KR20080046542A - Image forming apparatus - Google Patents

Abstract

An image forming apparatus is provided to reduce a driving noise, a material cost, and power consumption by reducing the number of driving sources and to reduce a stress of a color developing agent due to separately driving the color developing agent as a third driving source. An image forming apparatus includes a developing unit, a loading unit(150), a discharge roller(163), a first driving source, a developing unit power control unit, and a loading unit power control unit. The developing unit forms an image on a printing medium to be conveyed along one surface printing path with a developing agent. The loading unit loads the developing agent on the printing medium. The discharge roller discharges the printing medium passed through the loading unit. The first driving source drives the developing unit, the loading unit, and the discharge roller. The developing unit power control unit selectively transfers power of the first driving source to the developing unit. The loading unit power control unit selectively transfers the power of the first driving source to the loading unit.

Description

Image Forming Device {IMAGE FORMING APPARATUS}

1 is a cross-sectional view of a conventional image forming apparatus;

2 is a schematic cross-sectional view of an image forming apparatus according to the present invention;

3A is a perspective view illustrating main parts of the image forming apparatus of FIG. 2;

FIG. 3B is a schematic view for explaining an operation process of the double-sided printing detecting unit of the image forming apparatus of FIG. 3A;

4 is a plan view of main parts of a power transmission device of the image forming apparatus of FIG. 2;

5 is a perspective view of a power transmission device of the image forming apparatus of FIG.

6 is a block diagram of the image forming apparatus of FIG. 2.

Explanation of symbols on the main parts of the drawings

100: image forming apparatus 110: paper feeding unit

120: print carrier transfer unit 130K: mono developer

130Y, 130M, 130C: color developing machine 150: fixing unit

160: discharge part 163: discharge roller

170: duplex printing detection unit 171: first lever

171a: first lever protrusion 172: second lever

172a: second lever protrusion 174: elastic member

177: light sensor 183: first driving source

185: second drive 187: third drive

190: control unit 193: print mode determination unit

200: power transmission device 205: developer power intermittent

213: fuser power intermittent

The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus capable of reducing toner stress and power consumption.

In the conventional electrophotographic image forming apparatus 1, as illustrated in FIG. 1, the paper feeding unit 10, the paper conveying unit 20, and the developing devices 30C, 30M, 30Y, and 30K each store toner of a predetermined color. , A plurality of transfer rollers 40, a light scanning unit (LSU) 43, a fixing unit 50, and a discharge unit 60. The print medium loaded on the knock-up plate 12 elastically supported by the spring 11 is picked up by the pickup roller 13 and the front end of the print medium is aligned by the register roller 14. The aligned print media advances toward the developing unit 130 by the paper conveying belt 25 of the paper conveying unit 20, and color toner images are formed on the printing medium through the developing units 30C, 30M, 30Y, and 30K. . The color toner image formed on the print medium is fixed by heat and pressure by the heat roller 53 and the press roller 55. The print medium which has been printed after passing through the fixing unit 50 is discharged to the outside by the discharge roller 63.

By the way, the conventional image forming apparatus 1 includes four motors for driving the fixing unit 50, the paper conveying belt driving roller 27, the discharge roller 63, and the pickup roller 13, and each developing unit 30C, A total of eight motors are used, including four developer drive motors driving 30M, 30Y and 30K) respectively. In addition, each developer driving motor (not shown) drives the respective photosensitive drums 35C, 35M, 35Y, and 35K, developing rollers 33C, 33K, 33Y, and 33K, and an agitator (not shown). The power transfer from the not shown) to the developing rollers 33C, 33K, 33Y, 33K and agitator (not shown) is interrupted by the solenoid.

The conventional image forming apparatus 1 uses a total of eight motors, which makes the power transmission structure complicated and increases power consumption, material cost, and driving noise. In addition, the power of the developing roller and the stirrer may be interrupted by the solenoid during the black and white printing, but the photosensitive drum is still driven, thereby increasing the toner stress.

It is therefore an object of the present invention to provide an image forming apparatus that can simplify the power transmission structure.

Another object of the present invention is to provide an image forming apparatus which can reduce driving noise.

Further, another object of the present invention is to provide an image forming apparatus that can reduce toner stress.

Further, another object of the present invention is to provide an image forming apparatus that can reduce the material cost.

Further, another object of the present invention is to provide an image forming apparatus that can reduce power consumption.

The object is an image forming apparatus, comprising: a developing device for forming an image with a developer on one surface of a printing medium conveyed along a one-side printing path; A fixing unit for fixing the developer to the print medium; A discharge roller for discharging the print medium passing through the fixing unit to the outside; It can be achieved by the image forming apparatus, characterized in that it comprises a first driving source for driving both the developing unit, the fixing unit and the discharge roller.

The apparatus may further include a developer power control unit for selectively transmitting power of the first driving source to the developing unit.

Here, the fixing apparatus may further include a power fixing unit for selectively transferring power of the first driving source to the fixing unit.

In addition, the developer is provided in plural to store the developer of different colors therein; Each developer may include a photosensitive member, a developing roller for developing the photosensitive member with a developer, and an agitator for stirring the developer.

The developing unit may include a mono developing unit installed closest to the fixing unit among the developing units and storing a developer having a black color, and the first driving source may drive a developing roller and a stirrer of the mono developing unit.

Here, the driving unit may further include a second driving source for rotationally driving all the photoconductors of the respective developing devices.

In addition, a plurality of transfer rollers disposed side by side on each photosensitive member with a print medium therebetween; The apparatus may further include a print media transport unit which transfers the print media between the photosensitive member and the transfer roller and is driven by the second driving source.

The developing unit may include a color developing unit storing a developer having a color, and further comprising a third driving source driving the developing roller and the stirrer of the color developing unit.

The apparatus may further include a duplex guide for guiding the print medium from the discharge roller to the developing unit so that the other side of the print medium may be printed. The discharge roller may be rotated forward and backward to move the print medium to the duplex guide. It can be provided as possible.

The apparatus may further include a duplex printing detector configured to detect whether the print medium moves to the duplex guide.

The duplex printing detector may also detect whether the print medium passes through the fixing unit.

The double-sided printing detecting unit may include: a first lever interposed between the fixing unit and the discharge roller to rotate in contact with a printing medium passing through the fixing unit; A second lever which is interlocked by the first lever and rotates in contact with the print medium which is driven by the reverse rotation of the discharge roller; It may include a sensor for sensing the position of at least one of the first lever and the second lever.

Here, when there is a duplex printing request, the controller may further include a control unit for controlling the first driving source so that the discharge roller rotates forward and backward according to the detection result of the duplex printing detection unit.

A pair of register rollers disposed in front of the developing device with respect to the one-side printing path and driven by the second driving source; The control apparatus may further include a control unit configured to stop at least one of the second driving source and the third driving source from the time when the printing medium passes through the fixing unit and immediately before the printing medium is caught between the regulating rollers.

In addition, in the duplex printing mode, the discharge roller may further include a control unit for stopping at least one of the second drive source and the third drive source while the reverse rotation.

In the case of the duplex printing mode, the controller may further include a control unit to determine which of the other side print data to be printed on the other side of the one-side printed print medium corresponds to black and white or color printing.

Here, when the other surface printing data corresponds to the black and white printing mode, the control unit may change the time from when the one surface of the print medium passes through the fixing unit to finish printing on one side until the other surface of the print medium is printed and discharged to the outside. The third drive source can be left at rest.

The method may further include a controller configured to determine whether the image data requested for printing corresponds to the black and white printing mode, and to control the third driving source to stop the third driving source when the black and white printing mode corresponds to the black and white printing mode.

In addition, the above object is, according to the present invention, in the image forming apparatus, a first photosensitive member, a developer storage unit for storing a black developer, and providing the black developer to the first photosensitive member with the black developer A mono developer having a first rotating body; A color developing device having a second photosensitive member, a developer storing portion storing a color developer, and a second rotating body providing the color developer to the second photosensitive member; A fixing unit for fixing the mono developer and the color developer to the print medium; A discharge roller for discharging the print medium passing through the fixing unit to the outside; A first driving source driving all of the first rotating body, the fixing unit, and the discharge roller; A second driving source for driving the first photosensitive member and the second photosensitive member; It can also be achieved by an image forming apparatus comprising a third drive source for driving the second rotating body.

In addition, the medium conveyance belt for orbiting the print medium to the photosensitive member; A plurality of transfer rollers arranged side by side on the first and second photosensitive members with the medium transfer belt interposed therebetween to transfer the mono and color developer to a print medium transferred by the medium transfer belt; It may further include a drive roller driven by the second drive source for driving the medium transport belt.

Here, the discharge roller is provided to be capable of forward and reverse rotation, and may further include a duplex guide for guiding the print medium from the discharge roller to the color developing.

The apparatus may further include a controller configured to control the first driving source so that the discharge roller rotates backward to enter the duplex guide from the print medium passing through the fixing unit.

The control unit may control at least one of the second drive source and the third drive source such that at least one of the second drive source and the third drive source is in a stationary state while the discharge roller is reversely rotated.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 2, the image forming apparatus 100 according to the present invention includes a paper feeding unit 110, a print medium transporting unit 120, a plurality of developing devices 130C, 130M, 130Y, and 130K, and a plurality of transfer rollers. 140, an exposure unit 143, a fixing unit 150, and a discharge unit 160.

A plurality of developing devices 130C, 130M, 130Y, 130K, a plurality of transfer rollers 140, and a fixing unit 150 are disposed along the one-side printing path SP from the resist roller 114 to the discharge roller 163, which will be described later. The image is formed on the print medium while passing through the one-side printing path SP.

The paper feeding unit 110 includes a knock up plate 112, an elastic member 111, and a pickup roller 113. The print medium loaded on the knock-up plate 113 elastically supported by the elastic member 111 is picked up by the pickup roller 115 and enters the register roller 114.

In addition, the paper feeding unit 110 may further include a manual feed cassette 116 that is manually fed and a manual pickup roller 119 that picks up a print medium on the manual feed cassette 116.

On the other hand, the print media aligned by the front end roller 114 is charged to the predetermined charge by the print media charging roller 117 is attached to the print media transfer belt 125 to be described later, the photosensitive drum 135Y of the developer 130Y. ) And the transfer roller 140.

The print media transport unit 120 includes a print media transport belt 125 and a transport belt drive roller 127 and a driven roller 123 for driving the print media transport belt 125. The print media conveyance belt 125 is circulated in an endless track by the conveyance belt drive roller 127 and the driven roller 123. And, it can be provided with a conductive belt so that the charged print medium can be attached.

On the other hand, each developing device 130Y, 130M, 130C, 130K is a photosensitive member (135Y, 135M, 135C, 135K), feed rollers (131Y, 131M, 131C, 131K), developing rollers (133Y, 133M, 133C, 133K) and development And a developer storage unit 136Y, 136M, 136C, and 136K for storing the agent.

Each developing unit 130Y, 130M, 130C, and 130K may be detachably provided to the image forming apparatus 100, respectively. As necessary, each of the developing devices 130Y, 130M, 130C, and 130K may be provided to be detachably attached to the image forming apparatus 100 except for the photosensitive members 135Y, 135M, 135C, and 135K.

Each developer storage unit 136Y, 136M, 136C, and 136K stores a developer of yellow (Y), magenta (M), cyan: C, and black (K) color, respectively. Each of the supply rollers 131Y, 131M, 131C, and 131K supplies the developer stored in the developer storage units 136Y, 136M, 136C, and 136K to the developing rollers 133Y, 133M, 133C, and 133K. Then, the developing rollers 133Y, 133M, 133C, and 133K supply the supplied developer to each of the photosensitive members 135Y, 135M, 135C, and 135K to provide an electrostatic latent image formed on each of the photosensitive members 135Y, 135M, 135C, and 135K. Develop.

The electrostatic latent images are generated when the surface of the photosensitive member 135 is exposed by the exposure unit 143 to generate an exposure area and a non-exposure area, and a potential difference therebetween occurs.

The exposure unit 143 has photosensitive members 135Y, 135M, 135C, and 135K such that electrostatic latent images corresponding to print data of yellow, magenta, cyan, and black colors are formed on the surfaces of the photosensitive members 135Y, 135M, 135C, and 135K. Is exposed. That is, the exposure unit 143 exposes only a portion of the surface of the photosensitive member 135C to which the cyan toner is to be applied to form an electro-static latent image corresponding to the cyan color image information. The latent electrostatic image is developed with a cyan color developer by the supply roller 131C and the developing roller 133C.

As a result, a visible image composed of a developer of cyan color on the surface of the photosensitive member 135C is formed, and the visible image is transferred to the print medium on the print medium transport belt 125 by the transfer roller 140. The print medium to which the cyan developer is transferred is magenta and yellow, respectively, passing between the developer 130M, 130Y, and 130K, which transfers the developer of another color, along the transfer medium belt 125, and the transfer roller 140, respectively. Toner of black color is overlapped. As a result, a color image is formed on the print medium.

The color image is fixed to the print medium by heat and pressure while passing through the fixing unit 150. The print medium on which one surface of the print medium is printed by passing through the fixing unit 150 is discharged to the outside by the discharge unit 160.

The discharge unit 160 includes a discharge roller 163 and idle rollers 165 and 167.

In addition, the fixing unit 150 is an idle roller for orbiting the fixing belt 157 together with the press roller 151, the fixing belt 157, the fixing belt driving roller 153, and the fixing belt driving roller 153. 155. The press rollers 151 to idle rollers 155 may be accommodated in the fixing unit frames 158 and 159.

The press roller 151 elastically pressurizes the fixing belt driving roller 153 with the fixing belt 157 interposed therebetween, and is driven by the fixing belt 157. A heating element (not shown) is provided inside the fixing belt driving roller 153 to heat the fixing belt 157 to a predetermined fixing temperature. Accordingly, the developer may be fixed to the print medium by applying heat and pressure to the print medium interposed between the fixing belt 157 and the press roller 151.

Meanwhile, the image forming apparatus 100 according to the present invention further includes a first driving source 183 as shown in FIG. 6.

As shown in FIGS. 4 and 5, the first driving source 183 is a power source for driving all of the mono developer 130K, the fixing unit 150, and the discharge roller 163. More precisely, the developing roller 133K and the supply roller 131K of the mono developer 130K storing the above-mentioned black color developer, the fixing belt drive roller 153 of the fixing unit 150, and the discharge roller. 163 is a power source for driving all. The first driving source 183 may be provided as a step motor. In addition, of course, it can also be provided as an electric motor of another method.

On the other hand, the image forming apparatus 100 according to the present invention passes through the fixing unit 150, and transfers the one-sided print media back to the developing unit 130 to print the two-sided printing path for printing the other side of the print medium ( It may further include a duplex guide 118 to form DP).

The duplex guide 118 guides the movement of the print medium from the discharge unit 160 back to the developing unit 130C. As shown in FIG. 2, the duplex guide 118 guides the print medium to the regulating roller 114 so that the double-sided printing path DP joins the one-sided printing path SP. In addition, a pair of duplex rollers 115 for conveying the print medium along the duplex guide 118 may be arranged in several places.

On the other hand, the discharge roller 163 may be provided to transfer the print medium in a direction opposite to the direction in which the print medium is discharged to the duplex guide 118 to the outside in order to print the other side of the print medium. To this end, the discharge roller 163 may be provided to be capable of forward and reverse rotation.

On the other hand, the image forming apparatus 100 according to the present invention, as shown in Figure 4 and 5, the power of the first driving source 183 is the mono developer 130K, the fixing unit 150 and the discharge roller 163 It further comprises a power transmission device for transmitting to).

A mono developer power that is transmitted from the first drive source 183 to the mono developer 130K is transmitted to drive the mono developer 130K, the fuser 150, and the discharge roller 163 as one drive source. It is preferable to provide intermittent portions 205 and 213 on a transmission path and a fuser power transmission path through which power is transmitted from the first drive source 183 to the fuser 150. Because, in order to print both sides of the print medium, the discharge roller 163 should be capable of bi-directional rotation of the forward and reverse rotation, while the fixing unit 150 and the mono developer 130K has a constant traveling direction of the print medium, so that only one direction It is desirable to rotate.

The power transmission path to the mono developer 130K by the power transmission device 200 is as follows. As shown in FIG. 4, the developer gear 208K is exposed outside the casing 138K of the mono developer 130K to enable power transmission from the outside. The developer gear 208K transfers power to a plurality of gears G1 to G6 housed inside the casing 138K.

The power transmission path from the drive pinion 201 connected to the drive shaft (not shown) of the first drive source 183 to the developer gear 208K is as follows.

It is transmitted from the drive pinion 201 to the developer gear 208K via the gears 202, 203, 209, 204, the developer power interrupter 205, and the gears 206, 207. The developer gear 208K is installed in the mono developer 130K and is attached to and detached from the image forming apparatus 100 as a unit with the developer 130K. Accordingly, when the developer 130K is attached or detached, the developer gear 208K is engaged with and disengaged from the gear 207. Then, power transmission from the developer gear 208K to the developing roller gear G5 connected to the rotating shaft of the developing roller 133K is performed via the gears G1-> G2-> G6. As a result, when the driving pinion 201 rotates in the forward direction F, the developing roller 133K also rotates in the forward direction.

Further, power transmission from the developer gear 208K to the feed roller gear G4 connected to the rotation shaft of the feed roller 131K is made through the gears G1-> G2-> G6. Accordingly, the feed roller 131K is also rotated in the forward direction like the developing roller 133K. This is to rotate in the same direction to frictionally charge the developer contained therein.

Further, power transmission from the developer gear 208K to the stirrer gear G3 connected to the rotating shaft of the stirrer (not shown) is made through the gears G1-> G2. Accordingly, the agitator (not shown) is rotated in the reverse direction (H), it is possible to transfer the developer to the supply roller (131K) side.

On the other hand, the developer power interrupting unit 205 is provided as a one-way gear to transfer power to the mono developer 130K only when the drive pinion 201 rotates in the forward direction, and blocks power transmission when rotated in the reverse direction. The developer power control unit 205 may be provided with a known power control device such as an electromagnetic clutch, a swing gear, and a latch gear, rather than a one-way gear.

On the other hand, the power transmission path to the fuser 150 by the power transmission device 200 is as follows.

As shown in FIGS. 4 and 5, the power transmission from the drive pinion 201 to the fuser gear 219 connected to the fixing belt drive roller 153 is carried out through the gears 202-> 211-> 212 and the fuser power interrupter. The first gear train 213a and the gears 215-> 217 of 213 are sequentially made. Accordingly, when the drive pinion 201 rotates forward (F), the fixing unit gear 219 rotates in reverse (H). This is because, as shown in Figure 5, the fixing belt drive roller 153 has to rotate in accordance with the advancing direction of the print medium passing through the one-side printing path (SP). The rotation direction may vary depending on how the driving and driven rollers are selected among the rollers 151, 153, and 155 of the fixing unit 150.

The fixing unit power control unit 213 may be provided with a latch gear. A first gear train 213a and a second gear train 231b are provided along the latch gear shaft 213c. The first gear train 213a transmits power to the gear 215 only when the drive pinion 201 rotates forward, and power is transmitted to the gear 215 when the drive pinion 201 reverses. Block it. That is, the fixing unit 150 is driven only when the driving pinion 201 rotates forward. The fuser power control unit 213 may be replaced with another power control device such as a one-way gear or an electronic clutch, not a latch gear.

On the other hand, the power transmission path to the discharge roller 163 by the power transmission device 200 is as follows.

4 and 5, the power transmission from the drive pinion 201 to the discharge gear 227 connected to the rotating shaft of the discharge roller 163 is the gear (202-> 211-> 212) and the fuser power intermittent The second gear train 213b and the gears 221-> 223-> 225 of 213 are sequentially formed. Accordingly, the discharge gear 227 is rotated in the same direction as the rotation direction of the drive pinion 201. That is, as the drive pinion 201 rotates forward and backward, the discharge gear 227 also rotates forward and backward. Accordingly, in order to rotate the discharge roller 163 forward and backward, the driving pinion 201 may control the rotational axis rotation direction of the first drive source 183 so as to rotate forward and reverse, respectively.

In addition, the image forming apparatus 100 according to the present invention may further include at least one of the second driving source 185 and the third driving source 187.

The second driving source 185 may drive the photosensitive members 135Y, 135M, 135C, and 135K of each of the above-described developing devices 130Y, 130M, 130C, and 130K. Each photoreceptor 135Y, 135M, 135C, 135K may receive power from the second drive source 185 by the coupling C, as shown in FIG. If necessary, it may be provided to drive the pick-up rollers 113 and 119, the register roller 114, the duplex roller 115, the transfer belt drive roller 227. Since the rotation directions of the respective photosensitive members 135Y, 135M, 135C, and 135K and the rollers 113, 114, 115, and 227 are constant, a path for transmitting power of the second driving source 185 can be easily realized by appropriately combining gears. The description thereof will be omitted.

The third driving source 187 may be provided to drive only the color developing devices 130Y, 130M, and 130C storing the color developer among the above-described developing devices 130Y, 130M, 130C, and 130K. Among the components accommodated in the color developing devices 130Y, 130M, and 130C, the developing rollers 133Y, 133M, and 133C, except for the photosensitive members 135Y, 135M, and 135C, the supply rollers 131Y, 131M, and 131C, and an agitator (not shown). ) Can be provided to drive all. If necessary, it may be provided to drive only a part of them.

The developing rollers 133Y, 133M, and 133C, the feed rollers 131Y, 131M, and 131C and the stirrer (not shown) may stir the developer stored in the color developing devices 130Y, 130M, and 130C, or the photoconductors 135Y and 135M. , 135C), which may cause stress to the developer as members to be fed or triboelectrically charged.

The second drive source 185 and the third drive source 187 may be provided as a brushless DC motor (BLDC motor). Of course, it may be provided as an electric motor of other manners.

Meanwhile, the image forming apparatus 100 according to the present invention may further include a duplex printing detector 170 as shown in FIGS. 2 and 3.

The duplex printing detector 170 detects whether the print medium is traveling along the duplex printing path (DP of FIG. 2). That is, it is detected whether a print medium is entering the duplex guide 118.

If necessary, the duplex printing detecting unit 170 detects whether the print media is traveling on the duplex printing path (DP of FIG. 2), and also prints the fixing unit 150 for cost reduction and structural simplicity. It may also be arranged to detect whether it is passing. That is, it is possible to detect whether the print medium passes through the fixing unit 150 and the duplex printing path (DP of FIG. 2) with one sensor, and its structure and operation principle are as follows.

The duplex printing detecting unit 170 includes a first lever 171, a second lever 172, an elastic member 174, and an optical sensor 177, as shown in FIGS. 2, 3A, and 3B. do.

The first lever 171 and the second lever 172 may be rotatably supported by the fuser frame 159. The first lever 171 and the second lever 172 may be provided with a center of rotation concentrically, it may be eccentric.

The first lever 171 rotates the first lever 172a and the second lever 172 when the first lever 171 rotates when the first lever 171 strikes the front end of the printing medium passing through the fixing unit 150. It has an interlocking rotation protrusion 171b.

The second lever 172 has a second lever protrusion 172a, a second interlocking rotation protrusion 172b, a bent portion 172c, and a locking protrusion 172d.

The second lever protrusion 172a rotates the second lever 172 in contact with the print medium which advances the double-sided printing path DP from the discharge roller 163.

The second interlocking rotation protrusion 172b rotates in conjunction with the second lever 172 when the first lever 171 rotates, but is provided so that the first lever 171 does not rotate in rotation when the second lever 172 rotates. To this end, as shown in FIG. 3B, the second interlocking rotation protrusion 172b may be provided to be in contact with each other under the first interlocking rotation protrusion 171b. As a result, when the first lever 171 rotates in the J direction, the first lever interlocking protrusion 171b pushes the second lever interlocking protrusion 172b downward so that the second lever 172 also rotates in the J direction.

However, when the second lever protrusion 172a is pressed by the printing medium P2 traveling along the double-sided printing path DP and the second lever 172 rotates in the A direction, the second lever interlocking protrusion 172b ) Is spaced apart from the first lever interlocking protrusion 171b so that only the second lever 172 is rotated without the interlocking rotation of the first lever 171. Accordingly, when the first lever 171 rotates in coordination with the second lever 172, the print medium in which the first lever protrusion 171a of the first lever 171 travels on the double-sided printing path (DP of FIG. 2). The printing surface L of (P2) may be scratched to prevent scratches from occurring on the printing surface.

On the other hand, the bent portion 172c performs a function of blocking or unblocking the light of the light emitting portion 177a of the optical sensor 177 to be described later reaches the light receiving portion 177b.

The second lever 172 is preferably formed integrally with the projections (172a, 172b, 172d) and the bent portion 172c in terms of productivity.

The elastic member 174 is the first lever when one of the first lever 171 and the second lever 172 does not come into contact with the print medium as the print medium is moved while being rotated in contact with the print medium. 171 and the second lever 172 serves to restore the original position. That is, an elastic force is applied to the second lever 172 or the first lever 171 in a direction that prevents the first lever 171 and the second lever 172 from rotating. As shown in FIG. 3A, one end of the elastic member 174 may be connected to the engaging protrusion 172d of the second lever 172 and the other end may be connected to the fixing unit frame 159.

As illustrated in FIG. 3A, the optical sensor 177 may be disposed at an end side of the bent portion 172c of the second lever 172. The light sensor 177 is composed of a light emitting portion 177a and a light receiving portion 177b, and a bent portion 172c of the second lever 172 is interposed therebetween. Accordingly, as shown in FIGS. 3A and 3B, before the print medium contacts the first lever 171 or the second lever 172, the bent portion 172c of the second lever 172 may emit light 177a. ) Is in the blocking position B that blocks light from reaching the light receiving portion 177b.

On the other hand, when the first lever 171 or the second lever 172 is in contact with the print medium, the bent portion 172c is rotated to be in the unlocking position (C) spaced apart from the blocking position (B). Light of 177a reaches the light receiving portion 177b.

The optical sensor 177 may be provided to detect the rotation of the first lever 171 instead of the second lever 172. That is, for this purpose, the bent portion 172c may be provided in the first lever 171. In addition, as long as it can detect whether the first lever 171 or the second lever 172 is rotated instead of the optical sensor 177, another type of sensor such as a contact sensor may be used.

Meanwhile, the image forming apparatus 100 according to the present invention further includes a controller 190 as illustrated in FIG. 6.

The controller 190 controls the components included in the image forming apparatus 100 so as to form an image on a print medium, and performs the following characteristic control operations.

The image forming apparatus 100 may further include an interface unit 240 connected to a host device (not shown) to transmit and receive data with each other. The interface unit 240 may communicate with each other through a parallel interface, a serial interface such as a USB interface, and a network such as a local area network (LAN).

The controller 190 may further include a print mode determination unit 193 that determines a print mode of the print data transmitted through the interface unit 240.

The print mode determiner 193 determines whether the print data received through the interface unit 240 corresponds to a duplex print mode in which both sides of the print medium are to be printed and a single print mode in which only one side is printed. In addition, the print mode determination unit 193 further determines whether the print data corresponds to a color printing mode for driving a plurality of color developers to print with a color developer and a black and white printing mode for driving only a mono developer to print with a black developer. can do.

In the one-side printing mode, the control unit 190 controls the first drive source 183 so that the discharge roller 163 is rotated forward (F) to discharge the print medium to the outside. In addition, in the case of the black-and-white printing mode, the control unit 190 may include the second developing bodies 131Y, 131M, 131C, 133Y, 133M, Since it is not necessary to drive 133C, the third drive source 187 can be turned off. Accordingly, by controlling only one third driving source 187, not only the operation of the entire color developing devices 130Y, 130M, and 130C can be controlled, but also the developer is suppressed by suppressing unnecessary operations of the color developing devices 130Y, 130M, and 130C. It can reduce your stress. In addition, unnecessary power consumption can be reduced, and driving noise can be reduced.

Meanwhile, in the duplex printing mode, the control unit 190 contacts the first lever protrusion 171a while the print medium printed on one side along the one side printing path SP passes through the fixing unit 150 and thus the double side printing detecting unit 170. It is sensed that 1-side printing is completed by). The control unit 190, the printing medium printed on one side completely passes through the fixing unit 150, until the holding point of the rear end of the printing medium is held between the discharge roller 163 and the idle rollers (165, 167), discharge roller ( 163 controls the first drive source 183 to forward rotation (F). That is, the rotation shaft of the first drive source 183 is rotated forward.

The gripping point may be estimated in consideration of the detection signal of the duplex printing detector 170 and the transfer speed of the print medium.

In more detail, when the light receiving start point at which the light receiving unit 177b starts receiving light at the light sensor 177 of the duplex printing detecting unit 170, the leading end of the printed medium is placed on the first lever protrusion 171a. It is time to hit and start passing through the fixing unit 150. In addition, the light-receiving point at which the light receiving unit 177b does not receive light again passes through the fixing unit 150 and exactly the double-sided printing detecting unit 170. Therefore, the point of time elapsed by a predetermined time in consideration of the transfer speed of the print medium from the point of non-receipt of light can be estimated as the holding point. If necessary, the light reception time may be the gripping point.

Then, the controller 190 controls the first drive source 183 so that the discharge roller 163 reversely rotates from the gripping point. That is, from the gripping point, the rotational axis rotation direction of the first driving source 183 is reversed from the previous one. Accordingly, the one-side printed print medium moves along the duplex guide 118 in a direction opposite to the movement direction up to now, which has been moved along the one-side printing path SP.

On the other hand, as the rotating shaft of the first driving source 183 reversely rotates, the first rotating body (developing roller 133K except for the photosensitive member 135K), which is accommodated in the mono developing unit 130K by the intermittent portions 205 and 213, is supplied. Power of the first driving source 183 is cut off by the roller 131K, the stirrer (not shown), and the fixing unit 150. Accordingly, since the mono developer 130K and the fixing unit 150 are not driven while the print medium is traveling along the double-sided printing path DP, the stress of the developer in the mono developer 130K may be reduced. In addition, the driving load applied to the first driving source 183 can be reduced. In addition, it is possible to drive both the fixing unit 150, the mono developer 130K and the discharge roller 163 with one first driving source 183, thereby simplifying the power structure and reducing material costs.

When one side of the printed media moves along the double-sided printing path DP by reverse rotation of the discharge roller 163, the front end of the printed media again contacts the second lever protrusion 172a of the double-sided printing detecting unit 170. From the point of contact, the light receiving unit 177b starts receiving the light of the light emitting unit 177a again.

Then, the light receiving unit 177b does not receive the light from the point of release of contact at which the rear end of the print medium is released from the second lever protrusion 172a. Accordingly, it can be seen from the detection result of the double-sided printing detecting unit 170 that the print medium completely exits from the discharge unit 160 and proceeds along the duplex guide 118.

Therefore, the control unit 190 is all within the time range from the release of the contact after the discharge roller 163 reversely rotated before the print medium passes between the mono developer 130K and the transfer roller 140 again. Alternatively, the first driving source 183 may be stopped for some time. This is because it is not necessary to drive the fixing unit 150, the mono developer 130K and the discharge roller 163 within the time range.

If necessary, the controller 190 grips the regenerative roller 114 from the time when the contact is released, precisely when the print medium moving along the double-sided printing path DP is released from the discharge roller 163. The first drive source 183 may be controlled such that the rotation axis of the first drive source 183 rotates forward at an arbitrary time within a time range up to the time point at which it starts to become. In some cases, the control unit 190 forwardly rotates the first driving source 183 just after the one-side printed print medium passes through the reg roller 114 and just before passing between the mono developer 130K and the transfer roller 140. You can also

On the other hand, the control unit 190 may stop the third drive source 187 because the discharge roller 163 does not need to drive the color developing devices (130Y, 130M, 130C) while the reverse rotation. In addition, when the second drive source 185 is to drive only all the photosensitive member (135Y, 135M, 135C, 135K) and the print medium transfer unit 120, the control unit 190 may also stop the second drive source (185). have. Accordingly, the operation of the entire developing apparatus 130K, 130Y, 130M, 130C including the mono string 130K is stopped while the discharge roller 163 is rotating in reverse, so that the phenomenon inside the developing apparatus 130Y, 130M, 130C, 130K is maintained. Not only can I reduce my stress, but I can also reduce power consumption.

In addition, the control unit 190 is in the time range from the time when the printed media on one side completely exits the fixing unit 150, the print media moves along the duplex guide 118 and immediately before being bitten by the regulating roller 114 again. The third driving source 187 may be stopped for all or part of the time, that is, while the print medium is in progress along the double-sided printing path DP. This is because it is not necessary to drive the color developing devices 130Y, 130M, and 130K. In addition, when the second drive source 185 is to drive only all the photosensitive member (135Y, 135M, 135C, 135K) and the print medium transfer unit 120, the control unit 190 may also stop the second drive source (185). have.

Meanwhile, in the duplex printing mode, the print mode determination unit 193 may determine which of the monochrome print mode and the color print mode corresponds to each printing surface of the print medium. As a result of the determination, when one surface of both sides of the print medium is a black and white printing mode, the operation of the third driving source 187 may be stopped while printing the corresponding surface.

For example, when one side of the printing medium is in the color printing mode while the other side is in the black and white printing mode, the printing medium on which one side is printed is moved along the double-sided printing path DP by the reverse rotation of the discharge roller 163. The third driving source 183 may be continuously stopped from the time when the rear end of the printing medium is separated from the discharge roller 163 until the other surface of the printing medium is printed and discharged to the outside. Accordingly, the developer stress and power consumption can be reduced by dividing the black and white print mode and the color print mode by stopping the third driving source 183 in the black and white print mode.

Meanwhile, when the print data received through the interface unit 240 corresponds to the black and white print mode, the control unit 190 determines that the third drive source 187 is in the stopped state when the print mode determination unit 193 determines. The third driving source 187 may be controlled. This is because black and white printing can be performed by driving only the first drive source 183 and the second drive source 185.

Although the present invention has been described with reference to the illustrated embodiments, it is merely exemplary, and those skilled in the art will understand that various modifications and variations can be made therefrom. Accordingly, the scope of the invention should be defined by the appended claims and their equivalents.

The image forming apparatus according to the present invention has the following effects.

First, the power transmission structure can be simplified by reducing the number of driving sources.

Second, driving noise, material cost and power consumption can be reduced by reducing the number of driving sources.

Third, since only the color developing device is driven by a separate third driving source, it is not necessary to drive the third driving source when printing in black and white, thereby reducing the stress of the color developer.

Fourth, by operating the fixing unit, the mono developer, and the discharge roller as one first driving source, the first driving source can be stopped while the print media leaves the discharge roller and transported to the duplex printing path, thereby reducing the stress of the black and white developer. Can be.

Fifth, it is possible to implement a compact image forming apparatus by simplifying the driving structure.

Claims (23)

In the image forming apparatus, A developing unit for forming an image with a developer on one surface of a printing medium conveyed along the one side printing path; A fixing unit for fixing the developer to the print medium; A discharge roller for discharging the print medium passing through the fixing unit to the outside; And a first driving source for driving all of the developing device, the fixing unit, and the discharge roller. The method of claim 1, And a developer power control unit for selectively transmitting power of the first driving source to the developing unit. The method of claim 1, And a fuser power intermittent for selectively transmitting power of the first driving source to the fuser. The method of claim 1, The developing device is provided in plural to store the developer of different colors therein; And each developing unit includes a photosensitive member, a developing roller for developing the photosensitive member with a developer, and an agitator for stirring the developer. The method of claim 4, wherein The developing unit includes a mono developing unit installed closest to the fixing unit among the developing units and storing a developer of a black color, And the first driving source drives the developing roller and the stirrer of the mono developer. The method of claim 4, wherein And a second driving source for rotationally driving all of the photoconductors of each of the developing devices. The method of claim 6, A plurality of transfer rollers arranged side by side on each photosensitive member with a print medium in between; And a print medium transfer unit which transfers the print medium between the photosensitive member and the transfer roller and is driven by the second driving source. The method of claim 6, The developing device includes a color developing device for storing a developer of a colored color, And a third driving source for driving the developing roller and the stirrer of the color developing device. The method according to any one of claims 6 to 8, And a duplex guide for guiding the print medium from the discharge roller to the developing unit so that the other side of the print medium can be printed. And the discharge roller is provided to be capable of forward and reverse rotation to move the print medium to the duplex guide. The method of claim 9, And a duplex printing detector for sensing whether the print medium moves to the duplex guide. The method of claim 10, And the duplex printing detector detects whether the print medium passes through the fixing unit. The method of claim 11, The duplex printing detection unit, A first lever interposed between the fixing unit and the discharge roller and rotating in contact with a printing medium passing through the fixing unit; A second lever which is interlocked by the first lever and rotates in contact with the print medium which is driven by the reverse rotation of the discharge roller; And a sensor for sensing a position of at least one of the first lever and the second lever. The method of claim 10, And a control unit for controlling the first driving source so that the discharge roller rotates forward and backward according to a detection result of the duplex printing detection unit in the duplex printing mode. The method of claim 9, A pair of register rollers disposed in front of the developing device with respect to the one-side printing path and driven by the second driving source; The second drive source and the second drive source and the third drive source such that at least one of the second drive source and the third drive source stops from the time when the print medium has passed through the fixing unit and immediately before the print medium is caught between the register rollers; And a controller for controlling at least one of the third driving sources. The method of claim 9, Control unit for controlling at least one of the second drive source and the third drive source so that at least one of the second drive source and the third drive source is stationary while the discharge roller is rotated in reverse when there is a duplex print request. Image forming apparatus further comprises. The method of claim 8, In the duplex printing mode, the image forming apparatus further comprises a control unit for determining whether the printing data on the other side of the one-side printed print medium corresponding to the monochrome printing mode. The method of claim 16, When the control unit is in the black and white printing mode, the third driving source is stopped from the time when one surface of the printing medium passes through the fixing unit and the one side printing is completed, and the other surface of the printing medium is printed and discharged to the outside. And a third driving source to control the third driving source. The method of claim 9, And a control unit which determines whether the print data corresponds to the black and white printing mode and controls the third driving source so that the third driving source is in a stopped state when the printing data corresponds to the black and white printing mode. In the image forming apparatus, A mono developer having a first photosensitive member, a developer storage portion storing a black developer, and a first rotating body which provides the black developer to the first photosensitive member as the black developer; A color developing device having a second photosensitive member, a developer storing portion storing a color developer, and a second rotating body providing the color developer to the second photosensitive member; A fixing unit for fixing the mono developer and the color developer to the print medium; A discharge roller for discharging the print medium passing through the fixing unit to the outside; A first driving source driving all of the first rotating body, the fixing unit, and the discharge roller; A second driving source for driving the first photosensitive member and the second photosensitive member; And a third driving source for driving the second rotating body. The method of claim 19, A media conveyance belt for orbiting the print media to convey the photosensitive member; A plurality of transfer rollers arranged side by side on the first and second photosensitive members with the medium transfer belt interposed therebetween to transfer the mono and color developer to a print medium conveyed by the medium transfer belt; And a drive roller which is driven by the second drive source and drives the medium transfer belt. The method of claim 19 or 20, The discharge roller is provided to be forward and reverse rotation, And a duplex guide for guiding the print medium from the discharge roller to the color developer. The method of claim 21, In the duplex printing mode, the image forming apparatus further comprises a control unit for controlling the first driving source so that the discharge roller is rotated in reverse to enter the print media passed through the fixing unit into the duplex guide. The method of claim 22, The control unit controls at least one of the second drive source and the third drive source so that at least one of the second drive source and the third drive source is in a stationary state while the discharge roller is rotated in reverse. Forming device.

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