Liquid ejection recording head including a symbol indicating information used for changing the operation of the head

A liquid ejection recording head in which information associated with energy generating members for forming flying droplets discharged from discharge ports is symbolized and recorded at a predetermined location on the head.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a liquid ejection recording apparatus for 
ejecting flying droplets to a recording medium and recording character 
images or the like thereon and to a liquid ejection recording head used in 
such apparatus, and more particularly, to a liquid ejection recording head 
suitable for being removably mounted on a carriage scanning relative to 
the recording medium and to a liquid ejection recording apparatus in which 
a driving voltage for driving the liquid ejection recording head is 
adjustable for each liquid ejection recording head. 
2. Description of the Prior Art 
The non-impact recording methods have recently drawn attention in that the 
occurrence of noise during the recording is negligibly small. Among them, 
the ink jet recording method (the liquid ejection recording method) which 
is capable of accomplishing high-speed recording and moreover, can 
accomplish full color printing without requiring a special process of 
fixation for recording on plain paper is a very effective recording 
method, and various types of such recording method have heretofore been 
proposed and some of them have already put into commercial use and some of 
them are still being studied 
Such liquid ejection recording method effects the recording by causing 
droplets of recording liquid called ink to fly and adhere to a recording 
medium, and may be divided broadly into several types by the method of 
forming the droplets of the recording liquid and the method of controlling 
the direction of flight of the formed droplets. 
Among them, the liquid ejection recording methods disclosed, for example, 
in U.S. Pat. Nos. 3,683,212, 3,747,120 and 3,946,398 are the so-called 
drop-on-demand recording method in which droplets are discharged from 
discharge orifices in accordance with a recording signal and these 
droplets are caused to adhere to the surface of a recording medium to 
thereby accomplish the recording. In this recording method, only the 
droplets necessary for the recording are discharged and therefore, it is 
not necessary to install any special means for recovering or treating the 
discharged liquid unnecessary for the recording and thus, the apparatus 
itself can be made simple and compact and nowadays, this recording method 
particularly attracts attention due to the fact that it is unnecessary to 
control the direction of flight of droplets discharged from discharge 
orifices and the fact that multi-color recording can be accomplished 
easily. 
A liquid ejection recording method entirely different from the 
above-described liquid ejection recording method in the principle of 
formation of flying droplets is disclosed in Japanese Laid-Open Patent 
Application No. 51837/1979. This liquid ejection recording method is not 
only very effectively applicable to said drop-on-demand recording method, 
but also can easily realize a highly dense multi-orifice recording head, 
and therefore, it has a feature that recorded images of high resolution 
and high quality can be obtained at a high speed. 
The liquid ejection recording apparatus used in these drop-on-demand 
recording methods is usually of a structure having a recording head 
comprised of discharge ports (orifices) for discharging droplets, liquid 
flow paths communicating with the orifices and having energy generating 
elements for forming flying droplets, and a liquid chamber communicating 
with the liquid flow paths and storing therein liquid to be supplied to 
these flow paths. 
However, in the liquid ejection recording apparatus having the construction 
as described above, the optimum driving voltages inherent to the liquid 
ejection recording heads thereof are different and irregular, and 
therefore, it is necessary to adjust a driving voltage generating circuit 
in the liquid ejection recording apparatus in accordance with the optimum 
driving voltage inherent to the liquid ejection recording head. 
If this adjustment is neglected, the following problem will arise. That is, 
when a liquid ejection recording head whose inherent voltage is higher 
than the driving voltage supplied from the driving voltage generating 
circuit of the liquid ejection recording apparatus is mounted on the 
recording apparatus, stable flying droplets cannot be obtained or, in the 
worst case, droplets cannot be discharged. Conversely, when a liquid 
ejection recording head whose inherent voltage is lower than the driving 
voltage supplied from the driving voltage generating circuit of the liquid 
ejection recording apparatus is mounted on the recording apparatus, 
unnecessary droplets, called satellites, are secondarily ejected or an 
excessively great load is applied to the energy generating elements to 
remarkably reduce their service life, and in the worst case, the energy 
generating elements may be destroyed. 
Accordingly, when the liquid ejection recording head is to be interchanged 
by reason of trouble with it or the like, a high-degree of maintenance 
work which requires a part of the driving voltage generating circuit to be 
changed becomes necessary, and this has led to a problem that the 
manufacturer must make expensive liquid ejection recording heads whose 
trouble rate is very low. 
In fact, in the liquid ejection recording apparatus of this type, the 
liquid ejection recording head (hereinafter referred to simply as the 
head) has often been interchanged from the viewpoint of securing the 
reliability of the head. However, each head has its inherent optimum 
driving voltage and the value of that voltage differs from head to head, 
and therefore, it has been necessary to adjust the driving voltage 
generating circuit in the liquid ejection recording apparatus in 
accordance with the optimum driving voltage value of the head. 
Thus, each manufactures has shown the optimum driving voltage value by 
directly writing the voltage value on the head or by sticking, on the 
head, a label on which the optimum driving voltage value is written. 
Therefore, when actually interchanging the head, a cumbersome procedure 
wherein according to the voltage value written or stuck on the head, the 
operator such as the user or serviceman must adjust the driving voltage 
generating circuit on the basis of a corresponding table, or the like, 
which must be resorted to. Also, the voltage value directly written on the 
head is apt to fade away during the transportation or the label stuck on 
the head may peel off during transportation, and this has led to the 
occurrence of a trouble that the driving voltage value becomes unknown. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to eliminate the above-noted 
disadvantages and to provide a liquid ejection recording head having an 
accurate and clear driving voltage display which can be automatically 
read. 
It is another object of the present invention to provide a liquid ejection 
recording apparatus in which the driving voltage display of the liquid 
ejection recording head can be read to adjust the driving voltage to a 
level suitable for individual liquid ejection recording heads and thereby 
ensure stable image recording. 
It is still another object of the present invention to provide a liquid 
ejection recording head in which the value of the optimum driving voltage 
supplied to energy generating members for forming flying droplets is 
symbolized and recorded at a predetermined location on the head. 
It is yet another object of the present invention to provide a liquid 
ejection recording apparatus having a liquid ejection recording head 
provided with discharge ports and energy generating members for generating 
energy used to discharge liquid and form flying droplets, and a carriage 
for mounting said liquid ejection recording head thereon and wherein 
reading means is provided for reading the symbol of a driving voltage 
value supplied to said energy generating members which is symbolized and 
recorded on said liquid ejection recording head. 
It is a further object of the present invention to provide a liquid 
ejection recording apparatus which comprises a liquid ejection recording 
head having energy generating members for generating energy utilized to 
form flying droplets and a symbol recording the value of a driving voltage 
supplied to said energy generating members, voltage generating means for 
generating said driving voltage supplied to said energy generating 
members, reading means for reading the recorded content of said symbol, 
and control means for controlling the voltage of said voltage generating 
means in accordance with said recorded content read by said reading means 
and in which the adjusting operation during the mounting and the 
interchange of said recording head is easy.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The liquid ejection recording head of the present invention will 
hereinafter be described in detail with reference to the drawings. 
Referring to FIG. 1, which shows the construction of the liquid ejection 
recording head of the present invention, reference numeral 1 generally 
designates the liquid ejection recording head. Reference numeral 2 denotes 
discharge ports for discharging flying droplets, reference numeral 3 
designates a liquid flow path constituting portion for constituting liquid 
flow paths having energy generating elements for generating flying 
droplets and communicating with the discharge ports 2, reference numeral 4 
denotes a liquid chamber constituting portion for constituting a liquid 
chamber for storing therein liquid to be supplied to the liquid flow 
paths, and reference numeral 5 designates wires for supplying a driving 
voltage to the energy generating elements in the liquid flow paths. 
Reference numeral 7 designates a symbol display in which the driving 
voltage value inherent to the liquid ejection recording head 1 is 
displayed and recorded in a binary form at a predetermined position on the 
head. This symbol display 7 actually belongs to a substrate (for example, 
a substrate of ceramics, glass, plastics or the like) 6 on which the wires 
5 are provided, and when the liquid ejection recording head 1 is inspected 
for shipping by the manufacturer, the protrusions of the symbol display 
are cut away by pincers or the like in accordance with the driving voltage 
value inherent to this recording head measured during the inspection, so 
as to represent binary numbers obtained by transforming the voltage value 
into a binary form. Thus, the symbol display 7 clearly and accurately 
displays the driving voltage value inherent to the recording head by 
binary numbers, for example, with the protrusions as "1" and the positions 
at which the protrusions have been cut away as "0". FIG. 2 shows another 
embodiment of the present invention. In FIG. 2, components 1-6 are similar 
to those in FIG. 1, but the substrate 6 representing the symbol display 7 
is initially formed with through-apertures, and these apertures are filled 
up with an adhesive agent or the like in accordance with the driving 
voltage value inherent to the recording head when the recording head is 
inspected for shipping by the manufacturer. In this case, the symbol 
display 7 is represented, for example, by binary numbers with the 
apertures as "1" and the positions at which the apertures have been filled 
up as "0". 
The symbol display 7 in the embodiments of FIGS. 1 and 2 uses a 4-bit 
display, but the meaning of the symbol display will not be changed even if 
the number of bits is increased or decreased in accordance with the width 
of the driving voltage and the resolving power on the side which supplies 
the voltage. Also, a symbol display such as a bar code display is 
considered to be a symbol transformed into a binary form and therefore, 
can be applied to the present invention. Also, the binary numbers of these 
symbol displays 7 can be read by conventional symbol reading means such as 
a photosensor or a photocoupler, and the driving voltage automatically 
adjusted on the basis of the driving voltage value of the thus read binary 
numbers can be supplied to the energy generating elements in the liquid 
flow paths. Consequently, it becomes unnecessary to adjust the driving 
voltage generating circuit by hand and also, since the binary numbers are 
displayed by protrusions or apertures, the inconvenience that the driving 
voltage value becomes unknown is eliminated. 
FIG. 3 is a perspective view schematically showing an embodiment of the 
liquid ejection recording apparatus of the present invention. In FIG. 3, 
reference numeral 19 designates recording paper. The recording paper 19 is 
moved on a platen 15 at a predetermined speed in the subsidiary scanning 
direction (the direction of arrow A) by a paper feeding roller 14 and a 
pinch roller 16. Reference numerals 17 and 18 denote pulleys supported on 
respective shafts and rotated by a drive source (not shown). A carriage 
driving belt 12 is passed over the pulleys 17 and 18. 
A carriage 13 is integrally fixed to the carriage driving belt 12. The 
carriage 13 is guided by guide shafts 8 and 11 and is reciprocally movable 
in the major scanning directions (the directions of arrow B) by the 
rotation of the pulleys 17 and 18. A roller 20 adapted to roll on the 
guide shaft 11 is disposed on the underside of the carriage 13. 
A connector 22 electrically connected to flexible wiring 21 is disposed 
substantially in the central portion of the carriage 13, and a head 
aligner 23 for aligning the liquid ejection recording head (hereinafter 
referred to simply as the recording head) 1 when the wires 5 of the 
recording head 1 are connected and fixed to the connector 22 is vertically 
provided on the carriage 13. Accordingly, the recording head 1 is 
removable from the carriage 13 by the connector 22. Also, a sensor 24 for 
detecting the home position of the carriage 13 is provided. 
The recording head 1 has a substrate 6, which in turn has thereon discharge 
ports 2 for discharging ink droplets which are flying droplets, a liquid 
flow path constituting portion 3 for constituting liquid flow paths 
communicating with the discharge ports 2 and having energy generating 
members such as heat generating elements for forming flying ink droplets, 
and an ink chamber for storing therein ink to be supplied to the liquid 
flow paths. To the energy generating members of the recording head 1, a 
driving voltage is supplied from a driving voltage generating circuit 29 
shown in FIG. 4 through the connector 22 and the flexible wiring 21 and 
also, a discharge control signal for controlling the discharge of ink 
droplets from the discharge ports 2. 
Further, the recording head 1 is provided with the symbol display 7 (FIGS. 
1 and 2) which is a driving voltage displaying, portion displaying in 
advance, in binary numbers, the optimum driving voltage inherent to the 
recording head 1, i.e., the driving voltage supplied to the energy 
generating members for generating energy utilized to form the flying 
droplets. The optimum driving voltage displayed by the symbol display 7 
(FIGS. 1 and 2) is measured when the recording head 1 is inspected for 
shipping, and in conformity with the measured value, the symbol display is 
provided in the form of 4 bits on the substrate 6 represented, for 
example, by the presence or absence of projections. 
Reference numeral 26 designates a reading unit which is provided on the 
carriage 13 at a position opposed to the symbol display 7 provided on the 
substrate 6 of the recording head 1 and which reads the display content of 
the symbol display 7, i.e., the voltage value. 
FIG. 4 is a block diagram showing an example of the electrical system of 
the apparatus of the present invention. 
In FIG. 4, reference numeral 27 designates a head changing detection sensor 
disposed at a predetermined location in FIG. 3 so as to detect the 
changing of the recording head 1. Reference numeral 28 denotes a control 
circuit actuated by the head changing detection sensor 27 to actuate and 
control the reading unit 26 and also, control a driving voltage generating 
circuit 29 so as to generate the voltage displayed at the symbol display 7 
of the recording head 1. This control circuit 28 is electrically connected 
to the head changing detection sensor 27 and the reading unit 26 through 
the flexible wiring 21. Reference numeral 30 designates a drive circuit 
for driving the energy generating members of the recording head 1. A 
driving voltage is supplied to the drive circuit 30 from the driving 
voltage generating circuit 29. 
The control process of the control circuit 28 shown in FIG. 4 will now be 
described wit reference to the flow chart of FIG. 5. 
When the head changing detection sensor 27 detects that the recording head 
1 has been newly changed (step S1), the detection output thereof is 
supplied to the control circuit 28. Subsequently, the control circuit 28 
instructs the reading unit 26 to read the driving voltage displayed at the 
symbol display 7 of the recording head 1 (step S2). 
Then, the control circuit 28 delivers a control signal to the driving 
voltage generating circuit 29 on the basis of the voltage read from the 
symbol display 7 by the reading unit 26 so as to generate the same voltage 
as the driving voltage displayed at the symbol display 7 of the recording 
head 1 (step S3). In response to this control signal, the driving voltage 
generating circuit 29 generates the driving voltage displayed at the 
symbol display 7 of the recording head 1 (step S4), and this voltage is 
supplied to the drive circuit 30 to enable the energy generating members 
of the recording head 1 to be driven. 
In the above-described embodiment, it has been described that the setting 
of the driving voltage inherent to the recording head is effected during 
the changing of the recording head, but instead, it is possible to re-set 
the driving voltage at each predetermined time in the same recording head. 
Also, of course, in the liquid ejection recording apparatus of the present 
invention, the recording head may have a single discharge port or may have 
a multinozzle having multiple discharge ports. Further, of course, the 
recording head may be of the type in which a plurality of recording heads 
are mounted on the carriage. 
Furthermore, in the above-described embodiment, the driving voltage display 
of the recording head has been shown as being in the form of the presence 
of four projections, but instead, this driving voltage display may be in 
any form of display. Still further, the reading unit for reading the 
driving voltage display of the recording head may be of any type if it can 
read in accordance with the form of the driving voltage display of the 
recording head. 
According to the present invention, as described above, a driving voltage 
inherent to the liquid ejection recording head mounted on the carriage can 
be set for each recording head by simple means and therefore, the problem 
peculiar to the prior art that each time the recording head is mounted or 
changed, the driving voltage thereof must be adjusted is greatly 
alleviated and thus, the operability of the recording head can be improved 
much more. 
FIG. 6 is a schematic perspective view showing an example of the 
construction of the essential portions of a liquid ejection recording 
apparatus on which the recording head shown in FIG. 2 is mounted. 
Reference numerals indicated in FIG. 6 are similar in significance to 
those indicated in FIGS. 1 to 3. In FIG. 6, reference numerals 8 and 11 
designate guide rails for scanning the carriage 13, which is moved along a 
recording medium, not shown, by the belt 12. 
The liquid ejection recording head 1 is fitted and fixed to a fitting 
portion provided on the carriage 13. Reading means for reading the symbol 
recorded on the head 1 is provided in the carriage 13. 
FIG. 7 is a schematic perspective view showing an example which uses 
optical means as the symbol reading means. In FIG. 7, reference numeral 9 
designates a photosensor for detecting light. The photosensor 9 may 
suitably be a photodiode, a phototransistor, or the like. Light entering 
the photosensor 0 is applied by illuminating means (light-emitting means) 
10. 
In FIG. 7, the symbol display 7 is in the form of through-apertures formed 
in the substrate 6, except 7b. Accordingly, light beams 10a-10b emitted by 
the illuminating means 10 enter cells 9a-9d provided correspondingly to 
the symbol displays 7a-7d of the photosensor 9 except the symbol display 
7b. (In FIG. 7, no light enters the cell 9b). By this, which of the symbol 
displays transparent to the light and which of the symbol displays are not 
is detected and by the detected information, the driving voltage of the 
recording head is adjusted to an optimum value or an optimum range. 
In FIG. 7, the photosensor 9 and the illuminating means 10 are spaced apart 
from the display symbols, but it is preferable from the viewpoint of the 
compactness of the apparatus that they be installed so as to be 
substantially in intimate contact with the substrate 6. 
The detected information may not only be automatically adjusted, but also 
may indicate the driving voltage value to the display means and may be 
manually adjusted. When the detected information is manually adjusted, the 
driving voltage can be adjusted very simply if, for example, the display 
means is made to effect a bar graph display or a pointer display so that 
adjustment can be effected by adjusting the pointer of the volume, or the 
like, to the position thereof. 
According to the present invention, as described above, the driving voltage 
value inherent to each liquid ejection recording head can be clearly and 
accurately displayed by simple means and moreover, the occurrence of the 
trouble that the driving voltage value disappears or is lost during the 
transportation of the head is eliminated, and how to adjust the driving 
voltage generating circuit when actually changing the head can be judged 
at a glance. Also, cumbersome adjustment is unnecessary, and if the 
mounting of the recording head is done properly, stable image recording 
can always be accomplished. 
Not only is the optimum driving voltage of the head displayed by the 
utilization of protrusions or apertures, but also the display 
corresponding to the type of the liquid contained in the head (for 
example, the color or the ink corresponding to the recording medium) may 
be added. In this latter case, it is also preferably to display the type 
of the liquid on the apparatus body side. 
As discussed above and as shown in FIGS. 1, 2 and 7, for example, the 
symbol display 7 of the recording head 1 is independent of the energy 
generating members, which generate the energy utilized to form the ink 
droplets. The symbol display 7 is disposed at a predetermined location on 
the recording head 1, separate from the energy generating members, and 
indicates the value of a driving voltage to be supplied to the energy 
generating members. 
FIG. 8 shows the constitution of the liquid ejection recording head in 
which reference numeral 33 denotes an orifice from which a liquid flying 
droplet generated by an energy generating member 37, which may be an 
electro-thermal or electro-mechanical converting member, the orifice 33 
being provided in an orifice plate 34. 
The liquid needed for forming the droplets is supplied through a flow path 
35. 
The symbolizing portions are not restricted to protrusions or apertures as 
described above, but may be cut-away or other concave portions 40, as 
shown in FIGS. 9A and 9B, provided in a head constituting member (for 
example, the substrate) or electrically conductive portions 41 provided 
separately from those connected to the energy generating members, as shown 
in FIG. 10. The reading of such symbolizing portions may suitably be 
accomplished not only by optical means utilizing the transmission or 
reflection of light as described above, but also by the mechanical means 
42 shown in FIGS. 9 and 11 that detect mechanical displacement resulting 
from the contact or fitting between the binarized symbolizing portion and 
the apparatus body (for example, by using the switches 43, or another 
mechanico-electrical converting member such as a piezoelectric element, as 
shown in FIG. 11), or by the electrical means 44 shown in FIG. 10 that 
detect variations in electrical resistance (for example, through the 
electrical connections made by the contacts 45 or the like).