JP4725151B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus, and more particularly to transporting a platen of an ink jet recording apparatus.

  Conventionally, in a recording apparatus, in order to prevent an operator from being injured due to movement or rotation of parts inside the apparatus, various measures such as providing a case and controlling it so that it does not operate when the cover is open. Has been made. For example, in the image forming apparatus of the invention described in Patent Document 1, in an image forming apparatus protected by a case with a door, an open / closed state of the door is detected, and when the door is in an open state, the image forming apparatus is used for image formation. When a rotation command is issued to the rotating body (photosensitive drum, revolver, roller, etc.), the rotating speed of the rotating body is rotated at a lower speed than usual.

In addition, a support portion (platen) having a support surface for supporting the fabric, which is a printing medium, from below is provided, and printing is performed on the fabric by conveying the support portion in a direction perpendicular to the direction in which the ink discharge portion moves. A fabric printing apparatus has been proposed (for example, Patent Document 2).
JP 2000-221845 A JP 2004-291430 A

  However, in the fabric printing apparatus of the invention described in Patent Document 2, in order to set a fabric such as a T-shirt that is a printing medium on the support portion, the operation is performed by opening the main body cover. In the case of such a printing apparatus, since the medium to be printed is manually replaced every time printing is performed, it is troublesome to open and close the cover every time the cover is covered with the cover. There was a problem, and there was a problem that the efficiency was poor when the platen did not move when the cover was open. Further, as in the image forming apparatus of the invention described in Patent Document 1, even if the platen is moved at a low speed when the cover is open, there is a risk that if the force is strong, the platen is pushed with a strong force. In addition, there is a problem that if the motor does not stop even at a low speed, it continues to be pushed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an ink jet recording apparatus that performs safe platen conveyance.

In order to solve the above-described problem, in the ink jet recording apparatus according to the first aspect of the present invention, a recording unit including a nozzle surface on which a nozzle for performing recording by ejecting ink onto a recording medium is formed, and facing the nozzle surface A platen that supports the recording medium at a distance from the nozzle surface, a recording start position at which recording of the platen is started by the recording means, and a recording end position at which recording by the recording means ends And a feed mechanism that transports the platen before and after the start of recording, and an instruction to transport the platen from the standby position to the recording start position, or the platen Accelerating means for accelerating the platen with normal torque when an instruction to transfer the recording end position to the standby position is input, The acceleration end determining means for determining whether or not to end the acceleration of the platen by the acceleration means, and when the acceleration end determining means determines that the acceleration is to be ended, the transport torque of the platen is set to be greater than the normal torque. A constant speed moving means for moving the platen at a constant speed with low torque, a deceleration start determining means for determining whether to start deceleration of the platen, and a determination to start deceleration by the deceleration start determining means. And a decelerating means for decelerating the platen using the conveying torque of the platen as the normal torque .

In the ink jet recording apparatus according to the first aspect of the present invention, the platen is conveyed with a normal torque during acceleration and deceleration, and is conveyed with a low torque at a constant speed. Therefore, since the torque is normal during acceleration and deceleration that require force for conveyance, the platen can be sufficiently conveyed. Further, at a constant speed, even if the platen is touched, the torque is low, so that the feed mechanism can easily step out and the platen transport is stopped, which is safe.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, an inkjet printer 1 (corresponding to an “inkjet recording apparatus”) according to the present embodiment will be described with reference to FIGS. 1 to 3. 1 is a plan view of the inkjet printer 1, FIG. 2 is a right side view of the inkjet printer 1, and FIG. 3 is a block diagram showing an electrical configuration of the inkjet printer 1. As shown in FIG.

  In the present embodiment, the inkjet printer 1 is a well-known inkjet printer that supplies ink to an inkjet head 21 (see FIG. 3) having a nozzle surface for ejecting ink and performs printing on a recording medium. This is an ink jet printer for handling a fabric such as a T-shirt as a recording medium and performing printing on the fabric such as a T-shirt based on input image information or the like. As shown in FIGS. 1 and 2, the ink jet printer 1 protects the recording mechanism and the recording mechanism on the flat plate-like base 2 and on the back side of the ink jet printer 1 (upper side in FIG. 1, right side in FIG. 2). Main body cover 10 is provided. In the main body cover 10, an inclined surface wall 12 extends from an upper end of a plate-like front wall 11 disposed in a direction perpendicular to the base 2 in an obliquely upward direction on the back side. An upper surface wall 13 parallel to the base 2 extends from the back end of the inclined surface wall 12, and a back wall 14 extends in the vertical direction of the base 2 from the back end of the upper surface wall 13 to the base 2. Installed to protect the recording mechanism. A right wall 16 extends to the right end of the front wall 11, the inclined surface wall 12, the upper surface wall 13 and the rear wall 14 in the vertical direction of the base 2 to the base 2. At the left end of 13 and the back wall 14, a left wall 17 extends to the base 2 in the vertical direction of the base 2.

  The recording mechanism in the main body cover 10 is a well-known inkjet recording mechanism, and is a carriage mounted with an inkjet head 21 (corresponding to “recording means”) in the left-right direction (arrow A direction in FIG. 1) of the inkjet printer 1. Guide rails are installed to guide the movement. A carriage motor 24 (see FIG. 3) is provided near the left end of the guide rail, a pulley is provided near the right end, and a carriage belt is installed between them. The carriage belt is fixed to the back surface of the carriage, and the carriage is reciprocated in the direction of arrow A along the guide rail engaged with the engaging portion provided on the back surface by driving the carriage motor 24. It is like that. In the present embodiment, the lower side in FIG. 1 and the left side in FIG. 2 are the front side of the inkjet printer 1, the upper side in FIG. 1 and the right side in FIG. 2 are the back side of the inkjet printer 1, and the left side in FIG. The left side and the right side of the printer 1 are the right side of the inkjet printer 1. The left-right direction of the inkjet printer 1 (the direction of arrow A in FIG. 1) is the scanning direction of the inkjet head 21.

  Further, the base 2 has a feed mechanism 7 (see FIGS. 4 and 4) for guiding the movement of the platen 5 for setting the recording medium in the front-rear direction of the inkjet printer 1 (the direction of arrow B shown in FIGS. 1 and 2). FIG. 5) is provided. A stepping motor 71 (see FIGS. 4 and 5) is provided at the rear end of the feed mechanism 7 (the upper end in FIG. 1), and the platen 5 reciprocates in the direction of arrow B by the stepping motor 71. The stepping motor 71 is protected by the motor cover 3 provided on the back side of the main body cover 10. The feeding mechanism 7 will be described later in detail using schematic diagrams shown in FIGS. 4 and 5.

  The platen 5 is a substantially rectangular plate having a longitudinal direction in the direction of arrow A in a plan view, and a recording medium made of a cloth such as a T-shirt is placed on the upper surface of the platen 5 horizontally. It is. Further, a chevron handle 55 is provided at the front end of the platen 5 from both ends. There are a plurality of types of the platen 5, and the type of the platen 5 to be used is determined depending on the size of a recording medium such as a T-shirt.

  Below the platen 5, there is provided a tray 4 having a bottom surface substantially parallel to the upper surface of the platen 5 and having an outer periphery that is slightly larger than the platen 5 in plan view. The tray 4 receives a sleeve so that the sleeve of the T-shirt does not fall on the base 2 when the user places the T-shirt on the platen 5. A cover 6 for protecting the lower part of the inkjet printer 1 such as the feeding mechanism 7 is provided in front of the main body cover 10.

  As shown in FIG. 1, an ink cartridge storage section 30 that stores ink cartridges for the respective colors is provided on the left side of the main body cover 10. Each of the ink cartridges stored in the ink cartridge storage unit 30 is provided with an ink supply tube, and is connected to the inkjet head 21 to supply ink to the inkjet head 21. As shown in FIGS. 1 and 2, an operation panel 28 for operating the ink jet printer 1 is provided at a position in front of the right side of the ink jet printer 1.

  Next, the electrical configuration of the inkjet printer 1 will be described with reference to FIG. As shown in FIG. 3, the control unit 100 of the inkjet printer 1 is provided with a CPU 110 that controls the entire inkjet printer 1, and various control programs executed by the CPU 110 are stored in the CPU 110 via a bus 115. A stored ROM 120 and a RAM 130 for temporarily storing data are connected. Further, the CPU 110 drives a head driving unit 140 for driving a piezoelectric actuator provided in each channel of the inkjet head 21, a carriage motor driver 145 for driving the carriage motor 24, and a stepping motor 71. The stepping motor driver 146, the timing generation clock counter 170 for measuring the control timing of the CPU 110, and the input detection unit 160 to which the operation panel 28 and sensors not shown are connected are connected via the bus 115. ing.

  Next, a feed mechanism for the platen 5 of the inkjet printer 1 will be described with reference to FIGS. 4 is a plan view schematically illustrating the feeding mechanism of the platen 5, FIG. 5 is a left side view schematically illustrating the feeding mechanism of the platen 5, and FIG. 6 is a control of the stepping motor 71 of the inkjet printer 1. It is a block diagram. FIG. 7 is a graph showing the elapsed time when the platen 5 is conveyed from the standby position to the recording start position or from the recording end position to the standby position, and the rotation speed of the stepping motor 71. FIG. 5 is a graph showing elapsed time and a rotation speed of a stepping motor 71.

  As shown in FIGS. 4 and 5, in the feed mechanism 7, a motor belt 79 is installed on a motor pulley 73 and a large pulley 72 that rotate as the stepping motor 71 rotates. 73 rotates and the large pulley 72 rotates. A first belt pulley 74 having a rotation axis that is the same as the rotation axis of the large pulley 72 is provided, and the first belt pulley 74 also rotates in synchronization with the rotation of the large pulley 72. These stepping motor 71, motor pulley 73, large pulley 72, and first belt pulley 74 are provided on the back side of the inkjet printer 1 and inside the main body cover 10. Corresponding to the first belt pulley 74, a second belt pulley 75 is provided on the front side of the inkjet printer 1, and a timing belt 78 is installed. The diameter of the second belt pulley 75 is the same as that of the first belt pulley 74, and the timing belt 78 is installed perpendicular to the scanning direction of the inkjet head 21 of the inkjet printer 1 (the left-right direction of the inkjet printer). A straight line connecting the center of the first belt pulley 74 and the center of the second belt pulley 75 is arranged to be perpendicular to the scanning direction of the inkjet head 21. Further, the platen 5 is fixed to the timing belt 78 by the platen mounting portion 51, and the platen 5 moves in the front-rear direction of the inkjet printer 1 as the timing belt 78 rotates. In this way, the rotational motion of the stepping motor 71 is changed to the horizontal motion of the platen 5 via the motor pulley 73, the motor belt 79, the large pulley 72, the first belt pulley 74, the timing belt 78, and the second belt pulley 75. Yes. 4 and 5, the left side is the front side of the ink jet printer 1, and the right side is the back side of the ink jet printer 1.

  Here, the conveying operation of the platen 5 during printing will be described. The platen 5 is conveyed in the front-rear direction (the direction of arrow B in FIGS. 4 and 5), that is, in the direction perpendicular to the scanning direction of the inkjet head 21. The platen 5 is made to wait at the front end of the feed mechanism 7 (the lower end in FIG. 1, the left end in FIGS. 4 and 5; corresponding to the “standby position”) before printing is started or after printing is performed. At the start of printing, the platen 5 waiting at the standby position is transported to the back side of the ink jet printer 1 and transported to a position where the ink jet head 21 scans (corresponding to a “recording start position”). When printing is performed, the platen 5 is conveyed forward by one line from the recording start position scanned by the inkjet head 21. When the printing is completed, the platen 5 on which the recording medium at which the recording has been completed (corresponding to the “recording end position”) is placed is further transported to a standby position positioned on the front side, and a series of operations ends.

  Here, the stepping motor 71 will be described. The stepping motor 71 is a well-known 1-2 phase excitation type stepping motor. A stator that serves as an electromagnet is provided around the rotor, and the rotor is attracted to the electromagnet (stator) by exciting the stator. The rotor rotates step by step. Specifically, the stator has four excitation phases of A phase, reverse A phase, B phase, and reverse B phase. A phase, B phase, reverse A phase, reverse B phase, A phase, They are arranged in the order of B phase. And only A phase, A phase and B phase, B phase only, B phase and reverse A phase, only reverse A phase, reverse A phase and reverse B phase, only reverse B phase, reverse B phase and A phase, A phase Only when the excitation phase is excited and the excited excitation phase has an N pole, the S pole of the rotor is attracted and the N pole is moved away, thereby rotating the rotor step by step.

  That is, by performing excitation continuously, the stepping motor 71 can be rotated, and the platen 5 can be horizontally moved in the front-rear direction of the inkjet printer 1. Further, the angle at which the rotor rotates by one excitation is determined by the number of N poles and S poles of the rotor, and the moving distance of the platen 5 can be controlled by the number of rotation steps of the stepping motor 71.

  As shown in FIG. 6, the excitation control in the stepping motor 71 is performed while the first phase control signal is being sent from the CPU 110 to the stepping motor driver 146 (the pulse signal is in a high state). A phase signal for exciting the phase is sent to the stepping motor 71, and the A phase is excited. Further, while the second phase control signal is being sent (when the pulse signal is high), a B phase signal for exciting the B phase is sent from the stepping motor driver 146 to the stepping motor 71 and the B phase is excited. . Further, while the third phase control signal is being sent (the pulse signal is in a high state), a reverse A phase signal for exciting the reverse A phase is sent from the stepping motor driver 146 to the stepping motor 71 and the reverse A phase is Excited. Further, while the fourth phase control signal is being sent (when the pulse signal is high), the reverse B phase signal for exciting the reverse B phase from the stepping motor driver 146 is sent to the stepping motor 71 and the reverse B phase is Excited.

  Therefore, if the switching interval of the first to fourth phase control signals is lengthened, the rotation of the stepping motor 71 becomes slow, and if the switching interval is shortened, it becomes faster. However, when the rotation of the stepping motor 71 is started, if the phase control signal is suddenly switched at short intervals, the rotor may not be able to catch up with the excited excitation phase, and the rotor may not rotate. Conversely, when stopping the rotation of the stepping motor 71, if the excitation is suddenly stopped, the rotation of the rotor may be rotated as it is due to the law of inertia.

  Therefore, when the rotation of the stepping motor 71 is started and stopped, that is, when the movement of the platen 5 is started and stopped, the phase control signal is not set as an interval of the phase control signal that suddenly becomes the moving speed. Accelerate by gradually shortening the switching interval of, accelerate to the moving speed, rotate (move) at a constant speed by switching at a constant cycle, and gradually increase the switching interval when stopping Decelerate and stop. Note that a clock counter 170 and an acceleration table (not shown) are used for switching the phase control signal in the CPU 110. In the acceleration table stored in the RAM 130, the count value indicating the switching timing is a plurality of count values when accelerating (a plurality of count values gradually decreasing), a constant speed (one count value because it is constant), and a plurality of times gradually increasing The CPU 110 controls the switching of the phase control signal at the timing when the count value of the clock counter 170 becomes the count value read from the acceleration table.

  Therefore, the relationship between the rotation speed of the stepping motor 71 (the moving speed of the platen 5) and the elapsed time has a substantially trapezoidal shape including an acceleration area, a constant speed area, and a deceleration area, as shown in FIG. The graph has such a shape when the platen 5 is moved from the standby position to the printing start position or moved from the printing end position to the standby position. When the platen 5 is conveyed line by line from the print start position side to the print end position side during printing (line feed), since the moving distance of the platen 5 is very small, as shown in FIG. This is a repetition of a substantially triangular shape having no area and a rest area where the platen 5 is stopped.

  In the control of the stepping motor 71, it is very common to suppress the current in order to suppress power consumption and heat generation. When the current is suppressed, the magnetic force generated by the excitation is weakened, so that the generated torque is reduced in proportion to the control amount of the current. The current control signal from the CPU 110 to the stepping motor driver 146 shown in FIG. 6 is for this purpose. When receiving the current control signal, the stepping motor driver 146 suppresses the output current.

  The current control signal is also used for lowering the conveying torque of the platen 5 which is the main part of the present invention. In order to make the conveyance torque of the platen 5 low, the torque of the stepping motor 71 may be low. That is, the current used for exciting the stepping motor 71 is suppressed. In the present embodiment, assuming that the normal current is 100%, the current is limited to 50% when the torque is low. At this time, the generated torque of the stepping motor 71 is 20% of the normal torque of 100%. The attenuation rate of the generated torque with respect to the current suppression rate varies depending on the weight of the platen 5 and the normal current amount. However, if the current is suppressed, the torque is always attenuated.

  In the present embodiment, a mode that outputs a normal current of 100% is called a “normal torque mode”, a mode that outputs a current limited to 50% is called a “low torque mode”, The pulse output of the current limiting signal is in a “high” state.

  Next, the feed control of the platen 5 of the inkjet printer 1 will be described with reference to the flowchart of FIG. FIG. 9 is a control flowchart of the platen 5. This process is started when the inkjet printer 1 receives print data from a connected personal computer (not shown) and the print button on the operation panel 28 is pressed by the user, and the platen 5 is moved from the standby position. Move to the print start position. Further, similar processing is started when printing is completed, and the platen 5 is moved from the printing end position to the standby position.

  First, various initial settings are made (S1). For example, the movement distance is calculated from the size of the print image, the bit pattern corresponding to the rotation phase position of the stepping motor at the current position of the platen (stop position when moved last time) is taken from the truth table, or accumulated Initialization such as resetting the movement distance to 0 is performed.

  Then, one of the phase control signals (for example, only the first phase control signal) is output according to the first bit pattern read in S1, and is held for a certain time (for example, 0.1 second) for stability. Excitation is started (S2). Then, an acceleration end point and a deceleration start point are calculated from the total movement distance and a predetermined maximum speed (S3). Next, the normal torque mode is set, and the pulse output of the current control signal is set to the low state (S4).

  Then, the first count value of the clock counter 170 is read from the acceleration table and set in the clock counter 170 (S5). If there is a timer interrupt from the clock counter 170 (S6: YES), the processing after S7 is performed.

  First, the stepping motor 71 is rotated by the total movement distance measured in S3, and it is determined whether or not the movement is completed (S7). The number of rotation steps of the stepping motor 71 is counted up when the excitation phase is switched in S13 described later. Since the movement has just started and the movement has not been completed (S7: NO), it is determined whether or not a stop instruction has been issued by pressing the stop button on the operation panel 28 (S8). If no stop instruction has been issued (S8: NO), it is determined whether or not the acceleration end point has been reached (S9). Since acceleration has just started and the acceleration end point has not been reached (S9: NO), it is determined whether or not the deceleration start point has been reached (S10). Since the vehicle is still accelerating and has not reached the deceleration start point (S10: NO), the process directly proceeds to S13.

  Then, excitation phase switching processing is performed (S13). Here, the bit pattern of the next phase control signal (for example, “1” only for the first phase control signal and the second phase control signal) is read from the truth table and output. Further, the number of rotation steps of the stepping motor 71 is counted up. Then, the next count value is read from the acceleration table, set to the clock counter 170, and the next timer is started (S14). Since the current state is “acceleration”, the count value set here is shorter than the count value set in S5.

  Then, the process returns to S6 and waits for a timer interrupt from the clock counter 170. When the next count value is measured and the timer interrupt is performed (S6: YES), the processes from S7 to S14 are performed. In this way, when the processes of S6 to S14 are repeated and the acceleration end point is reached (S6: YES, S7: NO, S8: NO, S9: YES), the current state is set to “constant speed”. Thus, the “low torque mode” is set, and the pulse output of the current control signal is set to the high state (S12). Then, excitation phase switching processing is performed (S13), the next count value is read from the acceleration table, set to the clock counter 170, and the next timer is started (S14).

  In step S6, a timer interrupt from the clock counter 170 is awaited. When the next count value is measured and the timer interrupt is performed (S6: YES), the processes from S7 to S14 are performed. Here, since the current state is “constant speed”, the same count value as the previous value is set in the clock counter 170 in S14.

  In this way, when the processes of S6 to S14 are repeated and the deceleration start point is reached (S6: YES, S7: NO, S8: NO, S9: NO, S10: YES), the current state is “deceleration. ”And“ normal torque mode ”is selected, and the pulse output of the current control signal is set to the low state (S11). Then, excitation phase switching processing is performed (S13), the next count value is read from the acceleration table, set to the clock counter 170, and the next timer is started (S14). Here, since the current state is “deceleration”, a value longer than the previous count value is set.

  When the processes of S6 to S14 are repeated and the stepping motor 71 rotates by the total movement distance measured in S3 and the movement is completed (S6: YES, S7: YES), the excitation is released (S15). The process ends. Even when the stop button is pressed and a stop instruction is issued (S6: YES, S7: NO, S8: YES), the excitation is released (S15) and the process ends.

  As described above, when the platen 5 is accelerated and decelerated, the platen 5 is conveyed with normal torque, and at a constant speed, it is conveyed with low torque. Accordingly, the platen 5 can be sufficiently transported because the torque is normal during acceleration and deceleration that require force for transport. At a constant speed, even if the platen 5 is touched, the torque is low, so the magnetic force is weak, the stepping motor 71 is easily stepped out, and the transport of the platen 5 is stopped safely.

In the movement control during printing platen 5, at the time of printing acceleration, deceleration, a repeat of the pause, because there is no constant speed state, is initially set during the "normal torque mode", it is conveyed in the normal torque continues However, since the platen 5 only moves shortly to a position where it wants to face the inkjet head 24 and further moves inside the main body case 10, the risk of touching by the user is low.

  The CPU 110 that performs the process of S12 in the above embodiment corresponds to “first drive control means” and “second drive control means”.

  The ink jet recording apparatus of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention. In the above embodiment, the torque in the conveyance from the standby position to the recording start position and the conveyance torque from the recording end position to the standby position are set to low torque with the same current limit of 50%. The current limiting ratio may be different, and it is sufficient that the torque is lower than the normal torque.

  In the ink jet recording apparatus of the present invention, the excitation method of the platen-driven stepping motor is the 1-2 phase excitation method, but the effect is not changed even if the one phase excitation method or the two phase excitation method is used. In the present invention, the step interval of the stepping motor uses separate tables for acceleration and deceleration. Of course, the same table is used to read out in the direction of shortening during acceleration and in the direction of increasing during deceleration. It may be used in this way.

  The ink jet recording apparatus of the present invention is applicable to an ink jet recording apparatus in which recording is performed while a platen on which a recording medium is placed is conveyed.

1 is a plan view of an inkjet printer 1. FIG. 1 is a right side view of an inkjet printer 1. FIG. 1 is a block diagram showing an electrical configuration of an inkjet printer 1. FIG. FIG. 5 is a plan view schematically illustrating a feeding mechanism of a platen 5. It is the left view which modeled the feeding mechanism of the platen 5. 3 is a control block diagram of a stepping motor 71 of the inkjet printer 1. FIG. 6 is a graph showing the elapsed time and the rotation speed of the stepping motor 71 when the platen 5 is transported from the standby position to the recording start position or from the recording end position to the standby position. 6 is a graph showing the elapsed time during printing and the rotation speed of the stepping motor 71. 4 is a control flowchart of the platen 5.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 5 Platen 7 Feed mechanism 21 Inkjet head 24 Carriage motor 71 Stepping motor 72 Large pulley 73 Motor pulley 74 First belt pulley 75 Second belt pulley 78 Timing belt 79 Motor belt 100 Controller 110 CPU
146 Stepping motor driver 170 Clock counter

Claims (1)

A recording means having a nozzle surface on which nozzles that perform recording by jetting ink onto a recording medium are formed, and is disposed to face the nozzle surface, and supports the recording medium at a distance from the nozzle surface. A platen to be moved, a recording start position at which recording by the recording means is started, a recording end position at which recording by the recording means is ended, and a standby position of the platen before and after the recording is started. In an inkjet recording apparatus provided with a feeding mechanism
Accelerating means for accelerating the platen with normal torque when an instruction to convey the platen from the standby position to the recording start position or an instruction to convey the platen from the recording end position to the standby position is input. ,
Acceleration termination judging means for judging whether or not to terminate the acceleration of the platen by the acceleration means;
A constant-speed moving means for moving the platen at a constant speed with the conveying torque of the platen being a low torque lower than the normal torque when it is determined by the acceleration end determining means to end the acceleration;
Deceleration start determination means for determining whether to start deceleration of the platen;
Deceleration means for decelerating the platen with the conveying torque of the platen as the normal torque when it is determined by the deceleration start determination means to start deceleration.
An ink jet recording apparatus comprising:

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