Liquid heating apparatus and image forming apparatus

Abstract

A liquid heating apparatus for heating a liquid that is supplied to a liquid droplet ejection head is provided. The liquid heating apparatus includes a liquid chamber unit configured to be disposed on the supply route of the liquid and to temporarily store the liquid, and a temperature-adjusting flow path unit configured to heat the liquid supplied from the liquid chamber unit.

Claims

1. A liquid heating apparatus for heating a liquid that is supplied in a liquid supply direction through a supply route to a liquid droplet ejection head, the liquid heating apparatus comprising: a liquid chamber disposed upstream of the liquid ejection head in the liquid supply direction and disposed on the supply route of the liquid and configured to temporarily store the liquid supplied from a liquid tank; a temperature-adjusting flow path disposed downstream of the liquid chamber in the liquid supply direction, the temperature-adjusting flow path including a predetermined length having a serpentine shape configured to heat the liquid supplied from the liquid chamber, the liquid flowing in the liquid supply direction through the predetermined length having the serpentine shape from one end of the predetermined length having the serpentine shape to the other end of the predetermined length having the serpentine shape; a housing to house the liquid chamber and the temperature-adjusting flow path; and a heater surrounding the liquid chamber and surrounding the temperature-adjusting flow path, to heat both of (i) the liquid chamber and (ii) the temperature-adjusting flow path including the predetermined length having the serpentine shape through which the liquid flows from one end of the predetermined length having the serpentine shape to the other end of the predetermined length having the serpentine shape.

2. The liquid heating apparatus according to claim 1, wherein a combined flow path volume of the liquid chamber and the temperature-adjusting flow path is equal to or greater than a product of a maximum ejection flow amount of the liquid droplet ejection head and time for heating the liquid.

3. An image forming apparatus comprising: the liquid heating apparatus according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a block diagram illustrating a schematic configuration of an image forming apparatus that uses a liquid heating apparatus according to a first embodiment of the present invention.

(2) FIG. 2 is a piping diagram illustrating the configuration of the liquid heating apparatus.

(3) FIG. 3 is a piping diagram illustrating an example configuration of the liquid heating apparatus in which the temperature-adjusting flow path unit is formed to have an increased length.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) A liquid heating apparatus according to a first embodiment of the present invention and an image forming apparatus which uses the liquid heating apparatus will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a schematic configuration of an image forming apparatus that uses a liquid heating apparatus according to a first embodiment of the present invention.

(5) In FIG. 1, as an example, an inkjet-type printer 100 (hereinafter, printer) is shown illustrating an embodiment of an image forming apparatus. The printer 100 shown in FIG. 1 includes an ink tank 10, an ink heating apparatus 20 as a liquid heating apparatus, an ink ejection head 30 as a liquid droplet ejection head, and a drive unit 40.

(6) The ink tank 10 has a volume in which a predetermined amount of liquid (hereinafter, ink) can be stored. The ink tank 10 conveys the ink by using, for example, the hydraulic head between a nozzle surface of the ink ejection head 30 and a liquid surface of the ink tank 10. It should be noted that the conveyance of ink is not limited to the use of the hydraulic head.

(7) The ink tank 10 and the ink heating apparatus 20 are connected via a first supply tube 11, and the ink heating apparatus 20 and the ink ejection head 30 are connected via a second supply tube 21.

(8) In other words, the ink stored in the ink tank 10 is supplied to the ink heating apparatus 20 via the supply tube 11. Further, the ink is heated to a predetermined temperature in the ink heating apparatus 20 and supplied to the ink ejection head 30 via the supply tube 21. Further, the ink is ejected from the ink ejection head 30 onto a recording medium (sheet) 9 based on a drive signal transmitted in a timely manner from the drive unit 40.

(9) FIG. 2 is a block diagram illustrating a schematic configuration of the ink heating apparatus 20. The ink heating apparatus 20 is an apparatus for heating the ink to be supplied to the ink ejection head 30, and includes a liquid chamber 50, a temperature-adjusting flow path unit 60, and a heater 70. In other words, the liquid chamber 50 and the temperature-adjusting flow path unit 60 are disposed on the supply route of the ink that is supplied to the ink ejection head 30.

(10) The liquid chamber 50 according to the present embodiment is used for temporarily storing the ink supplied from the ink tank 10, and has a predetermined volume in order to reduce fluctuations in ink temperature caused by the flow amount change of the ink that is supplied to the ink ejection head 30.

(11) The temperature-adjusting flow path unit 60 is used to heat the ink flowing in the temperature-adjusting flow path unit 60 and has a predetermined length by having a serpentine shape. It should be noted that the temperature-adjusting flow path unit 60 is not limited to having a serpentine shape, but it may have, for example, a spiral shape.

(12) In the present embodiment, the liquid chamber 50 is disposed upstream of the ink ejection head 30 in a supplying direction and the temperature-adjusting flow path unit 60 is disposed downstream of the liquid chamber unit 50. The heater 70 heats the ink flowing in the liquid chamber 50 and the temperature-adjusting flow path unit 60.

(13) FIG. 3 is a piping diagram illustrating a configuration of the liquid heating apparatus based on an assumption that only the temperature-adjusting flow path unit 60 is formed to have a long length. It should be noted that the same reference numbers are given to the units which have already been described in FIGS. 1 and 2, and the descriptions may be omitted. In order to increase transfer efficiency of the heat from the heater 70, the temperature-adjusting flow path unit 60 may be formed to maximize its length as shown in FIG. 3. However, increasing the length of the temperature-adjusting flow path unit 60 will lead to pressure loss in the temperature-adjusting flow path unit 60.

(14) If the pressure loss is increased, when the ink is supplied by using the hydraulic head as described above, ejection failure may occur due to the ink supply shortage caused by the pressure loss when large amount of ink is ejected from the ink ejection head 30.

(15) Therefore, in the present embodiment, in order to keep the pressure loss to a level equal to or below an allowable level, the liquid chamber 50 and the temperature-adjusting flow path unit 60 are combined to form the ink heating apparatus 20.

(16) As a result, the volume of the liquid chamber 50 and the volume of the temperature-adjusting flow path unit 60 are set as follows. As described above, in order to improve the heat transfer efficiency, it is desirable to maximize the length of the temperature-adjusting flow path unit 60. Therefore, the volume of the temperature-adjusting flow path unit 60 is set as maximum volume A ml, which is derived from the allowable pressure loss.

(17) On the other hand, the volume of the liquid chamber 50 is set as equal to or greater than B*CA ml, where assumed maximum ink ejection amount per unit time is B ml/min, and required time for the ink in the ink heating apparatus 20 to be heated to a predetermined temperature is C min. Specifically, the setting is as follows.

(18) According to calculation results, the volume of the temperature-adjusting flow path unit 60 is 1 ml which is derived from the allowable pressure loss. Further, it is assumed that the maximum ejection amount per unit time is 5 ml/min, and the required time for the ink in the ink heating apparatus 20 to be heated to the predetermined temperature is 0.5 min. In this case, the volume of the liquid chamber 50 may be 1.5 ml or more, and the volume of the entire ink heating apparatus 20 may be 2.5 ml or more. It should be noted that, it depends on the viscosity of the ink to be used, but it is desirable to make the inner diameter of the supplying tube about mm in the case of typical UV-curable ink. It should be noted that the combined flow path volume of the liquid chamber 50 and the temperature-adjusting flow path unit 60 is equal to or greater than the product of the maximum ejection amount of the ink ejection head 30 and the ink heating time.

(19) According to the printer 100 described above, the following effects can be obtained. Because the liquid chamber 50 having a predetermined volume is disposed on the ink supplying route, it is possible to reduce fluctuations in ink temperature due to the ink flow amount change. Further, the volume of the temperature-adjusting flow path unit 60 can be maximized based on the allowable pressure loss. Therefore, it is possible to reduce the time from power ON to the start of liquid ejection and to reduce the mass fluctuation of the ink droplet.

(20) The present invention is not limited to the specifically described embodiments, and variations and modifications may be made without departing from the scope of the present invention.

(21) The present application is based on and claims the benefit of priority of Japanese Priority Application No. 2015-052170 filed on Mar. 16, 2015, the entire contents of which are hereby incorporated herein by reference.