JPH03208664A - Ink jet recording apparatus and ink jet recording head - Google Patents

Abstract

PURPOSE:To control the temperature of a recording head accuratly by providing heaters at two points in the vicinity of a discharge port and a temperature detecting means, and using the heaters separately to raise and maintaine the temperature. CONSTITUTION:There are provided four heaters for a recording head, namely, two front heaters HRU 7-1, HRL 7-2 in the vicinity of a discharge port, and two rear heaters HFU 7-3, HFL 7-4 further than the discharge port which become close to a thermistor 12 when a discharge element 1 is mounted to a recording head. These two heaters, front or rear, are connected with each other in parallel within the discharge element 1. When the recording head is heated, heating elements of the two systems are driven to speedily raise the temperature of the head. When the temperature of the recording head is to be maintained, only the heating element near the temperature detecting element 12 is driven. Accordingly, it is possible to catch up with the temperature rise when the temperature of the recording heat when it is raised is to be detected. As a result, an overshoot of the temperature, for example, when the temperature is to be maintained is lessened, making it possible to control the temperature with high accuracy without generating the density irregularity during recording.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording device and an inkjet recording head, and particularly to an inkjet recording device that controls the temperature of the recording head.

[Prior Art] In an inkjet recording device, the ejection characteristics of ink droplets, particularly the diameter of ejected ink droplets, change depending on the ink temperature. In general, a print head tends to accumulate heat and increase ink temperature as it prints, and as a result, the diameter of ink droplets may change and the print density may change. For this reason,
Temperature control is performed to keep the print head temperature (ink temperature) constant so that the print density does not change due to the ink temperature.

In particular, the problem of ink temperature appears particularly in so-called bubble jet recording heads that heat ink to generate bubbles in the ink, and eject ink by changes in the bubbles.

As shown in FIG. 6, this type of recording head has a heater 17-1 for heating the head made of the same material as the heater 6 for ejection on a silicon substrate 2. 17-2 is provided near the discharge port. Further, as will be described later with reference to FIG. 2, the temperature of the recording head is detected by a thermistor (not shown in FIG. 6) arranged on the base plate in parallel with the ejection elements.

FIG. 7 shows that the heater 17-1. This is a conventional example of a control circuit for controlling the recording head temperature by controlling the power supply to the recording head 17-2. Based on this control configuration, temperature control has conventionally been performed, for example, as shown in the flowchart of FIG. 8.

As shown in FIG. 8, after turning on the power, steps 3801 to S
It is once heated to 25° C. by the process 804 and kept at 25° C. until a recording signal is input.

When the recording signal is input, steps 8805 to S807
The sample is heated to 32° C. before recording starts.

When the temperature reaches 32° C., recording is started through the processing of steps 8808 to S811, and the temperature is maintained at 32° C. during recording.

After determining the end of recording in step S812, the 25
Keep it warm at ℃ and wait for the next recording signal input.

[Problems to be Solved by the Invention] By the way, when controlling according to the control procedure shown in FIG. It is desirable that this heating time be as short as possible since it becomes a recording waiting time. Therefore, in the conventional heating heater, it was necessary to provide a large-capacity heater near the discharge port.

However, such a large-capacity heater is no longer necessary to maintain the temperature once heated to 25° C. or 32° C. Conversely, when keeping warm during recording, the time response of the temperature detection by the thermistor cannot keep up with the rapid heating by the large-capacity heater, so turning the heater on and off causes a significant temperature difference in the recording. There was a problem in that this appeared as a difference in recording density.

The present invention has been made based on the above-mentioned viewpoint, and includes providing heaters for heating the recording head at two points, one near the ejection port and one near the temperature detection means, and using the respective heaters separately when raising the temperature and when keeping the temperature. An object of the present invention is to provide an inkjet recording head and an inkjet recording apparatus that enable highly accurate temperature control.

[Means for Solving the Problems] To this end, the present invention provides an inkjet that includes an ejection energy generating element for generating ejection energy and performs recording by ejecting ink droplets from an ejection port using the ejection energy. The recording head includes a first heating element disposed near the ejection port for heating the recording head, a temperature detection element for detecting the temperature of the recording head, and a temperature detection element for detecting the temperature of the recording head from the first heating element. A second heating element is provided near the detection element for heating the recording head.

More preferably, an ejection port for ejecting ink droplets;
A recording head having an ejection energy generating element for generating ejection energy used to eject ink droplets from the ejection opening, and performs recording by attaching the ink droplets to a recording medium. In the inkjet recording apparatus, a first heating element disposed near the ejection port and for heating the recording head, a temperature detection element for detecting the temperature of the recording head, and a temperature sensing element for detecting the temperature of the recording head; a second heating element disposed near the temperature detection element for heating the recording head; and a second heating element for driving the first and second heating elements during heating to increase the temperature of the recording head; The apparatus is characterized in that the apparatus further comprises head temperature control means for driving the second heating element during heat retention to keep the temperature constant.

[Function] According to the above configuration, when heating the recording head, the head temperature can be quickly raised by driving two systems of heating elements, and when keeping the recording head warm, only the heating element near the temperature detection element is activated. By driving the head, it is possible to improve the followability of head temperature detection with respect to heating.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, and is a perspective view of an ejection element 1 which is a main part of a bubble jet recording head.

In FIG. 1, on a silicon substrate 2, an ejection heater 6 and a head heating heater 7-+( Hru),? -a(HrL). 7-s
(H+=u), 7-4 (HRL) is formed of a thin film of HfB2. These heaters are wired by aluminum electrode wires 8 to wire bonding pads 9 provided at the rear of the ejection element 1. A top plate made of photosensitive resin for forming the ink chamber 4 and orifice 5 is further laminated on the silicon substrate 2 coated with a thin film.

A glass plate in which a common liquid chamber 3 communicating with ink liquid chamber 4 is formed is bonded to this top plate.

FIG. 2 is a perspective view showing the main parts of the inkjet recording head 1l incorporating the ejection elements shown in FIG. It is bonded together with the printed wiring board 13 onto the base plate l4. Ink is supplied by an ink supply system (not shown) through an ink supply port IO formed in a glass plate constituting the common liquid chamber 3, as shown in FIG.

The ejection element 1 and thermistor 12 are arranged in parallel, and each wiring is electrically connected to the printed wiring board 13 by wire bonding 15 through each other's wire bonding pads. Furthermore, the recording head l1 is
It is connected to the recording apparatus main body through a connector terminal 16 provided at the rear thereof.

There are four heaters for heating the recording head, as shown in Figure 1, but two front heaters (HF
U7-,, HFL7-2), and two rear heaters (H
++u7-s, H++L? -4) is provided. These two heaters are each connected in parallel within the discharge element 1, and the heater electrodes wired to the discharge element 1 are one common for the four heaters, one each for the front heater and the rear heater, for a total of three electrodes. It becomes a book.

FIG. 3 is a circuit block diagram showing an example of a control circuit for these two systems of heaters and thermistor 12. Thermistor l2 and resistor R1 control the supply voltage vce (for example 5V
) is divided into voltages, and the voltage output is the A/D converter 20
The signal is input to the CPU 21 as a digital signal via the .

The CPU 21 reads the temperature based on this signal, and outputs the signals Hpu7-+, HrL7-i, HllU7--, H through heater drivers formed by transistors Tri and Tr2, respectively.
Drive FIL7--.

1 1 FIG. 4 is a flowchart showing an example of a heater control procedure. After the power is turned on, in steps S401 and S402, the four heaters of front heater Hru7-1, HFL7-2 (hereinafter referred to as H) and rear heater HRL17-8,}IRL7-4 (hereinafter referred to as H8) are driven. Heat to 25°C.

In this case, in order to obtain the same temperature rise time as the conventional recording head shown in FIG. 6, the number of heaters is doubled from 2 to 4, so the capacity of each heater is only %. Step 3
If it is determined in step S401 that the head temperature has reached 25° C., the driving of the front heater HF and rear heater HR is stopped in step S403.

Once the temperature is raised to 25°C, steps 8404 to S4
By the process 07, control is performed to keep the print head warm at 25° C. until a print signal is input. Here, since only heat retention is required, a large capacity of heat is not required, and only the rear heaters H and I are driven.

If it is determined in step S407 that the recording signal was manually generated,
In steps 3408 and S409, the front and rear four heaters HF and HR are fully driven to raise the temperature to 32°C, and when it is determined in step S408 that the temperature has reached 32°C, the front and rear heaters are heated in step S410. Rear heater H1H
, l is stopped and recording is started.

In step S411, a one-dot recording operation is performed at each ejection port, and each time this operation is performed, steps S412 to S41 are performed.
The head temperature is monitored and kept at 32° C. through the process in step 4. Here too, a large capacity is not required, so the rear heater H
, l only.

Rear heater HR. That is, heater 7-i, ? % of the capacity of the conventional heater, and since it is provided relatively close to the thermistor 12, the temperature detection by the thermistor can follow the heating by these heaters with good responsiveness. As a result, highly accurate temperature control is possible with less temperature overshoot during the heat retention mode, etc., and density unevenness does not occur during recording.

FIG. 5 is a perspective view showing another embodiment of the present invention. In this example, the head heater is attached to the base plate l4 from the back side.

In the figure, the discharge element 18 is of a type other than the bubble jet type, in which a heater can be easily provided inside. Therefore, in the head heating heaters H, 19-,, H, l19-2, HFl9-, is located near the discharge port on the back surface of the base plate, and HRl9-. H, 19- is provided in the center of the base plate closer to the thermistor 12 so that the entire base plate can be heated. The control procedures for these two systems of heaters are shown in Figures 3 to 4.
The control circuit and flowchart of the first embodiment shown in the figure can be applied as is.

(Others) The present invention brings about excellent effects particularly in a bubble jet type recording head and recording apparatus among inkjet recording types.

This is because such a system can achieve higher recording density and higher definition, and it is expected that the fixing speed will be even slower depending on the recording pattern.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, it is necessary to arrange the liquid (ink) in accordance with the sheet and liquid path that hold it. The electrothermal converter that is
Generating thermal energy in the electrothermal transducer and producing film boiling on the thermally active surface of the recording head by applying at least one drive signal that corresponds to recorded information and provides a rapid temperature rise above nucleate boiling. As a result, bubbles in the liquid (ink) can be formed in one-to-one correspondence with this drive signal, which is effective. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening (ejection port) to form at least one droplet. It is more preferable to use this drive signal in a pulse form, since the growth and contraction of bubbles can be carried out immediately and appropriately, making it possible to eject liquid (ink) with particularly excellent responsiveness. This pulse-shaped drive signal is described in US Pat. No. 4,463,359 and US Pat.
5262 is suitable. Incidentally, US Pat. No. 4,313,124 of the invention regarding the temperature increase rate of the heat acting surface 1 5
By adopting the conditions described in the specification, even better recording can be achieved.

The configuration of the recording head includes, in addition to the combination configuration of ejection ports, liquid channels, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, a heat acting section. The present invention also includes configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose configurations in which the bending area is arranged in a bending region. In addition, Japanese Patent Application Laid-Open No. 1989-5 discloses a configuration in which a common slit is used as a discharge part of a plurality of electrothermal converters.
No. 9-123670 and Japanese Patent Application Laid-Open No. 59/1989 which discloses a configuration in which a discharge portion is made to correspond to an opening that absorbs pressure waves of thermal energy.
- The effects of the present invention are also effective even with a configuration based on Publication No. 138461. In other words, regardless of the form of the recording head, recording can be performed reliably and efficiently.

Furthermore, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by a recording apparatus.

Such a recording head may have either a configuration in which the length is satisfied by a combination of a plurality of recording heads, or a configuration as a single recording head formed integrally. In addition, even serial type recording heads like the one above can be installed in the main body of the device, making it possible to electrically connect to the main body of the device and supply ink from the main body of the device.Replaceable chip-type recording heads Alternatively, the present invention is also effective when using a cartridge type recording head that is provided integrally with the recording head itself.

In addition, regarding the type and number of recording heads installed, for example, in addition to one type that corresponds to single-color ink, there is also a plurality of recording heads that correspond to multiple inks with different recording colors and densities. It may be something that can be done.

In addition, the inkjet recording apparatus of the present invention can be used as an image output terminal of information processing equipment such as a computer, a copying apparatus combined with a reader, etc., or a facsimile apparatus having a transmitting and receiving function. It may be something that takes .

[Effects of the Invention] As explained above, according to the present invention, the head temperature can be quickly raised by driving two systems of heating elements when heating the recording head, and the temperature detection element can be activated when keeping the recording head warm. By driving only the nearby heating elements, it is possible to improve the followability of head temperature detection with respect to heating.

As a result, it is possible to quickly raise the temperature, reduce temperature fluctuations during keeping warm during recording, and record without density unevenness.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an ejection element that is the main part of a print head embodying the present invention, FIG. 2 is a perspective view of a print head configured using the ejection element shown in FIG. 1, and FIG. , a circuit block diagram showing a control circuit for the heater and thermistor in the discharge element shown in FIG. 1, FIG. 4 is a flowchart showing a procedure for controlling the heater by the circuit shown in FIG. FIG. 6 is a perspective view of an ejection element showing a conventional example of the main part of the print head; FIG. 7 is a perspective view of the ejection element shown in FIG. FIG. 8 is a circuit block diagram showing the control circuit. FIG. 8 is a flowchart showing a heater control procedure by the circuit of FIG. 1, l8... Discharge element, 2... Silicon substrate, 3... Liquid chamber, 4... Ink liquid chamber, 5... Orifice (discharge port) 6... Discharge heater, 7- +, 7-z, 7-s. 7--, 19-+, 19-2
... Heater for head heating, 8 ... Aluminum electrode wiring, 9 ... Wire bonding pad, lO ... Ink supply port, l1 ... Recording head, l2 ... Thermistor, 13 ... Print Wiring board, 14... Base plate, l5... Wire bonding, l6... Connector terminal. JP-A-3 208664 (8) JP-A-3 208664 (10)

Claims (1)

[Scope of Claims] 1) An inkjet recording head that has an ejection energy generating element for generating ejection energy and performs recording by ejecting ink droplets from the ejection port using the ejection energy, the ejection port comprising: a first heating element disposed nearby to heat the recording head; a temperature detection element detecting the temperature of the recording head; disposed closer to the temperature detection element than the first heating element; and a second heating element for heating the recording head. 2) a recording head having an ejection opening for ejecting ink droplets and an ejection energy generating element for generating ejection energy used to eject the ink droplets from the ejection opening; An inkjet recording apparatus that performs recording by depositing ink droplets onto a recording medium, comprising: a first heating element disposed near the ejection port for heating the recording head; and a first heating element configured to detect the temperature of the recording head. a second heating element disposed closer to the temperature detection element than the first heating element and for heating the recording head; and a second heating element for heating the recording head; An inkjet recording apparatus comprising: head temperature control means for driving the first and second heating elements and driving the second heating element during heat retention to keep the temperature of the recording head constant. 3) The ejection energy generating element is an electrothermal conversion element that heats the ink to generate bubbles in the ink, and ejects ink droplets from the ejection port as the bubbles change. The inkjet recording head or inkjet recording apparatus according to claim 1 or 2.