JPH0545735U - Image forming device - Google Patents

Abstract

(57) [Summary] [Object] To provide an image forming apparatus capable of detecting the remaining amount of a developer with an inexpensive and simple configuration without using an expensive sensor or a complicated stirring mechanism. [Structure] In a developing tank 13 of a developing device 12, a conductive moving member 18 is provided which is placed on the upper surface of a developer T and descends as the developer T decreases. The moving member 18 comes into contact with the developing roll 14 when the remaining amount of the developer T reaches a predetermined amount which causes defective development when the amount of the developer T further decreases.
On the apparatus main body side, a contact 21 that contacts the conductive lid 19 of the developing device 12 and a detection circuit 22 connected to the contact 21 are provided. When the developer T reaches the predetermined amount and the moving member 18 contacts the developing roll 14, the developing roll 14,
The conductive path is formed between the bias power supply 17 and the detection circuit 22 via the moving member 18, the elastic member 20, the lid 19 and the contact 21, so that the remaining amount is detected.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as various printers, copiers, and facsimiles adopting an electrophotographic method, and more particularly, to improvement of a remaining amount detecting means of a developer in the developing means.

[0002]

[Prior Art]

 Generally, in the image forming apparatus, as shown in FIG. 4, there is provided a developing device 2 as a developing means for developing the electrostatic latent image formed on the surface of the photosensitive drum 1 with a developer. The developing device 2 includes a developing tank 3 containing a developer, and a developing roll 4 as a roll member to which a predetermined voltage is applied, which carries and conveys the developer in the developing tank 3 to the surface of the photosensitive drum 1. Is equipped with. Further, when the remaining amount of the developer in the developing device 2 decreases below a predetermined amount, defective development occurs. Therefore, various sensors 5 as a developer remaining amount detecting means are usually placed at predetermined positions in the developing device 2. It is provided. Examples of such a sensor 5 include, for example, a piezoelectric element that detects the fluidity of the developer to detect the presence or absence of the developer, and whether or not the developer blocks the optical axis formed in the developing tank 2. A photosensor that detects the presence or absence of the developer based on the above, or a coil that detects the presence or absence of the developer by detecting the change in inductance due to the flow of the magnetic developer is used. Further, in the case where such a sensor 5 is used, in order to prevent the developer in the developing tank 3 from blocking on the surface of the sensor 5 or in the vicinity thereof to prevent normal detection of the remaining amount, It was necessary to provide a stirring member such as a stirring rod 6 in order to stir the developer described in (4) above so as to always have appropriate fluidity.

[0003]

[Problems of the prior art]

 Conventionally, as described above, the sensor 5 such as the piezoelectric element, the photo sensor, and the coil is provided as the developer remaining amount detecting means in the developing device 2. However, such a sensor 5 is expensive, The ratio of the cost occupied by the sensor 5 to the entire container 2 is extremely high. Moreover, it is necessary to provide a stirring member such as the stirring rod 6 as described above, and the drive mechanism therefor is very complicated.

[0004]

[The purpose of the device]

 In view of the above conventional problems, the present invention aims to provide an image forming apparatus capable of detecting the remaining amount of the developer with an inexpensive and simple configuration without using an expensive sensor or a complicated stirring mechanism. And

[0005]

[Key points of the device]

 In order to achieve the above-mentioned object, the present invention provides a developing means including a developing tank containing a developer and a roll member for carrying and carrying the developer in the developing tank, to which a predetermined voltage is applied, and the developing tank. An image forming apparatus having a remaining amount detecting means for detecting that the remaining amount of the developer in the developing tank reaches a predetermined amount, the remaining amount detecting means is placed on the upper surface of the developer in the developing tank. A moving member, which is at least partially conductive and is arranged to descend as the developer decreases, and a contact between the moving member and the roll member are electrically detected based on the application of the predetermined voltage. And a detection circuit that operates.

[0006]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a structure of a remaining amount detecting means of the developer in the developing device in the image forming apparatus of the first embodiment of the present invention. FIG. A cross-sectional view of a state in which the amount of the developer is sufficiently larger than the fixed amount is seen from the side surface, (b) is a cross-sectional view of the state in which the remaining amount of the developer reaches the predetermined amount, seen from the side surface side, and (c) is It is sectional drawing at the time of seeing the state of said (a) from the front side.

This embodiment is applied to an image forming apparatus in which a developing device 12 as a developing means develops an electrostatic latent image on the surface of the photosensitive drum 11 with a non-magnetic one-component developer T. The developing device 12 includes a developing tank 13 containing a developer T, an image roll 14 made of, for example, a conductive rubber roll, which is a roll member that carries and conveys the developer T on the surface of the photosensitive drum 11. A supply roll 15 that is a roll member that is arranged below the developing roll 14 and carries and conveys the developer T in the developing tank 13 to the surface of the developing roll 14, and an unnecessary amount of the developer is scraped off from the surface of the developing roll 14 for development. A blade 16 for forming a thin layer of developer is provided on the surface of the roll 14. A predetermined bias voltage is applied to the developing roll 14 by a bias power source 17.

Further, in the developing tank 13, a conductive moving member 18 placed on the upper surface of the developer T and descending as the developer T decreases is provided. A conductive elastic member 20 such as a spring provided between the conductive lid 19 which can be opened and closed with respect to the opening of the upper part of the movable member 18 and the movable member 18 is urged downward, whereby the developer T can be appropriately moved. It is constantly pressed downwards with great force. The moving member 18 is configured to come into contact with the developing roll 14 as shown in FIG. 1B when the amount of the developer T reaches a predetermined amount that causes defective development when the remaining amount of the developer T decreases further. Has been done. Note that the elastic member 20 has an appropriate pressing force that does not press the developer T too strongly, and FIG. 1C shows an example in which the elastic members 20 are provided at three positions. As long as the upper surface of the developer T can be pressed uniformly, the number of positions may be one, two, or four or more. On the other hand, on the apparatus main body side of the image forming apparatus, there are provided a contact 21 that contacts the lid 19 when the developing device 12 is mounted on the main body of the apparatus, and a detection circuit 22 connected to this contact 21. The detection circuit 22 is a circuit for detecting contact between the moving member 18 and the developing roll 14 based on whether or not a predetermined bias voltage of the developing roll 14 is applied to the circuit itself.

In the above configuration, when the developer T in the developing tank 13 is sufficiently larger than the predetermined amount, as shown in FIGS. 1 (a) and 1 (c), the moving member 18 is more than the developing roll 14. Although the developer T is located above and is pressed, the moving member 18 also descends as the developer T gradually decreases, and when the developer T finally reaches the predetermined amount, as shown in FIG. The moving member 18 contacts the developing roll 14 as shown in FIG. By this contact, the predetermined voltage of the bias power supply 17 is applied to the detection circuit 22 through the developing roll 14, the moving member 18, the elastic member 20, the lid 19 and the contact 21, so that the detection circuit 22 makes the above contact. Upon detection, a signal indicating that the remaining amount of the developer T has reached a predetermined amount is sent to the control section in the apparatus main body. In this way, the remaining amount of the developer is detected. That is, the bias power source 17, the developing roll 14, the moving member 18, the elastic member 20, the lid 19, the contact 21 and the detection circuit 22 constitute a developer remaining amount detecting means.

According to the present embodiment, an expensive sensor (see FIG. 4) for detecting the remaining amount of the developer is not required in the developing device 12, and the bias power source is simply provided when the developer reaches a predetermined amount. Since only the conductive path is formed from 17 to the detection circuit 22, the remaining amount of the developer can be detected with an extremely simple and inexpensive structure.

Furthermore, since there is no conventional sensor in the developing device 12 as described above, there is no need to worry about the blocking of the developer on the sensor surface or in the vicinity thereof, and the moving member can be eliminated. Since 18 is placed on the upper surface of the developer T and the developer T is pressed downward by the urging force of the elastic member 20, the developer T is always uniformly filled in the developing tank 13, and therefore, as shown in FIG. No stirring member such as the stirring rod 6 or a complicated drive mechanism therefor is required at all.

Next, FIG. 2 is a sectional view showing the structure of the remaining amount detecting means of the developer in the developing device in the image forming apparatus of the second embodiment of the present invention. In this embodiment, the conductive supply roll 15 is arranged above the developing roll 14 and is applied to the supply roll 15 to which a predetermined voltage is applied by the bias power supply 23. In this case, when the developer T decreases and reaches the predetermined amount, the moving member 18 comes into contact with the supply roll 15, so that the predetermined voltage of the bias power source 23 causes the supply roll 15, the moving member 18, and the elastic member. It is provided to the detection circuit 22 via 20, the lid 19 and the contact 21. That is, in the present embodiment, the bias power supply 23, the supply roll 15, the moving member 18, the elastic member 20, the lid 19, the contact 21, and the detection circuit 22 described above constitute a developer remaining amount detecting means. According to this embodiment, the same effect as that of the first embodiment can be obtained.

Next, FIG. 3 is a sectional view showing the structure of the remaining amount detecting means of the developer in the developing device in the image forming apparatus of the third embodiment of the present invention. The present embodiment is a case where it is applied to the developing device 12 in which the supply roll 15 is not provided. In this case as well, the remaining amount detecting means can be configured similarly to the first embodiment shown in FIG. 1, that is, when the developer T decreases and reaches a predetermined amount, the moving member 18 develops. By contacting the roll 14, a predetermined voltage of the bias power source 17 is applied to the detection circuit 22 via the developing roll 14, the moving member 18, the elastic member 20, the lid 19 and the contact 21. Also in this embodiment, the same effect as that of the first embodiment can be obtained.

The entire surface of the moving member 18 does not need to be conductive, and if the moving member 18 has conductivity from the contact portion with the developing roll 14 and the supply roll 15 to the connecting portion with the elastic member 20. It is enough. The same applies to the lid 19, and it is sufficient that the lid 19 has conductivity from the connection portion with the elastic member 20 to the contact portion with the contact 21. In short, some kind of conduction path may be formed from the bias power supply 17 or 23 to the detection circuit 22 while the moving member 18 is in contact with the developing roll 14 or the supply roll 15, and the path is not limited to a specific one. Not done.

Further, in the above embodiment, the developer T is pushed downward by the pressing force of the elastic member 20, but the developer T is pushed by the weight of the moving member 18 and the developer T is reduced. The moving member 18 may be moved down with a small amount, and in such a case, a conductive member such as a lead wire may be used instead of the elastic member 20.

Further, in the embodiment shown in FIG. 2, it is not always necessary to provide the bias power source 23 on the supply roll 15, and at least a part of the supply roll 15 should be made conductive so that the bias force may be applied when the moving member 18 is contacted. The voltage of the power supply 17 may be sent to the moving member 18 side via the developing roll 14 and the supply roll 15.

In addition, in the above embodiments, only the case of the non-magnetic one-component developer has been shown, but the present invention can be applied to the case of other developers such as the magnetic one-component developer.

[0018]

[Effect of the device]

 According to the present invention, the remaining amount of the developer can be detected with a simple structure without the need for an expensive sensor, and a special stirring member for preventing the blocking of the developer and a complicated drive mechanism therefor are required. Therefore, an inexpensive image forming apparatus can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a remaining amount detecting means of a developer in a developing device in an image forming apparatus of a first embodiment of the present invention,
(A) is a cross-sectional view of a state in which the remaining amount of the developer in the developing device is sufficiently larger than a predetermined amount as viewed from the side, and (b) is a state in which the remaining amount of the developer reaches the predetermined amount. Is a sectional view when viewed from the side surface side, and (c) is a sectional view when the state of (a) above is viewed from the front surface side.

FIG. 2 is a sectional view showing a structure of a remaining amount detecting means of a developer in a developing device in an image forming apparatus according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a structure of a remaining amount detecting means of a developer in a developing device in an image forming apparatus of a third embodiment of the invention.

FIG. 4 is a cross-sectional view showing a structure of a remaining amount detecting means of a developer in a developing device in a conventional image forming apparatus.

[Explanation of symbols]

 12 developing device 13 developing tank 14 developing roll 15 supply roll 16 blade 17 bias power supply 18 moving member 19 lid 20 elastic member 21 contact 22 detection circuit 23 bias power supply

Claims (1)

[Scope of utility model registration request] 1. A developing means comprising a developing tank for containing a developer, and a roll member for carrying and carrying the developer in the developing tank, to which a predetermined voltage is applied, and a residual of the developer in the developing tank. In an image forming apparatus provided with a remaining amount detecting means for detecting that the amount has reached a predetermined amount, the remaining amount detecting means is placed on an upper surface of the developer in the developing tank and at least a part of which is conductive. A moving member arranged to move down as the developer decreases, and a detection circuit for electrically detecting the contact between the moving member and the roll member based on the application of the predetermined voltage. An image forming apparatus characterized by the following.