Suction mechanism for ink jet recording apparatus

Abstract: A suction mechanism for use in an ink jet recording apparatus, said suction mechanism comprising a first cap (37) for effecting recovery suction on a first ink jet recording unit (10,11,12); a second cap (34) for effecting recovery suction on a second ink jet recording unit (19,20,21,22,23,24,25); a switching mechanism (41) for enabling recovery suction of at least one of said first and second caps (34,37); and a pump (45) for communication with said first and second caps through said switching mechanism, characterised in that said switching mechanism (41) is movable between a first position in which said first and second caps (34,37) are in communication with said pump (45) and a second position in which only said first cap (37) is in communication with said pump (45).

Description: This invention relates to a suction mechanism for a serial type recording apparatus which is applicable to a recording apparatus in a business machine or a communication instrument such as a copying machine, a facsimile apparatus, a personal computer or an office computer, and in particular to a recording apparatus which can be effectively applied to an ink jet recording apparatus in which a carrier is caused to scan in the direction of recording column to thereby accomplish recording. Among serial type recording apparatuses, such as ink jet recording apparatuses, wire dot printers and heat transfer printers, proposed before the present invention, there is one in which a recording head is carried on a single carriage and when image recording using different ink is to be effected, the recording head is interchanged with another recording head by a manual operation and recording with the different ink is effected. However, in such apparatus, it is not intended that a plurality of recording heads be carried on the carriage to effect color recording, and such apparatus is not constructed so that a plurality of recording heads are carried on the carriage. In any case, actually, black documents and the black printing mode by data processing are more often used for the printing in a terminal instrument than colored graphics and colored documents. Instead of the manual operation, it is conceivable to move always serially a carriage carrying a plurality of recording heads thereon to thereby enable printing in any color to be accomplished, but this will result in a construction in which a recording head or heads unused for recording are always moved or continue to be moved in a state capable of recording. Accordingly, in the heretofore known ink jet recording, a recording head or heads not used at all are subjected to the recovery process or ink is heated and this leads Particularly to the waste of time and the waste of electric power. Also, the carriage carries the maximum weight thereon at all times and therefore, the load for moving the carriage becomes great. On the other hand, a color ink jet printer has carried recording heads for four colors, i.e., Bk (black), Y (yellow), M (magenta) and C (cyan) in parallel on a single carriage and has effected printing by causing the carrier to scan. However, in the ink jet printer, during black printing, the other printing heads are exposed to the atmosphere, and this causes problems such as clogging and adherence resulting from the desiccation of ink. These problems arise earlier in the recording head being not used than in the recording head being used, and even if the recovery process is carried out, the period during which these problems arise becomes very short. As the recovery process, it is usually the practice to return the carriage periodically to its home position even during black printing to thereby effect idle discharge as the recovery process, or to effect suction of ink from the color printing heads even during the closing of the main switch or the suction recovery operation, and this brings about the inconvenience that the recording time is prolonged. Also, by this recovery process, the color inks are wastefully consumed, and this has been remarkably uneconomical. Also, even when high-speed printing, like the data output in black printing, is to be effected, it has been necessary to drive the heavy carrier carrying the four recording heads thereon and thus, an expensive and bulky motor for driving the carrier has been necessary. Also, even under printing conditions under which black printing can be executed, the absence of other color inks makes printing impossible. Also, in spite of the execution of printing being possible if the temperature control of only the black head is effected under printing conditions under which black printing can be executed, waste such as effecting the temperature control of the other colour heads, for example, warming all the heads so as to assume 35°C or higher, is unavoidable. US-A-4492969 describes a capping device for a multi-ink jet head wherein respective areas of a capping means are simultaneously brought into contact with respective ink jet heads and the suction recovery means is arranged to isolate suction recovery tubes of the respective ink jet heads from one another to prevent mixing of ink sucked out of the capping means during a suction recovery operation. According to the present invention, there is provided an ink jet recording apparatus for recording using first and second ink jet recording units, said apparatus having a suction mechanism comprising: a first cap for capping a first ink jet recording unit; a second cap for capping a second ink jet recording unit; and a pump for communicating with said first and second caps to perform suction recovery of said first and second caps, characterised by further comprising a switching mechanism movable between a first position in which said first and second caps are in communication with said pump to effect suction recovery of said first and second ink jet recording units and a second position in which only said first cap is in communication with said pump to effect suction recovery of only said first ink jet recording unit. The present invention also provides a suction mechanism in accordance with Claim 8. Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a general perspective view showing an embodiment of an ink jet recording apparatus according to the present invention; Figures 2A and 2B are fragmentary cross-sectional views showing the cap changing-over operation of the recovery system in Figure 1; Figures 3A - 3C are fragmentary plan views showing the scanning by the connection and separation of the two carriages in Figure 1. Figure 4 is a block diagram of the control system of the recording apparatus of Figure 1. Figure 5 is a flow chart showing the operation Procedure of the control system of Figure 4. Figure 6 illustrates connection and separation of two carriages. Figure 7 is a conceptional view illustrating the control of Figure 6. Figure 8 is a flow chart of another embodiment of the control of the present invention. Figure 9 is a flow chart of the interruption sub-routine of Figure 8. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will hereinafter be described with reference to the drawings. Figure 1 is a perspective view showing an embodiment of the present invention. The reference numeral 1 designates a base formed with a left side plate 1a and a right side plate 1b, and a rear side plate 1c. The reference numeral 2 denotes an intermediate side plate provided upright at a predetermined location on the base 1. The reference numeral 3 designates a platen roller formed of an elastic material of great coefficient of friction such as rubber. The reference numeral 4 denotes a platen roller shaft extending through the center of the platen roller 3 and rotatably supported on the right side plate 1b and the intermediate side plate 2. The reference numeral 5 designates a paper feeding motor fixed to the right side plate 1b and adapted to rotate the platen roller shaft 4 through a gear train, not shown. The reference numeral 6 denotes a paper pan extending from the rear of the platen roller 3 and below the platen roller and guiding a sheet or paper forwardly. The reference numeral 7 designates a printing sheet wound on the platen roller 3 and urged against the platen roller 3 with a predetermined pressure force by a pinch roller, not shown The printing sheet 7 is conveyed in synchronism with the rotation of the platen roller 3. The reference numeral 8 denotes an A guide shaft, and the reference numeral 9 designates a B guide shaft. The A and B guide shafts 8 and 9 are supported parallel to each other on the left side plate 1a and the right side plate 1b. The reference numeral 10 denotes a carrier for a black ink recording head (hereinafter referred to as the black carrier). The black carrier 10 is slidably supported on the A guide shaft 8 and the B guide shaft 9. The black carrier 10 is formed with a clamp portion 10a having a groove having inside thereof teeth similar in shape to a timing belt which will be described later in order to clamp the timing belt. The reference numeral 11 designates a black ink recording head (hereinafter referred to as the black head) carried on the black carrier 10. The reference numeral 12 denotes a tank containing black ink therein. The tank 12 is removably mounted on the black carrier 10, and the ink is supplied therefrom to the black head 11 through a supply system, not shown. The reference numeral 13 designates a connecting lever having a hook portion 13a formed at the fore end thereof and having a control pin 14 studded in the lower portion thereof. The connecting lever 13 is rotatably supported on a rotary shaft 15 studded in the lower portion of the black carrier 10, and is biased in one direction by a spring 16. The reference numeral 17 denotes a compression spring mounted at a predetermined location on the black carrier 10 and adapted to be compressed when coupled to a carrier 19 for color printing which will be described later, to thereby bias it in a direction to separate the carriers 10 and 19 from each other and eliminate the back-lash during the connection. The reference numeral 18 designates a flexible cable which electrically connects the black head 11 to a control board, not shown. The reference numeral 19 denotes a carrier for color printing (hereinafter referred to as the color carrier). The color carrier 19, like the black carrier 10, is slidably supported on the A guide shaft 8 and the B guide shaft 9. Figure 3 shows the operation of the connecting portion between the black carrier 10 and the color carrier 19. An engagement pin 19a for engaging with the connecting lever 13 is formed on the lower portion of the color carrier 19, as shown in Figure 3. A Y (yellow) head 20, an M (magenta) head 21 and a C (cyan) head 22 are mounted at a predetermined pitch on the color carrier 19. Also, a Y (yellow) tank 23, an M (magenta) tank 24 and a C (cyan) tank 25 are removably mounted on the color carrier 19. The reference numeral 26 designates a flexible cable for color. The reference numeral 27 denotes a tension pulley rotatably supported on a shaft 28. The shaft 28 is studded on a tension plate 29, and is fixed by imparting predetermined tension to a timing belt which will be described later. A carrier motor 30 is mounted on the right side plate 1b, and a pulley 31 is fixed to the shaft thereof. The reference numeral 32 designates a timing belt mounted on the pulley 31 and the tension pulley 27 with predetermined tension and coupled to the black carrier 10 at a crank portion 10a. Accordingly, the black carrier 10 is scanned and driven by the rotation of the carrier motor 30. The reference numeral 33 denotes a cap guide shaft supported between the left side plate 1a and the intermediate side plate 2. The reference numeral 34 designates a cap for the color heads 20, 21 and 22 (hereinafter referred to as the color cap). The color cap 34 is slidably and rotatably held on the cap guide shaft 33. Denoted by 34a is an opening-closing can formed integrally with the color cap 34 and having an inclined surface portion formed on one side thereof. By this opening-closing cam 34a bearing against an opening-closing pin 39 (Figure 3) which will be described later, the color cap 34 is moved while pivoting toward the printing head. The color cap 34 is engaged with the carrier 19 by an engagement portion, not shown, and is capped onto the head when the color carrier 19 is scanned toward the left side plate 1a. Designated by 34b is a spring hooking shaft studded on the color cap 34. The reference numeral 35 denotes a compression torsion spring having the functions as a compression spring and a torsion spring. The compression torsion spring is inserted in the cap guide shaft 33, and one end thereof is hooked on the spring hooking shaft 34b of the color cap 34 and the other end thereof is hooked on a hook 36 rising from the base 1. The reference numeral 37 designates a cap for capping a recording head for black printing (hereinafter referred to as the black cap). The black cap 37, like the color cap 34, is slidably and rotatably supported on the cap guide shaft 33, and is moved by an engagement portion, not shown, in synchronism with the movement of the black carrier 10 and is operated by an opening-closing cam 37a so as to cap the black head 11. The reference numeral 38 denotes a compression torsion spring which, like the aforedescribed compression torsion spring 35, is mounted on a spring hooking shaft 37b. The reference numerals 39 and 40 designate opening-closing pins studded on the base 1. The opening-closing cams 34a and 37a bear against the opening-closing pins 39 and 40, respectively. The reference numeral 41 denotes a change-over valve having a piston 41a (Figure 2) in which a flow path is formed. By the piston 41a being moved in a cylinder 41b, the black cap and the color cap are changed over to a case where the color cap 34 is communicated with a pump and a case where both of the black cap and the color cap are communicated with the pump, as shown in Figure 2. The reference numeral 42 (Figures 1, 2A and 2B) designates a change-over shaft secured to the piston 41a of the change-over valve 41 and adapted to be synchronized with the movement of the piston 41a. The reference numeral 43 (Figures 2A and 2B) denotes a change-over plate mounted on the fore end of the change-over shaft 42. When the piston 41a is moved toward the carrier side (the normal position of Figure 2B), the change-over plate 43 bears against the control pin 14 of the connecting lever 13 and therefore, the connecting lever 13 and the engagement pin 19a of the color carrier 19 do not come into engagement with each other. The reference numeral 44 designates a solenoid connected to the piston 41a. When electric power is supplied to the solenoid 44 to attract it, it causes the piston 41a to move against the force of a spring 41c, as shown in Figure 2A. At this time, the change-over plate 43 is retracted and therefore, the connecting lever 13 and the engagement pin 19a come into engagement with each other, and the black carrier 10 and the color carrier 19 are connected together and become movable as a unit. The reference numeral 45 denotes a pump. By the shaft 45a of the pump 45 being pushed into the pump, negative pressure can be generated in the pump to thereby suck the ink from the black cap 37 and the color cap 34. The pump 45 is mounted on the rear side plate 1c by means of a mounting plate 49. The reference numeral 47 designates a recovering motor mounted on the rear side plate 1c. A cam 48 is secured to the shaft of the recovering motor 47, and the cam 48 is rotated by the rotation of the recovering motro 47, and the shaft 45a of the pump 45 is pushed in by the cam portion of the cam 48 to thereby operate the pump 45. The reference numeral 46 denotes a discharged liquid tank for collecting liquid discharged from the pump 45. The discharged liquid tank 46 is installed at a predetermined location. The reference numeral 47 designates a discharged liquid tube for guiding the discharged ink. The operation of the above-described color ink jet recording apparatus will now be described. First, during black printing, as shown in Figure 3A, only the black carrier 10 scans in the direction of print column and effects printing. At this time, the solenoid 44 is not electrically energized and as shown in Figure 2B, the piston 41a is moved toward the black carrier 10 by the spring 41c and stopped thereat. When the black carrier 10 is returned to its home position for preliminary discharge or capping, the black carrier 10 first comes into engagement with the black cap 37, and the black cap 37 also moves in synchronism with the movement of the black carrier 10, and the opening-closing cam 37 bears against the opening-closing pin 40, whereby the black cap 37 is urged against the black head 11 and caps the latter. At this time, as shown in Figure 2B, the change-over plate 43 is within the range of movement of the connecting lever 13 and therefore, as shown in Figure 2B, the change-over plate 43 bears against the control pin 14 of the change-over lever 13 and the change-over lever 13 is rotated in the direction of arrow A and therefore, the hook Portion 13a does not come into engagement with the engagement pin 19a of the color carrier 19. Also, since the black cap 37 is in communication with the pump, the change-over valve 41 sucks the ink from only the black head 11 even if the ink is sucked by the pump 45. Even if in the state of Figure 2B, the black carrier 10 scans in the rightward direction for printing, the color carrier 19 remains stopped at its original position. In this manner, during normal printing, only the black carrier 10 scans and the recovering system also acts on only the black head 11. Description will now be made of the scanning of the color carrier 19 for color printing. When, as previously described, the solenoid 44 is electrically energized to pull the piston 41a in a state in which the black carrier 10 is capping, the change-over plate 43 is retracted as shown in Figure 2A and the connecting lever 13 is pulled by the spring 16 and rotated thereby in the direction of arrow B, and becomes connected to the engagement pin 19a of the color carrier 19. At this time, a slight gap Δℓ is created between the hook portion 13a and the engagement pin 19a, but this gap Δℓ is eliminated by the compression spring 17 when the black carrier 10 is moved to the left and connected to the color carrier 19. When the black carrier 10 is moved to the right, the black cap 37 and the color cap 34 are moved by a predetermined amount by the compression torsion springs 35 and 38 and the opening-closing cams 34a and 37a whereby the caps are released Color printing is usually in one direction with the order of superposition of colors and the printing accuracy taken into account, and does not effect high-speed printing of draft characters or the like and therefore, even if the weight of the color carrier 19 is increased, the increase in the load to the carrier motor 30 is slight. In the suction recovering operation during color printing, when the carrier is at its home position as shown in Figure 3B, capping is effected and the solenoid 44 is electrically energized as previously described, whereby the piston 41a is brought to the position shown in Figure 2A and both of the black cap 37 and the color cap 34 are communicated with the pump 45, and the recovering motor 47 is rotated to operate the pump 45, whereby the suction recovering operation can be accomplished from all the black and color heads. Also, the solenoid 44 may be electrically deenergized during printing, and can be electrically energized only when the black carrier connects the color carrier 19 or when suction is effected from all heads, and thus, power consumption can be reduced. The ink for recovery may be supplied from the ink tank by a supply tube and in that case, the supply recovery of black ink which is high in frequency of use can be decreased and thus, working property can be improved. As is apparent from the foregoing description, according to the above-described embodiment, there is provided an economical color ink jet recording apparatus in which the carrier for black printing and the carrier for color printing are separated from each other (that is, the scannings of the recording heads are separated from each other) and black printing is effected by the scanning of the black carrier and color printing is effected by the scanning of the black carrier and the color carrier, whereby the fluctuation of the load of the motor in the high-speed printing during black printing and the low-speed printing during color printing can be minimized and a compact and inexpensive motor can be used and it is not necessary to take the heating of the heads, the preliminary discharge, etc. into consideration to prevent the color head from being secured to black prints and which is easy to control and does not wastefully consume the color ink. Figure 4 is a block diagram showing the control system of the ink jet recording apparatus of Figure 1. In Figure 4, a CPU (microprocessor) 121 is connected to a host machine 114 such as a computer through an interface 122, and controls the recording operation on the basis of a command signal and a record information signal read from the host machine into a data memory 123 and a program stored in a program memory 124 and an ROM such as a working memory 125. The CPU 121 controls the carriage motor 30 (Figure 1) and the sheet feeding motor 5 (Figure 1) through an output port 126 and a motor driver 127, and also controls the recording heads 11, 20, 21 and 22 through a head control circuit 129 on the basis of record information stored in the data memory 123. The reference numeral 130 in Figure 4 designates a sheet sensor for detecting whether a recording medium 7 (Figure 1) is present between conveying rollers, and the detection signal is transmitted to the CPU 121 through an input port 131. The output of each operation key 116 on an operation panel is transmitted to the CPU 121 through an input port 132, and electricity is supplied to an alarm lamp 116 such as an alarm lamp or a voltage source lamp through an output port 136. The reference numeral 133 in Figure 4 denotes a dip switch provided on the bottom surface of an armor, and the output thereof is transmitted to the CPU 121 through an input port 134. In Figure 4, a logic driving voltage VCC (5 V) for operating a control logic circuit, a voltage VM (30 V) for driving the various motors, a reset voltage RESET, a heat voltage (head voltage) VH (25 V) for heating the dot forming elements of the recording heads 11, 20, 21 and 22, and a back-up voltage VDDH for protecting the recording heads are output from a voltage source circuit 128. The operation of the control system of Figure 4 will now be described with reference to the flow chart of Figure 5. After the initialization of the control unit (step S101) during the closing of the main switch, the CPU 121 is in a reception standby state in which it can receive the input of the control command and printing data of the host computer 114 connected to the printer, through the interface 122 (Step S102). It is to be understood that the color setting with the host computer in the present embodiment is executed in the following specification. The data from ESCn and on are determined by n. n = 0 is black, n = 1 is R color, n = 2 is G color, n = 3 is B color, n = 4 is Y color, n = 5 is M color, and n = 6 is C color. When at step S102, printing data is input from the host computer 114 connected to the printer, the CPU 121 stores the data into a receiving buffer provided in a buffer for storing data 123, and repeats steps S102 - S103 until it discriminates the completion of the reception of prescribed printing data from the host computer 114 (step S103). When it discriminates the completion of the reception of the prescribed printing data from the host computer 114, the CPU 121 detects the aforementioned color setting at step S104. If ESC0 is transmitted, only the black head is judged at step S105, and advance is made to step S106, where only the black head is rendered drivable by the aforedescribed carrier separation. Subsequently, at step S107, the capping process for the unused color head is carried out. Further, at step S109, FLAG using only the black head is rendered ON so as to indicate the presence or absence of the suction recovery, the idle discharge, the temperature control of the heads and the ink detection which will be described later. At step S110, the used head flag operated at step S109 is detected and the suction recovery (or the pressing and circulation) of only the black head is executed. At step S111, the used head flag operated at step S109 is detected and the idle discharge from only the black head is executed. Further, again at step S112, the used head flag operated at step S109 is detected, and the heater carried on the head is turned on so that only the black head assumes a prescribed temperature, e.g. 35°C or higher, whereby the black head is controlled by detecting a thermistor on the head. At step S113, the used head flag operated at step S109 is detected as previously described and only the black ink is detected. Although the detecting method is not specifically shown, for example, an electrode is put between the inks and the presence or absence of the ink is detected from the resistance value thereof. At step S114, the CPU 121 excites the carrier motor 30 in a rightward direction from an output port 126 to move the carrier in a direction OPT through the driver 127. Subsequently, at step S115, from the control circuit 129, printing data is set in the head 11. After the setting, at step S116, a prescribed pulse is applied to the head 11. The pulse width at this time is prescribed by the next timer t1 (step S117). After the time is up, electrical energization of the head is cut off (step S118). At step S119, in each cycle of electrical energization, 1 is added to a recording cycle counter provided in the working. Whether printing has been completed is discriminated by that recording cycle counter. If at step S120, the recording cycle counter does not exceed a prescribed print dot value, return is made to step S113, and the operation of steps S113 - S120 is repeated. If at step S120, the recording cycle counter exceeds the prescribed print dot value, advance is made to step S121, where the carrier motor is excited in a leftward direction front the output port 126 to move the carrier in a direction CR through the driver 127 and the CR process is executed, and at step S122, the LF process, i.e., the sheet feeding process, is carried out, whereby printing of one line is completed. If at step S104, ESC1 is transmitted, in the case of ESC1, that is, R(Y + M) , Y and M heads are discriminated at step S105 and advance is made to step S108, where both of the black head and the color head are rendered drivable by the aforedescribed carrier connecting process (step S108). At step S109, FLAG using Y and M is turned on so as to indicate the presence or absence of the suction recovery, the idle discharge, the temperature control of the heads and the ink detection which will be described later. At step S110, as previously described, the suction recovery of only the Y and M heads (color heads) is executed. At step S111, as previously described, the idle discharge from only the Y and M heads is executed. Further, at step S112, the heater carried on the head is turned on so that only the Y and M heads assume a prescribed temperature or higher. The ON - OFF control of this heater is effected on the basis of the detection signal of a temperature detector such as a thermistor carried on each head. Also at step S113, the detection control of only the Y ink and the M ink is executed so that printing can be executed even if the C ink and the black ink are absent. Thereafter, printing of one line is executed by an operation procedure similar to that in the case of only black. As is apparent from the foregoing description, according to the color ink jet recording apparatus of the present invention, the carrier for black printing and the carrier for color printing are separated from each other, whereby the idle discharge and the suction recovery of the head for preventing the adherence of the ink to the color head are also separeted from each other and the color ink is not unnecessarily consumed and it becomes easy to effect ink detection and temperature control for each head used and thus, the unnecessary controlling operations can be curtailed. Figures 6 and 7 show another example of the connecting and separating mechanism of the present invention, and more particularly shows a U-shaped connecting member 51 instead of the connecting lever 13. In the present example, the carriers 10 and 19 are made integral with each other by the U-shaped member 51 during connection and the U-shaped member 51 is removed during separation, whereby movement of only the carrier 10 becomes possible. The carriers 10 and 19 are provided with recesses 121 and 191 engaged in advance by the U-shaped member 51. The U-shaped member 51 has its movement controlled by a solenoid 54, and the engagement and separation between the U-shaped member 51 and the solenoid 54 are controlled by rotation of an eccentric cam 55. The solenoid 54 caused a pivotable shaft 53 having a U-shaped member supporting portion 52 formed with a V-shaped groove at the fore end thereof to be moved in the direction of arrow indicated in Figure 6. The pivotable shaft 53 is parallel-moved by the cam 55 which is in a state indicated by a solid line in Figure 7, and is lowered from its gravity while being guided to the cam 55 as it is in a state indicated by a broken line in Figure 7 by 180° rotation of the cam 55 relative to the center 59. Thereby the U-shaped member 51 and the supporting portion 52 are separated from each other. Conversely, when the pivotable shaft 53 is moved up to its solid-line position by further 180° rotation of the cam 55, the U-shaped member 51 and the supporting portion 52 become connected together. At this time, the supporting portion 52 returns in the direction of arrow, whereby the U-shaped member 51 is separated from the two carriers. In the present embodiment, the connection and separation between the carriers 10, 19 and the U-shaped member 51 are effected at the home position of Figure 3A, and such connection and separation are accomplished in conformity with the mode setting by mode setting means (automatic or manual) 57. The reference numeral 56 designates drive means which governs the movement and rotation of the solenoid 54 and the cam 55. Control means 58 determines the timing of the operation and stoppage of the drive means 56, and controls said connection and separation. The control means 58 can operate only when both of the carriers 10 and 19 are at their home positions. The control means 58 brings the solenoid 54 and the U-shaped member 51 into the normal standby state of Figure 6 and brings the cam 55 into the solid-line state of Figure 7 (the normal standby state) in response to the closing of the main switch or the recording completion signal, and maintains the pivotable shaft 53 rectilinearly movable. When the black printing mode is selected in this normal standby state, the drive means 56 is maintained as it is. Conversely, when the color printing mode is selected in this standby state, the control means 58 operates the solenoid 54 by the drive means to connect the carriers 10, 19 and the U-shaped member 51 together, and thereafter separates the supporting portion 52 from the U-shaped member 51 by 180° rotation of the cam 55 (the state indicated by a dot-and-dash line in Figure 7: the color mode standby state). Thereby the carriers 10 and 19 are made integral with each other and at the same time, scanning for recording becomes possible. When in subsequence to the color printing mode, the black printing mode is set manually or by the aforementioned automatic detection, the carriers 10 and 19 come to their home positions. At this time, the control means 58 causes further 180° rotation of the cam 55 by the drive means, and brings the supporting portion 52 into engagement with the U-shaped member 51. After the termination of this rotation of the cam, the solenoid pulls back the supporting portion by the control means 58, whereby the separation of the carriers 10 and 19 is accomplished. That is, again the control means maintains the respective carriers in said normal standby state. Accordingly, by said control, appropriate carriers are selected for the black printing mode and the color printing mode, respectively. Assuming that the velocity of movement of the carrier 10 in the black printing mode is V cm/sec., the velocity of movement of the carriers 10 and 19 as a unit in the color printing mode is ν cm/sec. ( ν < V). Consequently, in the black printing mode, high-speed printing can be accomplished, and in the color printing mode, a printing speed suitable for the color can be reliably obtained with the drive force kept in the same state. Figures 8 and 9 show a modification of the flow chart of Figure 5 in which even when the carrier is moved in the black printing area in a case where the black printing area is slight and the rest is the color printing area in the printing area in one scan of the carrier, printing is effected with the carriers 10 and 19 as a unit and minimization of the whole recording time of one scan unit is accomplished. That is, when the black printing area in one scan is less than 20% of one scan printing area, the carriers 10 and 19 are moved as a unit, and when said black printing area is 20% or more of one scan printing area, the recording by only the carrier 10 and the recording by the carriers 10 and 19 as a unit are effected via a change-over process. This discrimination is done by the step S104 of Figure 9 for checking the print color. The other steps are similar to the steps of Figure 5, and only the differences will hereinafter be described. The above-mentioned percentage may be determined with 30% as the standard in an embodiment, but basically, by the return of the carriers during printing, it can be judged on the basis of the comparison with the time during which scanning is made with the carriers 10 and 19 as a unit, rather than the time required for the connection or separation of the carriers. Figure 8 shows the main routine which has the stroke of interruption ENABLE (or the command transmitting process to other CPU) between the stroke S102 of host data presence discrimination and the receiving buffer stroke S103. This interruption ENABLE is the interruption routine of Figure 9 for checking the print color (or may be what is executed by other CPU of 2 chips), and is determined with the selection of the carrier necessary for printing being always discriminated from the print data. The main routine of Figure 8 excludes the print color checking step S104 of Figure 5 to the ink detecting step S113 and therefore, appropriately drives the carrier determined by the "interruption ENABLE" and effects recording based on the received signal. The aforedescribed Figure 5 shows a flow chart effective for the case where printing of one line can be processed by the same printing mode, and the case where when a substantially different printing mode is on one line and that printing mode is to be recorded, the connection or separation of the carriers 10 and 19 is effected with the carriers returned to their home positions without fail and only the appropriate carrier is scanned for that printing mode. In contrast with Figure 5, in the main routine of Figure 8, the data to be printed in the carrier state (the two carriers united or one carrier singly) discriminated by the "interruption ENABLE" is set at step S115, and the loop until this data is completely printed provides steps S114 - S120. When this printing is completed, the data in the next printing area is already discriminated by the "interruption ENABLE" of the sub-routine. When the result of this discrimination requires the change of the carrier state, the carrier used in the previous printing is moved to the left home position at step S121, and immediately the carrier state is changed into a different carrier state and printing of the data being discriminated is effected. When, it is judged that the next printing area discriminated at this time can be continued with the carrier state during the previous printing kept unchanged, the carrier is not returned to the home position but recording is effected with the carrier state maintained by the return for printing. Thereafter, in a similar manner, the above-described discrimination and recording are effected until all the data of the host to be printed are completely received by the buffer. The interruption routine of Figure 9 effects the discrimination for checking the aforedescribed printing data and minimizing the recording time, for each predetermined number of lines (or each line). Although simple in this flow chart, it is preferable to adopt the following chart when in the black printing mode, the next printing is judged as color printing and the connection of the carriers 10 and 19 is required. That is, it is preferable that only one of the heads 20, 21 and 22 on the carrier 19 in the standby state which is necessary for color printing be subjected in advance to the temperature control of step S112 or/and the ink detection of step S113 and shift be made to the printing stroke upon connection of the carriers. More preferably, the recording preparation processes such as the suction recovery process S110 and the idle discharge process S111 should be carried out in advance in addition to the temperature control S112. In any case, in the present interruption routine, the signal transmitted between the steps S102 and S103 of Figure 8 is discriminated with respect to an amount corresponding to a predetermined recording signal (preferably is determined in conformity with the amount of memory), and if the result is the use of only the black head, steps S109 - S113 are carried out via the steps S106 and S107. Conversely, if the result is the use of the color head and the black head, steps S109 - S113 are carried out via the step S108. At the same time, the transmitted signal is received by the buffer and therefore, the steps S114 - S120 are carried out and the main routine is executed. According to the present embodiment, the control collectively expressed as an embodiment of the present invention is realized and more shortening of the recording time is achieved. The above-described embodiments are ones in which the heads and carriers to be used in the black printing mode and the color printing mode in a color recording apparatus are selected for connection or separation, but the present invention can be applied to a recording apparatus in which different heads are used in arbitrary combination or singly in different recording modes. That is, if the head 11 in the above-described embodiments is replaced with a single head of light black ink and the heads 20, 21 and 22 are set as a single head of dark black ink, said control can be regarded as two modes of dark printing and light printing, instead of color printing and black printing. In such case, although limited to black printing, the printing speed of at least one mode (preferably the light printing mode) can be improved in conformity with the discrimination of the signal. If in the field wherein, conversely to the above-described embodiments, the main use is color printing, the positions of the carriers 10 and 19 are changed and said control is effected reversely, there will be provided a more preferable apparatus. Also, the recording heads 20, 21 and 22 may be replaced with only a single particular color head for use in a two-color recording apparatus. According to the present invention, there can be provided a recording apparatus in which the desired main recording can be speeded up without being limited to the kinds of the recording heads (heads such as thermal transfer heads and piezo type ink jet heads) and other recording modes can also be suitably realized without greatly changing the drive source. In the above-described embodiments, the carrier referred to herein is what carriers recording heads thereon, but it also includes a construction in which the recording heads themselves are used also as a carrier. As the means for connecting and separating the carriers, adoption may be made of a construction in which a fixed permanent magnet (N pole) is provided on one carrier and a rotatable permanent magnet of variable S and N poles is provided on the other carrier and the selection of the S and N poles of the rotatable permanent magnet is variable in conformity with the selection of the recording modes, or a construction in which a metal is provided on one carrier and an electromagnet is provided on the other carrier and electrical energization of the electromagnet is changed over in conformity with mode selection to thereby accomplish the connection and separation of the carriers. Also, the present invention, when applied to a recording apparatus using as a recording head an ink jet recording head having an electrothermal converting member generating head energy, is a particularly advantageous invention which can greatly decrease the recovery process of the head and the consumption of ink. The above-described embodiment for discriminating the recording signal may be constructed so that when different prints other than the black printing mode (color prints or prints of a light color or the like) are present in one scan prints, printing is effected with the carriers 19 and 10 connected together and only in the case of only the black printing mode in one scan, the carriers 19 and 10 are separated from each other and printing is effected by only the carrier 10. Since generally the black printing is dominant, the effect of the present invention is sufficiently displayed.

Claims: An ink jet recording apparatus for recording using first and second ink jet recording units (11, 22), said apparatus having a suction mechanism comprising: a first cap (37) for capping a first ink jet recording unit (11); a second cap (34) for capping a second ink jet recording unit (22); and a pump (45) for communicating with said first and second caps to perform suction recovery of said first and second caps, characterised by further comprising a switching mechanism (41-44) movable between a first position in which said first and second caps (11, 22) are in communication with said pump to effect suction recovery of said first and second ink jet recording units (11, 22) and a second position in which only said first cap (37) is in communication with said pump (45) to effect suction recovery of only said first ink jet recording unit (11). An ink jet recording apparatus according to claim 1, wherein said switching mechanism (41-44) comprises a piston (41a) movable within a cylinder (41b) so that in the first position a flow path through the piston brings the first and second caps (37 and 34) into communication with the suction recovery means (45) and in the second position the flow path through the piston (41a) brings only the first cap (37) into communication with the suction recovery means (45). An ink jet recording apparatus according to claim 1 or 2 wherein said second ink jet recording unit (22) includes a plurality of heads (20, 21, 22). An ink jet recording apparatus according to claim 3, wherein said second ink jet recording unit (22) is adapted to discharge colour ink and said first ink jet recording unit (11) is adapted to discharge black ink. An ink jet recording apparatus according to any one of the preceding claims, comprising first and second ink jet recording units (11 and 22) adapted to discharge ink using thermal energy. An ink jet recording apparatus according to any one of the preceding claims, further comprising selection means (13-16) for determining whether said first and second ink jet recording units (11 and 22) are to be joined together or separated in use of the apparatus in accordance with operation of said switching mechanism (41-44). An ink jet recording apparatus according to claim 6, wherein said selection means (13-16) are arranged such that in use of the apparatus said first and second ink jet recording units (11, 22) are separated when said switching mechanism (41-44) is arranged to allow only said first cap (37) to communicate with said suction recovery means (45) and are joined together when said switching mechanism allows both said first and second caps to communicate with said suction recovery means. A suction mechanism for use in an ink jet recording apparatus for recording using first and second ink jet recording units (11, 22), said suction mechanism comprising: a first cap (37) for capping a first ink jet recording unit (11); a second cap (34) for capping a second ink jet recording unit (22); and a pump (45) for communicating with said first and second caps to perform suction recovery of said first and second caps, characterised by further comprising a switching mechanism (41-44) movable between a first position in which said first and second caps (11, 22) are in communication with said pump to effect suction recovery of said first and second ink jet recording units (11, 22) and a second position in which only said first cap (37) is in communication with said pump (45) to effect suction recovery of only said first ink jet recording unit (11). A suction mechanism according to claim 8, wherein said switching mechanism (41-44) comprises a piston (41a) movable within a cylinder (41b) so that in the first position a flow path through the piston brings the first and second caps (37 and 34) into communication with the suction recovery means (45) and in the second position the flow path through the piston (41a) brings only the first cap (37) into communication with the suction recovery means (45).

Inventors: FUKUI HIROSHI, HIRANO HIROFUMI, OMO SHINICHI, FUKUI, HIROSHI, HIRANO, HIROFUMI, OMO, SHINICHI, FUKUI, HIROSHI, C/O CANON KABUSHIKI KAISHA, HIRANO, HIROFUMI, C/O CANON KABUSHIKI KAISHA, OMO, SHINICHI, C/O CANON KABUSHIKI KAISHA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1989
Main classification: B41J2
IPC codes: B41J2, B41J3, B41J29