Abstract:
A recording apparatus using full-line type ink jet recording heads needs a large amount of electrical power for ink ejection due to a large number of nozzles of the recording heads. Therefore, a power supply capacity of the recording apparatus needs to be increased, resulting in increase in an overall apparatus cost. When simultaneously recording on plural recording media using a recording apparatus having recording heads with different electrical power consumptions arranged in a transfer direction of the recording media, recording is performed so that the recording heads to be simultaneously driven are combined so as to be a combination of the recording heads with different electrical power consumptions.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a recording method and a recording apparatus which achieve recording with a low electrical power consumption. 
     2. Description of the Related Art 
     In an image recording apparatus, full-line type recording heads (recording devices) have been used, that is, recording heads extending along the entire width of a recording region on a recording medium are used. As such full-line type recording heads, there are line-type inkjet recording heads and LED type recording heads, etc. Any of these full-line type recording heads can record high-resolution images at a high speed by making use of line-type characteristics. 
     In the full-line type recording heads, the number of nozzles is 7200 per one recording head, for example. For forming images, the recording apparatus has individual heads for cyan ink, yellow ink, magenta ink and black ink. 
     However, in a recording apparatus using such full-line type inkjet recording heads, since the number of nozzles of the recording head is large, large electrical power is required for ink ejection. In particular, when simultaneously using the large number of nozzles (at a high recording duty-factor), the electrical power reaches its peak value. 
     Accordingly, corresponding to the peak value of the power consumption, a power supply capacity of the recording apparatus needs to be increased, resulting in increase in an overall apparatus cost. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a recording apparatus and a recording method in which the peak value of an electricity consumption is decreased when recording by using full-line type recording heads with each head having a different electricity consumption per one recording head. 
    
    
     Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of an entire mechanical structure of a recording apparatus. 
     FIG. 2 is a sectional view of a recording apparatus according to a fifth embodiment showing the arrangement of five recording heads and positions of two pages of recording media. 
     FIGS. 3A-3E are tables showing the comparison of electrical power consumptions in the fifth embodiment. 
     FIG. 4 is a sectional view of a recording apparatus according to a third embodiment showing the arrangement of four recording heads and positions of two pages of recording media. 
     FIGS. 5A-5F are tables showing the comparison of electrical power consumptions in the third embodiment. 
     FIG. 6 is a block diagram of a control system according to a first embodiment. 
     FIG. 7 is a sectional view of a recording apparatus according to a fourth embodiment showing the arrangement of five recording heads and positions of three pages of recording media. 
     FIGS. 8A-8H are tables showing the comparison of electrical power consumptions in the fourth embodiment. 
     FIG. 9 is a sectional view of a recording apparatus according to the first embodiment showing the arrangement of five recording heads and positions of two pages of recording media. 
     FIGS. 10A-10D are tables showing the comparison of electrical power consumptions in a second embodiment. 
     FIGS. 11A-11D are tables showing the comparison of electrical power consumptions in the first embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a sectional view of an entire structure of a recording apparatus according to the present invention. 
     Referring to FIG. 1, a sheet feeding section, a transfer section, a recording head section, and a sheet discharge section will be described. 
     In the sheet feeding section, a pressure plate  21  for stacking recording sheets P and a feeding roller  22  for feeding the recording sheets P are rotatable about a rotational shaft connected to a base  20  and the pressure plate  21  is urged to the feeding roller  22  by a pressure plate spring  24 . The pressure plate  21  is provided with a separating pad (not shown) made from a material with a high coefficient of friction for preventing piled-up feeding of the recording sheets P and a separating claw (not shown) for separating the recording sheets P one by one. There is provided a release cam (not shown) for releasing the abutment between the pressure plate  21  and the feeding roller  22 . 
     In the structure mentioned above, the release cam pushes down the pressure plate  21  in a standby mode. The abutment between the pressure plate  21  and the feeding roller  22  is thereby released. When a driving force of a sheet-feeding motor  25  is transmitted to the feeding roller  22  and the release cam via gears, etc., the release cam is separated from the pressure plate  21 . Thereby, the pressure plate  21  moves upwardly and the feeding roller  22  abuts the recording sheet P so as to pick up the recording sheet P along with the rotation of the feeding roller  22  and to start the sheet feeding. The feeding roller  22  rotates until the recording sheets P are fed to the transfer section. 
     The transfer section comprises a transfer belt  31  for holding and transferring the recording sheets P and a PE sensor (not shown). 
     The transfer belt  31  is driven by a driving roller  34  and looped over a transfer roller  32  and a tightening roller  35 , which are follower rollers. A belt motor  50  drives the driving roller  34 . 
     The transfer belt  31  is made from a synthetic resin such as polyethylene and is endless belt-shaped. Power dispatching means F applies a voltage of from 0.5 kV to 10 kV across the recording sheet P so as attract the sheet to the transfer belt (description of the power dispatching means, high-voltage generating means, and high-voltage controlling means is omitted). 
     The transfer belt  32  moves at a speed of 170 mm/sec in a recording mode. 
     At a position opposing the transfer roller  32 , a pinch roller  33  is abutted, which follows the transfer belt  32 . Recording heads H 1 , H 2 , H 3 , H 4 , and H 5  are sequentially arranged in the transfer direction downstream of the transfer roller  32 . Along the transfer direction, the recording head H 1  is placed at the most upstream position while the recording head H 5  is placed at the most downstream position. The distance between these recording heads is 10 cm. 
     Each recording head has a resolution of 600 DPI and employs a line-type ink-jet method having 7200 recording elements arranged in a direction perpendicular to the transfer direction. 
     Each recording element comprises a nozzle and a driving unit for applying heat to ink with a heater. The ink is film-boiled due to the heat and the ink pressure is changed by growth or contraction of bubbles due to the film boiling, so that the ink is ejected from the nozzle so as to form images on the recording sheet P. 
     There are two classes of the electrical power consumption of each recording head, as follows. A yellow recording head YH has a power consumption of 50 Wh; a magenta recording head MH has a power consumption of 60 Wh; a cyan recording head CH has a power consumption of 60 Wh; a light cyan recording head LCH has a power consumption of 50 Wh; and a black recording head KH has a power consumption of 60 Wh. 
     The value for each of the recording heads is the standard electrical power consumption when the entire 7200 nozzles eject ink in an environment with a room temperature of approximately from 10° C. to 30° C. The difference in the electrical power consumptions is due to the difference in volumes of one drop of ejected ink. 
     The electrical power consumption is assumed to be steady with little dependence on the room temperature. 
     The sheet discharge section comprises a discharge roller  41  and a spur  42 , and the recording sheet P having images formed thereon is conveyed by the nip between the discharge roller  41  and the spur  42  pinched therebetween so as to be discharged into a discharge tray  43 . The linear speed of the discharge roller  41  is substantially the same as that of the transfer belt, and the discharge roller  41  moves at a speed of 170 mm/sec in a recording mode. 
     A sheet discharge sensor  40  checks for the existence of the recording sheet P in the sheet discharge section. A separation sensor  49  is disposed in the discharge side of the belt  31  for checking for the existence of the transferred sheet. 
     A cleaning roller  38  is used for cleaning the belt  31 . Numeral  39  denotes an electrostatic eliminating roller. 
     FIG. 9 is a schematic representation of a state that two recording sheets P 1  and P 2  are transferred when the recording heads are spaced at equal intervals. The distance between adjacent recording heads is 10 cm. The recording sheet P 1  is located under the recording heads H 3 , H 4 , and H 5 , from which ink is ejected. The recording sheet P 2  is located more upstream and not yet under the recording head H 1 , and recording is not yet performed. The distance between the recording sheets P 1  and P 2  is 20 cm. Immediately under the recording heads H 1  and H 2 , the recording sheet does not exist, so that those recording heads are not driven. In addition, the sheet feeding section feeds a recording sheet about every 1.18 sec so that the distance between the recording sheets P 1  and P 2  is to be 20 cm. 
     The recording sheets P 1  and P 2  are of A 4  size, and the distance between leading and trailing edges is 210 mm. 
     The recording region initiates at 5 mm inside the leading edge and ends at 5 mm back from the trailing edge of the recording sheet. 
     In this case, for one page of the recording sheet, recording is simultaneously performed with a maximum of three recording heads. 
     The start-timing reference of ejection by each recording head is starting of the feeding roller  22 . 
     In accordance with the distance from the feeding roller  22 , the start timing of ejection is set. 
     Ejecting duration T is obtained by “the distance of the recording region in the transfer direction÷the speed of the transfer belt”. 
     FIGS. 11A-11D show calculated results of the total amount of the electrical power consumption for every arrangement of the recording heads in the recording apparatus formed of five recording heads arranged at equal intervals as shown in FIG.  9 . 
     A first head is H 1 ; a second head is H 2 ; a third head is H 3 ; a fourth head is H 4 ; and a fifth head is H 5 . Numerals at the top of the tables indicate electrical power consumptions of each head. 
     The total amount of the electrical power consumptions is obtained for four different arrangements of the recording heads as shown in FIGS. 11A-11D. 
     For example, in the arrangement of FIG. 11A, the amount of the electrical power consumption of the first head is 50 Wh; that of each of the second through fourth heads is 60 Wh; and that of the fifth head, which is the most downstream, is 50 Wh. From t 1  to t 5 , the symbol x denotes a non-driven state. 
     When there is no recording sheet immediately under a recording head, that recording head is in a non-driven state. 
     Lapses of time indicated by t 1 →t 2 →t 3 →t 4 →t 5  show the progress of the recording medium moving from upstream to downstream. 
     The t 1  indicates a state that the recording heads H 3 , H 4 , and H 5  are ejecting while the recording heads H 1  and H 2  are not driven. Similarly, t 2  indicates a state that the recording heads H 1 , H 4 , and H 5  are ejecting while the recording heads H 2  and H 3  are not driven; t 3  indicates a state that the recording heads H 1 , H 2 , and H 5  are ejecting while the recording heads H 3  and H 4  are not driven; t 4  indicates a state that the recording heads H 1 , H 2 , and H 3  are ejecting while the recording heads H 4  and H 5  are not driven; and t 5  indicates a state that the recording heads H 2 , H 3 , and H 4  are ejecting while the recording heads H 1  and H 5  are not driven. 
     From the comparison of the amounts of the electrical power consumptions, it is understood that the maximum electrical power consumption values are lowest in the arrangements of FIGS. 11B and 11C. 
     In the arrangements of FIGS. 11B and 11C, specifically in FIG. 11B, the black recording head KH is located at the position H 1 ; the light cyan recording head LCH at the position H 2 ; the cyan recording head CH at the position H 3 ; the magenta recording head MH at the position H 4 ; and the yellow recording head YH at the position H 5 . 
     Also, in FIG. 11C, the black recording head KH is located at the position H 1 ; the cyan recording head CH at the position H 2 ; the light cyan recording head LCH at the position H 3 ; the magenta recording head MH at the position H 4 ; and the yellow recording head YH at the position H 5 . 
     As described above, the peak value of the electrical power consumptions can be kept low by combining the recording heads which are simultaneously driven so as to be a combination of the recording heads with different electrical power consumptions. Furthermore, according to the embodiment, the combination of the recording heads is to be the combination between the recording head with the maximum electrical power consumption and the recording head with the minimum electrical power consumption, so that the electrical power consumption can be efficiently reduced. 
     FIG. 6 shows control blocks of the apparatus according to the present invention. A control section  80  comprises a CPU  80   a  which operates according to a control program, a ROM  80   b  for storing the program, and a RAM  80   c  which is a work memory. A gate array is an LSI for controlling the driving signal of the recording head, the holding means, the sheet feeding section, and the transfer section together with the CPU. 
     The control section  80  is connected to the belt motor  50  for driving the transfer belt, the sheet-feeding motor  25  which is a driving source of the feeding roller  22 , the black recording head KH, the cyan recording head CH, the magenta recording head MH, the yellow recording head YH, and the light cyan recording head LCH. 
     According to a second embodiment, the recording heads have an arrangement shown in FIG.  9 . 
     As the description of FIG. 9 is similar to that of the first embodiment, it is omitted. The electrical power consumptions of the recording heads have three classes as follows. 
     A yellow recording head YH has a power consumption of 40 Wh; a magenta recording head MH has a power consumption of 60 Wh; a cyan recording head CH has a power consumption of 60 Wh; a light cyan recording head LCH has a power consumption of 50 Wh; and a black recording head KH has a power consumption of 60 Wh. 
     FIGS. 10A-10D show calculated results of the total amount of the electrical power consumptions for every arrangement of the recording heads in the recording apparatus formed of five recording heads arranged at equal intervals. 
     A first head is H 1 ; a second head is H 2 ; a third head is H 3 ; a fourth head is H 4 ; and a fifth head is H 5 . Numerals at the top of the tables indicate electrical power consumptions of each head. The units of the numerals are Wh. 
     The total amount of the electrical power consumptions is obtained for four different arrangements of the recording heads as shown in FIGS. 10A-10D. 
     For example, in the arrangement of FIG. 10A, the amount of the electrical power consumption of the first head is 50 Wh; that of each of the second through fourth heads is 60 Wh; and that of the fifth head, which is the most downstream, is 40 Wh. From t 1  to t 5 , the symbol x denotes a non-driven state. 
     When there is no recording medium immediately under a recording head, that recording head is in a non-driven state. 
     Lapses of time indicated by t 1 →t 2 →t 3 →t 4 →t 5  show the progress of the recording medium moving from upstream to downstream. 
     The t 1  indicates a state that the recording heads H 3 , H 4 , and H 5  are ejecting while the recording heads H 1  and H 2  are not driven. Similarly, t 2  indicates a state that the recording heads H 1 , H 4 , and H 5  are ejecting while the recording heads H 2  and H 3  are not driven; t 3  indicates a state that the recording heads H 1 , H 2 , and H 5  are ejecting while the recording heads H 3  and H 4  are not driven; t 4  indicates a state that the recording heads H 1 , H 2 , and H 3  are ejecting while the recording heads H 4  and H 5  are not driven; and t 5  indicates a state that the recording heads H 2 , H 3 , and H 4  are ejecting while the recording heads H 1  and H 5  are not driven. 
     From the comparison of the amounts of the electrical power consumptions, it is understood that the electrical power consumption maximum values of the arrangements of FIGS. 10B and 10C are the lowest. 
     In the arrangements of FIGS. 10B and 10C, specifically in FIG. 10B, the black recording head KH is located at the position H 1 ; the light cyan recording head LCH at the position H 2 ; the cyan recording head CH at the position H 3 ; the magenta recording head MH at the position H 4 ; and the yellow recording head YH at the position H 5 . 
     Also, in FIG. 10C, the black recording head KH is located at the position H 1 ; the cyan recording head CH at the position H 2 ; the light cyan recording head LCH at the position H 3 ; the magenta recording head MH at the position H 4 ; and the yellow recording head YH at the position H 5 . 
     By the arrangements of FIGS. 10A and 10C, the combination of the recording heads which are simultaneously driven is of recording heads with different electrical power consumptions, so that the peak value of the electrical power consumptions can be efficiently reduced. 
     Furthermore, by combining the recording heads so that at least one of the recording heads is stopped driving, the peak value of the electrical power consumptions can be efficiently reduced. 
     According to a third embodiment, the recording heads have an arrangement shown in FIG.  4 . 
     The electrical power consumptions of the recording heads have two classes as follows. 
     A yellow recording head YH has a power consumption of 40 Wh; a magenta recording head MH has a power consumption of 60 Wh; a cyan recording head CH has a power consumption of 60 Wh; and a black recording head KH has a power consumption of 50 Wh. The drawing is a schematic representation of a state that two recording sheets P 1  and P 2  are transferred when the four recording heads H 1 , H 2 , H 3 , and H 4  are arranged at equal intervals. The distance between adjacent recording heads is 8 cm. 
     The recording sheet P 1  is located under the recording heads H 3  and H 4 , from which ink is ejected. The recording sheet P 2  is located under the recording head H 1  from which ink is ejected. The distance between the recording sheets P 1  and P 2  is 10 cm. Immediately under the recording head H 2 , a recording sheet does not exist, so that recording head is not driven. The sheet feeding section feeds a recording sheet about every 0.58 sec so that the distance between the recording sheets P 1  and P 2  is to be 10 cm. 
     The recording sheets P 1  and P 2  are of A 5  size, and the distance between leading and trailing edges is 148 mm. 
     The recording region initiates at 5 mm inside the leading edge and ends at 5 mm back from the trailing edge of the recording sheet. In this case, for one page of the recording sheet, recording is simultaneously performed with a maximum number of two recording heads. 
     FIG. 5 shows calculated results of the total amount of the electrical power consumptions for every arrangement of the recording heads. 
     A first head is H 1 ; a second head is H 2 ; a third head is H 3 ; and a fourth head is H 4 . Numerals at the top of the tables indicate electrical power consumption of each head. The units of the numerals are Wh. 
     The total amount of the electrical power consumptions is obtained for six arrangements of the recording heads as shown in FIGS. 5A to  5 F. 
     From the comparison of the amounts of the electrical power consumptions, it is understood that the electrical power consumption maximum value of the arrangement of FIG. 5A is the lowest. 
     Specifically, the black recording head KH is located at the position H 1 ; the cyan recording head CH at the position H 2 ; the magenta recording head MH at the position H 3 ; and the yellow recording head YH at the position H 4 . 
     In the arrangements of the recording heads, according to the embodiment, by arranging the recording head with the maximum electrical power consumption at a position other than those on the most upstream side and the most downstream side in the arranging direction of the recording heads, the peak value of the total electrical power consumptions can be reduced to the lowest. 
     According to a fourth embodiment, the recording heads have an arrangement shown in FIG.  7 . 
     The drawing is a schematic representation of a state that three recording sheets P 1 , P 2 , and P 3  are transferred when five recording heads H 1 , H 2 , H 3 , H 4 , and H 5  are arranged at substantially equal intervals. The distance between adjacent recording heads is 10 cm. 
     The recording sheet P 1  is located under the recording head H 5 ; the recording sheet P 2  under the recording head H 3 ; and the recording sheet P 3  under the recording head H 1 , from each of which ink is ejected. The distances between the sheets P 1  and P 2  and between the sheets P 2  and P 3  are 10 cm, respectively. Under the recording heads H 2  and H 4 , a recording sheet does not exist, so those recording heads are not driven. The sheet feeding section feeds a recording sheet about every 0.58 sec, so that the distances between the sheets P 1  and P 2  and between the sheets P 2  and P 3  are to be 10 cm, respectively. 
     The recording sheets P 1  and P 2  are of A 6  size, and the distance between leading and trailing edges is 105 mm. 
     The recording region initiates at 5 mm inside the leading edge and ends at 5 mm back from the trailing edge of the recording sheet. 
     In this case, for one page of the recording sheet, recording is performed with one recording head. 
     The electrical power consumptions of the recording heads have three classes as follows. 
     A yellow recording head YH has a power consumption of 40 Wh; a magenta recording head MH has a power consumption of 60 Wh; a cyan recording head CH has a power consumption of 60 Wh; a light cyan recording head LCH has a power consumption of 50 Wh; and a black recording head KH has a power consumption of 60 Wh. 
     FIG. 8 shows calculated results of the total amount of the electrical power consumptions in the cases that three recording sheets are continuously transferred, and two recording sheets are transferred in the recording apparatus formed of five recording heads. 
     A first head is H 1 ; a second head is H 2 ; a third head is H 3 ; a fourth head is H 4 ; and a fifth head is H 5 . Numerals at the top of the tables indicate electrical power consumptions of each head. The units of the numerals are Wh. 
     The total amount of the electrical power consumptions is obtained for eight arrangements of the recording heads as shown in FIGS. 8A-8H. 
     For example, in the arrangement of FIG. 8A, the amount of the electrical power consumption of the first head is 50 Wh; that of each of the second through fourth heads is 60 Wh; and that of the fifth head, which is the most downstream, is 40 Wh. In t 1  and t 2 , the symbol x denotes a non-driven state. 
     When there is no recording sheet immediately under a recording head, that recording head is in a non-driven state. 
     A lapse of time indicated by t 1 →t 2  shows the progress of the recording medium moving from upstream to downstream. 
     In the state shown in FIG. 8A, t 1  indicates a state that the recording heads H 1 , H 3 , and H 5  are ejecting while the recording heads H 2  and H 4  are not driven. Similarly, t 2  indicates a state that the recording heads H 2  and H 4  are ejecting while the recording heads H 1 , H 3 , and H 5  are not driven. 
     From the comparison of the total amounts of the electrical power consumptions, it is understood that the electrical power consumption maximum values of the arrangements of FIGS. 8A and 8C are the lowest. Specifically, in FIG. 8A, the light cyan recording head LCH is located at the position H 1 ; the black recording head KH at the position H 2 ; the cyan recording head CH at the position H 3 ; the magenta recording head MH at the position H 4 ; and the yellow recording head YH at the position H 5 . 
     Also, in FIG. 8C, the black recording head KH is located at the position H 1 ; the cyan recording head CH at the position H 2 ; the light cyan recording head LCH at the position H 3 ; the magenta recording head MH at the position H 4 ; and the yellow recording head YH at the position H 5 . 
     As in FIG. 8A, by arranging the recording head with the maximum electrical power consumption at a position other than those on the most upstream side and the most downstream side, the peak value of the total electrical power consumptions can be reduced to the lowest. 
     According to a fifth embodiment, the recording heads have an arrangement as shown in FIG.  2 . FIG. 2 is a schematic representation of a state that two recording sheets P 1  and P 2  are transferred when recording heads are arranged at equal intervals. The distance between adjacent recording heads is 10 cm. 
     The recording sheet P 1  is located under the recording heads H 3 , H 4 , and H 5 , from each of which ink is ejected; and the recording sheet P 2  is located under the recording head H 1 , from which ink is ejected. The distance between the sheets P 1  and P 2  is 10 cm. Immediately under the recording head H 2 , a recording sheet does not exist, so that recording head is not driven. The sheet feeding section feeds a recording sheet about every 0.58 sec, so that the distance between the sheets P 1  and P 2  is 10 cm. 
     The recording sheets P 1  and P 2  are of A 4  size, and the distance between leading and trailing edges is 210 mm. 
     The recording region initiates at 5 mm inside the leading edge and ends at 5 mm back from the trailing edge in the transfer direction. 
     In this case, for one page of the recording sheet, recording is performed with a maximum number of three recording heads. 
     A yellow recording head YH has a power consumption of 50 Wh; a magenta recording head MH has a power consumption of 60 Wh; a cyan recording head CH has a power consumption of 60 Wh; a light cyan recording head LCH has a power consumption of 50 Wh; and a black recording head KH has a power consumption of 60 Wh. 
     FIGS. 3A-3E show calculated results of the total amount of the electrical power consumptions in the arrangement shown in FIG. 2. A first head is H 1 ; a second head is H 2 ; a third head is H 3 ; a fourth head is H 4 ; and a fifth head is H 5 . Numerals at the top of the tables indicate electrical power consumption of each head. The units of the numerals are Wh. 
     The total amount of the electrical power consumptions is obtained for the five arrangements of the recording heads shown in FIGS. 3A to  3 E. 
     For example, in the arrangement of FIG. 3A, the amount of the electrical power consumption of the first head is 50 Wh; that of each of the second through fourth heads is 60 Wh; and that of the fifth head, which is the most downstream, is 50 Wh. In t 1  and t 2 , the symbol x denotes a non-driven state. 
     When there is no recording sheet immediately under a recording head, that recording head is in a non-driven state. 
     Lapses of time indicated by t 1 →t 2 →t 3 →t 4  show the progress of the recording medium moving from upstream to downstream. 
     In the state of FIG. 3A, t 1  indicates a state that the recording heads H 1 , H 3 , H 4 , and H 5  are ejecting while the recording head H 2  is not driven. Similarly, t 2  indicates a state that the recording heads H 1 , H 2 , H 4 , and H 5  are ejecting while the recording head H 3  is not driven; t 3  indicates a state that the recording heads H 1 , H 2 , H 3 , and H 5  are ejecting while the recording head H 4  is not driven; and t 4  indicates a state that the recording heads H 2 , H 3 , and H 4  are ejecting while the recording heads H 1  and H 5  are not driven. 
     The total amount of electrical power consumption is 220 Wh from t 1  to t 3 , and 180 Wh at t 4 . 
     From the comparison of the total amounts of the electrical power consumptions, it is understood that the electrical power consumption maximum value of the arrangement of FIG. 3A is the lowest. 
     Specifically, the light cyan recording head LCH is located at the position H 1 ; the black recording head KH at the position H 2 ; the cyan recording head CH at the position H 3 ; the magenta recording head MH at the position H 4 ; and the yellow recording head YH at the position H 5 . 
     In the arrangement of the recording heads, by arranging the recording head with the maximum electrical power consumption at a position other than those on the most upstream side and the most downstream side, the peak value of the total electrical power consumptions can be reduced to the lowest. 
     From a different point of view, in the arrangement of the recording heads, by arranging the recording heads with the minimum electrical power consumptions at positions on the most upstream side and the most downstream side, the peak value of the total electrical power consumption can be reduced to the lowest. 
     In the embodiments described above, the recording sheet has been described as an example of a recording medium; however, it may be an OHP sheet or cloth. 
     The driving unit of the recording element in each of the embodiments is an electro-thermal converter for generating heat to ink with a heater, etc.; however, a piezo-element, for example, may be substituted for the electro-thermal converter. 
     As for the resolution of the recording head, other than 600 DPI, it may be a higher resolution such as 1200 DPI or a lower resolution such as 360 DPI. 
     The number of recording heads which are not driven on an interspace between adjacent recording media may be 3 or more. 
     Also, the number of classes of the recording heads with different electrical power consumptions may be 4 or more. 
     The number of recording heads used in recording also is not limited to 4 and 5. 
     Plural recording heads with the same colors may be used. The relationship between the color of the recording head and electrical power consumption is not limited to that in the embodiments; a head for ejecting black ink may have two classes of electrical power consumptions, for example. 
     The electrical power consumption of the recording head has been defined in the case when the entire nozzles eject ink simultaneously; however, it may be in another state such as an operational state that one nozzle is thinned out. 
     The cause of the difference in the electrical power consumption is not limited to the difference in a volume of one ejected ink drop; it may be due to a circuit structure within the recording head or a driving method. 
     The transfer speed is not limited to 170 mm/sec; it may be a higher speed. 
     The distance between recording media is not limited to those mentioned above, and the time interval of sheet-feeding operation is not also limited thereto as long as “time=distance between recording media÷transfer speed”. 
     The recording head may be not only an ink jet head, but also a recording device employing an LED array. 
     A transfer detecting sensor on a transfer line closer to the recording head than the feed roller may be used for the timing reference of ejection. 
     As described above, according to the present invention, in a recording apparatus formed of plural recording heads with different electrical power consumptions, when recording with the recording heads to be driven which are combined so as to be a combination of the recording heads with different electrical power consumptions, the total amount of electrical power consumptions can be reduced. 
     While the present invention has been described with reference to what are presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.