Patent Application
20110292107
The present application claims priority from Japanese Patent Application No. 2010-125158, filed on May 31, 2010, the disclosure of which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a piezoelectric actuator apparatus, and an ink-jet printer provided with the piezoelectric actuator apparatus.
2. Description of the Related Art
Conventionally, piezoelectric actuators, which drive objects by utilizing piezoelectric deformation (also referred to as piezoelectric strain) in the piezoelectric layer, have been widely used in various technical fields. Among those actuators, U.S. Patent Application Publication No. 2005/0219280 (corresponding to Japanese Patent Application Laid-Open No. 2005-289013) discloses a piezoelectric actuator which is usable in ink-jet heads.
The piezoelectric actuator described in U.S. Patent Application Publication No. 2005/0219280 is provided on a flow passage unit of an ink-jet head including a plurality of pressure chambers each communicating with a plurality of nozzles, and applies a pressure to the ink inside the pressure chambers respectively so as to jet ink droplets from the nozzles. More specifically, the piezoelectric actuator of U.S. Patent Application Publication No. 2005/0219280 has a piezoelectric layer (piezoelectric sheet) arranged to cover the plurality of pressure chambers of the flow passage unit, and two types of electrodes (a plurality of individual electrodes and a common electrode) provided on both surfaces of the piezoelectric layer, respectively. The plurality of individual electrodes are provided to overlap the plurality of pressure chambers respectively, and the common electrode commonly faces the plurality of individual electrodes sandwiching the piezoelectric layer therebetween. In this configuration, when a drive device (driver IC) applies a voltage between the individual electrodes and the common electrode, piezoelectric deformation occurs in a plurality of portions of the piezoelectric layer (piezoelectric elements) sandwiched between the plurality of individual electrodes and the common electrode, thereby applying a pressure to the ink inside the pressure chambers.
However, in the piezoelectric actuator described hereinabove, degradation of dielectric strength voltage sometimes occurs in the piezoelectric elements sandwiched between the two types of electrodes. For example, if a voltage is applied between the electrodes in a state that there is a crack in the piezoelectric element, migration may occur and develop along the crack. Further, if a voltage is applied in a state that water or moisture is absorbed in the crack, water tree phenomenon may occur and develop, thereby causing dielectric strength voltage to degrade in the piezoelectric element. Then, such degradation of dielectric strength voltage may be advanced due to continuous voltage application between the electrodes, and may finally cause a short circuit between the electrodes.
The piezoelectric actuator of U.S. Patent Application Publication No. 2005/0219280 is configured such that liquid droplets are jetted from each of the nozzles by a series of processes including applying a voltage to each of the piezoelectric elements as a standby state, releasing the application of the voltage, and applying the voltage again. Therefore, the voltage is also applied to the piezoelectric elements in an unutilized state (not causing jetting of the liquid droplets from the nozzles), that is, in the standby state. In view of this, in the piezoelectric actuator of U.S. Patent Application Publication No. 2005/0219280, in order to restrain the migration phenomenon from developing due to the same voltage application in the standby state, when only black nozzles are utilized to print a text, for example, the voltage is not applied to the piezoelectric elements (individual electrodes) for color nozzles which do not jet liquid droplets, so as to shorten the time of applying the voltage to each piezoelectric element.
In the piezoelectric actuator of U.S. Patent Application Publication No. 2005/0219280, in order to prevent a short circuit from occurring between the electrodes due to the progress of migration, the voltage is not applied to the unutilized piezoelectric elements thereby shortening the application time of the voltage. However, because it is not possible to specify which piezoelectric elements have a defect, it is not possible to individually shorten the application time of the voltage for the piezoelectric elements with the defects.
Further, as described hereinabove, the degradation of dielectric strength voltage in piezoelectric elements caused by migration and the like does not cause a complete short circuit between the electrodes in a short period of time after its occurrence, but it progresses gradually due to a continuous voltage application to the piezoelectric elements after the occurrence. Therefore, from the point of view of improving the product life, it is preferable to take an appropriate measure to prolong the life of the piezoelectric elements before they become degraded in dielectric strength voltage, that is, before they get into a state that a complete sort circuit has occurred between the electrodes and the piezoelectric elements become unusable.
Accordingly, an object of the present invention is to provide a piezoelectric actuator apparatus capable of perceiving the degree of dielectric strength voltage for each of a plurality of piezoelectric elements and thereby taking an appropriate measure for the piezoelectric elements which are degrading in dielectric strength voltage so as to prolong their life.
According to a first aspect of the present invention, there is provided a piezoelectric actuator apparatus which is connectable to a power supply, the apparatus including: a piezoelectric actuator which is provided with a plurality of piezoelectric elements each of which is sandwiched by two types of electrodes; a drive device which is connected to the power supply to drive each of the piezoelectric elements by applying drive pulse signals; a comparison section which compares a predetermined reference value with one of a supply voltage from the power supply to the drive device and an electric current flowing between the power supply and the drive device under the condition that the drive device applies the drive pulse signals to at least one piezoelectric element of the piezoelectric elements; and a judgement section which judges a degradation degree of dielectric strength voltage for the at least one piezoelectric element based on a comparison by the comparison section.
According to a second aspect of the present invention, there is provided an ink-jet printer which is connectable to a power supply and which jets ink droplets to a recording medium, the ink-jet printer including: an ink-jet head including a flow passage unit which has a plurality of nozzles for jetting the ink droplets toward the recording medium and ink flow passages communicating with the nozzles, and a piezoelectric actuator which is provided on the flow passage unit and which has a plurality of piezoelectric elements each of which is sandwiched by two types of electrodes to cause the ink droplets to be jetted from the nozzles; a drive device which is connected to the power supply to drive each of the piezoelectric elements by applying drive pulse signals; a comparison section which compares a predetermined reference value with one of a supply voltage from the power supply to the drive device and an electric current flowing between the power supply and the drive device under the condition that the drive device applies the drive pulse signals to at least one piezoelectric element of the piezoelectric elements; and a judgement section which judges a degradation degree of dielectric strength voltage for the at least one piezoelectric element based on a comparison by the comparison section.
In a piezoelectric element degrading in dielectric strength voltage, when a voltage is applied between the two types of electrodes sandwiching the piezoelectric element, an electric current flows in the piezoelectric element which was originally dielectric. Therefore, during the time of applying the voltage only to such piezoelectric elements, signs such as drop in the supply voltage from the power supply to the drive device, or the electric current flowing between the power supply and the drive device may appear. Further, the more the dielectric strength voltage degrades, the more the electric current flows through the piezoelectric element. This causes changes in the value of the supply voltage or the electric current between the power supply and the drive device. In view of this, in the present invention, the comparison section compares a predetermined reference value with one of the supply voltage from the power supply to the drive device and the electric current flowing between the power supply and the drive device when the voltage is applied to at least one piezoelectric element of the plurality of piezoelectric elements. Based on the comparison results, the judgement section judges a degradation degree of dielectric strength voltage for the at least one piezoelectric element. In this manner, by judging the degradation degree of dielectric strength voltage for the at least one of the piezoelectric elements, it is possible to take measures for the piezoelectric elements which are degrading in dielectric strength voltage but have not yet been completely short-circuited to restrain the degradation of dielectric strength voltage and thereby prolonging the life of the piezoelectric elements.
Hereinbelow, explanations will be made with respect to a preferred embodiment of the present invention. The embodiment is an example of applying the present invention to an ink-jet printer provided with an ink-jet head for jetting ink droplets to a recording paper.
First, explanations will be made with respect to a schematic configuration of an ink-jet printer 1 in accordance with the embodiment. As shown in
The carriage 2 is configured to be movable in a reciprocating manner along two guide shafts 17 extending parallel to the scanning direction (left-right direction of
The ink-jet head 3 is installed on the carriage 2, and includes a plurality of nozzles 30 (see
The transport mechanism 4 has a paper feeding roller 12 arranged on the upstream side in the transport direction with respect to the ink-jet head 3, and a paper discharging roller 13 arranged on the downstream side in the transport direction with respect to the ink-jet head 3. The paper feeding roller 12 and the paper discharging roller 13 are driven to rotate by a paper feeding motor 14 and a paper discharging motor 15, respectively. Then, the transport mechanism 4 transports the recording paper 100 from the upper side of
Next, the ink-jet head 3 will be explained. As shown in
First, the flow passage unit 6 will be explained. As shown in
As shown in
As shown in
Further, the plurality of nozzles 30 are formed in the nozzle plate 23 at the positions which respectively overlap the plurality of communication holes 29, in a plane view. As shown in
As described hereinabove and shown in
Further, in
Next, the piezoelectric actuator 7 will be explained. As shown in
The vibration plate 40 is, in a plane view, an approximately rectangular metallic plate which is, for example, formed of a ferrous alloy such as stainless steels and the like, a copper alloy, nickel alloy, titanium alloy, or the like. This vibration plate 40 is adhered to the cavity plate 20 in a state of being arranged on the upper surface of the cavity plate 20 to cover the plurality of pressure chambers 24. Further, the upper surface of the conductive vibration plate 40 is arranged on the lower surface side of the piezoelectric layer 41 to also act as a common electrode for generating an electric field in the piezoelectric layer 41 in its thickness direction between the plurality of individual electrodes 42 on the upper surface of the piezoelectric layer 41 and the common electrode. As the common electrode, the vibration plate 40 is connected to the ground wire of a driver IC 47 which will be described hereinafter to be constantly maintained at the ground potential.
The piezoelectric layer 41 is plate-shaped and formed of a piezoelectric material composed mainly of lead zirconium titanate (PZT) which is a ferroelectric and a solid solution of lead titanate and lead zirconate. As shown in
The plurality of individual electrodes 42 are arranged on the upper surface of the piezoelectric layer 41 in the areas facing the plurality of pressure chambers 24, respectively. Each of the individual electrodes 42 has a planar shape of an approximate ellipse which is slightly smaller than a pressure chamber 24 and faces the central portion of a pressure chamber 24. That is, the plurality of individual electrodes 42 are arranged to be spaced apart from each other to correspond to the plurality of pressure chambers 24, respectively. Further, from end portions of the plurality of individual electrodes 42, a plurality of contact portions 45 extend out, respectively, in the longitudinal direction of the individual electrodes 42 to be connected to a flexible wiring board (not shown) on which the driver IC 47 is installed.
Further, a plurality of portions in the piezoelectric layer (active portions 46) are sandwiched between the plurality of individual electrodes 42 and the vibration plate 40 as the common electrode. Those active portions are preliminarily polarized in the thickness direction of the piezoelectric layer 41. Then, when a potential difference (voltage) is generated between an individual electrode 42 and the vibration plate 40, a piezoelectric deformation (piezoelectric strain) occurs in the active portion 46 and, because of this deformation, a pressure is applied to the ink inside the pressure chamber 24 facing that active portion 46. That is, one active portion 46 corresponds to one piezoelectric element according to the present invention for applying a jetting pressure to the ink in one pressure chamber 24 and jetting ink droplets from one of the nozzles 30.
The flexible wiring board (FPC, not shown), on which the driver IC 47 (drive device) for driving the piezoelectric actuator 7 is installed, is connected to the piezoelectric actuator 7 and, via the wires on the FPC, the driver IC 47 is electrically connected with the plurality of individual electrodes 42 and the vibration plate 40 as the common electrode. Further, the driver IC 47 is also connected with a control device 8 (see
Next, explanations will be made with respect to the behavior of each of the active portions 46 of the piezoelectric actuator 7 when a drive pulse signal is supplied. When the driver IC 47 supplies a drive pulse signal (
Next, explanations will be made in detail with respect to the driver IC 47 (drive device) for supplying a drive pulse signal to the piezoelectric actuator 7. As shown in
As shown in
Further, as shown in
Next, explanations will be made with respect to an electrical configuration of the printer 1 with a focus on the control device 8 in reference to the block diagram of
Further, the following circuits are incorporated into the ASIC 74: a head control circuit 81 for controlling the driver IC 47 of the ink-jet head 3 and the carriage drive motor 19 respectively based on an image data inputted from the PC 79, a transport control circuit 82 for controlling the paper feeding motor 14 and paper discharging motor 15 of the transport mechanism 4 respectively in the same manner based on the image data, and the like.
The head control circuit 81 generates the waveform selection signal (SIN) for selecting one of the three types of drive pulse signals (see
However, in the active portions 46 of the piezoelectric actuator 7 described hereinbefore (between the individual electrodes 42 and the vibration plate 40 as the common electrode), degradation of dielectric strength voltage may occur due to the migration phenomenon, water tree phenomenon, and the like. For example, in the unimorph-type piezoelectric actuator 7 of the embodiment shown in
However, the degradation of dielectric strength voltage in the active portions 46 due to migration and the like gradually advances by a continuous voltage application to the active portions 46 after its occurrence. Therefore, if such a sign is detectable in a certain active portion 46 before the degradation of dielectric strength voltage becomes advanced and thereby causes a complete short circuit to occur between the individual electrode 42 and the vibration plate 40 becomes unusable, it is possible to take an appropriate measure for that active portion 46 to prolong its life. In view of this, in the embodiment, the degradation degree of dielectric strength voltage is judged at a plurality of levels for each of the plurality of active portions 46, and then the method for driving the active portions 46 is changed according to the level.
Hereinbelow, descriptions will be made with respect to a configuration for judging the degradation degree of dielectric strength voltage in each active portion 46 and a specific judgement method in reference to
At the time of judging the degradation level of dielectric strength voltage in the plurality of active portions 46, the driver IC 47 applies the voltage to the individual electrodes 42 one by one for each of the plurality of active portions 46 (the step S101 of
At the time of applying the voltage only to one of the plurality of active portions 46, if that active portion 46 is a normal active portion without degradation of dielectric strength voltage, then the supply voltage (the VDD voltage of
Here, the comparator 48 inside the driver IC 47 compares the VDD voltage with a plurality of reference voltages (for example, five types of reference voltages V1 to V5) when the driver IC 47 applies the voltage only to one active portion 46 (the step S102 of
On the other hand, the judgement circuit 49 of the control device 8 reads out the comparison results which are outputted from the comparator 48 after comparing the VDD voltage with the five types of reference voltages and stored in the storage section 50. Then, based on the comparison results, the judgement circuit 49 judges how much the dielectric strength voltage degrades, that is, the degradation level of dielectric strength voltage, for each of the plurality of active portions 46, and the judgement results are stored in the storage section 50 (the steps S105, S106 and S107 of
In the embodiment, from the comparisons between the VDD voltage and the five types of reference voltages V1 to V5 at the time of applying the voltage only to one active portion 46, the degradation level of dielectric strength voltage is determined as below. Further, the following table 1 shows an example of the output results from the comparator 48 and the degradation levels of dielectric strength voltage judged based on the results.
V1 or above→Degradation level of dielectric strength voltage: 0 (normal);
V2 or above but under V1→Degradation level of dielectric strength voltage: 1;
V3 or above but under V2→Degradation level of dielectric strength voltage: 2;
V4 or above but under V3→Degradation level of dielectric strength voltage: 3;
V5 or above but under V4→Degradation level of dielectric strength voltage: 4; and
Under V5→Degradation level of dielectric strength voltage: 5 (unusable due to short circuit between electrodes).
The above table 1 shows the comparison signal (L signal “0” or H signal “1”) with respect to the reference voltages outputted from the comparator, and the degradation levels of dielectric strength voltage in three active portions 46 (nozzles 30) at the time of applying the voltage to each of the three active portions 46 (No. 1 to No. 3) one by one. In the No. 1 active portion 46, the comparison signals are all “L” with respect to the five types of reference voltages. That is, the VDD voltage is V1 or above, and thus the degradation level of dielectric strength voltage is level 0 (normal) in this active portion 46. On the other hand, in the No. 2 active portion 46, the comparison signals are all “H” with respect to the five types of reference voltages. That is, as shown in
Further, in the No. 3 active portion 46, the comparison signals are “H” only with respect to V1 and V2. That is, as shown in
Further, in the embodiment, the driver IC 47 is provided on the inside with the comparator 48 for detecting the VDD voltage drop at the time of applying the voltage to one active portion 46. However, it is also possible to carry out the same judgement when the comparator is provided not on the side of the driver IC 47 but on the side of the control device 8. Nevertheless, as shown in
Further, at the time of carrying out judgement of the degradation level of dielectric strength voltage, because the driver IC 47 applies the voltage to the active portions 46 one by one, it is also conceivable that liquid droplets may be jetted from the nozzles 30 depending on the application voltage. Therefore, it is preferable to carry out judgement of the degradation level of dielectric strength voltage in the active portions 46 under such a condition as no problems may occur even if liquid droplets are jetted. For example, with respect to an ink-jet printer, in order to prevent the nozzles 30 from drying before or while carrying out printing on the recording paper 100, it is common to perform a so-called flushing operation, in which the ink-jet head 3 is moved to a position which does not face the recording paper 100 (such as both end positions in the left-right direction, i.e., the scanning direction in
Further, at the time of judging the degradation level of dielectric strength voltage described hereinabove, the voltage applied to the active portions 46 may be the drive voltage (the voltage level of the drive pulse signals) at the time of actually driving the active portions 46, or may also be a voltage different from the drive voltage. If the voltage to be applied at the above-mentioned judgement time is set to be lower than the drive voltage, it is possible to prevent liquid droplets from being jetted during the examination time. On the contrary, if the voltage at the judgement time is set to be higher than the drive voltage, the degree of the supply voltage drop will become conspicuous at the time of applying the voltage to the active portions 46 with degraded dielectric strength voltage, thereby improving the detection accuracy.
Further, in the embodiment, the configuration, which is composed of the piezoelectric actuator 7, the driver IC 47 (drive device) for driving the piezoelectric actuator 7, the comparator 48 (comparison section) incorporated in the driver IC 47, and the judgement circuit 49 (judgement section) provided in the control device 8, corresponds to the piezoelectric actuator apparatus of the present invention.
The head control circuit 81 of the control device 8 refers to the degradation level of dielectric strength voltage of each active portion 46 judged by the judgement circuit 49 and stored in the storage section 50, and carries out control of the driver IC 47 to restrain the dielectric strength voltage from further degrading. In particular, when the degradation level of dielectric strength voltage exceeds a predetermined level in an active portion 46, that is, when the degradation of dielectric strength voltage advances to a certain extent or more, such a measure as below is taken to restrain the degradation of dielectric strength voltage. Further, the predetermined level described hereinabove may be appropriately determined in view of the contents of the restraint measure described hereinbelow, the influence on printing (degradation in print quality) at the time of carrying out the measure, and the like. For example, it is possible to set the predetermined level at level 1 (when the VDD voltage has dropped under V1 in
The more (the number of times of applying the voltage) an active portion 46 is driven, or the longer the voltage is applied, the more the degradation of dielectric strength voltage advances in that active portion 46. In view of this, when the degradation level of dielectric strength voltage is judged as having exceeded the predetermined level in a certain active portion 46, comparison is made with the case of not exceeding the predetermined level, and the number of times of driving the active portion 46 (the number of times of applying the voltage) is restricted to a smaller number within a certain period, or the time of applying the voltage is restricted to a shorter time. That is, even though it is required to drive an active portion 46 a large number of times within a certain period, or to apply the voltage to the active portion 46 for a, long time, with respect to the active portion 46 degrading in dielectric strength voltage, from the point of view of life prolongation, the number of drives is restricted to be small, or the time of voltage application is restricted to be short. Hereinbelow, a few specific examples will be given.
In a case of carrying out printing on one sheet of the recording paper 100, the number of driving of one active portion 46 (the number of jetting liquid droplets of the corresponding nozzle 30) is determined by the image data inputted from the PC 79. Further, according to the number of driving, the total time of applying the voltage to the active portion 46 during printing the one sheet of the recording paper 100 is also determined for.
In view of this, with respect to an active portion 46 in which the degradation level of dielectric strength voltage exceeds a predetermined level, the number of driving (the time of voltage application) is reduced to be less than the number of driving determined from the image data. That is, the number of jetting liquid droplets from the nozzle 30 corresponding to that active portion 46, i.e., the number of dots to be formed on the recording paper 100 by that nozzle 30 is reduced. In such cases, some liquid droplets are not jetted to the positions where dots should have been formed. As a result, since dots are partially thinned out, print quality may degrade more or less. However, since the number of driving (drive frequency) or time of voltage application is reduced, it is possible to prolong the life of the active portions 46 degrading in dielectric strength voltage.
In the embodiment, each active portion 46 is supplied with one drive pulse signal selected from the three types of drive pulse signals (
Further,
Since the degradation of dielectric strength voltage in an active portion 46 advances more quickly when a higher voltage is applied to the active portion 46, the voltage applied to such active portions 46 may also be lowered in comparison with the normal active portions 46. In particular, the driver IC 47 is configured to be able to select one type of a plurality of types of voltage levels as the voltage to apply to each active portion 46, and to be able to adjust the pulse height (application voltage) of the drive pulse signal for each active portion 46. Further, while there is no specific limitation on the configuration of the circuit for generating the plurality of types of voltage levels, it is possible to adopt such a circuit configuration as to acquire a plurality of types of voltage levels equal to or under the VDD voltage level by dividing the VDD voltage into a plurality of levels with a plurality of impedances arranged in series between the VDD (high potential wire) and the VSS (low potential wire). Then, for the active portions 46 with the degradation level of dielectric strength voltage over a predetermined level, the driver IC 47 selects a drive voltage lower than that for the normal active portions 46 so as to supply the drive pulse signal with a low pulse height.
As explained hereinabove, in the embodiment, by judging the degradation degree of dielectric strength voltage at a plurality of levels for each of the plurality of active portions 46, it is possible to take measures for the active portions 46, which are degrading in dielectric strength voltage but have not yet been completely short-circuited, to restrain the degradation of the active portions 46 in dielectric strength voltage and thereby prolonging the life of the active portions 46.
Next, explanations will be made with respect to a few modifications which apply various changes to the embodiment. However, it should be appreciated that the constitutive parts or components, which are the same as or equivalent to those of the embodiment, are designated by the same reference numerals, any explanation of which will be omitted as appropriate.
In the embodiment, the degradation degree of dielectric strength voltage is judged for each of the plurality of active portions 46. However, for example, it may also be judged for each group of active portions 46 corresponding to the plurality of nozzles included in one nozzle row. In particular, the supply voltage from the power supply to the driver IC 47 is compared with a plurality of types of reference values at the time of applying the voltage to a group of active portions 46 corresponding to the plurality of nozzles included in one nozzle row and, based on the comparison results, the judgement circuit 49 may judge the degradation degree of dielectric strength voltage in the group of active portions 46 corresponding to the one nozzle row at a plurality of levels. In such cases, because it is possible to judge the degradation degree of dielectric strength voltage in the group of active portions 46 corresponding to each nozzle row, it is possible to take an appropriate measure for each nozzle row.
Further, in the embodiment, from the comparisons between the VDD voltage and the five types of reference voltages V1 to V5 at the time of applying the voltage only to one active portion 46, the degradation level of dielectric strength voltage is judged at five levels. However, it is also possible to take such measures as to compare the VDD voltage with one predetermined reference voltage, judge that the dielectric strength voltage is degrading in the one active portion 46 if the VDD voltage is lower than the reference voltage, and reduce the number of voltage applications to the one active portion 46 or shorten the time of voltage application, and the like.
At the time of applying the voltage only to one active portion 46 with degraded dielectric strength voltage, abnormal signs may appear not only in the supply voltage from the power supply (VDD) but also in the electric current flowing between the power supply and the driver IC 47 (piezoelectric actuator 7). That is, almost no electric current flows in the active portions 46 in a normal state, whereas an electric current keeps flowing in the active portions 46 degrading in dielectric strength voltage throughout the period of voltage application. That is, the electric current keeps flowing between the power supply and the driver IC 47 (piezoelectric actuator 7). Further, the more the dielectric strength voltage degrades in an active portion 46, the more the electric current flows through the active portion 46. In view of this, at the time of applying the voltage only to one active portion 46, the comparator 48 may also compare the electric current (flowing through the VDD or VSS of
In the embodiment, adjacent active portions 46 (piezoelectric elements) are connected via the surrounding piezoelectric layer 41. However, as shown in
In the embodiment, the piezoelectric actuator is configured to jet ink droplets from the corresponding nozzle by changing each piezoelectric element from a standby state under no voltage application to a state under a voltage application. However, it may also be configured to jet ink droplets from the corresponding nozzle by once releasing each piezoelectric element from a standby state under a voltage application and then putting the each piezoelectric element back again into the state under the voltage application.
The piezoelectric actuator which is an object of applying the present invention is not limited to that of an ink-jet head for jetting liquid droplets from nozzles. For example, it is also possible to apply the present invention to actuators for applying a pressure to liquids other than inks and, furthermore, to actuators for driving a solid object.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-125158 | May 2010 | JP | national |
