1. Field of the Invention
This invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus which is capable of performing a duplex print operation such that printing is performed on both sides of a sheet of paper.
2. Discussion of the Background
An ink jet recording apparatus has been used widely as an image forming mechanism in printers, copying machines, and so on. Some ink jet recording apparatuses are capable of operating in a duplex print mode in which a print operation can be performed on both sides of the recording sheet. One example of such a printer is described in Japanese Laid-Open Patent Publication No. JPAP08-337011 (1996). The ink jet recording apparatus according to this example is adapted to perform a duplex print operation by using two recording mechanisms which are positioned in the ink jet recording apparatus so as to be spaced apart from each other. Accordingly, the structure of the ink jet recording apparatus becomes complex and the apparatus itself becomes relatively large and expensive because of the use of two recording mechanisms, as well as, a plurality of paper transportation mechanisms required therein. As a result, the cost of manufacturing such a duplex mode printer is greatly increased.
In addition, such an apparatus may have a disadvantage with respect to the quality of a print image. This is because in the above-mentioned ink jet recording apparatus, the sheet is transported to the second recording mechanism while the printed surface of the sheet contacts or is rubbed against a surface of a guide plate connecting the first recording mechanism to the second recording mechanism. Yet, with ink jet recording, time is required to dry the printed surface and, therefore, the printed surface should be protected from contacting any material or any object that might smudge or affect the quality of the printed image on the sheet.
In order to overcome the problems described above, preferred embodiments of the present invention provide an ink jet recording apparatus which has a very small size and is constructed to print high quality printed sheets in a duplex print mode such that both sides of a sheet are printed.
Further, preferred embodiments of the present invention provide a method and apparatus for ink jet printing in which two sides of a sheet can be printed by ink jet printing but using only a single ink jet print head, thereby eliminating the need for two ink jet print head or printing units as is required in conventional devices. That is, preferred embodiments of the present invention provide a method and apparatus for ink jet printing in which two sides of a sheet can be printed by the same ink jet print head.
In addition, preferred embodiments of the present invention provide a method of ink jet printing on both sides of a sheet such that a sheet that has been printed on one side is fed to a location outside of the printer and then is fed back into the printer to have the second side of the sheet printed.
In addition, preferred embodiments of the present invention provide a method and apparatus for ink jet printing in which a pair of exit rollers are capable of being driven in a reverse direction so as to feed a sheet that has been printed on one side thereof back into the printer so that the second side of the sheet can be printed.
Additional preferred embodiments provide an ink jet printing apparatus in a sheet diverting mechanism diverts the feed of a sheet that has been printed on one side thereof so that the sheet is printed on the second side thereof.
According to one preferred embodiment of the present invention, an ink jet recording apparatus performs a print operation by controlling an ink jet recording head so as to eject ink drops therefrom onto front and back surfaces of a recording sheet. The ink jet recording apparatus transports a portion of the recording sheet to a location outside of the apparatus after a completion of the print operation on the front surface of the recording sheet and before the print operation on the rear surface of the recording sheet.
The portion of the recording sheet transported to the location outside of the apparatus may include a surface that has the ink drops disposed thereon.
The recording sheet which has been printed on the front surface thereof may be reversely transported to the print position again using a switchback mechanism.
The location outside of the apparatus may be positioned below the print position or may be an upper surface of an input sheet cassette that contains a plurality of recording sheets.
The recording sheet may be transported to the print position by a transport mechanism that includes a transport belt.
The recording sheet may be moved at a speed which is substantially the same as a moving speed of the transport belt when the recording sheet is reversely transported to the print position again.
The apparatus may have a single print mechanism that includes the ink jet recording head.
Drying elements such as a fan, heater or timing controlled sheet feeding mechanism may be provided in the printer for ensuring that the one-side-printed sheet is dried before the sheet is fed back into the printer for printing of the second side.