JPS60143969A - Liquid jet recording head - Google Patents

Abstract

PURPOSE:To provide a highly reliable recording head, by providing a temperature-detecting unit filled with a liquid containing no electrolyte and a means for detecting the temperature of the liquid in the unit. CONSTITUTION:Droplet-forming means A and B are used for two separate functions of recording an temperature detection, respectively. The means B is provided with a temperature sensor 305 which makes direct contact with the liquid contained in a liquid reservoir 304. A recording liquid such as an ink is supplied into a liquid reservoior 104 in the droplet-forming means A for recording, while the liquid containing no electrolyte, e.g., a glycol such as ethylene glycol, is supplied into the liquid reservoir 304 in the droplet-forming means for temperature detection. Even when variations are generated in the ambient temperature of the recording head or the like, the tmeperatures of the liquid charged in the droplet-forming means A, B are varied in substantially the same manner. Accordingly, by detecting the temperature of the liquid in the means B and performing temperature control by a heater 306 on the basis of the detected temperature, the temperature of the recording liquid charged in the means A can be accurately controlled to an optimum temperature for recording, even when the ambient temperature or the like is varied.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field The present invention relates to a liquid jet recording head that performs recording by jetting liquid and forming flying droplets.

(2) Background technology The inkjet recording method (liquid jet recording method) is capable of high-speed recording, in that the noise generated during recording is extremely small to the extent that it can be ignored, and in addition, it uses a special process of fixing on so-called plain paper. Recently, there has been particular interest in the ability to perform recording without the need for.

Recording devices used in inkjet recording methods, especially on-demand inkjet recording devices, do not require high voltage generators or waste ink recovery devices that are required in continuous inkjet recording devices, and can be made smaller. Therefore, its application in many fields is considered promising.

However, one of the practical problems with this on-demand type inkjet recording apparatus stems from the liquid, generally ink, used for recording. The physical properties of such liquids, such as viscosity, usually change with temperature. The temperature of the liquid in the inkjet recording head (hereinafter referred to as the recording head) used in the above device changes with changes in the environmental temperature, etc., and such temperature changes cause the physical properties of the liquid to change as described above. ,
This appears as changes in the size of the ejected droplets that are formed,
This may lead to phenomena such as changes in the recording dots on the recording medium, and problems such as the inability to obtain good image recording if the environmental temperature falls outside a certain temperature range.

Conventionally, in order to solve such problems, heating means such as heaters and detection means for detecting temperature such as thermocouples or thermistors (hereinafter referred to as temperature detection means) have been used.
A method has been used to control the temperature of the liquid to a certain predetermined temperature using Recording heads that perform this type of temperature control are roughly divided into two types.The first type uses a temperature sensing means such as a thermocouple or thermistor installed outside the recording head to detect the environmental temperature. This determines the power to be applied to a heating means such as a heater, and the second type is one that installs a temperature detection means in the liquid to be discharged, detects the liquid temperature, and determines the power to be applied to the heater. . Typical examples of these recording heads are shown in FIGS. 1 and 2. 1st
The figure shows an example of a first type of recording head, and FIG. 2 shows an example of a second type of recording head, and is a schematic vertical cross-sectional view of the recording head for explaining the outline of the configuration. In the following description, the heating means and the temperature sensing means will be mainly discussed, and the description of the entire recording head will be omitted.

In FIGS. 1 and 2, reference numerals 106 and 206 respectively indicate heaters serving as heating means, and numerals 105 and 205 respectively indicate temperature sensors serving as temperature detecting means.

In FIG. 2, temperature sensor 205 is provided in direct contact with the liquid for the purpose of directly sensing the temperature of the liquid within reservoir 204. On the other hand, in Figure 1,
A temperature sensor 105 is provided outside the liquid reservoir 104 to measure the environmental temperature of the print head.

Of these two types, the first type detects the environmental temperature outside the print head to determine the power applied to the heater, but the environmental temperature and the temperature of the liquid inside the print head do not necessarily match. First, especially when the recording device is used intermittently, that is, when the switch is turned on and off after a certain period of time, the temperature of the liquid may be considerably higher than the outside air temperature due to, for example, the difference in heat capacity between the liquid and the outside air. I don't struggle,
Heat is generated in the heater according to the outside temperature, and phenomena such as the temperature of the liquid becoming higher than the target temperature occur.
Problems such as the fact that the original purpose of controlling the diameter of the ejected dots cannot be carried out with high accuracy may occur. In addition, in the second type of method in which a temperature detection means is provided in the liquid to be discharged to detect the liquid temperature and determine the power to be applied to the heater, the liquid temperature cannot be controlled because the liquid temperature is directly detected. Although it can be done with high precision, the dye used in the recording liquid itself is an electrolyte, and it also contains Na'', Ca'', and C.
Because it contains impurities such as l-, SO42-, etc., the recording liquid becomes an electrolyte solution, which corrodes the metal parts of temperature sensors such as thermocouples and thermistors used as liquid temperature detection means, reducing the reliability of the sensor. This caused problems such as deterioration. In order to prevent this, treatments such as enclosing the temperature sensor in glass or coating it with Teflon have been used, but this increases the cost and makes real-time control difficult because the heat capacity of the temperature sensor increases. There were drawbacks such as:

(3) Disclosure of the Invention The present invention has been made in view of the above points, and its main object is to provide a recording head that can accurately control temperature and is highly reliable.

The above object of the present invention is achieved by the following recording head.

In a recording head having a droplet forming means provided for ejecting a liquid and forming ejected droplets, and a heating means for heating the liquid, a temperature sensing unit filled with a liquid not containing an electrolyte is provided. A recording head characterized in that it has a detection means for detecting the temperature of liquid within the unit.

(4) Best Mode for Carrying Out the Invention The present invention will be described in detail below with reference to the drawings.

FIG. 6 shows a first embodiment of the recording head according to the present invention, and is a three-sided view for explaining the general configuration thereof. In order to accurately control the temperature, the recording head of this example has two droplet forming means of the recording head shown in FIGS. 1 and 2 in parallel, and a temperature sensing means is provided on one of them. This is designed to be used as a temperature detection unit.

In FIG. 3, A and B are droplet forming means, each having an orifice 301. It is composed of an energy generator 602, a liquid flow path 303, and a liquid reservoir 304. These components have the same configuration except that a temperature sensor 305 as a temperature detection means is provided in the liquid reservoir 304 of the droplet forming means B.
That is, although the shapes and materials are the same, the droplet forming means B provided with the temperature sensor 305 is used as a temperature detection unit and is not used for recording. The temperature sensor 305 is provided in the droplet forming means B so as to be in direct contact with the liquid filled in the liquid reservoir 304 thereof. 306 is a heater serving as a heating means;
A part of the wall constituting the liquid reservoir 304 of the droplet forming means A and B,
That is, it is provided outside the liquid reservoir bottom wall 309 in a manner that A and B share the same.

The droplet forming means A and B are used with two functions separated, one for recording and one for temperature detection. In A, ejecting liquid and recording on a recording medium such as paper is performed, and in B, only temperature measurement is performed. Therefore, the energy generator 302 at B is not actually activated. Furthermore, since the liquids used for A and B have different properties, it is necessary that they do not mix.

In this example, a part of the wall constituting each liquid reservoir 604,
That is, by separating the liquid reservoir side walls 308 (in this example, they are of a shared type), the liquids filled in each side are prevented from mixing.

A recording liquid such as ink is supplied from a supply port (not shown) to the liquid reservoir 304 in the droplet forming means A used for recording. As a supply means, it is possible to use methods that are generally widely used in these technologies,
Among these, a type that can control the height of the liquid level 307 in the liquid reservoir 604 to a desired position is preferable. On the other hand, a liquid that does not contain an electrolyte, such as glycols such as ethylene glycol, is supplied from a supply port (not shown) to the liquid reservoir 304 in the droplet forming means B used for temperature detection. The height of 307 is preferably the same as that of A, and the shape of the supply port is also preferably the same as that of A. The liquid used in step B must not contain an electrolyte as described above, but it is preferable to use a liquid whose specific heat is the same as that of the liquid used for recording. In addition, it is preferable to use the same method as in A as the supply means in B, but since it is not used for recording, it should be filled to a predetermined level in advance, and if the amount greatly deviates from the predetermined level. It may also be in the form of refilling the liquid.

The temperature of the liquid is determined by a temperature sensor 30 serving as temperature detection means.
5 and a heater 306 serving as heating means, the temperature is controlled to a predetermined temperature. The recording head of the present invention is characterized in that it includes a temperature detection unit filled with a liquid that does not contain an electrolyte, and a detection means that detects the temperature of the liquid in the unit. Accordingly, the object of the present invention can be achieved. Therefore, it is not necessarily necessary that the temperature detection unit be placed in parallel with the recording unit or that the shapes of both units be the same, but in the recording head of this example, the droplet forming means A Since the configurations of and B are almost the same, the heat vomiting of both is almost the same.Furthermore, by making the specific heat of the liquid filling both the same, even if there is a change in the environmental temperature of the recording head, etc. The temperature of the liquid filling B undergoes almost the same change. Therefore, by detecting the temperature of B and controlling the temperature using the heater 306 based on this, the temperature of the recording liquid filled in A can be adjusted to the optimum temperature for recording even if there are changes in the environmental temperature, etc. It is possible to precisely control the temperature. In order to perform such precise temperature control, it is preferable that the droplet forming means of the recording head and the temperature detection unit main body have the same structure as in this example.

In addition, although the temperature detection means must be a method that directly detects the temperature of the liquid as described above, by using a liquid that does not contain electrolyte as the liquid used for temperature detection, the temperature detection means does not contain any electrolyte. For example, there is no need to treat the temperature sensor 305 with Teflon coating or the like as described above, and therefore the cost of the temperature sensor 305 can be reduced, and furthermore, the heat capacity of the temperature sensor 605 can be reduced. This makes real-time temperature control possible.

In the above example, there are two droplet forming means, one for recording and one for temperature measurement, but it is also possible to use two or more droplet forming means for recording. It is possible, and it is also possible to use two or more droplet forming means for temperature measurement. Furthermore, it is also possible to use one or more membrane droplet forming means for the orifice, liquid flow path, and energy generator in one discharged droplet forming means.

FIG. 4 shows a second embodiment of the recording head according to the present invention, and is a three-sided view illustrating the general configuration thereof. The recording head of this example has a configuration in which the energy generator of the M droplet forming means used for temperature measurement in the recording head of FIG. 3 has been removed for the purpose of cost reduction.

In order to perform accurate control, it is preferable that the droplet forming means used for recording and the droplet forming means used for temperature measurement have the same configuration as shown in FIG. Among the components of the droplet forming means B used for temperature measurement as in this example, even if those having a relatively small heat capacity, such as the energy generator 402, are removed, the object of the present invention can be sufficiently achieved. Is possible. The present invention can be applied not only to commonly known energy generating bodies such as electromechanical transducers and electrothermal transducers, but also to recording heads that utilize electrostatic attraction and electromagnetic waves.

As described above, the present invention makes it possible to provide a highly reliable recording head that is capable of precise temperature control and that can perform stable recording over a long period of time.

[Brief explanation of the drawing]

1 to 2 are schematic vertical cross-sectional views of a conventional recording head, and FIGS. 6 to 4 are embodiments of a recording head according to the present invention. It is a three-sided view. 101.201.301.401... Orifice 1
02, 202, 302, 402... Stingray, Lugi Generator 103.203.3 [16,403...
Liquid flow paths 104, 204, 604, 404...
Liquid reservoir 105.205.305.405... Temperature sensor 106.206.306.406... Heater 307, 407... Liquid level 308, 408... Liquid reservoir side wall 309, 409. ...Liquid reservoir bottom wall A, B ...Salmon droplet forming means Patent applicant: Canon Co., Ltd. Figure 1 Figure #I2 Figure 3 Figure 4

Claims (1)

[Claims] A temperature sensing unit filled with a liquid that does not contain an electrolyte in a liquid ejection recorder having a droplet forming means provided for ejecting a liquid and forming ejected droplets, and a heating means for heating the liquid. What is claimed is: 1. A liquid jet recording head, characterized in that the unit is provided with a detecting means for detecting the temperature of the liquid within the unit.