KR100362386B1 - Image forming appratus capable of forming a duplex image on one sheet - Google Patents

Abstract

Disclosed is a double-sided printable image forming apparatus in which a double-sided printing unit is integrally installed on a main body to form a built-in type that can be opened and closed. The cover frame is formed between the door panel and the cover frame by selectively constraining the cover frame installed on one side of the main body and the printing paper conveyed on the discharge path of the discharge unit. A first guide means for guiding the printing paper circulation path, and a second conveying means for transferring the printing paper onto the printing paper circulation path installed on the facing surface of the door panel and the cover frame, and on the printing paper circulation path. Printed paper to be conveyed on the printing paper conveying path formed along the developing unit and the fixing unit. And second guide means for guiding re-entry. According to this configuration, it is possible to obtain a printing efficiency that is proportional to that of one-side printing at the time of double-sided printing, and to eliminate jam paper processing by easier and simple measures.

Description

Image forming appratus capable of forming a duplex image on one sheet}

The present invention relates to an image forming apparatus such as a laser printer, and more particularly to an image forming apparatus having a so-called built-in type duplex printing unit to maximize the duplex printing efficiency.

Laser printers, which are one of the representative image forming apparatuses for printing desired information on a page basis mainly connected to a computer network, unlike conventional dot printers or ink jet printers, laser printers scan a laser beam on a charged photosensitive medium to prevent electrostatic latent images. And an electrophotographic printing method in which the electrostatic latent image is developed into a visible image by toner particles to transfer and fix on a printing paper. Such a laser printer is usually provided with a duplex printing unit capable of sequentially printing desired information on both sides of one sheet of printing paper.

In the case of the conventional laser printer, the duplex printing unit has a structure that is separated from the printer main body so as to be detachable when necessary by a so-called option.

Therefore, in the case of a conventional laser printer, as the user purchases the duplex printing unit separately by using an option and selectively installs it, the purchase cost is increased and there is an inconvenience in use.

In addition, since the conventional laser printer has a structure in which the duplex printing unit is detached from the printer body and thus detached from the printer body, various structural restrictions are followed in forming the printing paper circulation path for double-sided printing. There are many cases.

Therefore, in the related art, it is difficult to miniaturize the external standard of the printer device, and it is difficult to obtain an efficiency corresponding to one-sided printing at the time of double-sided printing.

That is, conventional image forming apparatuses such as copiers and laser printers can print about 28 sheets of printing paper when printing on both sides, for example when 32 sheets of A4 paper can be printed on one side. . Therefore, the conventional conventional image forming apparatus has a problem that the printing efficiency is lowered by about 80 to 85% compared to when printing on one side when printing on both sides.

On the other hand, conventional conventional image forming apparatuses, such as a copier or a laser printer, are formed in a state in which a printing paper feed path through which printing paper is conveyed during the printing operation is fixed so as to be mostly closed inside the printer main body, and only a part of the printing is performed. Only the paper feed path is formed to be exposed from the printer body.

Therefore, the conventional image forming apparatus is not easy to handle and repair the jam paper, so as not only has an inconvenience in use, but also such a configuration problem acts as a deterrent to the operation efficiency.

Accordingly, the present invention was created to improve the problems of the conventional double-sided printable image forming apparatus as described above, and the first object of the present invention is to form a so-called built-in type so that the double-sided printing unit is integrally provided in the main body. To provide a double-sided printable image forming apparatus having a more compact configuration.

A second object of the present invention is to provide a double-sided printable image forming apparatus having a printing paper circulation path capable of obtaining the same printing efficiency as double-sided printing.

In addition, the third object of the present invention is to solve the jam paper generated on the printing paper conveyance path by easier and simple measures, and at the same time to facilitate repair and repair in the event of an internal failure. An object of the present invention is to provide an image forming apparatus having a function.

1 is a perspective view schematically showing an open state of a main portion of an image forming apparatus according to the present invention;

2 is a cross-sectional view schematically showing the overall configuration of an image forming apparatus according to the present invention;

3 is a schematic partial perspective view showing the main portion of the printing paper pickup unit shown in FIG.

Figure 4 is a perspective view of the main portion taken to illustrate an example of the printing paper transport means of the image forming apparatus according to the present invention,

5 is a partial perspective view schematically showing the main portion of the duplex printing unit of the image forming apparatus according to the present invention;

6 is an exploded perspective view schematically showing the manual feed transfer unit of the image forming apparatus according to the present invention;

7 is a view for explaining the operation of printing on one side of the image forming apparatus according to the present invention and the printing paper feed path;

8 is a view for explaining a duplex printing operation process and printing paper feed path of the image forming apparatus according to the present invention;

9 is a view for explaining the printing operation process and the printing paper feed path by manual feeding of the image forming apparatus according to the present invention.

Explanation of symbols on the main parts of the drawings

10, 20 ... Print paper cassette 30 ... Photo sensor

50 ... Bypass Cassette 80 ... Tray

110 ... body 111 ... fixed panel

112 Cover panel 120 Pick-up unit

121 Lever bracket 122 Pick-up roller

130 Developing unit 130 Photosensitive drum

132 ... Transfer roller 140 ... Toner supply unit

150 ... Laser Scanning Unit (LSU) 160 ... Fixing Unit

161 Pressing roller 162 Heating roller

170 ... Medium unit 175 ... Medium orientation guide member

177 ... badge roller 178 ... backup roller

180 Duplex Unit 181 Door Panel

186 ... Cover frame 189 ... Paper reversing guide member

190 ... Transfer Unit 191 ... Slide Plate

196.Open plate L ... Swivel lever

G1, G2 ... guide member

In order to achieve the above objects, a double-sided printable image forming apparatus according to the present invention includes a printing paper cassette detachably installed on a main body, a pickup unit for picking up the printing paper loaded on the cassette, and the picked up printing paper. First conveying means for conveying the toner in one direction, a developing unit for forming a toner image on printing paper, a fixing unit for compressing and fixing the toner image transferred to the printing paper to an image image, and passing through the fixing unit. A double-sided printable image forming apparatus comprising a double-sided printing unit which recirculates one printing sheet into the developing unit and circulates to form an image on the back side thereof, and a discharge unit for discharging the printing sheet on which the image image has been fixed. The double-sided printing unit is one-sided printing is completed by the fixing unit and the double It is characterized in that the built-in type integrally installed to face the one side of the main body to form a printing paper circulation path for selectively restraining the printing paper conveyed in the inverted state to the paper unit to re-enter the developing unit.

According to the image forming apparatus according to the present invention having the above configuration, the duplex printing unit has another feature of being installed in a state in which one side is rotatable and open with respect to the main body. This configuration feature is to ensure that the image forming apparatus according to the present invention has the shortest printing paper circulation path for maximizing the duplex printing efficiency, the printing paper circulation path is arranged side by side in the vertical direction of the main body approximately Complementary elliptical tracks.

According to an aspect of the present invention, the duplex printing unit includes: a door panel installed at one side of the main body in a state capable of opening and closing and supporting the transfer roller; A cover frame formed on one side of the main body in a state in which a circulation path through which printing paper is transported is formed between the door panel and is opened and closed by rotation; First guiding means for selectively confining the printing paper conveyed on the discharge path of the discharge unit to enter the printing paper circulation path formed between the door panel and the cover frame; Second conveying means installed on a facing portion of the door panel and the cover frame to convey printing paper on the printing paper circulation path; And second guide means for guiding the printing paper conveyed on the printing paper circulation path onto the printing paper conveying path formed along the developing unit and the fixing unit.

According to another aspect of the present invention, the printing paper cassette is installed so that at least two or more are stacked on the main body side by side in a vertical state, in particular installed to be detached in a direction orthogonal to the discharge direction of the printing paper discharged through the discharge unit. Has a characteristic configuration.

According to another aspect of the present invention, the discharge unit is a discharge direction determining means that is driven to select and discharge the printing paper in any one of the front and rear direction of the main body, and interferes with the printing paper conveyed through the fixing unit And a guide member rotatably installed on the printing paper transfer path of the discharge unit to set the first and second postures to selectively determine the transfer direction thereof, and the printing paper of the discharge unit to enable forward and reverse rotation driving. It is preferable to include a discharge roller installed on the transfer path and a backup roller driven correspondingly.

According to another aspect of the present invention, the manual feed cassette is provided on the other side of the main body, the manual paper feed path through which the printing paper picked up from the manual feed cassette is transferred to the main body between the printing paper cassette and the developing unit. It is preferable that the formed transfer unit is provided to be opened and closed by sliding from the main body.

According to the present invention, the transfer unit has a slide plate provided so that a plurality of rotation rollers are arranged at equal intervals, and a plurality of tension rollers installed to correspond to the plurality of rotation rollers, respectively, and are mounted on the slide plate in an upward rotation. It is characterized by including an open plate that is opened and closed by.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the image forming apparatus according to the present invention.

Figure 1 schematically shows the appearance of the main portion of the image forming apparatus 100 according to the present invention in an open state, as in the conventional image forming apparatus such as a copying machine, a laser printer, etc. Not shown) and the engine unit 100A is incorporated.

The controller unit analyzes the data received from the computer and sends image data to be printed to the engine unit 100A as a control signal in the form of a unit page, and sequentially drives various driving devices of the engine unit 100A and the like. The control signal for controlling the signal is transmitted.

The engine unit 100A performs an electrophotographic printing process under the control of the controller, and includes a developing unit 130, a laser beam scanning unit (LSU) 150, a toner supply unit 140, and the like. And a fixing unit (not shown) for fixing the toner image onto the printing paper.

One of the main features of the image forming apparatus 100 according to the present invention is integrally formed so that the duplex printing unit 180 can be opened to face the discharge side B surface of the main body 110 as shown in FIG. 1. The so-called built-in type is installed. This configuration will be described in detail below, but to form the printing paper circulation path in the shortest distance in order to maximize the duplex printing efficiency.

The duplex printing unit 180 forms a printing paper circulation path (see symbol “C” in FIG. 2) by a complementary action with the main body 100.

The printing paper circulation path is transported for reentry into the engine unit 100A by selectively restraining the printing paper conveyed in the inverted state on the discharge unit 170 after one side printing is completed. Used as a route.

Further, another main feature of the image forming apparatus 100 according to the present invention is as shown in Figure 1, the unit printing paper cassette 10, 20, the feeding direction (a) and discharge direction of the main body 110 It is provided so that attachment or detachment may be carried out in substantially orthogonal direction with respect to (b), and it is installed in a multilayered structure.

In addition, as another main feature of the image forming apparatus 100 according to the present invention is schematically shown in Figure 1, the main portion of the printing paper transport path to which the printing paper is transported during the printing operation process of the main body 110 It is formed to be openly exposed to most of the interior.

According to the present invention, in particular, the transfer unit 190, which is configured between the engine unit 100A and the unit printing paper cassette 20, is configured in a so-called drawer type and is exposed by sliding from the main body 110 so as to be opened. The transfer unit 190 is provided with a manual paper feed path (see symbol “T” in FIG. 2) which is fed from the manual paper feed cassette 50.

Such a configuration is intended to provide a function that can solve the jam paper generated on the printing paper feed path by easier and simple measures, and at the same time, make the repair and repair easier in the case of an internal failure. .

The overall configuration of the double-sided printable image forming apparatus 100 according to the present invention having the above main features will be described in detail with reference to FIG. 2 as follows.

The pickup unit 120 is installed inside the main body 110 to sequentially pick up one sheet of printing paper, which is positioned above the unit printing paper cassettes 10 and 20, respectively.

As shown in FIG. 3, the pickup unit 120 includes a pickup roller 122 whose setting position level varies according to a detachable state of the unit printing paper cassettes 10 and 20 and a printing paper loading level. In addition, the pickup roller 122 includes a pickup lever 121 rotatably installed on the main body 110 with a hinge structure for rotatably supporting the pickup roller 122 and adjusting the level thereof.

The pickup roller 122 may be configured in various forms such as, for example, a configuration connected to a belt (not shown) or a gear (not shown) connected to the output shaft of the driving motor M1.

The printing paper cassette is a first transfer means for transferring the printing paper picked up by the pickup unit 120 to the engine unit 100A on the discharge side B fixing panel 111 of the main body 110. And a plurality of rotation rollers 113 and 115 rotatably installed on the paper exit side of the (10) and (20) 20 and a plurality of tension rollers 114 and 116 respectively installed to rotate correspondingly thereto.

As shown in FIG. 4, the rotary rollers 113 and 115 have a common rotary shaft installed in the fixing panel 111 below the discharge side B of the main body 110 to be rotated by the driving motor M. As shown in FIG. It is arrange | positioned on 111a at substantially equal intervals.

In addition, the tension rollers 114 and 116 are installed in a state in which they face the fixed panel 111 of the main body 110 and are installed inside the cover panel 112 that is opened and closed by rotation, and a spring (not shown). It is arranged at approximately equal intervals on the common rotating shaft 112a which is elastically struck by) so as to elastically press the rotating rollers 113 and 115.

On the other hand, between the fixing panel 111 and the cover panel 112 of the main body 110 is formed a transport path for transporting the printing paper picked up from the printing paper cassette 10, 20, the cover panel ( On the inner side of 112, as shown, a plurality of thin ribs 112b are arranged at equal intervals vertically. This configuration is to minimize the area rubbed with the printing paper to suppress the jam (jam) that may occur during the transfer of the printing paper.

Reference numeral 30 in the drawing denotes a photo sensor for detecting the printing paper conveyed by the rotation driving force of the rotary rollers 113, 115 and the tension rollers 114, 116 in a non-contact manner, depending on whether the printing paper is detected. The driving of the alignment roller 31 and the backup roller 32 provided upstream is controlled. As a result, the alignment roller 31 and the backup roller 32 align and control the printing paper entering the developing unit 130 at the correct position and at the constant speed so that the developing unit 130 may perform a normal image forming operation. Give it.

The developing unit 130 is detachably installed from the main body 100 as shown in FIG. 1, and is charged by, for example, corona discharge to irradiate the laser beam from the laser beam scanning unit (LSU) 150. And a photosensitive drum 131 on which an electrostatic latent image of a printed image is formed.

Reference numeral 160 in the drawing denotes a fixing unit for pressing and fixing the toner image transferred to the printing paper by the photosensitive drum 131 and the transfer roller 132, and includes a pressing roller 161 and a heating roller 162. do.

Reference numeral 170 in the drawing denotes a discharge unit for discharging the printing paper on which the fixing of the image image is completed by the fixing unit 160. The discharge unit 170 includes a plurality of transfer rollers 172 and a backup roller 173. Are installed so as to correspond to each other. Therefore, the discharge unit 170 transfers the printing paper in the discharge direction determined by the rotational driving force of the transfer roller 172 and the backup roller 173. Here, reference numeral 175 denotes a discharge direction guide member which is installed to be positioned at the end of the printing paper feed path (P) and rotates to restrain the printing paper which is conveyed and to selectively determine its discharge direction. 177 and 178 denote a discharge roller and a backup roller which are controlled to enable forward and reverse rotation depending on the discharge direction of the printing paper.

The guide member 175 is formed to have a shape structure that can be arranged in equal intervals on the common rotating shaft installed in the width direction of the printing paper to guide the leading end of the printing paper in the desired transport direction.

The double-sided printing unit 180 is installed on the upper side of the discharge side B of the main body 100 so as to be openable and closed, and a door roller 181 on which a transfer roller 132 is supported therein, and the door panel 181. The cover frame 186 is installed to be opened and closed to face the outer surface of the cover) to form a circulation path in which one side of the printed paper is inverted and circulated.

Printing formed between the door panel 181 and the cover frame 186 by selectively restraining the printing paper conveyed on the printing paper discharge path of the discharge unit 170 on the free end of the cover frame 186. In order to guide and enter the paper circulation path (C), a paper inversion guide member 189 driven to change the setting position is provided.

As shown in FIG. 1, the paper reversing guide member 189 is arranged on the common rotating shaft 189a installed in the width direction of the printing paper at equal intervals to guide the tip of the printing paper in a desired conveying direction. It is formed to have a shape structure.

A plurality of rotary rollers 182, 187 and tension rollers 183, 188 are correspondingly installed on the surface portions of the door panel 181 and the cover frame 186, and the printing paper is driven by their rotational driving force. Circulating conveyed.

The rotation rollers 182 and 187 are disposed at equal intervals on a common rotation shaft 181a installed to cross the door panel 181 so as to be rotated by the driving motor M as shown in FIG. 5. .

The tension rollers 183 and 188 are installed inside the cover frame 186 and are disposed at equal intervals on a common rotation shaft 186a elastically viced by a spring (not shown). 187) is elastically pressed.

On the other hand, between the door panel 181 and the cover frame 186 is formed a circulation path for transporting the printed paper on which one-side printing is completed for double-sided printing, the door panel 181 and the cover frame ( A plurality of thin ribs 181b and 186b are arranged at equal intervals in the vertical direction at the facing portions of the 186. This configuration is for preventing jams and the like by preventing the printing paper from being easily adsorbed on the plane when transported along the plane.

In FIG. 5, reference numeral L denotes a rotation lever L installed on the printing paper feed path P and the circulation path C to rotate by contact with the printing paper, wherein the rotation lever L is, for example. It is supported by a rotating shaft connected to a limit switch or a solenoid, and rotates in contact with the conveyed printing paper, thus serving as a sensor for detecting the transport position of the printing paper.

Reference numeral G1 of FIG. 2 denotes a printing paper conveying path P formed along the developing unit 130 and the fixing unit 160 of the engine unit 100A for printing the paper conveyed onto the printing paper circulation path C. FIG. A guide member for reentering into the phase is shown.

According to the present invention, the printing paper feed path P formed in the engine unit 100A forms a vertical path such that the printing paper is transferred upward from the lower side of the main body 100 as shown.

In addition, the printing paper circulation path C formed between the door panel 181 and the cover frame 186 of the duplex printing unit 180 is vertical so that the printing paper is transferred from the upper side to the lower side of the main body 100. It will form a path.

Therefore, the printing paper feed path P formed in the engine unit 100A and the printing paper circulation path C formed in the double-sided printing unit 180 form a path on the complementary elliptical track as shown in FIG. 2. Done.

According to the printing paper feed path of the configuration as described above, it is possible to form the printing paper circulation path for the double-sided printing in the shortest distance to improve the printing efficiency and to improve the overall appearance of the image forming apparatus 100 A configuration that is advantageous for miniaturization is achieved.

Reference numeral 50 in FIG. 2 denotes a manual feed cassette, and 60 shows a pickup unit having a pickup roller 61 for picking up printing paper loaded on the manual feed cassette 50. As shown in FIG.

According to the image forming apparatus 100 according to the present invention, the printing paper picked up from the manual feed cassette 50 by the pickup roller 61 of the pickup unit 60 is the engine unit 100A and the unit printing paper. It is conveyed on the printing paper conveyance path P formed in the engine part 100A through the transfer unit 190 provided in the main body 110 between the cassettes 20. As shown in FIG.

According to the invention, the transfer unit 190 is configured in a so-called, drawer type is installed in a state capable of opening by sliding from the main body 110.

FIG. 6 illustrates a state in which the transfer unit 190 is opened from the main body 110. As shown in FIG. 6, a plurality of rotating rollers 192 are arranged at equal intervals, and a plurality of slide plates 191 are provided. It has a plurality of tension rollers (197) installed to correspond to the rotary rollers 192, respectively, and is provided on the slide plate (191) and has an open plate (196) opened and closed by upward rotation.

The tension roller 197 is elastically biased by a leaf spring body 198 installed on the open plate 196 as shown in order to freely rotate in a state of pressing the rotary roller 192 with a constant tension force. It is.

According to the configuration of the transfer unit 190 as described above, the slide plate 191 and the open plate 196 is complementary to the printing paper conveyed from the manual feed cassette 50 by the engine unit 100A The manual feed feed path (T) for feeding to the to form a. Reference numeral L in FIG. 6 denotes a pivoting lever configured to perform substantially the same function as the pivoting lever L described by FIG. 5.

In the printing operation process of the image forming apparatus 100 according to the present invention, the signals outputted according to the point of time when the rotation levers L come in contact with printing paper, respectively, are the printing paper feed path P and the circulation path ( C) and the guide members 175 and 189 and the rotary rollers 113 and 115, the alignment roller 31, the feed rollers 182 and 187 provided on the manual feed feed path T, and the rotary rollers. The driving system including the driving rollers 131 and 133 and the discharge roller 178 can be used as the basis for controlling the sequence sequentially.

Unexplained reference numeral 80 of FIG. 2 denotes a discharge bin on which printed sheets are discharged and stacked.

The operation of the single-sided printing, the double-sided printing and the manual feeding printing of the image forming apparatus according to the present invention having the configuration as described above and the activation state of each component will be described as follows.

First, Figure 7 is a view for explaining the printing process of one side of the image forming apparatus according to the present invention, the thick and thick lines shown on the printing paper feed path (P) of the engine unit 100A is printed in the printing process The paper feed path is shown.

First, while the unit printing paper cassettes 10 and / or 20 on which the printing paper is loaded are mounted on the main body 100, the pickup roller 122 of the pickup unit 120 is controlled by the operation control of the controller unit according to a computer command. As it rotates while being in close contact with the printing paper, one printing paper is picked up and transferred between the feeding roller 31 or 33 and the tension roller 32 or 34.

The printing paper picked up as described above is guided by the rotation driving force of the transfer roller 31 or 33 and the tension roller 32 or 34 and the guide member G, and is conveyed to the developing unit 130. At this time, the printing paper is sensed by the photosensor 30 immediately before entering the developing unit 130 and aligned by the alignment roller 31 and the backup roller 32 at the constant speed and the fixed position.

The sorted printing paper passes through the developing unit 130, wherein the toner image is transferred to the printing paper by the photosensitive drum 131 and the transfer roller 132. That is, the laser beam scanning unit (LSU) 150 scans a laser beam to form an electrostatic latent image by attaching toner particles to the electrostatic latent image on the surface of the photosensitive drum 131 charged by corona discharge. The visible image is compressed on the photosensitive drum 131 and the transfer roller 132 and applied to the transfer roller 132 by the high pressure applied to the transfer roller 132 (having a polarity opposite to the toner, usually having a "+" polarity). Will be moved. Thereafter, the toner image transferred to the printing paper is fixed to the printed image by thermal compression of the fixing roller 161 and the heating roller 162 of the fixing unit 160.

The printing paper on which the desired image is printed through the above-described process is determined by the guide member 175 provided in the discharge unit 170 and discharged. That is, the guide member 175 is selectively rotated in accordance with a signal input for determining the discharge direction in advance at the time of initial printing operation to determine the setting position.

Therefore, according to the image forming apparatus according to the present invention, the discharge direction of the printing paper is discharged to either one of the front and rear sides of the main body 110, that is, the left and right sides of the drawing in accordance with the optional position of the guide member 175. It becomes possible.

Such a configuration may include discharge of so-called face-up state in which the print image is discharged upwardly and discharge in so-called face-down state in which the print image is discharged downwardly concealed. You can select to do it.

Next, a duplex printing operation process of the image forming apparatus according to the present invention will be described with reference to FIG. 8. The thick and thick lines shown on the printing paper circulation path (C) of the duplex printing unit 180 in the drawing shows the transport path including the process of printing the paper in the printing process.

The printing paper, which has been printed on one side through the process as described with reference to FIG. 7, is inverted on the transport path of the discharge unit 170 as shown in FIG. 8 to the discharge roller 177 and the backup roller 178. Are aligned. At the same time, as the discharge roller 177 is sequence controlled to be driven in reverse rotation, the printing paper on which one side printing is completed is transferred to the discharge stage 80.

Following the reverse rotation driving of the discharge roller 177, the setting position is determined so that the setting position of the paper reversing guide member 189 provided at the upper end of the double-sided printing unit 180 is determined upward.

The sequence control as described above is subject to control of a drive source such as a limit switch or a solenoid operated by the rotation levers L on the printing paper feed path formed in the engine unit 100A.

As a result, the printing paper conveyed to the discharge table 80 on the conveyance path of the discharge unit 170 is constrained by the interference of the paper reversing guide member 189, and thus the door panel 181 and the cover frame 186 are separated. Enter the printing paper circulation path (C) formed between. The printing paper on which the one-side printing is entered in this way is conveyed downward by the rotational force of the rotary rollers 182 and 187 and the tension rollers 183 and 188 forming the second conveying means.

The printing paper conveyed on the path as described above is re-entered to the alignment roller 31 and the backup roller 32 by the guide members G1 and G2. Subsequently, the printing paper is transferred on the same path as that of the one-side printing to complete the two-sided printing process.

Finally, referring to Figure 9 will be described the feed path of the printing paper during manual feeding of the image forming apparatus according to the present invention.

From the manual feed cassette 50 mounted on one side of the main body 100, the pickup roller 61 of the pickup unit 60 is picked up one sheet of printing paper by rotational driving while being in close contact with the printing paper, and the transfer is performed. Transfer to the unit 190.

The printing paper conveyed to the transfer unit 190 is applied to the rotation driving force of the rotary roller 192 and the tension roller 197 on the printing paper feed path T formed between the slide plate 191 and the open plate 196. It is conveyed to the discharge stage 60 by the direction. The printing paper conveyed as described above is guided by the guide member G2 to enter the alignment roller 31 and the backup roller 32. Subsequently, the printing paper is transferred on the same path as that of the single-sided printing to complete the manual feeding process.

On the other hand, according to the image forming apparatus according to the present invention, for processing jam paper generated on the feed path (T) during manual feeding, the slide plate 191 of the transfer unit 190 from the main body 100 The jam sheet can be easily and simply processed by lifting and opening the open plate 196 upward in a state of sliding out.

In addition, the image forming apparatus according to the present invention, when the conveyed paper is jammed, the free end of the door panel 181 and the cover frame 186 of the cover panel 112 and the duplex printing unit 180. By rotating outwards, the jam sheet can be easily and simply processed.

As described above, according to the double-side printing image forming apparatus according to the present invention, the following unique effects can be obtained.

First, by forming the printing paper circulation path for the double-sided printing in the shortest distance it is possible to obtain a printing efficiency substantially proportional to the one-sided printing when printing on both sides.

In fact, according to the image forming apparatus according to the present invention, when the single side of A4 paper is configured to print 70 sheets per minute, 35 sheets can be printed on double-sided printing. Correspondingly, printing efficiency of 100% can be obtained.

Second, by embedding the duplex printing unit in the main body, not only can the printer standard be more compactly constructed, but also the manufacturing cost can be reduced, thereby reducing the purchase cost of the consumer. It can greatly improve the convenience of.

Third, since the processing of jam paper generated on the printing paper feed path can be eliminated by easier and simple measures, it is expected to maximize the operating efficiency of the printer device.

The present invention is not limited to the above-described specific embodiments, and various modifications can be made by those skilled in the art without departing from the gist of the present invention described in the claims. .

Claims (15)

A printing paper cassette detachably attached to the main body, a pickup unit for picking up the printing paper loaded on the cassette, first transfer means for conveying the picked up printing paper in one direction, and a toner image formed on the printing paper. A developing unit for heat-pressing and fixing a toner image transferred to a printing paper to fix it to an image image, and reprinting the printing paper passing through the fixing unit into the developing unit to form an image on the back side thereof. A double-sided printable image forming apparatus comprising a double-sided printing unit for circulating and a discharge unit for discharging a printing paper on which image fixing is completed, The duplex printing unit, One side printing is completed by the fixing unit to integrally confront the one side of the main body so as to form a printing paper circulation path for selectively restraining the printing paper conveyed in the inverted state to the discharge unit and reentering the developing unit. Double-sided printable image forming apparatus, characterized in that the built-in installed. The method of claim 1, And the duplex printing unit is installed in a state in which one side is rotatable and open with respect to the main body. The method of claim 1, And a printing paper conveyance path formed between the developing unit and the fixing unit and a printing paper circulation path formed on the duplex printing unit in the shape of a complementary elliptical track. The method of claim 1, On the printing paper circulation path formed in the main body, a rotation lever connected to the sensing means is installed so as to interfere and rotate by contact with the conveyed printing paper, and the sensing means transfers the printing paper according to the rotation state of the rotation lever. And speed information is detected and output as a signal. The method of claim 1, wherein the duplex printing unit, A cover frame which faces a side of the main body and is formed with a circulation path through which printing paper is transported and is opened and closed by rotation; First guiding means for selectively confining the printing paper conveyed on the discharge path of the discharge unit to enter the printing paper circulation path formed between the main body and the cover frame; Second conveying means installed on a facing portion of the main body and the cover frame to convey printing paper on the printing paper circulation path; And And a second guide means for guiding the printing paper conveyed on the printing paper circulation path onto the printing paper conveying path formed along the developing unit and the fixing unit. Device. The method of claim 1, wherein the duplex printing unit, A door panel installed at one side of the main body to be opened and closed and supported by the transfer roller; A cover frame formed on one side of the main body in a state in which a circulation path through which printing paper is transported is formed between the door panel and is opened and closed by rotation; First guiding means for selectively confining the printing paper conveyed on the discharge path of the discharge unit to enter the printing paper circulation path formed between the door panel and the cover frame; Second conveying means installed on a facing portion of the door panel and the cover frame to convey printing paper on the printing paper circulation path; And And a second guide means for guiding the printing paper conveyed on the printing paper circulation path onto the printing paper conveying path formed along the developing unit and the fixing unit. Device. The method of claim 1, And the printing paper cassette is installed to be detachable in a direction orthogonal to the discharge direction of the printing paper discharged through the discharge unit. The method of claim 1, And the printing paper cassette is installed on the main body so that at least two or more of them are stacked in a state of being parallel to each other. The method of claim 1, On the printing paper transfer path between the first transfer means and the developing unit, printing paper alignment means is provided for detecting whether the printing paper passes and controlling the transfer speed at a constant speed. Image forming apparatus. The paper sheet aligning means of claim 9, And a photo sensor for non-contact sensing of the conveyed printing paper, and a rotation roller and a backup roller controlled to be driven at a constant speed in accordance with a signal output from the photo sensor. The method of claim 1, The discharge unit determines the discharge direction driven to discharge the print paper by selecting in one of two opposite directions of the main body so that the image formed on the print paper can be discharged by selecting one of the upward and downward directions in one direction. And a means for printing on both sides of the image forming apparatus. The method of claim 11, wherein the discharge direction determining means, A guide member rotatably installed on the printing paper transfer path of the discharge unit so as to set the first posture and the second posture interfering with the printing paper conveyed through the fixing unit to selectively determine its conveying direction; And a backup roller installed on the printing paper transport path of the discharge unit to enable rotational driving, and a backup roller driven correspondingly thereto. The method of claim 1, The manual feed cassette is installed on the other side of the main body, and the transfer unit having a manual feed feed path through which the print paper picked up from the manual feed cassette is formed is provided on the main body between the printing paper cassette and the developing unit. A duplex printable image forming apparatus, characterized in that. The method of claim 13, And the transfer unit is provided to be opened and closed by sliding from the main body. The method of claim 13, wherein the transfer unit, It includes a slide plate provided so that the plurality of rotation rollers are arranged at equal intervals, and a plurality of tension rollers installed to correspond to the plurality of rotation rollers, respectively, and mounted on the slide plate to open and close by upward rotation. A duplex printable image forming apparatus, characterized in that.