JPH04358843A - Ink jet printer - Google Patents

Abstract

PURPOSE:To reduce the recording interrupting time without training increase of electric power when ink is melted in an ink jet printer which uses ink being solid at ordinary temperature by liquefying it by heating. CONSTITUTION:In an ink jet printer which performs recording by discharging ink drops from a plurality of nozzles 55 while a carrage 21 is being transferred to recording paper 1 to be carried by melting ink 32 which is solid at room temperature by heating, a residual quantity of liquefied ink 61 is calculated from melting speed of solid ink 32 to be replenished and a quantity of a recording data, and recording operation after replenishing the ink is controlled.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is an ink that is solid at room temperature (
The present invention relates to an inkjet printer that forms an ink image on a recording medium such as recording paper by heating and melting hot melt ink and causing ink droplets to fly.

0002

2. Description of the Related Art In general, an inkjet recording apparatus using hot melt ink has the advantage of being highly compatible with paper types and free from clogging due to ink evaporation during rest periods. However, due to the principle that ink is used by changing its phase from solid to liquid, time is lost when warming up after power is turned on and when adding a new solid ink block when the ink runs out. Conventionally, this involved applying a large amount of power to speed up the melting of the ink, leaving a sufficient amount in the inkjet head so that printing could continue even if an ink end signal was received, or stopping printing and waiting for the ink to melt. , etc. were adopted.

0003

SUMMARY OF THE INVENTION In the above-mentioned conventional inkjet printer, a power source for supplying a large amount of electric power is expensive. Moreover, storing a large amount of ink in an inkjet head is disadvantageous in terms of heat capacity and size. Furthermore, interruption of recording is inconvenient for the user.

[0004] The purpose of the present invention is to solve the above problems and
To provide a small-sized inkjet printer that reduces interruptions in recording without placing a burden on a power source.

[0005]

[Means for Solving the Problems] The inkjet printer of the present invention is an inkjet printer that performs recording by heating and melting ink that is solid at room temperature and ejecting ink droplets from a plurality of nozzles onto a conveyed recording medium. The present invention is characterized in that the remaining amount of ink is calculated from the melting speed of the solid ink to be replenished and the amount of recording data, and the recording operation after the ink is replenished is controlled.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing a schematic configuration of an inkjet printer according to an embodiment of the present invention. Recording paper 1 is
It is inserted along the paper guide 2 and is held between the paper feed roller 3 and the paper press roller 4. A paper feed motor 5 rotates a paper feed roller 3 via a motor pinion 6 and a paper feed gear 7. A carriage 21 carrying an inkjet head 11 reciprocates along a guide shaft 26. A belt 24 drives the carriage 21 using the carriage motor 22 as a power source. 23 is a drive pulley directly connected to the carriage motor 22. 25 is an idler pulley that applies tension to the belt 24. 31 is an ink cartridge that houses solid ink 32 to be supplied therein. The solid ink 32 is transferred from the ink cartridge 31 to
the inkjet heads 11 through the supply port 12 one by one.
supplied to 13 is an FPC (flexible printed circuit) that follows the movement of the inkjet head 11. The FPC 13 is connected at one end to the inkjet head 11 and at the other end to the control circuit via the connector 14.

FIG. 2 is a sectional view of the inkjet head 11 shown in FIG. 1. The inkjet head 11 is made of an aluminum alloy with good thermal conductivity, and is heated to a predetermined temperature by a heater 41 provided at the bottom. Reference numeral 52 denotes an ink melting chamber, which converts the charged solid ink 32 into liquefied ink 61. The ink melting chamber 52 includes a filter 51 on the lower surface. Dust is removed by this filter 51 and liquefied ink 61 is stored in the inkjet head 11. 53 is an ink sensor that senses the presence or absence of liquefied ink 61.

[0008] 57 is a piezoelectric transducer. Piezoelectric transducer 57
is fixed to the base 58 about half in the longitudinal direction, and further electrically connected to the FPC 13 at the end. Piezoelectric transducer 57
The other half is unconstrained and expands and contracts in response to the electric field. The ends of the piezoelectric transducers 57 that expand and contract are respectively joined to the elastic plates 56. The elastic plate 56 faces the nozzle plate 54 having a plurality of nozzles 55 with a small gap therebetween. The liquefied ink 61 is sucked up and filled by capillary force between the gaps.

The ink replenishment operation will be explained. In FIG. 1, the carriage 21 is moved to the lower part of the ink cartridge 31. A piece of solid ink 32 is dropped from the ink cartridge 31 to the supply port 12 of the inkjet head 11 by a power (not shown).

The ink droplet ejection operation will be explained. Figure 2
At this point, an electric field is applied to the piezoelectric transducer 57 through the FPC 13. This causes the piezoelectric transducer 57 to contract. next,
Release this electric field. Piezoelectric transducer 57 stretches and returns to its original length. This causes a volume change in the gap portion surrounded by the nozzle plate 54 and the elastic plate 56, and ink droplets are ejected from the nozzle 55.

The recording operation will be explained.

In FIG. 2, when the power is turned on, the heater 41 generates heat, raising the entire inkjet head 11 to a predetermined temperature above the melting point of the solid ink 32. On this occasion,
When the amount of liquefied ink 61 (solid before melting) stored inside the inkjet head 11 is large, a large amount of heating energy and heat of fusion is required. In other words, in order to liquefy the material quickly, it is necessary to input a large amount of electric power or to input a small amount of electric power and wait for a long time. Therefore, in the present invention, the amount of liquefied ink 61 is made very small to reduce the amount of input energy. Specifically, the amount of ink is about 3 g.

Next, the ink sensor 53 determines whether or not liquefied ink 61 is present. If the liquefied ink 61 is present, that is, the liquid level 61a is above the ink sensor 53, preparation is complete. If there is no liquefied ink 61, that is, if the liquid level 61a is below the ink sensor 53, solid ink 32 is replenished and the ink sensor 53 waits for confirmation that liquefied ink 61 is present.

After the warm-up is completed, recording is performed by repeating the above-described ink droplet ejection operation while moving the carriage 21 and transporting the recording paper 1 by rotating the paper feed roller 3 in accordance with the recording signal. be exposed.

As recording progresses, the liquefied ink 6 in FIG.
The liquid level 61a of No. 1 is lowered. When the liquid level 61a falls below the ink sensor 53, the ink sensor 53 senses this,
The process moves on to the ink replenishment operation described above. Refilled solid ink 3
2 gradually begins to melt within the ink melting chamber 52. but,
The liquid level 61a does not rise above the ink sensor 53 immediately.

Here, in order to avoid interruption of recording, recording is continued while performing the following calculations. Note that the calculation means is a CPU (not shown) installed in the printer.

The amount of liquefied ink 61 stored in the inkjet head 11 below the ink sensor 53 is expressed as A.
(g). Let the ink melting speed in the ink melting chamber 52 be B (g/sec). The amount of print data ejected by the inkjet head 11 per unit time is C (dots/second). Let the weight of one ink droplet be D (g/dot). Let t (seconds) be the time elapsed after the solid ink 32 was introduced.

The calculation formula is set as X=A+B×t−C×D×t, and the recording operation is continued as long as X≧E (E is a constant value greater than 0) holds. In addition, the value of B×t is solid ink 3
2.Do not exceed 1g, which is the weight of one piece. Each numerical value in this example is A=2 (g), B=0.02 (g/sec), C=6×
105 (maximum dots/sec), D=1×10-7 (g/
dot). Therefore, if the maximum data continues, B
- Liquefied ink 61 at a speed of C x D = 0.04 (g/sec)
decreases, so if the value of E is set to 0.5 (g), X≦E will be satisfied in about 30 seconds. This means that immediately after the ink sensor 53 detects the ink end and replenishes the ink, full solid printing can be performed for more than 30 seconds without interrupting printing.

By the way, if we wait for the solid ink 32 to completely melt, 1 (g) ÷ 0.02 (g/sec) = 50 (
(seconds) interruption time is required. If the maximum data continues after 30 seconds, the recording operation is stopped, but this is unlikely to happen in reality. Alternatively, as another control method, the moving speed of the carriage 21 can be slowed down. In other words, the value of C is reduced. For example, if the moving speed of the carriage 21 is halved, the value of C will be 3×
105 (maximum dots/second). If we perform the same calculation as above, we will be able to continue recording for 150 seconds until X≦E.

The above calculation is for the most severe case, and in normal recording, the value of C is about 3.times.10.sup.4 (average dots/second), and no interruption of recording occurs. As mentioned above, the solid ink 32 completely becomes the liquefied ink 61 in 50 seconds, so the control based on the above calculation only needs to be performed for 50 seconds after replenishing the ink, and thereafter the ink sensor 53 measures the liquid level 61a. All you have to do is monitor.

In this embodiment, the inkjet head 11
It should also be noted that since the amount of liquefied ink 61 stored inside is about 3 g, the temperature rises quickly with a small amount of electric power when the power is turned on.

[0022]

Effects of the Invention As explained above, even if an ink end signal is received during recording, the inkjet printer of the present invention calculates the ink melting speed and recording data amount after replenishing ink and immediately continues recording. can. Since the calculation is performed by the CPU (central processing unit) installed in the printer, there is no cost increase at all.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the inkjet head of the same embodiment.

[Explanation of symbols]

11 Inkjet head 32 Solid ink 53 Ink sensor 61 Liquefied ink

Claims (1)

[Claims] [Claim 1] In an inkjet printer that records by heating and melting solid ink at room temperature and ejecting ink droplets from a plurality of nozzles onto a conveyed recording medium, the melting speed and An inkjet printer characterized by comprising a control means for calculating the remaining amount of ink from the amount of recording data and controlling the recording operation after ink replenishment.