JPH08216411A - Thermal head substrate for thermal ink jetting and driving method thereof - Google Patents

Abstract

PURPOSE: To reduce occupying areas of elements and reduce the cost by connecting heating bodies of a first layer of a two-layer heating body of a plurality of ink discharge channels to one or more of common electrodes respectively, and connecting heating bodies of a second layer in a state independently driven respectively. CONSTITUTION: Heating bodies 2a-2x of a first layer are connected to first layer heating body common electrodes A4 and B5 in parallel. The common electrode A4 is connected to a driver at the outside of a thermal head substrate 1. The common electrode B5 is connected to a driving power source through a stabilizing resistance at the outside of the substrate 1. A second layer heating body common electrode 7 is connected to the driving power source through the stabilizing resistance at the outside of the substrate 1. Accordingly, the heating bodies 2a-2x of the first layer of a plurality of ink discharge channels are driven regardless of whether a liquid is to be discharged or not and only heating bodies 3a-3x of the second layer relating to a channel which lets out the liquid of the heating bodies of the second layer are driven. Thus, ink discharge can be controlled by energy control of smaller heating bodies.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal ink jet thermal head substrate and a method for driving the thermal ink jet substrate. For example, a thermal ink jet thermal head substrate for ejecting liquid from an orifice by the action of thermal energy for recording and a thermal ink jet thermal head substrate. It relates to a driving method.

[0002]

2. Description of the Related Art Conventionally, non-impact recording methods have been of particular interest in that noise during recording is extremely small to a negligible extent. inside that,
The inkjet recording method, which enables high-speed recording and can perform recording without requiring a special fixing process on plain paper, is an extremely effective recording method, and various methods have been proposed so far. The inkjet recording method is one in which a small droplet of a recording liquid called ink is ejected and adhered to a recording member to perform recording. The recording liquid is classified into several methods according to the generation method thereof.

The so-called bubble jet recording method is a method in which ink in a heat acting portion is rapidly heated and vaporized by a heating element, and a small droplet of ink is ejected from an orifice by the pressure of bubbles generated. The generated air bubbles are cooled by the surrounding ink, and the vapor of the ink in the air bubbles condenses and returns to the liquid, so that they disappear at last. The ink consumed by the ejection is replenished from the ink reservoir through the ink flow path by the capillary force of the ink that acts on the ink mechanism retracted into the orifice.

Listed below are examples of publications related to the technical field of the present invention. In Japanese Patent Laid-Open No. 4-369544, ink can be selectively ejected using a common pressure generating member.

Japanese Unexamined Patent Publication No. 2-217253 discloses an ink jet recording apparatus in which a discharge heater chip and a driver can be easily separated, a low-cost disposable recording head is provided, and recording modes can be diversified. It is intended to be provided.

Japanese Laid-Open Patent Publication No. 61-266253 aims to provide a method of driving a thermal ink jet printer having high printing quality by increasing the printing speed by increasing the density and using multiple nozzles.

[0007]

One method for performing high-speed recording is to increase the ejection frequency of ink droplets ejected from the orifice. For this purpose, the ink consumed by ejection is ejected from the orifice. It is necessary to replenish the parts at high speed. However, replenishment of ink to the orifice portion is performed by the surface tension of the ink meniscus portion,
There is a limit to speeding up. Therefore, as another measure, the number of ejection channels incorporated in the print head, that is, the number of so-called nozzles has been increased.

When the number of nozzles is small, for example 50 or less, each nozzle often has one driver. However, when the number of nozzles is large, for example, when the number of nozzles exceeds 50, it is costly to allocate one driver to each nozzle. Further, particularly in the case of a disposable type cartridge, the number of contacts for electrical connection increases, which not only reduces reliability, but also places the contacts in the first place. Therefore, a method is adopted in which the heaters are divided into several groups and the required number of drivers and the number of contacts are reduced by so-called matrix connection.

When the matrix connection is performed, a backflow prevention diode is required for each heater in order to avoid secondary driving of other heaters by bypassing the current. In general, the thermal ink jet substrate uses a silicon wafer that has good thermal conductivity and excellent flatness. Therefore, a backflow prevention diode and a driver transistor are simultaneously formed on this substrate. Crowding is done.

In principle, the thermal ink jet requires rapid heating of the ink, and its heat generation rate is
It is approximately 1 kW / mm ² or more. For example, 300 dp
In the case of the head for i, the size of the thin film resistor is about 60μ.
m × 60 μm, and its resistance value is about 23Ω, so that the current value reaches about 400 mA. The area of the diode capable of handling a current of 400 mA requires 10 ⁴ μm ² or more, which is larger than the area of the heater itself. On the other hand, since the silicon process is performed on a wafer-by-wafer basis, the cost of the thermal head substrate used for the head is
It is determined by the number of substrates taken per wafer and the yield. Therefore, the fact that the diode portion occupies a large area means that the number of substrates to be taken is reduced, and there is a problem that the cost becomes high.

An object of the present invention is to provide a low cost thermal head substrate for a thermal ink jet and a driving method thereof.

[0012]

In order to achieve the above object, the thermal ink jet thermal head substrate of the present invention has a heating element formed therein, and a liquid is ejected from an orifice by the action of thermal energy generated by the heating element to record. A thermal head substrate for a thermal inkjet used in an inkjet print head for carrying out the above, wherein a heating element having a two-layer structure is formed for each ink ejection channel of a plurality of ink ejection channels, and a first layer of the heating element having a two-layer structure is formed. The heating element of the first layer is connected to one or more common electrodes, and the heating element of the second layer of the heating element of the two-layer structure is driven independently of the heating element of the second layer. It is characterized in that it is connected to and configured.

The second layer heating element may be formed in a matrix.

A method of driving a thermal ink jet thermal head substrate according to the present invention is a method of driving a thermal ink jet thermal head substrate in which a heating element is formed and liquid is discharged from an orifice by the action of thermal energy generated by the heating element to perform recording. A method of driving a heating element of a first layer among heating elements of a two-layer structure formed for each ink ejection channel of a plurality of ink ejection channels, regardless of whether or not liquid is ejected. One-layer heating element driving step and second-layer heating element driving step of driving only the second-layer heating element related to the channel for discharging the liquid of the second-layer heating element in the two-layer heating element And a step of driving the heating element of the first layer, which has an energy smaller than the energy required for ejecting the liquid, and a second energy lower than the energy required for ejecting the liquid. In the heating element driving step, the energy required for ejection of the liquid - greater energy - by generating, and performs recording by ejecting liquid from the orifice.

The heating element driving step for the first layer produces energy which is approximately 1/2 of the energy required for ejecting the liquid, and the heating element driving step for the second layer produces the energy required for ejecting the liquid. It is good to generate the energy of about 1/2 of −.

[0016]

Therefore, according to the thermal head substrate for thermal ink jet of the present invention and the driving method thereof, the heating element having the two-layer structure is formed for each ink ejection channel of the plurality of ink ejection channels, and the heat generation of the two-layer structure is performed. The heating elements of the first layer of the body are connected to one or more common electrodes, respectively, and the heating elements of the second layer of the heating element of the two-layer structure are connected to independent driving states. Therefore, the heating element of the first layer of the heating elements of the two-layer structure formed for each ink ejection channel of the plurality of ink ejection channels is driven regardless of whether or not the liquid is ejected, and Among the heating elements having a two-layer structure, only the heating element of the second layer that drives the liquid of the heating element of the second layer is driven. Ejection of the liquid is performed by driving the heating element of the first layer with energy lower than the energy required for ejecting the liquid and driving the heating element of the second layer with energy lower than the energy required for ejecting the liquid. Energy is generated which is greater than the energy required for.

[0017]

Embodiments of the thermal ink jet thermal head substrate and its driving method according to the present invention will be described in detail with reference to the accompanying drawings. 1 to 4, there are shown an embodiment of a thermal head substrate for thermal inkjet and a driving method thereof according to the present invention.

In the thermal ink jet thermal head substrate 1 of the present embodiment shown in FIG. 1, the first layer heating elements 2a to 2x, the second layer heating elements 3a to 3x, and the first layer heating element common electrode A4. In addition, the first layer heating element common electrode B5, the second layer heating element individual electrodes 6a to 6x, and the second layer heating element common electrode 7 are included. In addition, the first layer heating elements 2a to
2x and the heating elements 3a to 3x of the second layer are formed by being laminated on each other.

In the connection relation of each component, all the first
One of the layer heating elements 2a to 2x is connected to the first layer heating element common electrode A4 and the other is connected to the first layer heating element common electrode B5 to establish electrical conduction. One ends of the second layer heating elements 3a to 3x formed on the first layer heating element are all connected to the same second layer heating element common electrode 7, and the second layer heating elements 3a to 3x are connected.
The other end of 3x is connected to the second layer heating element individual electrodes 6a to 6x. These connection relationships are generally shown in FIG.

FIG. 2 is a circuit diagram showing the connection relationship between the thermal head substrate 1 and the drive circuit section of the thermal head substrate 1. In FIG. 2, the first layer heating elements 2a to 2x
Are configured to be connected in parallel with the first layer heating element common electrode A4 and the first layer heating element common electrode B5. The first-layer heating element common electrode A4 connected in parallel is connected to the driver 22 outside the thermal head substrate 1. The first-layer heating element common electrode B5 is connected to the driving power supply Vd via the stabilizing resistor 12 outside the thermal head substrate 1. The second layer heating element common electrode 7 is connected to the driving power supply Vd via the stabilizing resistor 13 outside the thermal head substrate 1.
The drive power supply terminal side to which the two stabilizing resistors 12 and 13 are connected is connected to the collector terminals of the drivers 93 and 94,
The application of the driving power supply Vd can be controlled. Further, the second layer heating element individual electrodes 6a to 6x connected to the other ends of the second layer heating elements 3a to 3x respectively pass through the diodes 16a to 16x formed on the thermal head substrate 1 and the thermal head substrate 1 It is connected to the outside drivers 100a to 100x.

In FIG. 2, diodes 16, 116, drivers 93, 94, 99, 10 not shown in FIG. 1 are shown.
0, 122, 193, 194, stabilizing resistors 12, 13,
112, 113, the power source Vd, and the heating element group 2a
-2x, 3a-3x different heating element groups 102a-102
x, 103a to 103x are also shown. Second layer heating element 1
03a to 103x are diodes 116a to 1 respectively.
It is connected to the drivers 100a to 100x through 16x, and the second layer heating elements are so-called matrix-connected. The size of both the first layer heating element and the second layer heating element is about 60.
The size is μm × 60 μm, the resistance value is about 25Ω, the stabilizing resistance is about 25Ω, and the power supply voltage Vd = about 14V. When the driver is turned on, a current of about 280 mA flows through the heating element.

Next, the operation of this embodiment will be described with reference to the drawings. When recording the pattern shown in FIG. 3, drive signals 94, 194 supplied to the terminals of FIG.
The driving timing of 101a to 101x, 99, and 199 is shown in FIG. The signal 900 indicates the basic clock for printing. The drive signals 94 and 194 are always turned on in synchronization with the basic clock for printing regardless of whether or not ink is actually ejected. However, the heat generated by the first heating element is about 500 W / mm ^2, which is about half the heat energy required for ink ejection, and this alone does not lead to ink ejection. The drive signals 101a to 101x, 99, and 199 form a matrix, and only the second layer heating element to be recorded is driven. Also in this case, the second layer heating element alone does not generate sufficient thermal energy for ejecting ink, but since the first layer heating element also generates heat in synchronization with the driving of the second layer heating element, the generated energy Are superimposed, and as a result, the energy required for ink ejection is supplied.

As described above, according to the present invention, each heating element has a two-layer structure. In one layer, a plurality or all of the heating elements are connected to a plurality of or one common electrode, and in the other one layer, each heating portion can be individually matrix-driven via a diode or a transistor. The heating element connected to the common electrode is driven with approximately ½ of the energy required for ejection at a drive timing determined regardless of whether or not those channels are ejected. The size of the diode or the transistor formed on the thermal head substrate can be reduced by driving the individual heat generating layers for only the channels to be ejected at the same time with about 1/2 of the energy required for ejection. For this reason,
The size of the thermal head substrate itself can be reduced.
In other words, there is an effect that the cost can be reduced.

The above embodiment is a preferred embodiment of the present invention, but the present invention is not limited to this embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0025]

As is apparent from the above description, in the thermal head substrate for thermal ink jet of the present invention and the driving method thereof, a heating element having a two-layer structure is formed for each ink ejection channel of a plurality of ink ejection channels. To be done. The heating elements of the first layer are connected to one or more common electrodes, and the heating elements of the second layer are configured to be driven independently. Thus, the first of the plurality of ink ejection channels
The heating element of the layer is driven regardless of whether or not the liquid is discharged, and only the heating element of the second layer related to the channel of the heating element of the second layer that discharges the liquid is driven. The driving of the heating element of the first layer and the driving of the heating element of the second layer with the energy smaller than the energy required for ejecting the liquid, the energy larger than the energy required for the channel relating to the liquid ejection. Is generated. By the separate driving by the two layers of heating elements, ink ejection can be controlled by controlling the energy of smaller heating elements.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of a thermal head substrate for thermal inkjet according to the present invention.

FIG. 2 is a diagram showing a circuit configuration example of a thermal ink jet thermal head substrate and a drive circuit unit of FIG.

FIG. 3 is a diagram showing an example of a recording pattern based on the thermal head substrate for thermal inkjet of FIG.

FIG. 4 is a diagram showing a timing example of a drive signal of the thermal head substrate for thermal inkjet of the embodiment.

[Explanation of symbols]

 1 Thermal Head Substrate 2a to 2x, 102a to 102x First Layer Heating Element 3a to 3x, 103a to 103x Second Layer Heating Element 4 First Layer Heating Element Common Electrode A 5 First Layer Heating Element Common Electrode B 6a to 6x 2 layer heating element individual electrode 7 2nd layer heating element common electrode 12, 13 stabilization resistance 16a-16x, 116a-116x diode 93, 94, 101a-101x driver

Claims (4)

[Claims] 1. A plurality of ink ejection channels in a thermal head substrate for a thermal ink jet used in an ink jet print head for performing recording by ejecting liquid from an orifice by the action of heat energy generated by the heat generating element. A heating element having a two-layer structure is formed for each of the ink ejection channels, and the heating element of the first layer of the heating element of the two-layer structure has one or more common electrodes on one or more common electrodes. The thermal head substrate for a thermal inkjet, wherein the heating elements of the second layer of the heating elements having a two-layer structure are connected to each other and are driven independently of each other. . 2. The thermal head substrate for thermal inkjet according to claim 1, wherein the heating elements of the second layer are arranged in a matrix. 3. A method of driving a thermal head substrate for a thermal ink jet, wherein a heating element is formed and liquid is ejected from an orifice by the action of thermal energy generated by the heating element to perform recording, and each of a plurality of ink ejection channels A first-layer heating element driving step of driving a first-layer heating element of a two-layer heating element formed for each ink ejection channel regardless of whether or not the liquid is ejected; A heating element driving step for driving only the heating element of the second layer related to a channel for discharging the liquid of the heating element of the second layer of the heating elements of the layer structure, The step of driving the heating element for the first layer, which is less than the energy required for discharging, and the step of driving the heating element for the second layer, which is less than the energy required for discharging the liquid. A method of driving a thermal head substrate for a thermal inkjet, wherein recording is performed by discharging the liquid from an orifice by generating energy larger than the energy required for discharging the liquid. 4. The heating element driving step for the first layer generates approximately half the energy required for ejecting the liquid, and the heating element driving step for the second layer ejects the liquid. 4. A method of driving a thermal head substrate for a thermal ink jet according to claim 3, wherein the energy required is about 1/2 of the energy required for the above.