JPS6034870A - Ink jet printer - Google Patents

Abstract

PURPOSE:To reduce a number of lead wires for connecting electrodes, by electrically connecting a second electrode contacted with ink to a support member having conductivity even when ink is not present in an amount reaching a desired level or more. CONSTITUTION:Only shorter electrodes 8 are provided to the upper surface of the liquid ink in a liquid ink chamber 2' and a lead wires 8a are connected to the electrodes 8. On the other hand, another extremely short electrode 13 is inlaid with the recessed part 2'a provided to the almost central part of the bottom surface of each liquid ink chamber 2'. One end of this electrode 13 is protruded into the liquid ink chamber 2' and the other end thereof is electrically contacted with the leaf spring comprising a conductive metal arranged on a carriage 9'. A head 1' is fixed on the chassis 15 provided to the upper surface of the carriage 9' and the chassis 15 is formed of a conductive metal and a lead wire 15a is connected to the end part of said chassis 15. This lead wire 15a and the previously mentioned lead wire 8a are connected to an alarm apparatus not shown in the drawing.

Description

TECHNICAL FIELD The present invention relates to an inkjet printer, and more particularly to an inkjet printer that performs recording using an inkjet recording head having an ink chamber provided with an electrode for detecting an ink level.

BACKGROUND OF THE INVENTION A conventional structure around an inkjet recording head of an example of this type of inkjet printer is shown in FIG.

In the figure, the reference numeral 1 indicates an inkjet recording head (hereinafter abbreviated as head), which has an ink chamber 2 formed integrally with the casing of the entire head 1. As shown in FIG. In the front view of this ink chamber 2 for recording, there is provided a nozzle 3 that performs recording by discharging ink droplets, and the ink chamber 2 is filled with recording ink 4 consumed by this nozzle 3. . This ink 4 is supplied by pressure from an ink tank (not shown) through an ink supply tube 5 connected to the side of the ink chamber 2 opposite to the nozzle 3.

Further, an air vent plug 6 is provided on the upper surface of the ink chamber 2, and a desired amount of air layer 7 is secured inside the ink chamber 2 via this plug 6.

Furthermore, two electrodes 8.9 are provided on the upper surface of the ink chamber 2 for detecting the liquid level of the ink 4 within the ink chamber 2. One of the electrodes 8 is short, and the other electrode is shaped like a long rod, and they are spaced apart from each other, protrude to the outside of the ink chamber 2, and are provided substantially perpendicularly downward within the chamber. Lead wires 8a and 9a are connected to respective ends of the electrodes 8.9 that protrude outside the ink chamber 2, and these lead wires 8a and 9a are connected to an alarm device (not shown). This alarm device detects the level of the ink liquid level, issues an alarm based on the detection result, and causes ink to be supplied.

The head I having the above configuration is mounted on a carriage designated by the symbol IO. The carriage 10 is slidably attached to two guide shafts 11, and is driven by a drive means (not shown) during recording to travel along the guide shafts 11 and transport the head l. At the same time, the nozzle 3 is driven to selectively eject ink droplets, thereby recording in a dot pattern.

When the ink chamber 2 is sufficiently filled with the ink 4, the liquid level of the ink 4 in the chamber is at a height indicated by the symbol Ll. That is, the liquid level of the ink 4 is lower than that of the shorter electrode 8.
on both sides than the lower end of.

Therefore, the electrodes 8,9 are electrically connected through the ink 4 existing therebetween with a resistance of several tens of ohms.

The volume of the ink 4 decreases due to consumption of the ink 4 by the recording operation or evaporation of the solvent in the ink from air vent holes, etc., and the liquid level of the ink 4 reaches the height indicated by symbol L2, and the lower end of the electrode 8 When the electrodes 8, 9 are separated from the ink surface, the conduction between the electrodes 8, 9 is interrupted. When this non-conducting state is notified to the alarm device connected to the lead wires 8a and 9a, the alarm device issues an alarm that the ink level is low, and the ink 4 is automatically or manually removed from the ink tank. Supplied. By supplying a desired amount of ink, the liquid level of the ink 4 is returned to the initial height indicated by the symbol Ll. In this way, air in the air layer 7 is prevented from entering the nozzle 3 and causing non-ejection of droplets or failure to eject droplets, allowing continuous and stable recording.

However, according to the conventional configuration described above, a lead wire is connected to each electrode for detecting the ink liquid level, so it is difficult to install many heads on a carriage, such as in this type of inkjet printer that performs multicolor recording. Inkjet printers record by scanning the loading head.
The number of lead wires connected to the head becomes large. This not only complicates the wiring and increases the cost, but also requires a large amount of space to move the wiring as these many wirings move together with the head. - There was a problem that the size of the printer also increased.

Also, if the wiring becomes complicated, it will get lost during maintenance.

The second drawback is not limited to inkjet printers of the type where the head 1 is mounted on a carriage and scanned to record as described in section 2 above, but the head is fixed to a fixed support member and scanning is not possible. This also applies to full-line type inkjet printers that do not.

Purpose The present invention has been made in order to solve the following drawbacks of the conventional inkjet printer. The purpose is to simplify the process of attaching and detaching the head, reduce costs, and downsize the inkjet printer.

EXAMPLES The present invention will be described in detail below by taking as an example the preferred embodiments of the present invention shown in FIGS. 2 to 4. In FIGS. 2 to 4, parts that are the same as those in FIG. 1 are designated by the same reference numerals, and therefore explanations of those parts will be omitted.

First Embodiment FIG. 2 shows the main structure of an embodiment of the present invention. In the same figure, the inkjet recording head C (hereinafter referred to as head) indicated by reference numeral 1' is head 1 as before.
' It has an ink chamber 2' that is integrated with the entire housing, a nozzle 3 is provided on the front side of the ink chamber 2', and the inside is filled with ink 4. The ink 4 is supplied to a hollow sealing member 1 provided inside the bottom surface of the ink liquid chamber 2'.
The ink is supplied from an ink tank (not shown) through an ink supply pipe 12 fitted into the hollow portion of the ink tank 1 . This ink supply tube 12 is fixed onto the carriage 9' with its tip protruding.

Further, as in the conventional case, an air layer 7 is secured within the ink chamber 2' through a plug 6 provided on the upper surface of the ink chamber 2'.

In this embodiment, only the shorter electrode 8 described in the conventional inkjet printer is provided on the upper surface of the ink chamber 2' as an electrode for detecting the ink level, and a lead wire 8a is connected to this electrode 8. has been done. Another very short electrode 13 is fitted into a recess 2'a provided approximately at the center of the bottom of the ink chamber 2'.

One end of this electrode 13 protrudes into the ink liquid chamber 2', and the other end is electrically contacted with a plate spring made of a conductive metal or the like arranged on the carriage 9'.

The above-mentioned headboard is fixed on a chassis 15 provided on the upper surface of the carriage 9'. This chassis is made of conductive metal, etc., and a lead wire is attached to the end of the chassis.
5a is connected. This lead wire 15a and the aforementioned lead wire 8a are connected to an alarm device (not shown).

Also, as shown in Figure 3, the head 1' is mounted on the carriage 9.
A plurality of them may be fixed on the chassis 15 (two in FIG. 3). Taking FIG. 2 as an example, FIG. 3 is a cross-sectional view taken along line A--A in the figure. As shown in FIG. 3, the headboard is fixed on the chassis 15 by being supported from both sides by two long and short support plates 16 and 17 bent in an L shape. Also, each head 1'
The electrodes 13 provided on the substrate are each electrically connected to one plate conductor 4. This leaf spring 14 is in contact with the electrode 13 at its upwardly curved portion, and is fixed onto the chassis 15 with screws 18.

According to the above configuration, the electrodes 13 provided on each of the plurality of heads 1' are connected to the conductive plate spring 14 and the chassis 15.
It is connected to the lead wire 15a via.

As the ink 14 is consumed during recording, and due to the increase in the air layer 7 caused by the evaporation of the ink solvent, the ink liquid level in the ink liquid chamber 2' changes from the level indicated by the symbol Ll to the level indicated by L2. Descend. Then ink 4
Due to this intervention, the electrical connection between the electrodes 8 and 13, which had been electrically connected at several tens of ohms, is cut off. This non-conducting state is detected by an alarm device connected to a lead wire 8a connected to the electrode 8 and a lead wire 15a connected to the electrode 13 via the board holder 4 and the chassis 15. Based on this detection result, a desired amount of ink 4 is supplied from an ink tank (not shown) into the ink liquid chamber 2', and the level of ink 4 is restored to the position indicated by Ll.

According to the configuration of the above embodiment, the electrodes 13 provided on each headboard are connected to the alarm device via the common plate 414, the chassis 15, and the lead wire 15a. When there are two heads as shown in FIG. 3, the number of lead wires is reduced by one.

If the number of heads 1' is n, then the number can be reduced by n-1.Second EmbodimentIn the configuration of the above embodiment, the electrode I3 is connected to the ink chamber 2'.
The electrode 13 and the chassis 15 are
FIG. 4 shows a schematic cross-sectional view of a preferred embodiment in which a separate leaf spring 14 is used to provide electrical continuity between the two. In this figure as well, only the essential parts of the inkjet printer are shown, as in the case described above.

In the figure, an electrode 13' having the same function as the electrode 13 described above is provided on a side surface near the bottom of the ink chamber 2'. One end of the electrode 13' projects into the ink liquid chamber 2', and the other end projects outside and is fixed. A support plate 17' is electrically connected to the end surface of the electrode +3' which protrudes outward. This support plate 17' is formed by bending a plate spring made of a conductive metal or the like into an abbreviated shape, and a part of it is in electrical contact with the electrode 13', and the other part is in contact with the ink liquid. It is fixed onto the chassis 15 of the carriage 9' with screws 19 so as to press against and support the outer surface of the chamber 2'. The support plate 17' electrically connects the electrode 13' and the chassis 15.

With the above configuration, not only can the same effects as in the previous embodiment be obtained, but also the leaf spring 14 can be made smaller than in the previous embodiment.
The number of parts can be reduced by that amount, and since four parts are not formed on the bottom of the ink chamber, further miniaturization can be achieved.

In the above two embodiments, the electrodes 13 and 13' are connected to the alarm device via the chassis 15 of the carriage 9', but the invention is not limited to this, and if the carriage 9' is conductive, the alarm can be directly connected to the alarm device from the carriage 9'. The device may also be wired. Also, if the carriage 9' is grounded to the inkjet printer, there is no need to provide a wire that is connected to the electrode 13' and moves with the carriage.
Further miniaturization is possible.

Third Embodiment In the above embodiment, two electrodes 8°13 (1
3'), but the ink chamber can also be formed of a conductive member and serve as one of the ink chambers 1Ei13 (13'). In this case, the other electrode 8 is provided insulated from the ink chamber.

In this case, since the ink chamber is fixed on the carriage, a more reliable electrical connection can be obtained than in the case of the electrode 13 (13').

Even with this configuration, the same effects as those of the above-mentioned embodiments can be obtained, and the number of parts can be further reduced, resulting in cost reduction.

Note that the configuration of the present invention can also be applied to a full-line type inkjet printer in which the head is fixed on a fixed support member.
The present invention can also be applied to a cartridge type ink chamber in which ink is not supplied.

Effects As is clear from the above explanation, in the inkjet printer according to the present invention, the first electrode contacts the ink when there is an amount of ink above a desired level in the ink chamber of the head, and the A support member that supports the head has a second electrode that is in contact with the ink even when there is no ink in an amount equal to or higher than the level of . Since the electrodes are electrically connected, the number of lead wires for electrode connection can be reduced. Therefore, the wiring for electrode connection is simplified,
It is possible to reduce the cost and size of an inkjet printer. In addition, it becomes easier to attach and detach the head during maintenance.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view showing the structure around the head of a conventional inkjet printer, FIG. 2 is a longitudinal sectional side view showing the structure around the head of the first embodiment of the present invention, and FIG.
A cross-sectional view taken along the line A--A in the figure, and FIG. 4 is a longitudinal cross-sectional side view of a main part according to a second embodiment of the present invention. 1'...Inkjet recording head 2'/i' (ink liquid chamber"...Ink 6...Plug 7...Air layer 8.13...Electrode 8a, 15a...Lead wire 9'
... Carriage 14... Board scrap, 15... Chassis 17, 17'... Support plate IN1 Fig. 1U M3 Fig. 2 A @ 1υ A @ Fig. 4

Claims (1)

[Claims] The first one that comes into contact with ink when there is an amount of ink above a desired level in the ink liquid chamber of the inkjet recording head.
and a second electrode that is in contact with the ink even when there is no ink above a desired level in the ink liquid chamber, and a part of the support member that supports the head is conductive. An inkjet printer characterized in that the second electrode and the support member are electrically connected.