Patent Application
20140300660
1. Field of the Invention
The present invention relates to a liquid ejection head substrate used in a liquid ejection head that ejects liquid, and to a liquid ejection head.
2. Description of the Related Art
In general, regarding inkjet print heads (hereinafter, also called “print heads”), which are representative examples of liquid ejection heads, the viscosity of ink used for printing increases as ambient temperature decreases. Hence, when a print head is used in environments with very low temperatures, there may be a case where the volume of ink ejected from the print head is decreased (variations in ejection volume) or ink is not ejected normally (defective ejection). In this case, in images obtained by printing, uneven density due to variations in ejection volume, unfavorable dot shapes due to defective ejection, or the like is observed. To solve these problems, control is performed in such a manner that the print head is heated before or during printing operations so as to be in a predetermined temperature range, thereby regulating temperature distribution.
Examples of known configurations for the above-described control include a configuration in which heat generating elements (hereinafter also called “heating elements”) for heat application are provided on an inkjet print head substrate (hereinafter, also called a “substrate”). By driving these heating elements, the temperatures of the substrate and ink within the substrate are adjusted.
In International Publication No. 2012/044299, as illustrated in FIG. 2 thereof, a configuration is disclosed in which an ink supply port having a shape extending along ejection port arrays are provided in the center of the substrate, and a plurality of temperature detection elements and a plurality of heating elements are provided for the ejection ports arranged on both sides of the ink supply port. With this configuration, regions having a low temperature can be selectively heated using the heating elements, by detecting the temperature distribution of the substrate using the temperature detection elements.
However, in International Publication No. 2012/044299, since the temperature detection elements and the heating elements are provided for each of the ejection port arrays, the numbers of the temperature detection elements and the heating elements are increased when the number of the ejection port arrays is increased to increase the number of colors and enhance image quality. As a result, a larger space in which to arrange the temperature detection elements, heating elements, and drive circuits for driving these elements is required, thereby causing increases in the area of the substrate and the manufacturing cost of the substrate. Since it is more advantageous when the number of the printing elements in the ejection port array is larger from the viewpoint of obtaining a higher speed and higher quality, it is preferable to decrease the length of the substrate in a direction perpendicular to the direction in which the ejection port arrays extend, thereby suppressing an increase in the area of the substrate, to realize a higher speed and higher quality together with suppression of the manufacturing cost.
On the other hand, when the temperature detection elements and heating elements are not provided for each ejection port array, since the substrate is partitioned by the supply port having a shape extending in the direction in which the ejection port arrays extend, it is difficult to sufficiently heat the regions on the two sides of the supply port. Hence, it becomes difficult to regulate the temperature distribution of the substrate.
Further, when the temperature detection elements and the heating elements are arranged close to each other, as in International Publication No. 2012/044299, the temperatures of regions heated by the heating elements are detected and, hence, the accuracy of temperature detection, which is the base of temperature control of the heating elements, is decreased, whereby it becomes difficult to regulate the temperature distribution over the whole substrate.
A liquid ejection head substrate according to the present invention includes:
a plurality of energy generating element arrays each including a plurality of energy generating elements configured to generate energy for ejecting liquid;
a supply port array in which a plurality of supply ports configured to supply liquid to the plurality of energy generating elements are arranged between the plurality of energy generating element arrays in an arrangement direction in which the plurality of energy generating elements are arranged;
a temperature detection element that is configured to detect a temperature of the liquid ejection head substrate and that is provided on one side of the supply port array; and
a heating element that is configured to heat the liquid ejection head substrate and that is provided on another side of the supply port array.
A liquid ejection head according to the present invention includes a liquid ejection head substrate and an ejection port forming member.
The liquid ejection head substrate includes:
a plurality of energy generating element arrays each including a plurality of energy generating elements generate energy for ejecting liquid;
a supply port array in which a plurality of supply ports configured to supply liquid to the plurality of energy generating elements are arranged between the plurality of energy generating element arrays in an arrangement direction in which the plurality of energy generating elements are arranged;
a temperature detection element that is configured to detect a temperature of the liquid ejection head substrate and that is provided on one side of the supply port array; and
a heating element that is configured to heat the liquid ejection head substrate and that is provided on another side of the supply port array.
In the ejection port forming member, an ejection port array including a plurality of ejection ports configured to eject liquid is provided so as to correspond to the energy generating element array.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
A plurality of printing element arrays (energy generating element arrays) each formed of a plurality of printing elements 102, functioning as energy generating elements, generating energy for ejecting liquid are provided on the element substrate 101 in a direction perpendicular to an arrangement direction in which the printing elements 102 are arranged. In the present embodiment, thermal energy generating elements that eject ink using thermal energy are used as the printing elements 102.
A plurality of ejection port arrays each formed of a plurality of ejection ports 201 for ejecting ink are provided in the ejection port forming member 200. As illustrated in
In the element substrate 101, supply ports 103 that supply ink to the printing elements 102 are formed in such a manner as to extend through the element substrate 101, and a supply port array formed of a plurality of the supply ports 103 is provided in a region between the arrays of the printing elements 102. Further, a drive circuit 104 for driving the printing elements 102 is provided for each array of the printing elements 102, and the drive circuit 104 is arranged in a region on a side of the array of the printing elements 102 opposite the side thereof where the array of the supply ports 103 is provided.
Ink is supplied to a region above the printing element 102 from the back surface of the element substrate 101 through the supply port 103. The printing element 102 selected by the drive circuit 104 is heated, whereby bubbles are generated in the ink above the printing element 102 and the ink is ejected from the ejection port 201.
As illustrated using broken lines in
In regions between the drive circuits 104 where the temperature detection elements 105 are not provided, heating elements 106 (106a to 106c) for heating the element substrate 101 to an extent insufficient to cause ink to be ejected are provided in such a manner as to correspond to the respective temperature detection elements 105a to 105c. In the present embodiment, with the group of the temperature detection elements 105 (group of the temperature detection elements 105a to 105c) as the center, two groups of the heating elements 106 (two groups of the heating elements 106a to 106c) are respectively arranged on the two sides of the group of the temperature detection elements 105 in such a manner that two of the heating elements 106 are arranged in each of the regions A to C.
Electric connection pads 107 for external electric connection are arranged along the edges of the element substrate 101. Through the electric connection pads 107, power is supplied from the outside to, and control signals are input/output to/from, the printing elements 102, the drive circuits 104, the heating elements 106, and the like.
Heating performed by the heating elements 106a to 106c is controlled by control signals provided through the control terminals 401a to 401c which are connected to the switching elements 301a to 301c. The two heating elements 106a provided in the region A are connected in parallel to the switching element 301a, the two heating elements 106b provided in the region B are connected in parallel to the switching element 301b, and the two heating elements 106c provided in the region C are connected in parallel to the switching element 301c. The two heating elements 106 in each of the regions A to C are controlled at the same time through driving control based on the control signal.
Pieces of temperature information detected through changes in the characteristics of the temperature detection elements 105 are converted into electric signals, which are input through the electric connection pads 107 to a main body circuit, outside of the inkjet print head 100, controlling the inkjet print head 100 or to a control circuit within the element substrate 101. The temperatures indicated by the detected temperature information are compared with a predetermined set temperature by a control circuit provided outside of the element substrate 101 or within the element substrate 101. When the temperature of one of the regions A to C is lower than the set temperature, a signal is input to a corresponding one of the control terminals 401a to 401c connected to the switching elements 301a to 301c, whereby the heating element 106 provided in the corresponding region is driven. When a temperature higher than the set temperature is detected by the temperature detection elements 105a to 105c, control is performed in such a manner that the driving of the corresponding heating element 106 is stopped.
As described above, in the present embodiment, the temperature detection elements 105a to 105c are provided respectively in the regions A to C, and the corresponding heating elements 106a to 106c provided in the regions A to C are controlled. In the case where the numbers of driving operations for the printing elements 102 per unit time are different among the regions, the heating elements 106 are continuously controlled in such a manner that the temperatures of the respective regions are maintained at the set temperature, as described above, thereby regulating the temperature distribution within the element substrate 101. As a result, variations in the ejection volume of ink and the ejection speed of ink are suppressed, resulting in high-quality printing.
Here, as illustrated in
A plurality of the arrays of the supply ports 103 are provided in a direction perpendicular to the arrangement direction in which the printing elements 102 are arranged. When these arrays are called the first supply port array, the second supply port array, and the third supply port array, from left to right in this order in
As described above, in the present embodiment, a plurality of the supply ports 103 are provided in the regions A to C arranged in the arrangement direction in which the printing elements 102 are arranged, and the element substrate 101 continuously extends, through regions among the plurality of the supply ports 103, in a perpendicular direction which is perpendicular to the arrangement direction in which the printing elements 102 are arranged. As a result, even when the temperature detection elements 105 and the heating elements 106 are not provided for each array of the printing elements 102, as is the case with the present embodiment, temperature control using the temperature detection elements 105 and the heating elements 106 can be performed in the perpendicular direction with high accuracy.
Hence, in the present embodiment, compared with the case in which the temperature detection elements 105 and the heating elements 106 are provided on both sides of the supply ports 103, the number of the temperature detection elements 105 and the number of elements for controlling the temperature detection elements 105 can be decreased. In this manner, according to the present embodiment, the temperature distribution in the element substrate can be regulated while suppressing an increase in the area of the element substrate due to the elements related to temperature control.
With this configuration, the number of power supply pads for supplying power to, for example, the printing elements 102 can be increased and, hence, a current flowing through each pad is decreased, whereby a voltage drop across the pad is decreased. As a result, power can be efficiently supplied to the printing elements 102. Further, since distances between the printing elements 102 and the electric connection pads 107 are reduced, the lengths of wiring lines for connecting them can be reduced, whereby power can be efficiently supplied to the printing elements 102. In the case where the number of pads for inputting data for selecting the printing elements 102 is increased, the number of data blocks input to the element substrate 101 per unit time is increased, whereby high-speed printing is realized.
Also in the present embodiment, similarly to the above-described embodiment, a plurality of the temperature detection elements 105 are arranged, in the center of the element substrate 101 in a direction perpendicular to an arrangement direction in which the printing elements 102 are arranged, in the arrangement direction. In portions between the drive circuits 104 where the temperature detection elements 105 are not provided, the heating elements 106 are respectively provided in regions, illustrated by broken lines in
Similarly to the above-described embodiment, a plurality of the supply ports 103 are provided for the array of the printing elements 102 in each region, and the element substrate 101 continuously extends, through regions among the plurality of the supply ports 103, in a perpendicular direction which is perpendicular to the direction in which the printing elements 102 are arranged. As a result, even when the number of the arrays of the printing elements 102 is large, it is only required that a single temperature detection element 105 be provided for each region in the center in the perpendicular direction. Hence, an increase in the area of the element substrate 101 due to elements related to temperature control is suppressed.
In the present embodiment, by providing the temperature detection elements 105 between the neighboring regions, the number of the temperature detection elements 105 can be decreased, compared with the first embodiment in which the temperature detection elements 105 are respectively provided for the regions A to C. As a result, an increase in the area of the element substrate 101 due to elements related to temperature control is further suppressed.
In the inkjet print head 1000 of the present embodiment, by arranging the plurality of inkjet print heads 1011 to 1014 in the arrangement direction in which the printing elements 102 are arranged, printing over a long distance in the arrangement direction is realized. An arrow X in
Here, a region A of the inkjet print head 1012 is arranged in such a manner as to partially overlap a portion of the inkjet print head 1011 when viewed in the direction of the arrow X. Hence, the same portion of a print medium can be printed by the inkjet print heads 1011 and 1012 using the printing elements 102 arranged in the overlapping region. Similarly, a region C of the inkjet print head 1012 is arranged in such a manner as to overlap a portion of the inkjet print head 1013 when viewed in the direction of the arrow X. Hence, the same portion of a print medium can be printed by the inkjet print heads 1012 and 1013 using the printing elements 102 arranged in the overlapping region. In the regions where the neighboring inkjet print heads overlap, by performing printing using ink droplets ejected from the two print heads, the occurrence of a case in which an image is emphasized due to an influence of manufacturing errors of the print heads can be suppressed.
When printing is performed in this manner, the driving frequencies of the printing elements 102 when an image having a uniform density is printed are as follows. In the case of the inkjet print head 1012, the driving frequencies of the printing elements 102 in the regions A and C are lower than that in the region B. Hence, the temperatures of the regions A and C of the inkjet print head 1012 are lower than the temperature of the region B. In this manner, the driving frequencies of the printing elements 102 are different in an overlapping region and a non-overlapping region in the inkjet print head when viewed in the conveyance direction of a print medium.
Also in the present embodiment, the temperature detection elements 105a to 105c and the heating elements 106a to 106c are provided respectively in the regions A to C, as described above. In other words, the temperature detection element 105 and the heating elements 106 are provided in each of the regions A and C overlapping with neighboring inkjet print heads and the region B not overlapping with the neighboring inkjet print heads. On the basis of information about the temperatures detected by the temperature detection elements 105 respectively arranged in the regions A to C, driving of the heating elements 106a to 106c is controlled, whereby temperature distribution within the inkjet print head can be regulated. When the driving frequencies of the printing elements 102 are different among the regions of the inkjet print head, temperature distribution can be regulated by providing the temperature detection element 105 and the heating elements 106 in each region.
The present embodiment employs a configuration in which six arrays of the ejection ports 201 are arranged in the inkjet print head 100. The temperature detection elements 105a to 105c are arranged at positions which are displaced from the centers of the element substrate 101 in a direction perpendicular to the direction in which the printing elements 102 are arranged (i.e., the direction in which the ejection ports 201 are arranged). The groups of the heating elements 106 (106a to 106c) are arranged in such a manner as to be asymmetrical about the group of the temperature detection elements 105 (105a to 105c). Specifically, for the temperature detection elements 105a to 105c, two of the heating elements 106 are arranged on the left side in the figure in each of the regions A to C, and one of the heating elements 106 is arranged on the right side in the figure in each of the regions A to C.
Also in the present embodiment, the element substrate 101 continuously extends, through regions among the plurality of the supply ports 103, in a perpendicular direction which is perpendicular to the direction in which the printing elements 102 are arranged. Hence, an uneven temperature distribution in the perpendicular direction is unlikely to be generated. In particular, when the length of the element substrate 101 in the perpendicular direction is small, the temperature distribution becomes more uniform. As a result, the configuration may be employed in which the temperature detection elements 105 and the heating elements 106 are not arranged symmetrically on the element substrate 101, as described above.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2013-077853, filed Apr. 3, 2013 which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-077853 | Apr 2013 | JP | national |
