1. Field of the Invention
The present invention relates to an image forming apparatus that makes use of an electrophotographic process, such as a copier, printer, facsimile machine, or multifunctional machine including functions of the copier, printer, and/or facsimile machine. More specifically, the present invention relates to an image forming apparatus having image forming units between a pair of frame plates oppositely disposed to each other so that a toner image formed on an image bearing member may be transferred onto a recording medium.
2. Discussion of the Background
As shown in FIG. 1, a background image forming apparatus 100 includes a main body 101, an image scanning mechanism 102 arranged above the main body 101, an automatic document feeder (ADF) 103 arranged above the image scanning mechanism 102, and a duplex print unit 104 at the right-hand side of the main body 102 of the image forming apparatus 100 of FIG. 1.
The main body 101 of the image forming apparatus 100 includes a sheet feeding mechanism 105, an image forming mechanism 106 arranged above the sheet feeding mechanism 105, a sheet discharging portion 107 arranged above the image forming mechanism 106, and a sheet conveying path 108.
The image forming mechanism 106 disposed in the main body 101 of the image forming apparatus 100 may be supported by a pair of frame plates (not shown) oppositely disposed to each other at front and rear sides of the image forming apparatus 100.
To record image data of an image from an original document to a recording medium, the original document is fed through the ADF 103 to the image scanning mechanism 102. The image scanning mechanism 102 reads the image data of the original document to form an image in the image forming mechanism 106 according to image data signals. While the image forming mechanism 106 forms the image, a recording medium is fed from one of sheet feeding cassettes in the sheet feeding mechanism 105, and is conveyed upward through the sheet conveying path 108 to the main body 101 of the image forming apparatus 100. After the image formed by the image forming mechanism 106 is transferred onto the recording medium, the recording medium is discharged to the sheet discharging portion 107.
To form images on both sides of a recording medium, a first image is formed as described above. A second image is formed such that the recording medium having a first image on one side thereof is conveyed to the duplex print unit 104, is reversed to the different surface side orientation, and is supplied to the image forming mechanism 106 of the main body 101 again. After the second image formed by the image forming mechanism 106 is transferred onto the rear side of the recording medium, the recording medium is discharged to the sheet discharging portion 107.
In recent years, however, making duplex copies has been encouraged from a view point of effective utilization of resources. For example, the image forming apparatus 100 as shown in FIG. 1 may have the duplex print unit 104 to perform a duplex print operation so that images may be formed on both sides of the recording medium. With the above-described structure, the duplex print unit 104 mounted to the image forming apparatus 100 has a longer path for conveying the recording medium and/or may handle different types or sizes of papers such as recycled papers, the quality of which may be degraded. Under the above-described conditions that the duplex print operation is performed with the duplex print unit 104, a paper jam is more likely to occur.
When the paper jam occurs in the image forming apparatus 100 of FIG. 1, the duplex print unit 104 is rotated about a lower portion thereof to open the duplex print unit 104 facing upward as shown in FIG. 2. An inner cover 109 is then rotated about a lower potion thereof to open to face upward, as shown in FIG. 3, so as to remove a jammed recording paper p.
In the above-described background image forming apparatus 100, the duplex print unit 104 may include a conveying member such as a roller for conveying a reversed recording medium having an image on one side thereof, a guiding member for guiding the reversed recording medium, a switching member such as a path selector for switching or selecting a direction of the reversed recording medium, and so on. The duplex print unit 104 may further include a drive source such as a drive motor for rotating the conveying member, a solenoid for switching the switching member, and a detecting member for detecting the recording medium during the travel thereof. By including the above-described members and units, the duplex print unit 104 tends to become large and heavy, which may cause poor operability of opening and closing the duplex print unit 104 when a paper jam occurs.
To solve the above-described problem, some background image forming apparatuses have been provided with, for example, a damper mechanism and/or a spring to improve the operability of opening and closing the duplex print unit 104. Such a structure of the image forming apparatus 100, however, has a complicated construction, resulting in increase of costs.