JPS644914B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charge amount control type inkjet recording apparatus in which ink in an ink tank is pumped to a head by a supply pump.

The principle of the charge control type inkjet recording device, which is commonly used as an inkjet recording device, is to apply ultrasonic vibration to pressurized ink.
The ink droplets are ejected in the form of a jet from a nozzle provided in the head, and the ink droplets are deflected according to the charge by giving the ink droplets an electric charge according to the print signal voltage and making them fly in a constant electric field.
Recording is performed by forming dots on recording media arranged opposite to each other at positions corresponding to print signals.

An example of the conventional device is explained with reference to FIG. 1. Ink in an ink tank 1 is supplied to a supply pump 2.
As a result, the liquid is supplied under pressure to the print head 7 via the accumulator 3, filter 4, control valve 5, and protection filter 6. The print head 7 is provided with a nozzle 8, and the ink that has been force-fed to the head 7 is given minute vibrations by an ultrasonic vibration generating means (not shown), so that the ink droplets are ejected from the nozzle 8 in the form of a jet. Ru. The path of the ejected ink droplets includes a charge electrode 9 that gives the ink droplets an electric charge corresponding to the print signal voltage corresponding to the amount of deviation of the dots forming characters, etc. to be recorded from the reference line, and a constant electric field. A pair of deflection electrodes 10 are provided that hold the . The ink droplets 0 charged by the charged electrodes 9 are deflected by an amount corresponding to the charge while flying between the deflection electrodes 10, and are deposited on the recording paper 11 placed facing each other, resulting in a print signal. A corresponding dot is formed and recorded. Since the ink droplets corresponding to the parts without dots in the characters or the parts without characters are not charged, the ink droplets travel straight between the deflection electrodes 10 and are collected by the gutter 12 provided directly opposite to them. 13, the ink is collected into the ink tank 1 and reused.

The supply pump 2 and the recovery pump 13 are normally driven by a solenoid, a motor, etc., but from the viewpoint of control, space, and cost, it is desirable that both the supply and recovery pumps have one driving source.

When a metering pump is used as a supply pump, the flow rate and pressure per unit time are determined by the diameter of the piston, stroke, and repetition frequency, but since the nozzle hole diameter of the head is small at about 30 to 50 μm, the amount of ink ejected is determined by the diameter of the piston, stroke, and repetition frequency. is small, and the piston stroke is small. Furthermore, the smaller the piston stroke and the higher the frequency, the smaller the pressure pulsations.
This has the advantage that the capacity of the accumulator can be reduced.

As mentioned above, the supply pump has a small cylinder volume and a high frequency, so the ink supply system (the pipe line from the ink tank 1 to the head 7 and the pipe line from the gutter 12 to the ink tank 1 in Fig. 1, and their If the ink tank 1 is filled with ink using a cartridge or the like, and the equipment (equipment installed on the way) is not filled with ink, it is impossible for the supply pump 2 to fill the ink itself with its own power. The power of the pump makes it impossible to fill the ink supply system with ink.

For this reason, in the past, it has been necessary for printing apparatuses to be filled with ink at the time of shipment, or for service personnel or the like to fill them with ink by another means when the apparatus arrives at the user's location. In the former case, countermeasures against ink leakage due to impacts during transportation are required, and in the latter case, the work of service personnel is complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus which eliminates the above-mentioned drawbacks associated with filling ink into the ink supply system of the conventional inkjet recording apparatus of the above-mentioned type.

In the present invention, the initial ink filling into the ink supply pump is performed using the ink recovery pump originally provided in this device. As mentioned above, it is desirable that the supply pump and recovery pump be driven by the same drive source, but the recovery pump needs to be able to recover ink in the gutter in a mixed state with air, and its ability is limited to that of the supply pump. several times to several tens of times as much.

The present invention focuses on this ability of the recovery pump, and uses the recovery pump to initially fill the supply pump.
To make it possible to fill the ink supply system with ink,
As will be described in detail below, the ink supply system is characterized in that a pipe valve or the like is provided in the ink supply system.

The present invention will be described in detail below based on drawings showing embodiments thereof.

FIG. 2 is a system diagram showing an embodiment in which the present invention is applied to the inkjet recording apparatus described in FIG. 1, and the differences from the apparatus shown in FIG. 1 are as follows.

In this device, from the gutter 12 to the recovery pump 13
Switch valve 1 immediately before the suction valve of the recovery pump in the pipeline leading to
4, the connection port A of the valve is a connection pipe to the pump, the connection port B is a pipe coming from the gutter 12, and the connection port C is a switching valve provided in the ink supply pipe immediately after the discharge valve outlet of the supply pump 2. A pipe 16 leading to a connection port C of 15 is connected. The connection port A of the switching valve 15 is connected to the supply pump 2
C is connected to the ink supply pipe on the discharge side of the ink supply pipe.

Since this device is configured as described above, at the time of initial ink filling, the switching valves 14 and 15 are
Close between B and open between A and C. When the recovery pump 13 is operated in this state, the ink tank 1
The newly filled ink is supplied to the supply pump 2,
The ink is sucked into the recovery pump 13 via the switching valve 15, the pipe 16, and the switching valve 14, and is returned to the ink tank 1 through its discharge port for circulation, thus initial filling of the supply pump 2 is performed. In addition, the switching valve 1
4, 15 switching control and recovery pump 13 on
-Off control is performed by a conventionally well-known control circuit.

Driving the supply pump 2 at the same time as the recovery pump 13 during the above operation is advantageous for smooth flow of ink within the supply pump and for removing air and bubbles within the supply pump.

When the supply pump 2 is filled with ink, the switching valves 14 and 15 are opened between A and B and closed between A and C, so that the ink supply system is filled with ink by the supply pump 2. The normal recording operation described above with reference to FIG. 1 becomes possible.

As described above, according to the present invention, it is possible to fill the supply pump with ink by using the collection pump originally provided in this type of inkjet recording device. This eliminates the need for initial filling and ink filling service upon arrival, and the problems associated with this can be solved.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an example of an ink supply system of a conventional ink jet recording apparatus, and FIG. 2 is a system diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Ink tank, 2... Supply pump, 3... Accumulator, 5... Control valve, 7... Head, 12... Gutter, 13... Recovery pump, 14, 15... Switching valve.

Claims (1)

[Scope of Claims] 1. A head for flying ink droplets, an ink tank for holding the ink, a gutter for collecting the ink droplets, and an ink connecting the ink tank and the head. A supply pump provided in a supply system for supplying ink from the ink tank to the head; and an ink collection system for connecting the gutter and the ink tank for supplying ink from the gutter to the ink tank. a recovery pump for recovering ink; and a flow path provided in the ink supply system between the supply pump and the head, connecting the flow path from the supply pump to the head, and the supply pump and the recovery pump. a first switching valve that selectively connects one of the flow paths; and a first switching valve that is provided in the ink recovery system between the recovery pump and the gutter and connects the flow path from the gutter to the recovery pump and the supply. a second switching valve that selectively connects one of the flow paths connecting the pump and the recovery pump; 1. An inkjet recording apparatus comprising: a control means for switching between a first switching valve and a second switching valve, and operating the recovery pump.