seat 25, and the ink inlet valve 5 is secured to the valve seat 25 through the use of a valve cap 24. At the top end of the pump chamber 20, another valve seat 21 is provided. An ink outlet passage 36 is formed through the valve seat 21, and the ink outlet valve 7 is secured to the valve seat 21 through the use of a valve cap 26.A block housing 37 is secured to the valve seat 21 in order to form the accumulator 8. 0-shaped rings 30, 31 and 32 are disposed between the valve seat 25 and the vibration pipe 22, between the valve seat 21 and the vibration pipe 22, and between the valve seat 21 and the block housing 37, respectively, for sealing purposes.

The vibration pipe 22 preferably has a thickness of about 0.2 mm. Around the cylinder shaped vibration pipe 22, a piezo element 23 is attached to through the use of an adhesive.

Accordingly, when a pulse drive signal is applied to the piezo element 23, the volume of the pump chamber 20 is varied to perform the pump operation.

Now assume that the piezo element 23 has a radius R, and a length I as shown in Figure 3.

When a pulse drive signal is applied to the piezo element 23, the piezo element 23 expands in the directions shown by arrows in Figure 3. When the pulse drive signal is not applied to the piezo element 23, the volume "v" defined by the piezo element 23 is expressed as follows: v=rrR21 When the pulse signal is applied to the piezo element 23, the radius R and the length I become R' and I' respectively.

V R'=R(1 +K-) t V l'=1(1 +K-) t Accordingly, the volume v is changed to (v+Av).

V v+Av=7rR21(1 +K)3 t V ~7rR21(1 +3K-) t where: K: strain constant R: radius of piezo element 23 I: length of the piezo element 23 V: voltage level of the pulse drive signal t: thickness of the piezo element 23 Av: volume variation The small amount ink liquid supply is conducted by the volume variation Av applied to the pump chamber 20.

V Av=(v+Av)-v=3R2lK t Example The cylinder shaped vibration pipe 22 is made of hard vinyl chloride resin, and has a thickness of 0.2 mm. The piezo element 23 having a thickness (t) of 1.5 mm, a length (I) of 40 mm, and a radius (R) of 13 mm is attached to the hard vinyl chloride resin pipe 22 through the use of an epoxy base adhesive. The strain constant K is 300x 10-12 m/V. When the pulse drive signal having a 700 Vpp level is applied to the piezo element 23, the volume variation Av is 8.8 mm3. In a preferred form, the pulse drive signal is applied to the piezo element 23 has a frequency of 122 Hz.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications are intended to be included within the scope of the following

Claims

claims. Claims

1. An ink liquid supply system for supplying ink liquid from an ink liquid reservoir to a printer head in an ink jet system printer of the charge amplitude controlling type, comprising: a pump system disposed between said ink liquid reservoir and said printer head, said pump system comprising: a pump chamber; and a piezo element secured to said pump chamber for varying the volume of said pump chamber in response to a drive signal applied thereto.

2. The ink liquid supply system of claim 1, further comprising: an accumulator disposed between said pump system and said printer head; and an electro-magnetic cross valve disposed between said accumulator and said printer head for selectively connecting said accumulator to said printer head.

3. An ink liquid supply system for supplying ink liquid from an ink liquid reservoir to a printer head in an ink jet system printer of the charge amplitude controlling type, comprising: a pump system disposed between said ink liquid reservoir and said printer head, said pump system comprising: a cylinder shaped housing for defining a pump chamber; a piezo element attached to said cylinder shaped housing so as to surround said cylinder shaped housing; and drive means for applying a pulse signal to said piezo element, thereby varying the volume of said pump chamber defined by said cylinder shaped housing.

4. The ink liquid supply system of claim 3, wherein said cylinder shaped housing is made of a resin sheet having a thickness of about 0.2 mm.

5. An ink jet system printer of the charge amplitude controlling type comprising: an ink liquid reservoir; a printer head for emitting ink droplets; a pump system disposed between said ink liquid reservoir and said printer head for supplying ink liquid from said ink liquid reservoir to said printer head, said pump system comprising: a pump chamber surrounded by a vibration plate: and a piezo element attached to said vibration plate for varying the volume of said pump chamber in response to a drive signal applied thereto; and an accumulator disposed between said pump system and said printer head for stabilizing the static pressure of the ink liquid developed from said pump system.

6. The ink jet system printer of claim 5, wherein said vibration plate comprises a cylinder shaped pipe made of hard vinyl chloride resin.

7. The ink jet system printer of claim 5, wherein said drive signal is a pulse signal having a frequency of about 122 Hz, and a voltage level of about700,~,.

8. A pump for supplying liquid to a print head, the pump comprising a chamber and a piezo device which can be electrically driven so as to vary the volume of the chamber.

9. A pump as claimed in claim 8, wherein the chamber is defined by a wall to which the piezo device is secured.

10. An ink jet system printer substantially as herein described with reference to the accompanying drawings.