JPH0466702B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a recording head used in a liquid jet recording device, and in particular to a method of ejecting droplets suitable for use in devices such as liquid jet copying machines and facsimile printers. The present invention relates to a method of manufacturing a liquid jet recording head.

Non-impact recording methods have recently attracted attention because the noise generated during recording is so small that it can be ignored. Among these, the so-called inkjet recording method is an extremely powerful recording method that enables high-speed recording and does not require special processing such as fixing on so-called plain paper. Until now, various methods have been proposed and devices to realize them have been devised, and some have been improved and commercialized, while others are still being worked on to put them into practical use. be.

Among them, for example, the liquid jet recording method described in Japanese Patent Application Laid-Open No. 54-51837 and German Opening Publication (DOLS) No. 2843064 applies thermal energy, which is droplet formation energy, to the liquid. It has a different feature from other liquid jet recording methods in that it obtains the motive force for ejecting droplets.

That is, in the recording method disclosed in the above-mentioned publication, the liquid subjected to the action of thermal energy undergoes a state change accompanied by a sharp increase in volume, and the acting force based on this state change causes the recording head portion to Droplets are ejected from the orifice at the tip, fly, and adhere to the recording member to perform recording.

In particular, the liquid jet recording method disclosed in DOLS 2843064 is not only very effectively applicable to the so-called drop-on demand recording method, but also can be easily applied by making the recording head part a full line type with high density multi-orifices. Since it can be realized, it has the advantage of being able to obtain high-resolution, high-quality images at high speed.

In this way, the liquid jet recording method described above has excellent features, but in order to record high-resolution, high-quality images at higher speeds, it is necessary to Flight speed and volume must be uniform.

The factors that determine the flying speed and volume of droplets ejected in the recording head applied to the above recording method are the amount of thermal energy acting on the liquid as droplet formation energy and the liquid flow path such as the orifice. The shape of To explain this point using a diagram, a recording head applied to the above recording method has a plurality of heat generating structures as shown in FIG. 1, for example. In the figure, electricity is used as a means of generating energy for flying droplet formation.
The heat converter 102 is in contact with the liquid introduced from arrow A through a heat action surface 109 as an energy action surface in a heat action section 107 which is a droplet formation energy action section. Such a configuration is adopted for the purpose of causing the generated thermal energy as droplet formation energy to act effectively and efficiently on the liquid in the heat acting section 107.

For this reason, although it depends on the recording liquid used, when using a recording liquid that uses ordinary water as a liquid medium, it is necessary to prevent electrical leakage between the electrodes 113 and 114 through the recording liquid. and heating resistance layer 1
A top layer 112 is formed during head fabrication to protect head 11 from the recording liquid and from thermal oxidation. At this time, it is also formed on the portion of the resistance layer in the heat generating section 108, that is, on the heat generating resistor section that performs electrical/thermal conversion.

The principle of droplet formation in the recording method using such a recording head is that, as mentioned above, when electricity is turned on to the electricity-to-thermal converter, heat is generated under the action of thermal energy, which is the droplet formation energy. The recording liquid in the heat acting part 107 undergoes a state change accompanied by a sudden increase in volume, that is, the recording liquid in the heat acting part 107 reaches a vaporized state within a very instant of about μsec or less, and the recording liquid in the heat acting part 107 reaches a vaporized state within a very instant of approximately μsec or less. At this time, bubbles are generated and grow instantaneously, and the heat acting part 107 and orifice 1
05 is ejected as droplets.

The magnitude of the thermal energy given to the recording liquid in the heat acting section 107 is determined by the surface area, thickness, specific resistance, and heat generating section of the heat generating resistor section, which is a resistance layer, at the position of the electrothermal converter that performs electrical/thermal conversion. 108 and its vicinity, but in actual head manufacturing, it is difficult to form these factors completely uniformly in each heat generating part 108 corresponding to a multi-orifice, and at the same time it is difficult to form a highly uniform heat generating part 108 corresponding to a multi-orifice. Requiring high performance from these components lowers the manufacturing yield of heads and increases manufacturing costs. Furthermore, for the same reason, it has been difficult to always supply recording heads with the same ejection characteristics.

This point is solved by the multi-orifice type, which uses a piezo element as an energy generating means for flying droplet formation, as disclosed in, for example, Japanese Patent Application Laid-open No. 47-2006 and Japanese Patent Application Laid-Open No. 48-9622. It is necessary to compensate for variations in the electrical characteristics of the piezo elements, which also occur in liquid jet recording heads.

The present invention has been made in view of this point, and includes:
Faster and with higher resolution than before,
The object of the present invention is to provide a method for manufacturing a liquid jet recording head that can record images of higher quality.

In order to achieve the above-mentioned object, the present invention was developed by examining the orifice of the recording head from various angles, actually designing and manufacturing a wide variety of recording heads, and repeatedly conducting experiments from various angles. It was discovered that the flying speed and volume of the droplet ejected from the heater vary depending on the electrical energy given to the heating resistor, and by controlling the given electrical energy, the droplet can be kept within a certain allowable range. This was based on the discovery that it is possible to maintain the droplet flying speed and its volume.

The present invention has discovered that the problems in manufacturing a recording head that performs recording using thermal energy are variations in the resistance values of various parts and the complexity of the manufacturing process. This simplifies the process, simplifies the correction of resistance values during the manufacturing process, and makes it possible to correct variations reliably and easily.

The method of manufacturing a recording head using thermal energy according to the present invention includes a plurality of heat generating resistors that generate heat when electrical energy is supplied thereto, and a method for supplying electrical energy to the heat generating resistors. A method for manufacturing a recording head using thermal energy, which includes electrodes provided corresponding to each of the plurality of heat generating resistor sections, comprising the steps of: forming a resistive layer on a substrate; and forming an electrode on the resistive layer. a step of laminating, and removing at least a part of the electrode,
The plurality of heat generating resistors and a current adjustment resistor for adjusting the amount of current flowing through the heat generating resistors,
The step of forming one of the current adjusting resistors to correspond to each of the heat generating resistors, and the step of forming the resistance value of the current adjusting resistor in order to match the recording characteristics of each of the heat generating resistors. The second invention is characterized by having a step of making variable adjustment by trimming, and the second invention is characterized by having a plurality of flow channels having orifices, and a flow channel provided corresponding to each flow channel and to which electrical energy is supplied. The heating resistor has a plurality of heat generating resistors that generate heat by heating, and an electrode provided corresponding to each of the heat generating resistors to supply electrical energy to the heat generating resistor. In a method of manufacturing a recording head,
a step of forming a resistance layer on the substrate, a step of laminating an electrode on the resistance layer, and removing at least a part of the electrode to form the plurality of heat generating resistor parts,
forming a current adjusting resistor for adjusting the amount of current flowing through the heating resistor so that one of the current adjusting resistors corresponds to each of the heating resistors, and the heating resistor The present invention is characterized by comprising the step of variably adjusting the resistance value of the current adjusting resistor by trimming in order to match the liquid ejection characteristics of each of the above.

According to the manufacturing method of the first and second inventions of the present invention having such characteristics, by removing a part of the electrode laminated with the resistance layer on the substrate, the current adjustment resistor and Because it forms a heat generating resistor,
There is no need to create a new connection process to connect the heat generating resistor and the current adjustment resistor, and it is possible to eliminate variations in the connection member itself and the electrical contact, so the modification process using this resistor is This has the effect of shortening the correction time required and allowing corrections to be made with high accuracy. Therefore, there is an advantage that the manufacturing cost of the recording head can be significantly reduced.

Conventionally, in a multi-orifice head that has a plurality of flow channels each having a liquid ejection orifice and a heating resistor section provided corresponding to each flow path, droplets ejected from each orifice of the recording head are Recording heads with non-uniform discharge characteristics (discharge conditions) and unsuitable for recording high-quality images also occurred during the manufacturing process, resulting in poor yields.However, in the second invention, the recording head The ejection characteristics (ejection state) of droplets from each orifice can be adjusted uniformly, which improves the yield in manufacturing recording heads and contributes to lower prices.

Note that in the recording head manufactured by the above manufacturing method, the amount of heat generated by the electrothermal transducer and the heat generation temperature are of course uniformized with high precision, so recording with thermal energy can be stably performed. It can be carried out. In particular, in a recording head that ejects liquid using thermal energy, the volumes and flight speeds of droplets ejected from each orifice can be made uniform, allowing high-resolution, high-quality images to be recorded at high speed.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 2a is a schematic plan view of the electrothermal converter of a liquid jet recording head to which the present invention is applied, seen from the surface side, and FIG. 2b is a portion indicated by a dashed line XY in FIG. FIG. 3 is a schematic cross-sectional view when cut.

The recording head shown in the figure is a grooved plate in which a predetermined number of grooves of a predetermined width and depth are provided at a predetermined linear density on the surface of a substrate 201 on which an electrothermal transducer 205 is provided. This grooved plate has a structure in which a liquid flow path of a liquid discharge part including an orifice for ejecting liquid and a heat acting part is formed by joining so as to cover the second grooved plate. It is omitted in FIG. 2b, and is virtually indicated by a dotted line in FIG. 2b.

The diagonal area surrounded by the dashed line in the figure is the area that becomes the recording liquid flow path and the common liquid chamber, and the upper protective layer 2
04 is formed. The electrothermal converter 205 includes a lower layer 202 provided on the substrate 201, and the lower layer 2
02, and an upper protective layer 204 provided on the heating resistor.

A resistor 206 for current adjustment, which is part of the resistor layer 203, is placed on the substrate 201 at a location away from the electrothermal converter 205 and where the grooved plate is not provided.
One end of the resistor 206 and one end of the heating resistor of the electrothermal converter 205 are electrically connected in series through a wiring conductor 207 serving as an electrode laminated with the heating resistor layer. There is. One end of a wiring conductor 208 as an electrode is provided at the other end of the heat generating resistor portion of the electrothermal converter 205.
An electrode pad 210 is formed at the other end of the wiring conductor 208. The other end of the resistor 206 is connected to an electrode pad 211 via a wiring conductor 209 laminated with the resistor layer. Now, when a pulse voltage is applied to the parts 210 and 211 by the driving power source, the heat generating resistor part of the electrothermal converter 205 generates heat depending on the value of the current passing therethrough, and the temperature of the heat acting surface 212 rises. , the current value in this case is determined by the circuit resistance from the pad 210 to the pad 211. Therefore, by trimming the resistor 206 using a mechanical, physical, or chemical method such as laser diamond cutting, sandblasting, or anodizing, the current flowing through the electrothermal converter 205 can be reduced and the temperature of the heat generated can be lowered. can.

FIG. 3 shows an example of a resistance trimming method for keeping the surface temperature of the heat acting surface of the electrothermal transducer of the recording head at a constant value according to the present invention. When a pulse voltage is applied from the drive power source 304 to the recording head 301 (the grooved plate is not yet installed) through the lead terminals 307 and 308, the surface temperature of the electrothermal transducer 302 rises, but this surface temperature is compared to the infrared temperature. 305, and the converted electrical signal is sent to a laser trimming device 306.
The resistance value of the resistor 303 is changed by feeding back to the control unit of the resistor 303 and comparing it with an electric signal corresponding to a preset temperature, and controlling the scanning of the laser beam irradiated by the laser trimming device. As a result, the surface temperature of the electrothermal converter 302 is set to a predetermined value. By repeating this for each segment, it is possible to equalize the temperature of all the heat generating parts in one recording head, thereby making the heating state of the recording liquid uniform and increasing the flying speed of the droplets ejected from the orifice. and the volume will be uniform.

FIG. 4 shows another embodiment of the recording head resistor trimming method according to the present invention. When a recording liquid is introduced into a recording head 401 and an appropriate voltage pulse is applied from a drive power source 402 to an electrothermal transducer as shown in the figure, the recording liquid is ejected from an orifice 404 and flying droplets 405 are formed.
The flight speed of the formed droplet 405 is determined by the orifice 4.
Detected by a photocoupler 406 installed at the front of 04, the signal is used to control the laser trimming device 407, and the resistance value of the resistor 408 is adjusted to eject droplets at a preset flying speed. A recording head is manufactured that can be used.

In the recording head manufactured by detecting the flying speed of the droplet, controlling the laser beam so that it becomes constant, and adjusting the resistance value of the resistor 408, the grooved plate 409 is It is also possible to eliminate non-uniformity in discharge due to minute manufacturing variations in the shape of the groove or orifice.

Also, a transistor that drives the electrothermal converter,
In a multi-segment recording head equipped with diodes, etc., variations in the current flowing through the electrothermal transducer due to variations in those elements are also affected by the resistor 408.
It can be absorbed by trimming the
Not only can a recording head with uniform ejection of all segments be obtained, but it also eliminates the need to adjust the drive power supply section by replacing the head.

The present invention will be specifically described below with reference to Examples.

Example 1 _Two SiO layers (lower layer) were formed on an alumina substrate to a thickness of 5 μm by sputtering, then HfB ₂ was deposited as a resistance layer to a thickness of 1000 Å, aluminum was deposited to a thickness of 3000 Å as an electrode, and then selectively etched. 50μm× by removing a part of it
A pattern of a 200 μm heat generating resistor and a current adjusting resistor was formed. Next, _two SiO layers were deposited as a protective layer (top layer) to a thickness of 3500 Å by sputtering to form an electrical/thermal converter on the substrate, and then the width
A glass plate with grooves of 50 μm x 50 μm deep was bonded so that the grooves matched the electrical/thermal converter. Subsequently, the distance between the tip of the electric/thermal converter and the orifice is
A recording head was created by polishing the end face of the orifice to a thickness of 250 μm. While supplying ink mainly composed of black dye and water to this recording head,
Figure 4 shows the flight velocity U of droplets ejected from 32 orifice segments when a 38V rectangular voltage pulse printing signal is applied at a cycle of 1mS for each segment number N every two segments. It is.

FIG. 5a shows the results when trimming for speed adjustment was not performed, and the variation in flight speed was approximately ±20%. Next, the speed of the droplet ejected from each orifice is detected, and the droplet flight speed of the other segments is trimmed with a laser beam so that the speed of the droplet ejected from each orifice is the same as that of the droplet with the slowest speed. By trimming, as a result of increasing the alignment voltage to 40V and driving, the droplet flying speed of each segment was ±5 as shown in Figure 5b.
It was down to %. Images recorded with a recording head without trimming adjustment deteriorated in image quality when the recording head was moved for high-speed recording, but with a recording head in which the ejection condition of each segment was made uniform through trimming as described above, high-speed scanning was achieved. No deterioration in image quality was observed even after this.

[Brief explanation of drawings]

Figures 1a and 1b are for explaining the structure of the recording head according to the present invention, and Figure 1a is
A schematic front partial view, FIG. 1b is a schematic cross-section partial view taken along the dashed line XY in FIG. 1a, and FIGS. 2a and b are records obtained by the present invention. This figure is for explaining the structure of the head. Figure 2a is a schematic plan view, and Figure 2b is a schematic cross-section taken along the dashed line X'Y' in Figure 2a. Figure 3 is a schematic explanatory diagram for explaining the first method of the present invention, Figure 4 is a schematic explanatory diagram for explaining the second method, Figure 5a, Figure 5 b is an explanatory diagram for explaining the results in the examples of the present invention. 101... Recording head, 102... Electrothermal converter, 103... Substrate, 104... Grooved plate, 105
... Orifice, 106 ... Liquid discharge part, 107 ...
...Heat acting part, 108... Heat generating part, 109... Heat acting surface, 110... Lower layer, 111... Resistance layer,
112... Upper layer, 113, 114... Electrode layer,
201...Substrate, 202...Lower layer, 203...
Resistance layer, 204... Upper layer, 205... Electrothermal converter, 206... Resistor, 207, 208... Wiring conductor, 210, 211... Electrode pad, 301
... Recording head, 302 ... Electrothermal converter, 30
3...Resistor, 304...Drive power supply, 305...
Infrared thermometer, 306...Laser trimming device, 401...Recording head.

Claims (1)

[Scope of Claims] 1. A plurality of heat-generating resistors that generate heat when electrical energy is supplied, and a heat-generating resistor that corresponds to each of the plurality of heat-generating resistors for supplying electrical energy to the heat-generating resistors. A method for manufacturing a recording head using thermal energy, comprising: forming a resistive layer on a substrate; laminating an electrode on the resistive layer; and at least a portion of the electrode. by removing the plurality of heat generating resistors and a current adjusting resistor for adjusting the amount of current flowing through the heat generating resistors, one of the current adjusting resistors is attached to each of the heat generating resistors. and a step of variably adjusting the resistance value of the current adjusting resistor by trimming in order to match the recording characteristics of each of the heat generating resistors. A method of manufacturing a recording head that utilizes thermal energy. 2. In the variable adjustment step, electric energy is applied to the heating resistor to generate heat, and the temperature near the heating resistor is detected, and trimming is performed using a laser beam in accordance with the detected temperature. A method of manufacturing a recording head using thermal energy as set forth in claim 1. 3 A plurality of flow channels having orifices, a plurality of heat generating resistors that are provided corresponding to the respective flow channels and generate heat when supplied with electrical energy, and a plurality of heat generating resistors that generate heat when electrical energy is supplied to the heat generating resistors. A method for manufacturing a recording head using thermal energy, comprising: an electrode provided corresponding to each of the heat generating resistor sections to provide a resistance to the heat generating resistor; a step of stacking electrodes on the heat generating resistors, and removing at least a part of the electrodes, and removing the plurality of heat generating resistor parts and a current adjusting resistor for adjusting the amount of current flowing through the heat generating resistor parts. forming one of the current adjusting resistors so as to correspond to each of the heating resistors; and adjusting the resistance value of the current adjusting resistor in order to match the liquid ejection characteristics of each of the heating resistors. A method for manufacturing a recording head using thermal energy, comprising: a step of variably adjusting the recording head by trimming. 4. In the variable adjustment step, electric energy is applied to the heat generating resistor to generate heat, and the temperature near the heat generating resistor is detected, and trimming is performed using a laser beam in accordance with the detected temperature. A method of manufacturing a recording head using thermal energy according to claim 3, wherein the method comprises: 5. The variable adjustment step includes manufacturing a recording head that ejects liquid from the orifice using heat generated by the heat generating resistor, and then ejecting the liquid by applying electrical energy to each of the heat generating resistors. 4. The method of manufacturing a recording head using thermal energy according to claim 3, wherein the current adjusting resistor is trimmed so as to equalize the ejection speed of the ejected droplets.