JPH0557885A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To prevent the lowering of printing quality with the elapse of time by suppressing the change of the diameter of an ink dot caused by the total number of ink drops injected from a nozzle by adjusting the driving voltage of a heater corresponding to the replacing number of ink cartridges by a voltage setting switch. CONSTITUTION:When a position setting cam 12 is present at a first position, the electric connection terminal of the head cartridge 4 in a recording head part 5 is pressed to an electric connector 14 by the position setting cam 12 and a spring like press member 13 to be fixed to a carriage plate 8. An ink cartridge 1 is guided along the guide groove 6 of the head cartridge 4 by its rib 2 and, at this time, a switch cam 3 rotates the gear of a voltage setting switch 11 by one notch in a clockwise direction. As a result, heater driving voltage is applied to a heater corresponding to the set value of the voltage setting switch 11. That is, the voltage setting switch 11 selects one driving voltage corresponding to the replacing number of ink cartridges 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called thermal type ink jet recording apparatus for applying heat energy to ink appropriately according to image information and ejecting the ink from the nozzle to print. , Improvement of heater driving method for applying thermal energy to ink.

[0002]

2. Description of the Related Art The following method is disclosed as a heater driving method in a so-called thermal type ink jet recording apparatus. In Japanese Patent Laid-Open No. 58-1571, the drive voltage is set to 1.02% to prevent secondary bubble generation.
It is specified that the pulse width is about 5 to 1.3 times and the pulse width is 2 to 20 μsec. Further, in JP-A-61-242850, in order to avoid the occurrence of satellites and ink mist due to the temperature rise of the recording head, the magnitude of thermal energy applied to the heater is adjusted according to the environmental temperature. No. 73569 states that the heating energy level is selected to modulate the size of the ink dots formed on the recording sheet. further,
In Japanese Patent Laid-Open Nos. 58-102776 and 1-202459, the pulse width of the driving voltage is adjusted to correct the drop amount and dot size between the jet that is at rest and the jet that continuously ejects ink. We propose a variable method. Further, in JP-A-2-78554, a sufficient electric signal for stabilizing the resistance value of the heater is applied to the heater in advance to perform aging by the heating process, and a good and stable droplet ejection state of the recording head is always obtained. Proposing a manufacturing method.

[0003]

By the way, according to the results of subsequent studies by the present inventors, since the heater temperature at the time of ejecting the ink drop from the nozzle rises to around 300 ° C., the ink drop It was revealed that the thermal efficiency of the heater changes over time for a long period of time due to the chemical interaction between the metallic heater and the liquid ink due to repeated ejection. FIG. 1 shows the relationship between the total number of ejected ink drops, that is, the total number of drive pulses applied to a heater, and the diameter of an ink dot formed on inkjet silica coated paper. According to this figure, it can be seen that the diameter of the ink dot gradually increases as the applied drive pulse increases, and the change in the thermal efficiency of the heater changes the volume of the ejected ink drop. That is, it is shown that the print image quality gradually deteriorates as the volume of the ink drop varies with time over a long period of time.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a simple structure for the number of pulses of the driving voltage applied to the heater and the total number of hours the driving voltage is applied. It is an object of the present invention to provide an ink jet recording apparatus capable of preventing the deterioration of print quality over time by appropriately adjusting the drive voltage of the heater according to the above.

[0005]

In order to achieve the above object, an ink jet recording apparatus of the present invention ejects ink from a nozzle provided in a recording head portion by thermal energy applied according to image information. In an ink jet recording apparatus that forms a recorded image, the recording head unit includes
A head cartridge having a heater for applying thermal energy to ink and the nozzle, an ink cartridge detachable from the head cartridge, and a heater set in advance each time a new ink cartridge is attached to the head cartridge. And a voltage setting switch for selecting one of the drive voltages according to the number of times the ink cartridge has been replaced.

[0006]

According to such a technical means, when a new ink cartridge is attached to the head cartridge, the voltage setting switch is set to a plurality of heater driving voltages set in advance in a stepwise manner to determine the number of times of replacement of the ink cartridge. Since a single driving voltage is selected according to the number of times the ink cartridge is replaced, that is, the total number of driving pulses applied to the heater, the optimum driving voltage can be applied to the heater. It is possible to suppress a change in ink dot diameter due to deterioration.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a detailed description of the ink jet recording apparatus of the present invention, given in reference to the attached drawings.

First, the structure of the recording head section and the method of designating the heater drive voltage will be described. FIG. 2 shows an overall view of the recording head section and the relationship between the carriage plate (8) for mounting and fixing the recording head section. The recording head part is composed of an ink cartridge (1) and a head cartridge (4) .The head cartridge (4) is a housing part of the ink cartridge (1) and a heater chip fixed to a heat sink (7) and a nozzle plate ( Heat sink not shown together
(It is on the back side of (7)). 12 / mm for heater chip
128 heaters and their driving circuits are built in at a pitch of, and a nozzle plate having 128 nozzles and a plurality of dummy nozzles is bonded onto the heater. The head cartridge (4) is installed at a predetermined position on the carriage plate (8) by the head cartridge rib (5) and the head cartridge guide groove (9). The switch cam (3) is for operating the voltage setting switch (11) when replacing the ink cartridge (1) as described later. The carriage plate (8) is connected to a guide shaft (not shown) through a guide shaft mounting hole (10). The ink ejection direction is downward.

3 to 5 respectively show a position setting cam (12)
It shows how the ink cartridge (1), the head cartridge (4) and the carriage plate (8) are connected by the operation of. Further, FIGS. 6 to 8 respectively show A of FIG.
FIG. 6 shows an arrow view, an arrow B view in FIG. 4, and an arrow C view in FIG. 5, showing the ink cartridge (1), the head cartridge (4), the voltage setting switch (11), and the spring-like pressing member (13). The respective positional relationships are shown. Each figure will be described below.

FIG. 3 shows a state in which the position setting cam (12) is located at the "ink cartridge mounting position". At this time, the electric connection terminals (not shown) of the head cartridge (4) are pressed against the electric connector (14) inside the carriage plate (8) by the position setting cam (12) and the spring-shaped pressing member (13). It is fixed to the carriage plate (8) after making a physical connection. A flexible cable (not shown) connects the electric connector (14) to a control circuit (not shown). The ink cartridge (1) is inserted into the head cartridge (4) by aligning the ink cartridge rib (2) with the ink cartridge guide groove (6) of the head cartridge (4). At this time, the switch cam (3) rotates the gear of the voltage setting switch (11) clockwise by one notch. The voltage setting switch (11) is a digital switch, and the number output is incremented by one each time the gear rotates one notch clockwise. For example, the voltage setting switch (11) in FIG. 3 has 6 teeth and outputs 0 to 5. Each number is an address when reading a look-up table in which the heater driving voltage is written in advance, and the heater driving voltage is applied to the heater according to the value of the voltage setting switch (11) that has been set.

FIG. 4 shows a state in which the position setting cam (12) is located at the "ink cartridge removing position". As is clear from FIG. 7, the switch cam (3) and the voltage setting switch (11) do not engage with each other, and the ink cartridge (1) does not rotate the voltage setting switch (11) in the counterclockwise direction. ) Can be pulled out. At this time, the head cartridge (4) is semi-fixed to the carriage plate (8) by the spring-like pressing member (13), and even if the ink cartridge (1) is pulled out upward, the head cartridge (4) is removed from the carriage plate (8). It does not come off.

FIG. 5 shows a state in which the position setting cam (12) is located at the "head cartridge attaching / detaching position". As is apparent from FIG. 8, the switch cam (3) and the voltage setting switch (11) are not meshed with each other, and the spring-shaped pressing member (13) is not pressing the head cartridge (4), so the head cartridge (4) Can be easily removed from the carriage plate (8). It can also be easily installed. When installing a new head cartridge (4) on the carriage plate (8), set the position setting cam (12) to the position and move the head cartridge (4).
Install on the carriage plate (8). Then set the position setting cam (12) to
Connect and fix (4) to the carriage plate (8) and insert the ink cartridge (1) into the head cartridge (4).

Further, when the present embodiment is used, since the voltage setting switch (11) is gear-shaped, if the wrong heater driving voltage is set by inserting / removing the ink cartridge (1), remove the ink cartridge (1). Arrow D in Figure 3 when left
It can be easily corrected by looking in from the direction and turning the voltage setting switch (11) with a rod-shaped (eg driver) object. At this time, the value of the voltage setting switch (11) corresponding to the heater driving voltage according to the rotation of the voltage setting switch (11)
It is convenient to be able to display (for example, 0 to 5 when there are 6 teeth). Also new head cartridge (4)
The value of the voltage setting switch (11) can be easily returned to "0" even when is attached.

In this embodiment, the number of teeth of the voltage setting switch (11) is six for convenience, but it may be set to an optimum value depending on the life of the heater and the amount of ink contained in the ink cartridge (1). .. Generally, the number of teeth of the voltage setting switch (11) is calculated from the life of the heater of one head cartridge and the number of ink cartridges used, and the time to replace the head cartridge can be easily known by making it approximately equal to the number of ink cartridges. I can do things. Also, if the number of teeth of the voltage setting switch (11) matches the number of ink cartridges used in one head cartridge in this way, the voltage setting switch will be replaced when the head cartridge is replaced and a new ink cartridge is installed. The value in (11) can be automatically reset to “0”.

Next, the relationship between the heater driving voltage, the number of printed sheets and the dot diameter will be described. When the ink capacity of the ink cartridge (1) is 30cc, the printing rate of one "A4" sheet is 0.4
When set to%, it is possible to print on about 10,000 sheets with one ink cartridge. Since the head cartridge (4) has 128 heaters, an average of 3 × 10 ⁶ dots is printed per heater. However, there is considerable variation in the position of the heater rather than a divided case which is driven 128 heaters none is uniformly for printing characters and the like, in many cases the heater 3 × 10 ⁷ cells 10 × 10 ⁷ or so dots Is printed. In this embodiment, "Kanji, hiragana, katakana, alphabet, checkered pattern and all solid" is "A4"
Using a test chart that gives a print rate of 50% with 1 heater and 1 × 5 ⁷ dots printed per ink cartridge
The dot diameter of a checkerboard pattern printed with a heater that printed 10 ⁶ dots was measured. (80 sheets of "A4" at 50% printing rate, printing rate
At 0.4%, it corresponds to 10,000 A4 sheets. )

FIG. 9 shows a heater driving voltage of 38 V (injection start voltage 3
The figure shows how the dot diameter changes when 16 ink cartridges (1) are exchanged at any time and printing is performed at a constant 4.5V × 1.1). The number of ink cartridges for the heater (5 × 10 ⁷ dots / 1 ink cartridge) that is used frequently, although the dot diameter does not change much for the heater (1 × 10 ⁶ dots / 1 ink cartridge) that is not used frequently. It can be seen that the dot diameter has increased significantly in accordance with. Also, the dot diameter started to decrease from the 15th ink cartridge because the heater has reached the end of its life. The heater drive voltage pulse width is 3 microseconds,
The driving frequency was 4.5 KHz.

FIG. 10 shows how the dot diameter changes when the heater drive voltage is lowered from 38 V to the drive voltage shown in Table 1 below each time the ink cartridge (1) is replaced using the method of the present invention. There is. The change in dot diameter is smaller than that in Fig. 9 for both the heaters used infrequently and the heaters used frequently. Since a heater that is frequently used lowers the heater driving voltage before the dot diameter significantly increases, the chemical interaction between the heater and the ink is suppressed, and as a result, the dot diameter increase can be suppressed.

Further, the reason why the dot diameter in the heater which is not frequently used does not decrease even if the driving voltage is lowered is that the range of voltage values shown in Table 1 is in the stable region as shown in FIG. The ink capacity of the ink cartridge (1) is 30cc.
In the case of 1, the number of gears of the voltage setting switch (11) is properly 12 to 16 from the life of the heater of the head cartridge (4). That is, it is possible to replace 12 to 16 ink cartridges (1) with one head cartridge (4).

[0019]

[Table 1]

[0020]

As described above, according to the ink jet recording apparatus of the present invention, since the voltage setting switch adjusts the driving voltage of the heater according to the number of ink cartridges to be replaced, the ink drop ejected from the nozzle is It is possible to suppress the variation of the ink dot diameter due to the total number and prevent the deterioration of printing quality over time.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the total number of drive pulses and the ink dot diameter.

FIG. 2 is an exploded perspective view showing a recording head unit and a carriage plate for fixing the recording head unit according to the first embodiment of the inkjet recording apparatus of the present invention.

FIG. 3 is a perspective view showing an “ink cartridge mounting position” in the first embodiment.

FIG. 4 is a perspective view showing an “ink cartridge removal position” in the first embodiment.

FIG. 5 is a perspective view showing a “head cartridge attachment / detachment position” in the first embodiment.

FIG. 6 is a view on arrow A in FIG.

FIG. 7 is a view on arrow B in FIG.

FIG. 8 is a view on arrow C of FIG.

FIG. 9 is a diagram showing a relationship between the number of ink cartridges to be replaced and an ink dot diameter when a constant drive voltage is applied to a heater.

FIG. 10 is a diagram showing the relationship between the number of replaced ink cartridges and the ink dot diameter when the heater drive voltage is adjusted each time the ink cartridge is replaced in this embodiment.

FIG. 11 is a diagram showing a relationship between a heater driving voltage and an ink dot diameter.

[Explanation of symbols]

1 ... Ink cartridge, 2 ... Ink cartridge rib, 3 ... Switch cam, 4 ...
・ Head cartridge, 5 ・ ・ ・ Head cartridge rib, 6 ・ ・ ・ ・ ・ Ink cartridge guide groove, 7 ・ ・
... Heat sink, 8 ... Carriage plate, 9 ... Head cartridge guide groove, 10 ...
..Mounting holes for guide shaft, 11 ... Voltage setting switch, 12 ... Position setting cam, 13 ...
..Spring-like pressing members, 14 ... Electric connectors

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 9012-2C B41J 3/04 103 B

Claims (2)

[Claims] 1. An ink jet recording apparatus for forming a recorded image by ejecting ink from nozzles provided in a recording head section by thermal energy applied according to image information, wherein the recording head section heats the ink with thermal energy. A head cartridge having a heater for applying a voltage and the nozzle, an ink cartridge that is attachable to and detachable from the head cartridge, and each time a new ink cartridge is attached to the head cartridge, a plurality of preset drive voltages of the heater are set. An ink jet recording apparatus comprising: a voltage setting switch for selecting one drive voltage according to the number of times the ink cartridge is replaced. 2. The ink jet recording apparatus according to claim 1, wherein the head cartridge is attachable / detachable to / from a supporting means for holding the head cartridge, and the head cartridge is counted by a voltage setting switch when the head cartridge is replaced with a new one. An ink jet recording apparatus characterized in that the number of times the ink cartridge is replaced is reset.