JPS6277945A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To make it possible not only to alter the diameter of a printing dot by selection but also to increase the density of a printing image or the degree of freedom of printing grade, by selectively setting the bias temp. of a recording head to a plurality of values and changing said bias temp. by changing over a switch. CONSTITUTION:When head-driving voltage is constant and the bias temp. of a recording head 6 is low, the growth of a bubble 13 is small, and an ink emitting amount and an ink emitting speed are small and, therefore, an ink droplet 14 is small and the diameter of a printing dot becomes small. Contrarily, when the bias temp. is high, the ink droplet 14 is large and the printing dot becomes large. A bias temp. control means selectively sets the bias temp. of the recording head 6 to a plurality of values by the switch provided to the control part of a recording apparatus and changes the bias temp. by changing over the switch. By this method, the diameter of the printing dot can be altered by the selection of a user and the setting of the density of a printing image to realize the enhancement of printing grade or the increase in the degree of freedom thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a means for controlling the bias temperature of a recording head in an ink jet recording apparatus equipped with a bubble jet recording head.

[Prior art]

2. Description of the Related Art An inkjet recording device equipped with a Hubble Jet 5.4 recording head is used as a type of recording device such as a printer or a facsimile.

This type of inkjet recording device provides an electrothermal converter made of a heating resistor, etc., corresponding to each of the plurality of ink ejection ports that form print dots, and drives each electrothermal converter based on print data. This causes bubbles to grow within the liquid ink, and the extrusion force causes the ink to be ejected to form flying ink droplets, thereby forming printed dots on the recording medium (paper, plastic sheet, etc.). .

By the way, in this type of bubble jet recording head, the head driving voltage is usually set to a constant value, so when the temperature of the recording head is low, the ink ejection amount and ejection speed decrease, and the print dot diameter becomes smaller. When the temperature of the recording head is high, the amount and speed of ink ejection increases, resulting in a larger print dot diameter.

Therefore, in order to obtain a stable print dot diameter, it is necessary to maintain the recording head within a predetermined temperature range.

Therefore, it has been proposed to provide the recording head with a heater and a temperature sensor, set the bias temperature of the recording head, and control the heater based on this set temperature.

However, in the bubble jet printing inkjet recording device related to this existing proposal, the bias temperature of the recording head was set so that the diameter of the printed dots was constant, so it was difficult to select the density of the printed image or to adjust the printing dots. It was not possible to meet requests such as reducing the diameter, increasing resolution, and improving print quality.

〔the purpose〕

The purpose of the present invention is to provide an inkjet recording device that can solve the problems of the prior art, can change the printing dot diameter according to the user's selection, and can increase the degree of freedom in the shading of printed images and printing quality. It is to provide.

〔overview〕

The present invention is configured to selectively set the bias temperature of the recording head to a plurality of values using a switch provided in a control section of the recording apparatus, and by changing the bias temperature of the recording head by switching the switch, the bias temperature of the recording head is changed. It accomplishes its purpose.

〔Example〕

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

FIG. 1 shows the main structure of an inkjet recording apparatus according to an embodiment of the present invention.

In FIG. 1, a recording medium 1, such as paper or a plastic sheet, is supported by conveyance rollers 2 and 3, each consisting of a pair of upper and lower rollers, and is conveyed in the direction of arrow A. A guide shaft 4.4 is provided in front of and parallel to the transport rollers 2, 3, and the carriage 5 is reciprocated in the direction of arrow B along the guide shaft.

A bubble jet recording head 6 is mounted on the carriage 5.

On the front surface of this bubble jet recording head, that is, on the surface facing the recording medium 1 at a predetermined interval (for example, 0.8 tm), there are a plurality of ink ejection ports 10 (for example, 24 or 32) in a vertical row (Fig. 2). The electrothermal converter 1) of each ink ejection port is formed based on the printing data (Fig. 2).
By driving the ink droplets, flying ink droplets are formed, and printing is performed while adhering print dots to the recording medium 1 in a predetermined pattern.

The recording head 6 (specifically, a heat sink) is provided with a temperature detector 7 made of a thermistor or the like and a heater 8 made of an electrothermal converter.

The CPU (microprocessor) of the recording device is connected to the host computer via an interface, and records based on command signals (commands) and print data signals read from the host computer, as well as programs stored in the ROM of the CPU. Movement is controlled.

21iU (A) and (B) schematically show the ink ejection ports 10 of the recording head 6, each ink ejection port 10 is provided with an electrothermal transducer 1), and a head driving voltage is applied to these. The ink 12 is heated and bubbles 13 grow, and the expanding force of the bubbles forms flying ink droplets 14, forming printed dots on the recording medium 1.

When the head drive voltage is constant, if the bias temperature of the recording head 6 (for example, the temperature of the heat sink of the recording head) is low, the growth of the bubble 13 is small as shown in FIG. 2 (A), and the ink ejection amount and ejection speed are small. , ink drop 1
4 is small, and the print dot diameter becomes small.

When the bias temperature of the recording head 6 is high, the growth of the bubble 13 becomes large as shown in FIG. 2(B), and the ink ejection amount and ejection speed become large, so that the ink droplet 14 becomes large and the printed dot becomes large.

Therefore, the bias temperature control means for the recording head 6 (for example, the temperature of the heat sink of the recording head 6) according to the present invention
The recording head 6 is controlled by a switch provided in the control section of the recording device.
The bias temperature is selectively set to a plurality of values, and the bias temperature is changed by switching the switch.

As this switch, a dip switch of several bits (for example, 3 bits) can be used, and the setting can be made in multiple stages.

FIG. 3 is a block diagram of a control system suitable for implementing the present invention.

In FIG. 3, a CPU (microprocessor) 20 of the recording apparatus is connected to a host computer via an interface 21, and controls the operation of a drive source 23 such as a carriage feed motor or a conveyance motor via a motor driver 22. The recording head 6 is connected via a head driver 25 mounted on the head unit 24.
control.

On the other hand, a switch 26 for selectively setting the bias temperature of the recording head 6 to a plurality of values, that is, a reference temperature setting switch 26 is connected to the CPU 20. This switch 26 can be composed of, for example, a 3-bit DIP switch, and allows the user to set a desired reference temperature according to his/her selection. Further, a heater 8 mounted on the recording head (specifically, its heat sink) 6 is controlled by the CPU 20.

The bias temperature signal from the temperature detector 7 mounted on the recording head (specifically, its heat sink) 6 is sent to the CPU 20.
The bias temperature of the recording head 6 is lower than the reference temperature by the CPU, and when the bias temperature of the recording head 6 is lower than the reference temperature, the heater 8 is turned on to heat the recording head.

On the other hand, when the bias temperature of the recording head 6 is higher than the reference temperature, the heater 8 is turned off.

In this manner, by providing a plurality of desired set reference temperatures in advance and selecting one of them using the switch 26, the bias temperature of the recording hand can be controlled to a desired temperature.

The print dot diameter changes depending on the temperature of the recording head 6. The lower the reference setting temperature is, the smaller the dot diameter can be for pale printing or high resolution printing, and the higher the reference setting temperature is, the larger the dot diameter is for dark printing. It can be performed. Therefore, it is possible to change the print dot diameter using only the recording device according to the user's preference or request for improved print quality, which allows the user to freely select the shading of the print image and improve the degree of freedom in print quality. It became possible.

Furthermore, by applying a predetermined bias temperature to the recording head 6, a state is obtained in which ink is ejected at a drive voltage higher than the head drive voltage that is actually applied. The ink ejection amount was obtained, and the ink viscosity was lowered, thereby making it possible to increase the ejection dot diameter (print dot diameter).

Furthermore, by applying a predetermined bias temperature to the recording head 6, it was possible to reduce the thermal energy applied during recording and increase the response frequency of the recording head.

Furthermore, part of the thermal energy required for ink ejection can be obtained from the bias temperature, and printing can be performed with a lower voltage, thereby improving the reliability and durability of the printing apparatus.

FIG. 4 is a flowchart illustrating the operation procedure of the control system shown in FIG.

In FIG. 4, when the recording operation is started in step 100, the CPU 20 reads the switch setting value set by the switch 26 for setting the reference temperature in step 101, and in step 102, the base 4! The temperature is set to a predetermined value.

Therefore, in step 103, the temperature detector 7 detects the bias temperature of the recording pad 6 and compares it with a reference temperature.

If the bias temperature is lower than the reference temperature (specifically, its lower limit), the process proceeds to step 104, where the heater 8 is turned on and the rad 6 is heated for a certain period of time.

After that, the process returns to step 103 again.

On the other hand, the bias temperature is the reference temperature (more specifically, its upper limit)
If the temperature is higher than that, the process proceeds to step 105, where printing is interrupted and cooling is performed after waiting for a certain period of time. After that, the process returns to step 103 again.

If the bias temperature is the reference temperature (specifically, a temperature between its upper and lower limits), the process advances to step 106 and recording is performed.

After recording for a certain period of time, the process returns to step 101 and the above operations are repeated.

Note that the present invention is equally applicable to an inkjet recording device equipped with a plurality of bubble jet type recording handles for color printing or grayscale printing, and furthermore, the present invention can be applied to an inkjet recording device equipped with a plurality of bubble jet type recording handles for color printing or grayscale printing. Alternatively, the present invention can be similarly applied to a page print type inkjet recording apparatus that records one page at the same time.

〔effect〕

As is clear from the above explanation, according to the present invention, since the bias temperature of the recording head is set by a switch provided in the control section, the print dot diameter can be changed according to the user's selection. It is possible to improve the density settings, print quality, and increase the degree of freedom.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing essential parts of an inkjet recording apparatus according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of an ink discharge port, and FIG. 3 is a control system of an inkjet recording apparatus according to the present invention. FIG. 4 is a flowchart illustrating the operation procedure of the control system in FIG. 3. 6--- Recording head, 7--- Temperature detector, 8-- Heater, 10-- Ink discharge port, 14-- Ink droplet, 2O---cpu, 2
6・------Switch for setting reference temperature.

Claims (1)

[Claims] (1) In an inkjet recording apparatus equipped with a bubble jet recording head, the bias temperature of the recording head is selectively set to a plurality of values by a switch provided in a control section, and the bias temperature of the recording head is set by changing the switch. An inkjet recording device characterized by changing temperature.