JP4994176B2 - Paper feeding device and image forming apparatus - Google Patents

Description

  The present invention relates to a paper feeding device of an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and an image forming apparatus equipped with the paper feeding device.

  In a sheet feeding device of an image forming apparatus including a first sheet cassette and a second sheet cassette disposed upstream of sheet feeding from the first sheet cassette, the sheet fed from the second sheet cassette is on the downstream side. If the first paper cassette is transported by a transport guide formed using a part of the shape of the first paper cassette located at the position of the first paper cassette, the first paper cassette is pulled out before transporting the paper from the second paper cassette. Since there was no conveyance guide, the paper could not pass and there was a risk of jamming.

  Therefore, in order to prevent such a jam from occurring, conventionally, for example, a method of preventing the first paper cassette from being pulled out by a lock mechanism using a solenoid (Patent Document 1) or the first paper cassette is used as a paper. A method of rotating a separate transport guide mechanism (auxiliary guide) and arranging the paper transport path of the auxiliary guide instead of the paper transport path of the first paper cassette (Patent Document 2) A method (Patent Document 3) is proposed in which the CPU stops the paper feeding operation from the second paper cassette when the detection mechanism detects that the first paper tray is detached.

However, the above-described conventional methods have a problem in that the number of parts such as a lock mechanism, a guide mechanism, and a detection mechanism increases in any case, resulting in an increase in cost.
Japanese Patent No. 2542064 JP-A-5-740 JP-A-11-240648

  Accordingly, the present invention solves the above-described conventional problems, reduces the cost by reducing the number of parts, and prevents jamming caused by removing the first paper cassette downstream of the paper feeding. An object of the present invention is to provide a sheet feeding device and an image forming apparatus that can perform the above operation.

In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a first paper cassette, a cassette detection slider that is displaced according to whether or not the first paper cassette is set, and paper feeding from the first paper cassette. A second sheet cassette disposed upstream of the sheet cassette, a sheet detection lever that is displaced according to the sheet stacking amount in the second sheet cassette, and one transmissive optical sensor. The cassette detection slider and the sheet detection In the paper feeding device that detects the displacement of the lever with the transmission optical sensor, the paper detection lever is arranged to switch the detection logic of the transmission optical sensor according to the presence or absence of paper in the second paper cassette, and the first paper When the cassette is pulled out, the cassette detection slider acts to displace the paper detection lever, and the transmissive optical sensor is moved. The detection logic is characterized by causing a transition to the same state as "no paper".

According to a second aspect of the present invention, there is provided a first paper cassette, a cassette detection slider that is displaced according to whether or not the first paper cassette is set, and a second paper disposed upstream of the first paper cassette in paper feeding. A paper cassette, a paper detection lever that is displaced according to the paper stacking amount in the second paper cassette, and a transmission optical sensor are provided, and the displacement of the cassette detection slider and the paper detection lever is determined by the transmission optical. In the paper feeding device that detects by the sensor, the paper detection lever includes first and second light shielding parts that shield the detection part of the transmission optical sensor on both sides of the concave part formed in the upper part thereof. In a state where there is no paper in the two paper cassette, the paper detection lever rotates by its own weight, and the first light shielding part shields the detection part of the transmission optical sensor, In the state where the detection logic of the sensor is changed to the “no paper” state and the first paper cassette is pulled out, the urging means for urging the cassette detection slider in the drawing direction of the first paper cassette, The slider is biased in the pull-out direction to act on the paper detection lever, and the lever is rotated in a direction opposite to the rotation, and the second light-shielding portion is used to detect the detection portion of the transmission optical sensor. The detection logic of the sensor is changed to the same state as the “no paper” state by shielding light .

According to a third aspect of the present invention, in the paper feeding device according to the first or second aspect, the second paper cassette is supported by an additional paper feeding unit separable from the image forming apparatus. According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising the paper feeding device according to any one of the first to third aspects.

The present invention is as described above. According to the first aspect of the present invention, the first sheet cassette, the cassette detection slider that is displaced according to whether the first sheet cassette is set, and the first sheet are provided. A second paper cassette disposed on the upstream side of paper feeding from the cassette; a paper detection lever that is displaced according to a paper stacking amount in the second paper cassette; and one transmission type optical sensor. In the paper feeding device that detects the displacement of the slider and the paper detection lever with the transmission optical sensor, the paper detection lever is arranged to switch the detection logic of the transmission optical sensor according to the presence or absence of paper in the second paper cassette, In the state where the first paper cassette is pulled out, the cassette detection slider acts to displace the paper detection lever, The detection logic of over-mold optical sensor because it is configured to transition to the same state as "no paper", without providing a sensor for detecting the set state of the first paper cassette, the first paper cassette is pulled out In this state, it is possible to prevent a problem that the sheet from the second sheet cassette is fed. Further, the number of parts relating to the conveyance of the sheet fed from the second sheet cassette can be reduced, and the product can be provided at a low cost. It is only necessary to provide one. Further, the number of parts can be reduced by switching the signal by the first paper cassette acting on the paper detection lever.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic view of a color laser printer using a general electrophotographic method. Cyan, magenta, yellow, and black photoconductor units 1a to 1d, a writing unit 2, an intermediate transfer unit 3, a first paper cassette 4, a secondary transfer unit 5, a fixing unit 6, a second paper cassette 7, and the like. Full-color printing is possible. The second paper cassette 7 is supported by an extension paper feeding unit (not shown) that is detachably disposed below the printer body. That is, the color laser printer as the image forming apparatus is placed on the upper surface of the additional paper feeding unit. A paper transport guide 8 for transporting paper fed from the second paper cassette 7 by the paper feed roller 9 is configured using a partial shape of the first paper cassette 4. In this configuration, the housing of the color laser printer and the additional paper feeding unit may be electrically connected by an automatic connector. In this way, the user's operation when installing the additional paper feeding unit can be facilitated.

[First Embodiment]
2 to 5 show a sheet feeding device according to the first embodiment, particularly a sheet detection mechanism and a cassette detection mechanism constituting the main part thereof. FIG. 2 shows a state in which no paper is set in the second paper cassette 7. In the figure, the paper detection lever 10 is rotatably supported by a pivot near the paper upper surface of the second paper cassette 7 and is urged counterclockwise by its own weight. The lower detection portion 10a of the paper detection lever 10 falls into a hole formed in the paper placement plate 14, and the upper light shielding portion 10b shields the detection portion of the transmission optical sensor 13 as a displacement detection sensor. The transmission optical sensor 13 outputs an electrical signal corresponding to the light shielding and transmission state of the detection unit 10a of the paper detection lever 10, and the state is transmitted to a control unit (not shown). Here, the transmission state is referred to as “paper present” and the light shielding state is referred to as “paper absence”, and the same applies to the following description.

  FIG. 3 shows a state in which sheets are set in the second sheet cassette 7. In this state, the detection unit 10a of the paper detection lever 10 contacts the upper surface of the paper and rotates clockwise, and the light shielding unit 10b does not shield the detection unit of the transmission optical sensor 13. On the other hand, the cassette detection lever 11 is rotatably supported by a pivot above the second paper cassette 7 and is urged clockwise by an urging means (not shown). In the state where the first paper cassette 4 is set at the operating position, the upper detection unit 11 a comes into contact with the protrusion 12 provided on the first paper cassette 4, and the lower light shielding unit 11 b is connected to the transmissive optical sensor 13. The detection unit is not shielded from light.

  FIG. 4 shows the corresponding positional relationship between the paper detection lever 10, the cassette detection lever 11, and the transmission optical sensor 13 in the state of FIG. Note that the positions of the paper detection lever 10, the cassette detection lever 11 and the transmission optical sensor 13 at this time do not have to be the same in the axial direction of the paper feed roller 9 as shown in the figure. As shown in FIG. The detection lever 10 is divided into a lower portion and an upper portion, and these portions are respectively fixed to both ends of a shaft provided in parallel with the axial direction of the paper feed roller 9, and the upper portion and the cassette detection lever 11 are axially moved from the lower portion. It may be arranged together with the transmissive optical sensor 13 at a position away from each other.

  FIG. 6 shows a state in which the first paper cassette 4 is pulled rightward as indicated by an arrow from the state of FIG. In this state, the cassette detection lever 11 is rotated clockwise by the biasing means described above, and the light shielding portion 11b shields the detection portion of the transmission optical sensor 13.

  According to the configuration as described above, when the first paper cassette 4 is pulled out, the transmission optical sensor 13 is always shielded by the light shielding portion 11b of the cassette detection lever 11 regardless of the presence or absence of paper in the second paper cassette 7. Become. For this reason, the state of “no paper” is transmitted to the control means, and the feeding of the paper S from the second paper cassette 7 is prohibited. Accordingly, it is possible to prevent a problem that the paper from the second paper cassette 7 is fed in a state where the first paper cassette 4 is pulled out without providing a sensor for detecting the set state of the first paper cassette 4. . Further, the number of parts related to the conveyance of the sheet fed from the second sheet cassette 7 can be reduced, and the product can be provided at a low cost.

[Second Embodiment]
7 to 9 show a sheet feeding device according to the second embodiment, in particular, a sheet detection mechanism and a cassette detection mechanism that constitute the main part thereof. FIG. 7 shows a state in which no paper is set in the second paper cassette 7. In the figure, the paper detection lever 10 is rotatably supported by a pivot near the upper surface of the paper in the second paper cassette 7, and is urged counterclockwise by its own weight. The lower detection portion 10 a of the paper detection lever 10 falls into a hole formed in the paper placement plate 14, and the upper light shielding portion 10 b shields the detection portion of the transmission optical sensor 13. The transmission optical sensor 13 outputs an electrical signal corresponding to the light shielding and transmission state of the detection unit 10a of the paper detection lever 10, and the state is transmitted to a control unit (not shown).

  FIG. 8 shows a state in which paper is set in the second paper cassette 7. In this state, the detection unit 10a of the paper detection lever 10 contacts the upper surface of the paper and rotates clockwise, and the light shielding units 10b and 10c do not shield the detection unit of the transmissive optical sensor 13. On the other hand, the cassette detection slider 15 is supported above the second paper cassette 7 so as to be movable in the left-right direction by a guide (not shown), and is urged rightward by an urging means 16 such as a spring. In the state where the first paper cassette 4 is set at the operating position, the upper detection unit 15a comes into contact with the protrusion 12 provided on the first paper cassette 4, and the link unit (light-shielding unit) 15b is connected to the paper detection lever 10. Is in a state of being separated from each other, that is, a state in which the detection unit of the transmission optical sensor 13 is not shielded from light.

  FIG. 9 shows a state in which the first paper cassette 4 is pulled rightward as indicated by an arrow from the state of FIG. In this state, the cassette detection slider 15 is moved rightward by the urging means 16, the link portion 15 b rotates the paper detection lever 10 in the clockwise direction, and the light shielding portion 10 c moves the detection portion of the transmission optical sensor 13. Shield from light. In this embodiment, a modified configuration as shown in FIG. 5 can be adopted.

  According to the above configuration, when the first paper cassette 4 is pulled out, the transmission optical sensor 13 is always shielded by the link portion 15b of the cassette detection slider 15 regardless of the presence or absence of paper in the second paper cassette 7. Become. For this reason, the state of “no paper” is transmitted to the control means, and the feeding of the paper S from the second paper cassette 7 is prohibited. Therefore, without providing a sensor for detecting the set state of the first paper cassette 4, it is possible to prevent a problem in which the paper S from the second paper cassette 7 is fed while the first paper cassette 4 is pulled out. it can. Further, the number of parts related to the conveyance of the sheet fed from the second sheet cassette 7 can be reduced, and the product can be provided at a low cost. Further, in this configuration, since only one part shields the transmission optical sensor 13 from light, a small and inexpensive sensor can be used.

  The configuration of the above embodiment is also effective when the second paper cassette 7 is provided as an additional paper feeding unit that can be separated from the printer body. In this case, the cassette detection lever 11, the cassette detection slider 15, the transmissive optical sensor 13, and the biasing means 16 in the two embodiments are not necessary when the additional sheet feeding unit is not used. By providing it on the additional paper feeding unit side, the cost of the printer main body can be reduced, and the product can be provided at a low cost.

[Third Embodiment]
FIGS. 10 to 11 show a sheet feeding device according to the third embodiment, particularly a sheet detection mechanism and a cassette detection mechanism constituting the main part thereof. FIG. 10 shows a state where the first paper cassette 4 is set in the printer main body. The transmissive optical sensor 17 is disposed so as to protrude from the upper surface of the second paper cassette 7 which is an additional paper feeding unit. A cassette detection rib 18 is integrally formed on the first paper cassette 4 to shield the detection part of the transmission optical sensor 17 from light. The transmissive optical sensor 17 outputs an electrical signal corresponding to the light shielding and transmissive state of the cassette detection rib 18, and the state is transmitted to a control means (not shown). Here, the transmission state is referred to as “no cassette”, and the light-shielding state is referred to as “with cassette”, and the same applies to the following description.

  FIG. 11 shows a state in which the first paper cassette 4 is pulled rightward as indicated by an arrow from the state of FIG. In this state, the cassette detection rib 18 is separated from the detection unit of the transmissive optical sensor 17, and “no cassette” is transmitted to the control means. In this embodiment, a modified configuration as shown in FIG. 5 can be adopted.

  According to the configuration as described above, when the first paper cassette 4 is pulled out, the transmissive optical sensor 17 is in a transmissive state without being shielded by the cassette detection rib 18. For this reason, the state of “no cassette” is transmitted to the control means described above, and the feeding of the paper S from the second paper cassette 7 is prohibited. Therefore, it is possible to prevent a problem that the sheet from the second sheet cassette 7 is fed in the state where the first sheet cassette 4 is pulled out. Further, since the sensor for detecting the first paper cassette 4 is provided in the additional paper feeding unit, the number of parts of the printer main body can be reduced and the product can be provided at low cost.

  Further, the signal from the transmissive optical sensor 13 and the signal from the transmissive optical sensor 17 can be converted into one paper feed permission signal through an AND circuit (not shown) and transmitted to the control means. FIG. 12 shows the inputs and outputs of the AND circuit. That is, as shown in the figure, “no paper” is detected in the second paper cassette 7 based on the signal from the transmissive optical sensor 13, and “no cassette” is detected in the first paper cassette 4 based on the signal from the transmissive optical sensor 17. At the time of detection, the feeding of the paper S is impossible, “no paper” is detected in the second paper cassette 7 by the signal from the transmissive optical sensor 13, and “first paper cassette 4” is detected by the signal from the transmissive optical sensor 17. When the “cassette present” is detected, the paper S cannot be fed, “the paper is present” is detected in the second paper cassette 7 by the signal from the transmission optical sensor 13, and the first paper is detected by the signal from the transmission optical sensor 17. When “no cassette” is detected in the cassette 4, the paper S cannot be fed, and “paper present” is detected in the second paper cassette 7 by the signal from the transmissive optical sensor 13. By the signal from the 17 "There cassette" in the first paper cassette 4 a feeding permission of only the sheet S at the time of detection.

  In this way, the two signals are converted into one signal, and the paper feeding permission / non-permission is transmitted to the control means by one signal. By reducing this input signal, the product can be made inexpensive. It becomes possible to provide. When the second paper cassette 7 is in the additional paper feeding unit, if the additional paper feeding unit is not attached to the printer main body, the first paper cassette 4 is removed from the second paper cassette 7 to the secondary transfer unit. This jam prevention prevents jamming of the paper that goes (the jam occurs when the transfer guide 8 is connected to the second paper cassette 7 so that there is no conveyance guide 8 provided in the first paper cassette 4 or when it is displaced). There is no need to detect the presence of the first paper cassette 4 for the purpose. In that sense, the fact that the detection means for detecting the presence or absence of the first paper cassette 4 is provided on the side of the additional paper feeding unit has an effect of lowering the cost than providing the detection means in the printer body.

  In the above embodiment, the paper detection lever 10 and the transmission optical sensor 13 constitute a paper detection means, and the cassette detection lever 11, the cassette detection slider 15 and the projection 12 constitute a signal switching means, and the transmission optical sensor 17. Although the cassette detecting means is constituted by the cassette detecting rib 18, each of these constituent members may be replaced with another member having the same effect. Further, the cassette detection lever 11 and the cassette detection slider 15 as cassette detection members are merely examples. In the above embodiment, the transmissive optical sensors 13 and 17 have been described as the displacement detection sensors. However, it goes without saying that the present invention is not necessarily limited to such transmissive optical sensors. Further, the shape of the paper detection lever 10, the cassette detection lever 11, the cassette detection slider 15, and the cassette detection rib 18 is only a preferable example, and other shapes and the like may be used. Of course.

Next, a characteristic effect of the invention described in claim 2 and the following claims will be described.
According to the second aspect of the present invention , the paper from the second paper cassette is fed in a state where the first paper cassette is pulled out without providing a sensor for detecting the set state of the first paper cassette. Can be prevented. Further, the number of parts relating to the conveyance of the sheet fed from the second sheet cassette can be reduced, and the product can be provided at a low cost. It is only necessary to provide one. Further, the number of parts can be reduced by switching the signal by the first paper cassette acting on the paper detection lever.

According to the invention described in claim 3 , the second sheet cassette can be an optional device that can be added to the main body of the image forming apparatus, and can be installed according to the needs of the user. According to the invention described in claim 4, it is possible to provide an image forming apparatus equipped with the sheet feeding device according to any one of claims 1 to 3. In addition, in the image forming apparatus, the number of parts of the image forming apparatus main body can be reduced, and the effect of the above-described invention can be achieved when an additional sheet feeding unit is installed.

It is the schematic of the color laser printer by a general electrophotographic system. FIG. 4 is an enlarged view showing a main part of the paper feeding device according to the first embodiment in a state where no paper is set in a second paper cassette. It is an enlarged view showing a state in which paper is set in the second paper cassette. FIG. 3 is an exploded perspective view of a portion showing a corresponding positional relationship among a sheet detection lever, a cassette detection lever, and a transmission optical sensor in the state of FIG. 2. It is a disassembled perspective view of the part which shows the modification same as the above. FIG. 4 is an enlarged view showing a state in which the first paper cassette is pulled rightward from the state of FIG. 3. FIG. 10 is an enlarged view showing a main part of a paper feeding device according to a second embodiment in a state where no paper is set in a second paper cassette. It is an enlarged view showing a state in which paper is set in the second paper cassette. FIG. 9 is an enlarged view showing a state in which the first paper cassette is pulled rightward from the state of FIG. 8. FIG. 10 is an enlarged view illustrating a main part of a paper feeding device according to a third embodiment in a state where a first paper cassette is set. It is an enlarged view which shows the state by which the 1st paper cassette same as the above was pulled out. It is a table | surface which shows the logic which converts the two signals from a sensor same as the above into one signal.

Explanation of symbols

4 First paper cassette 7 Second paper cassette 10 Paper detection lever 11 Cassette detection lever 12 Protrusions 13 and 17 Transmission type optical sensor (displacement detection sensor)
14 Paper loading plate 15 Cassette detection slider 16 Biasing means 18 Cassette detection rib

Claims (4)

A first sheet cassette; a cassette detection slider that is displaced according to whether the first sheet cassette is set; a second sheet cassette disposed upstream of the first sheet cassette; and the second sheet cassette. In a paper feeding device comprising a paper detection lever that is displaced according to the paper stacking amount in the paper and one transmission optical sensor, and detecting the displacement of the cassette detection slider and the paper detection lever by the transmission optical sensor.
When the paper detection lever is arranged to switch the detection logic of the transmissive optical sensor according to the presence or absence of paper in the second paper cassette, and the first paper cassette is pulled out, the cassette detection slider is used to detect the paper. A sheet feeding device which acts to displace a lever and causes the detection logic of the transmissive optical sensor to transition to the same state as “no paper” . A first sheet cassette; a cassette detection slider that is displaced according to whether the first sheet cassette is set; a second sheet cassette disposed upstream of the first sheet cassette; and the second sheet cassette. In a paper feeding device comprising a paper detection lever that is displaced according to the paper stacking amount in the paper and one transmission optical sensor, and detecting the displacement of the cassette detection slider and the paper detection lever by the transmission optical sensor.
The paper detection lever has first and second light shielding parts that shield the detection part of the transmissive optical sensor on both sides of a recess formed in the upper part thereof.
When there is no paper in the second paper cassette, the paper detection lever rotates by its own weight, and the first light-shielding part shields the detection part of the transmission optical sensor and detects the sensor. Transition the logic to the “no paper” state,
In a state where the first paper cassette is pulled out, the paper detection lever is urged in the pulling direction by the biasing means for biasing the cassette detection slider in the pulling direction of the first paper cassette. And the second light-shielding part shields the detection part of the transmissive optical sensor, and the detection logic of the sensor is set to “no paper”. The paper feeding device is changed to the same state as in FIG. 3. The paper feeding device according to claim 1 , wherein the second paper cassette is supported by an additional paper feeding unit that is separable from the image forming apparatus. An image forming apparatus comprising the paper feeding device according to claim 1 .

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