JP2003001822A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent defective ejection of ink drops to be ejected from an ink ejection port and clogging of the ink ejection port by preventing condensation of a coloring agent in ink and increase in ink thickening which is caused by Na in a sintered ceramic body melted when an ink jet recording head is exposed to an ink exhibiting alkaline property, in the ink jet recording head in which an ink pressure chamber in part is formed of the sintered ceramic body containing aluminum or an aluminum compound. SOLUTION: Na content in the sintered ceramic body is made not greater than 0.5 wt.% in terms of Na2 O, in the ink jet recording head 20 in which the ink pressure chamber 13 in part is formed of the sintered ceramic body containing aluminum or an aluminum composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to printing of characters and images.
Mounted on high-precision inkjet recording equipment used for
It relates to an inkjet recording head. [0002] 2. Description of the Related Art In recent years, personal computers have become widespread.
With the development of multimedia and multimedia,
Ink-jet recording device
The use of is rapidly expanding. In such an ink jet recording apparatus,
Is an inkjet recording head (hereinafter referred to as a head)
This type of head is filled with ink.
A heater as a pressurizing means in the
Heat the ink with a heater, boil it,
The ink is pressurized by bubbles generated in the pressure chamber,
Thermal jet ejected as ink droplets from ejection holes
Method and part of the wall of the ink pressurizing chamber filled with ink.
It is formed by a piezoelectric element, and this piezoelectric element is
And mechanically pressurize the ink in the ink pressurization chamber,
A piezoelectric method that discharges ink droplets from discharge holes is common
Is known to. For example, FIG. 2 shows an example of a piezoelectric head.
As shown, the head 40 is provided on the substrate 2 having an insulating property.
1. Piezoelectric ceramics with polarization directions different from each other
Two wall members 23 and 24 made of
Are arranged in parallel, and the space between these partitions 22 is filled with ink.
In addition to the flow paths 25, ink supply is provided at the bottom of each flow path 25.
Flow path member 27 having supply hole 28, and upper part of flow path member 27
And the ink discharge holes 32 communicating with the respective flow paths 25 are formed.
With the nozzle plate 31 provided and the open end side of the flow path member 27
A sealing plate 30 joined to the substrate 21 and the partition wall 2
2, a space composed of the nozzle plate 31 and the sealing plate 30
Are the ink pressurizing chambers 33, and the side surfaces and the
A piezoelectric ceramic for forming the partition wall 22 is provided at the bottom of the flow channel 25.
Drive electrodes 26 for energizing the box
Have been. Further, a piezoelectric cell for forming the wall members 23 and 24 is provided.
Lamix is based on lead zirconate titanate
A piezoelectric ceramic is used, and a substrate 21 and a sealing plate are used.
30 has porcelain properties such as strength, Young's modulus, corrosion resistance, workability, etc.
Al which can be obtained at a relatively low cost_TwoO_ThreeThe main component
Alumina sintered body is used. The other end of the flow path member 27 is closed.
It has a structure, and each drive
The lead wire 29 of the pole 26 is electrically connected to a driving circuit (not shown).
To be connected to. [0007] Then, using this head 40, a recording medium
To print on the drive, drive
When current is passed between the electrodes 26, the shearing mode of the piezoelectric ceramics
The partition wall 22 whose upper and lower sides are restrained by the c
Pressurizes the ink in the ink pressurizing chamber 33 for bending displacement
So that the ink is ejected from the ink ejection holes 32 as ink droplets.
Had become. [0008] However, in recent years, problems have been raised.
In order to take into account environmental issues
Demand for non-solvent ink for printheads
However, non-solvent inks have poor pigment dispersibility.
For example, make the ink alkaline and adjust the PH value slightly.
That have been adjusted to improve pigment dispersibility.
You. However, like the head 40 shown in FIG.
In addition, an alumina sintered body was used for a part of the ink pressurizing chamber 33.
Exposed to alkaline ink for a long time
And the amount of impurities contained in the alumina
Thorium (Na) elutes and cationizes,
The negative of the dispersant that uniformly disperses the colorant in the ink
This partially neutralizes the charge, resulting in ink viscosity
And the ink flow is hindered, and the ink ejection holes 3
2. The ejection amount and ejection speed of ink droplets ejected from 2 decrease.
At the same time, the colorant in the ink aggregates,
Clogging of the ink ejection holes 32 occurs due to the collected matter,
Accurate, clean, and clear printing because drop ejection is not possible
There was a problem that it became impossible. Further, such a problem is caused by the ink pressurizing chamber 3.
Similarly, when a protective film is formed in
Was raw. In other words, it has a micron-order size
It is difficult to apply a complete protective film in the ink pressurizing chamber 33.
Because there is a small pinhole, this pinhole
When the ink that has entered from above comes in contact with the alumina-based sintered body,
Sodium (Na) elutes into the ink as
Had a problem. Further, such a problem is caused by the ink pressurizing method.
Regardless of the thermal jet method other than the piezoelectric method and other
Ink jet recording head equipped with
Had also occurred. [0012] OBJECTS OF THE INVENTION It is an object of the present invention to reduce the colorant in the ink.
Prevents ink collection and ink viscosity from increasing, and clogs ink ejection holes.
Ink that can be printed accurately, neatly and clearly without blur
An object of the present invention is to provide a jet recording head. [0013] SUMMARY OF THE INVENTION Accordingly, the present invention provides
In consideration of the problem, at least one ink pressurizing chamber and
The ink discharge port communicating with the pressure chamber and the ink
Pressure to discharge ink droplets from the ink discharge holes.
Pressure means, and a part of the ink pressure chamber is made of alumina or
Consists of a ceramic sintered body containing an alumina compound
In the ink jet recording head, the ceramic firing
Na content in the condensate_Two0.5% by weight or less in O conversion
It is characterized by having. [0014] According to the present invention, ink pressure applied to ink is increased.
Containing alumina or an alumina compound that forms part of the chamber
Na content in the ceramic sintered body having_TwoO conversion
0.5% by weight or less
Ceramics even after prolonged exposure to resilient inks
Since the amount of Na eluted from the sintered body is small,
Suppress aggregation of colorant, generate aggregates and increase ink viscosity
Can be prevented and always stable from the ink ejection holes.
It is possible to eject ink droplets of the ejection speed and ejection amount
Become. [0015] DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
explain. FIG. 1 shows an ink jet recording according to the present invention.
It is the perspective view which fractured and showed one embodiment of a pad. This ink jet recording head 20 (hereinafter referred to as "head 20")
(Hereinafter, referred to as a head) is placed on an insulating substrate 1.
Two piezoelectric ceramics with different pole directions
Partition walls 2 formed by bonding two wall members 3 and 4 to each other
The space between these partitions 2 is used as an ink flow path 5.
And a flow path member provided with an ink supply hole 8 at the bottom of each flow path 5
7 is joined to the upper part of the flow path member 7 and communicates with each flow path 5
Nozzle plate 11 having ink discharge holes 12
Insulating sealing plate 1 joined to the open end side of member 7
0, substrate 1, partition 2, nozzle plate 11, and sealing
The space constituted by the plate 10 and the ink pressurizing chamber 13
Therefore, the entire side surface of each partition 2 and the bottom of the flow path 5
The drive electrode 6 is formed along the longitudinal direction,
The surface of the closed portion opposite to the open end of the road member 7 has a drive
A lead 9 for the electrode 6 is formed, and a driving circuit (not shown)
They are electrically connected. The wall members 3 and 4 constituting the partition 2 are as follows.
Piezoelectrics based on lead zirconate titanate (PZT)
Ceramics, lead magnesium niobate (PMN-based)
Piezoelectric ceramics as the main component, lead nickel niobate
(PNN-based) piezoelectric ceramics, and
Uses piezoelectric ceramics that combine these main components
be able to. The ink jet recording head 20
Then, the nozzle plate 11 is made of a Ni—Cr alloy,
Made of metal such as gold and molybdenum, and sealed
The plate 10 and the substrate 1 were made to have a Na content of Na._Two0 in O conversion.
Contains 5% by weight or less of alumina or alumina compound
Ceramic sintered bodies such as ceramics containing alumina
In the case of lamic sintered bodies, alumina-based sintered bodies (Al
_TwoO_Three), For ceramic sintered bodies containing alumina compounds
There is a mullite sintered body (3Al_TwoO_Three・ 2Si
O _Two), Mg spinel sintered body (MgAl_TwoO_Four),
Gillite sintered body (2MgO.2Al_TwoO_Three・ 5Si
O_Two). Using this head 20, a recording medium (shown below)
To print on the printer, use an ink tank (not shown)
Pressure of each of the inks having ink properties through the ink supply holes 8
While being supplied into the chamber 13, it is pulled from a drive circuit (not shown).
Between the driving electrodes 6 formed on both side surfaces of the partition 2 via the outgoing line 9
When power is supplied to the
The partition wall 2 whose upper and lower sides are constrained is bent and displaced in a
Therefore, due to the change in volume of the ink pressurizing chamber 13 occurring at this time,
The ink in the ink pressurizing chamber 13 is pressurized, and
2 to the recording medium as ink droplets,
Images are to be printed. According to the present invention, the ink pressurizing chamber 1
The sealing plate 10 and the substrate 1 constituting a part of 3 are made of alumina.
Or by a ceramic sintered body containing an alumina compound
Upon formation, Na content in this ceramic sintered body
Na amount_Two0.5% by weight or less in terms of O
Even if exposed to alkaline ink for a long time,
Since the amount of Na eluted from the ceramic sintered body is small,
Aggregation of colorant in ink
Since the increase in viscosity can be prevented, ink
Ink droplets of a stable ejection speed and ejection amount are ejected from the outlet.
Can be made. That is, it contains alumina or an alumina compound.
Ceramic sintered body has strength, Young's modulus, workability, etc.
It has excellent porcelain characteristics and can be obtained at relatively low cost.
In both cases, alumina and Mg spinel in particular have excellent corrosion resistance.
Used as a component of the head 20
Although the material is easy to use, the present inventor has proposed that the ink pressurizing chamber 13
Ceramics partially containing alumina or alumina compounds
When formed from a sintered body, the ink droplet ejection performance is poor.
Investigation into the cause
Colorant aggregates are suspended in the ink, and these aggregates
This causes clogging of the ejection holes 12 and ink viscosity.
They found that the degree was increasing. Therefore, the generation of this aggregate and the viscosity of the ink are reduced.
After studying the causes of the increase,
Is present in the cation, and the presence of this Na
Due to the dispersion, the colorant is evenly dispersed in the ink
Partially neutralizes the negative charge of the colorant, causing aggregation of the colorant.
And that this Na is Al_TwoO_ThreeTo
Be eluted from the contained ceramic sintered body
Ascertained. [0024] Further, alumina or alumina compound is contained.
Na in the ceramic sintered body having_TwoO_Threematerial
Often contained as impurities in the ink.
Experiments on the Na content that can suppress
When returned, contains alumina or alumina compound
Na content in ceramic sintered body_Two0 in O conversion.
It has been found that the content should be set to 5% by weight or less, and the present invention has been achieved.
It was. In addition, it contains alumina or an alumina compound.
Na content in the ceramic sintered body is determined by fluorescent X-ray analysis.
Method can be used to quantitatively measure
Or Na content_Two0.3% by weight or less in O conversion
More preferably, the content is 0.1% by weight or less. By the way, alumina or an alumina compound is
Na content in the ceramic sintered body_TwoO exchange
In order to make the weight 0.5% by weight or less, in particular, Al_TwoO_ThreeIn raw materials
Should be as small as possible
Al_TwoO_ThreeAs a starting material used to produce raw materials
The use of highly pure materials with extremely low Na content
Industrial Al_TwoO_ThreeCommonly used to produce raw materials
Bayer method can be used.
Solution method, sol-gel method, coprecipitation method, inorganic salt decomposition method, flame water content
If solution method is used, more Na content than Bayer method
Al with low content_TwoO_ThreeRaw materials can be manufactured. Then, ceramic firing containing alumina is performed.
When an alumina-based sintered body is used as the binder, Na
Al with low content_TwoO_ThreeMgO, Si
O_TwoSintering aids such as CaO and CaO
Molding and firing at a temperature of 1400-1800 ° C
Thus, the Na content is Na_Two0.5% by weight or less in O conversion
What is necessary is just to manufacture a certain alumina-based sintered body. However, sintering
If the content of the auxiliary agent is too large, the alumina-based sintered body
The corrosion resistance of the material decreases, and the strength and Young's modulus
Since the mechanical properties of_TwoO_ThreeContent
It is preferable to use an alumina sintered body of 96% by weight or more.
Good. Also, a ceramic containing an alumina compound may be used.
When a mullite sintered body is used as the sintered body,
Al with reduced Na content_TwoO_ThreeRaw material and SiO_TwoReact raw materials
Mullite raw material (3Al_TwoO_Three・ 2SiO_Two)
After that, the mullite raw material is formed into a predetermined shape,
By baking at a temperature of 0 to 1600 ° C.,
The amount is Na_TwoMullite that is 0.5% by weight or less in terms of O
What is necessary is just to manufacture a sintered body. Ceramic sintering containing alumina compound
When a Mg spinel sintered body is used as the body, N
Al with reduced a content_TwoO_ThreeReact the raw material with the MgO raw material
Mg spinel material (MgAl_TwoO_FourAfter making),
Into which the Mg spinel material is added
And firing at a temperature of 1400-1700 ° C.
And the Na content is Na_Two0.5% by weight or less in O conversion
An Mg spinel sintered body may be manufactured. Ceramic sintering containing alumina compound
When a cordierite sintered body is used as the body, N
Al with reduced a content_TwoO_ThreeRaw materials and MgO and SiO_TwoTo
After reacting, cordierite raw material (2MgO.2Al_TwoO_Three・
5SiO_Two), And then prepare this cordierite raw material
Form into a fixed shape and fire at a temperature of 1300-1400 ° C.
As a result, the Na content becomes Na_Two0.5 weight in O conversion
% Or less may be produced. It should be noted that Na contained in these ceramic sintered bodies was used.
In order to reduce the amount, Al_TwoO_ThreeAdditives other than raw materials
Is low in Na content, high purity
It is preferable to use raw materials of different degrees. Next, the ink jet recording head shown in FIG.
A method for manufacturing the claw 20 will be described. First, when the Na content is Na_Two0.5 in O conversion
Weight percent or less alumina or alumina compound
A substrate 1 made of a ceramic sintered body is prepared.
1 、 Piezoelectric ceramics with polarization treatment in the thickness direction
Two substrates so that their polarization directions are opposite to each other.
Place and use a bonding agent such as thermosetting adhesive or glass
After laminating sequentially, use a grinding device such as a dicing saw
One end is closed on two substrates made of piezoelectric ceramics.
By forming multiple twisted grooves at predetermined intervals,
The grooves are used as ink flow paths 5 and the walls separating the grooves are formed as partition walls 2.
Is manufactured. Then, the bottom of each channel 5
Supply holes by laser processing on the substrate 1 on which
Drill 8 Next, the side surface of the partition 2 and the bottom of the flow path 5 are aligned.
Vapor deposition method, sputtering on the surface of the closed portion of the flow path member 5
A metal film is applied by a film forming means such as an electroless plating method.
After that, cut off unnecessary parts of the metal film by laser processing
As a result, it is formed on the side surface of the partition 2 and the bottom surface of the flow path 5.
The metal film formed on the drive electrode 6 and the gold formed on the surface of the closed portion.
The metal film is used as a lead 9 of the driving electrode 6. The drive electrode 6 and the lead 9 are formed.
Platinum, gold, palladium, rhodium,
Metals such as nickel and aluminum, or platinum-gold,
Alloys mainly composed of palladium-silver, platinum-palladium, etc.
Can be used. Thereafter, each flow path 5 of the flow path member 7 is
Ni-Co alloy, Ni-Fe alloy, molybdenum, etc.
Of each nozzle plate 12 with each ink ejection hole 12
And then heat-set the nozzle plate 12 above the flow path member 7
Bonding using a bonding agent such as a conductive adhesive or glass
In addition, the Na content is Na on the open end face of the flow path member 7._TwoO exchange
0.5% by weight or less of alumina or alumina compound
The sealing plate 10 made of a ceramic sintered body containing
Joining using a bonding agent such as a curable adhesive or glass
Can be obtained by In FIG. 1, the substrate 1 and the sealing plate 10 are
a content of Na_TwoAl which is 0.5% by weight or less in terms of O
For ceramic sintered bodies containing mina or alumina compounds
Although an example in which the nozzle plate 11 is formed is shown in FIG.
Is formed by ceramic sintered body containing alumina compound
In this case, the ceramic sintered body may be used.
Na content in Na_Two0.5% by weight or less in O conversion
What is necessary is just to use an ink supply.
Part of the pressure chamber 13 contains alumina or an alumina compound
Ceramic sintered body, the ceramic sintered body
Na content in the body is Na_Two0.5% by weight or less in O conversion
What should be done. FIG. 1 shows a piezoelectric ceramic.
A material obtained by bonding two wall members 3 and 4 is referred to as a partition wall 2.
In the example shown, either one of the wall members 3 and 4 is
Edge ceramics may be used.
Is made of one piezoelectric ceramic.
It does not matter. Further, in FIG. 1, the nozzle plate 11 is
7 is shown in the upper portion of FIG.
What joined the nozzle plate 11 may be used. In this embodiment, the ink pressurizing chamber 13
Is partially formed of piezoelectric ceramics.
The ink in the ink pressurizing chamber 13 is removed by displacing the mix.
Ink jets ejected from the ink ejection holes 12
Although the recording head 20 has been described as an example, the present invention
It is limited to only the head having such a pressing means.
Instead of using a diaphragm as a part of the wall of the ink pressure chamber,
Vibrated by a separate actuator
By pressurizing the ink inside the ink pressurizing chamber,
Head, called a Kaiser type, or an ink pressurized chamber
Is provided with a resistance heating element as a pressurizing means.
Generate heat and generate bubbles in the ink inside the ink pressurization chamber.
By pressurizing the ink inside the ink pressurizing chamber,
Such as a thermal jet type head
Applicable to inkjet recording heads that have
It goes without saying that you can do it. [0041] (Embodiment 1) Here, the ink jet shown in FIG.
The substrate 1 and the sealing plate 10 of the recording head 20
Alumina sintered body (Al_TwoO_Three), Murai
To sintered body (3Al_TwoO_Three・ 2SiO_Two), Mg spinel
Quality sintered body (MgAl_TwoO_Four), Cordierite sintered body (2
MgO · 2Al_TwoO_Three・ 5SiO_Two) Formed by long time
Ejection speed and ink ejection holes
An experiment was conducted to examine the occurrence of clogging. Specifically, Al_TwoO_ThreeContaining
Alumina firing with different Na content
Consolidation (Al_TwoO_Three), Mullite sintered body (3Al_TwoO_Three・ 2
SiO_Two), Mg spinel sintered body (MgAl_TwoO_Four),
Cordierite sintered body (2MgO.2Al_TwoO_Three・ 5Si
O_Two) Are prepared, and the substrate 1
Zirconate titanate that has been polarized in the thickness direction
Two substrates made of lead-based piezoelectric ceramics are
Arrange the thermosetting adhesive so that the polarization directions are opposite.
After successively bonding, use a grinding machine such as a dicing saw
One of the two substrates made of piezoelectric ceramics
A groove with a closed end was formed with a width of 70 μm and a pitch of 141 μm.
By engraving several grooves, each groove becomes the ink flow path 5,
A flow path member 7 having a wall partitioning each groove as a partition 2 is manufactured.
Was. Then, the laser is applied to the substrate 1 forming the bottom of each flow path 5.
-Drill the ink supply holes 8 by processing, and
And the bottom of the flow path 5 and the surface of the closed section of the flow path member 7
Aluminum film is deposited by the film forming means of the sputtering method.
After laser processing, unnecessary parts of the aluminum film
By cutting off the bottom, the side surface of the partition wall 2 and the bottom of the flow path 5 are removed.
The aluminum film formed on the surface is used as the drive electrode 6,
Extraction of the drive electrode 6 from the aluminum film formed on the surface
Line 9 was used. In the channel 5, a film having a thickness of about several μm is provided.
The liparaxylylene film is used as a protective film by CVD.
I wore it. Thereafter, each flow path 5 of the flow path member 7 and
Each ink ejection hole of the nozzle plate 11 made of a Ni-Fe alloy
After positioning with the nozzle 12, the nozzle is
While joining the metal plate 11 using a thermosetting adhesive,
A sealing plate 10 of the same material as the substrate 1 is provided on the open end face of the flow path member 7.
Are joined by using a thermosetting adhesive.
20 was obtained. Then, the ink pressurization of these heads 20 is performed.
Alkaline ink (viscosity 2 to 5 mPa.
S) to eject ink droplets from the ink ejection holes 12.
And the discharge speed after discharging 1 billion times was examined. ink
The ejection speed of the droplet is determined by the flying state of the ink droplet using a CCD camera.
The ejection speed was determined by photographing and image analysis. So
And the ejection speed of the ink droplet was 5 m / sec or more.
Was determined to be good. In addition, the ink droplet after being ejected one billion times
The presence or absence of ejection is measured by a CCD camera, and the ink ejection holes 12 are measured.
Is checked by microscopic observation for clogging
Clogged ink discharge holes 12
Was determined (percentage). And this ratio is less than 4%
Those that were above were marked as unsuitable and indicated by x, 3% or more to 4%
Less than 1% is indicated as usable and indicated as 2% or more.
If it was less than 3%, it was appropriately marked with a circle and less than 2%
Those which were present were indicated by ◎ as preferred. The results are as shown in Table 1. [0048] [Table 1] As a result, Sample Nos. 1, 3, 7, 9, 1
As shown in 3,17, the content of Na is Na_Two0 in O conversion.
More than 5% by weight are ink drops after 1 billion ejections
Ink ejection speed is slow and clogged ink
The number of holes was large, and the overall evaluation was unsuitable. So
Here, the composition of the foreign matter clogging the ink ejection holes is described.
Was measured and found to be Na. And such N
a is a ceramic sintered body forming the substrate 1 and the sealing plate 10
Since it is hard to imagine mixing from the outside,
The one mixed from the ceramic sintered body forming the plate 10
Conceivable. On the other hand, Sample Nos. 2, 4 to 6, 8, 1
0 to 12, 14 to 16, 18 to 20
Na amount_TwoWhat is 0.5% by weight or less in terms of O
In each case, the ink droplet ejection speed even after 1 billion ejections
Degree can be 5 m / sec or more, and the discharge speed is low.
Ink ejection holes that are not seen below and are clogged
The number was excellent. In particular, the content of Na is low.
Deterioration of ink droplet ejection speed and clogging
The occurrence of balls is small and the Na content is reduced to Na_Two0 in O conversion.
3% by weight or less, and even 0.1% by weight or less
It was excellent. As a result, the substrate 1 and the sealing plate 10 are formed.
Ceramic sintering containing alumina or alumina compound
The content of Na in the body should be 0.5% by weight or less.
I understand that. [0052] As described above, according to the present invention, the ink
Part of the pressurized chamber contains alumina or alumina compound
For inkjet recording heads made of ceramic sintered body
Here, the Na content in the ceramic sintered body was changed to Na_Two
0.5% by weight or less in terms of O, alkalinity
Na elution is suppressed even after prolonged exposure to
Prevents aggregation of colorant in ink and increase in ink viscosity
Of ink from the ink ejection holes,
Droplets can be ejected at a desired ejection speed.
As a result, it is necessary to always obtain accurate,
Can be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially broken perspective view showing an embodiment of an ink jet recording head according to the present invention. FIG. 2 is a partially broken perspective view showing a conventional inkjet recording head. [Description of Signs] 1,21: Substrate 2, 22: Partition walls 3, 4, 23, 24: Wall member 5, 25: Channel 6, 26: Driving electrode 7, 27: Channel member 8, 28: Ink Supply holes 9, 29: Lead lines 10, 30: Sealing plates 11, 31: Nozzle plates 12, 32: Ink ejection holes 13, 33: Ink pressurizing chambers 20, 40: Ink jet recording head

Claims (1)

Claims: 1. An ink pressurizing chamber having at least one ink pressurizing chamber, an ink discharge port communicating with the ink pressurizing chamber, and an ink pressurizing the ink in the ink pressurizing chamber. Pressurizing means for discharging droplets, wherein the ink pressurizing chamber is partially made of a ceramic sintered body containing alumina or an alumina compound, wherein the Na content in the ceramic sintered body is Na. 0 in terms of ₂ O.
An ink jet recording head having a content of 5% by weight or less.