JP4706322B2 - Development device - Google Patents

Description

The present invention relates to a developing device used in an image forming apparatus using electrophotography, and more particularly to a developing device including a cleaning mechanism on a sensor detection surface of a toner empty detection sensor.

  In an image forming apparatus that forms an image using toner, a developing device that replenishes toner on a photosensitive member or a transfer member has a toner empty detection function. Conventionally, toner remains attached in the vicinity of a detection surface. In spite of the fact that the toner in the developing device has already run out, there is a problem of erroneously detecting that the toner is still present. To this toner adhesion, a cleaning mechanism is added to remove the adhering toner in the vicinity of the detection surface. Countermeasures have been taken (see, for example, Patent Document 1).

  In a conventional cleaning mechanism, for example, a method in which the end of a coil-shaped member rotates with respect to the detection surface, the cleaning member is disposed so as to cover the detection surface. There is a problem in that the toner does not easily reach the detection surface, and the toner supply cannot be detected because the toner is not detected even though the toner is supplied.

  In particular, when the toner is replenished, the toner bottle is agitated (shake the bottle by hand) to generate a repulsive force due to the frictional charge between the toners, resulting in characteristics close to liquid and extremely easy to reach the detection surface. Is insufficient, the fluidity is poor and the tendency to hardly reach the detection surface is promoted. Further, since it is necessary to use a member obtained by bending one end portion of the coil spring in a straight line in the radial direction, there is a problem in that the cost of the components increases.

  In addition, when the cleaning member described as a toner density sensor covers the entire surface of the detection surface, a method of cleaning the entire surface of the detection surface with a single cleaning operation is diverted to toner empty detection (for example, Patent Documents). However, when the cleaning member is stopped on the detection surface when the toner is replenished, the contact area of the cleaning member with respect to the detection surface increases, and a region where the replenished toner does not contact the detection surface is generated. There has been a problem that toner replenishment may not be detected despite toner replenishment.

  Also, a flexible material such as polyester film or polyurethane rubber is recommended as the cleaning member, and it is placed in contact with the detection surface. There was a problem.

In consideration of the above fact, the present invention detects the presence or absence of toner in a housing using an empty detection sensor, and uses a magnetic one-component toner in a developing device having cleaning means on the sensor detection surface. Even when the cleaning member stops on the detection surface of the toner empty detection sensor at the time of toner replenishment, the replenished toner can be detected reliably and the reliability is high. An object of the present invention is to provide a developing device that does not cause erroneous detection.
Japanese Patent Laid-Open No. 06-202474 JP-A-11-202610

  In view of the above facts, an object of the present invention is to provide a developing device that is highly reliable and does not cause erroneous detection.

The developing device according to claim 1, further comprising: a sensor that detects a toner remaining amount in a housing; and a cleaning unit that cleans a toner detection surface of the sensor. A plurality of rod-shaped cleaning members provided substantially vertically, and provided radially from the rotating base, each of the cleaning members provided at the tip of a rotating arm having a different length is the rotation direction of the rotating arm. the divided cleaning in contact with the toner detection surface along, from when the cleaning member provided at the tip of one of said pivot arm to clean the toner detection surface, the tip of the next of said pivot arm The cleaning member is not in contact with the toner detection surface until the provided cleaning member cleans the toner detection surface .

In the invention with the above configuration, by arranging the rod-shaped cleaning member perpendicular to the sensor detection surface, the contact area of the cleaning member tip with the sensor detection surface is reduced when the tip of the cleaning member stops on the sensor detection surface. And it can be set as the shape of a cleaning member which can obtain the space near a contact part widely. Normally, a stirring member (agitator) for the purpose of stirring the toner in the housing rotates in the vicinity of the toner empty detection sensor, and the agitator rotates by attaching a cleaning member to this agitator and rotating it together. It is possible to stir the toner and clean the sensor detection surface at the same time. In addition, since there is sufficient space for toner to flow in the vicinity of the detection surface, the flow of toner to the detection surface is good when the toner is replenished. There is no fear of obstructing. In addition, the rod-shaped cleaning member is divided into several rotation circles, and multiple radii from the rotation center of the cleaning operation are arranged in a stepwise difference setting (rotation arm length), and the detection surface is set according to the set radius. By dividing and cleaning the area, it is possible to clean almost the entire sensor detection surface. When the rod-shaped cleaning member is arranged vertically, the cleaning area for one rotation operation with respect to the sensor detection surface is reduced, but this can be compensated by the above configuration.

According to a second aspect of the present invention , there is provided the developing device including the six rotating arms having different lengths .

In the invention of the above configuration, the shortest member setting radius is the shortest dimension of the sensor detection surface from the rotation center, the longest member setting radius is the longest dimension of the sensor detection surface from the rotation center, and the remaining member radius is [R (n) By setting in stages according to = (n-1) * (longest dimension-shortest dimension) / (number of divisions-1) + shortest dimension], it is possible to clean almost the entire detection surface. Usually, the size of the sensor detection surface is often about φ10 mm, and the number of divisions is preferably about 6 divisions every 60 °. This is advantageous in that the distance between the adjacent cleaning members is reduced, and a space near the contact portion with the detection surface is obtained to ensure toner fluidity.

  The developing device according to claim 3 is characterized in that the tip of the cleaning member has a shape in which a cross-sectional area decreases as the tip approaches the tip.

  In the invention of the above configuration, the contact area of the cleaning member with respect to the sensor detection surface is reduced when the cleaning member stops in the sensor detection surface by forming the tip of the rod-shaped cleaning member into a shape having a small contact area such as a sphere or a cone. Can be reduced. The adverse effect of reducing the contact area can be compensated by arranging a plurality of cleaning members as described above.

  Since the present invention has the above-described configuration, it is possible to provide a developing device that is highly reliable and does not cause erroneous detection.

<Whole device>
FIG. 1 shows an image forming apparatus according to a first embodiment of the present invention.

As shown in FIG. 1, the image forming apparatus 10 of the present invention includes a photosensitive drum 12, a charging device 14 that forms an initial charge, an exposure device 16 that forms an electrostatic latent image on the photosensitive drum 12, and an electrostatic latent image. A developing device 18 that forms a toner image corresponding to the electrostatic latent image by flying and adsorbing toner on the image; a transfer / peeling device 20 that peels the paper P after transferring the toner image on the photosensitive drum 12 onto the paper P; The fixing unit 19 fixes the toner image on the paper P, and the cleaning device 22 removes the residual toner on the photosensitive drum 12 after the transfer.
<Developing device>
2 and 3 show a developing device according to the first embodiment of the present invention.

  As shown in FIG. 2, the developing device 18 includes a housing 26 that is filled with a toner 24 that is a magnetic one-component toner, a developing roll 28 that flies and attracts (= develops) the toner 24 onto the photosensitive drum 12, A charging blade 30 that frictionally charges the toner 24 on the developing roll 28, an agitator 32 that is a toner stirring member that supplies the toner 24 inside the housing 26 to the developing roll 28 while stirring, and a magnetic sensor 34 that detects the remaining amount of toner 24. The cleaning member 38 cleans the detection surface 36 of the magnetic sensor 34.

  As shown in FIG. 3, the agitator 32 is driven to rotate at 10.3 rpm in synchronization with the developing roll 28 via a gear (not shown). When the toner 24 in the housing 26 is consumed, the toner 24 is supplied from the upper part of the developing device 18 from the toner cartridge 25 shown in FIG.

  A magnetic sensor 34 is provided on the side plate 27 that forms one wall surface of the housing 26 of the developing device 18 to detect the magnetic powder of the toner 24 and determine the presence or absence of the toner 24. When there is sufficient toner 24 in the housing 26, the magnetic powder of the toner 24 is detected and judged as “toner present”. However, when the level of the toner 24 decreases, the magnetic powder cannot be detected and it is judged as “no toner”. .

  The detection surface 36 of the magnetic sensor 34 has a size of φ10 mm centered about 14.5 mm above the bottom surface of the housing 26, and is arranged on the same plane as the wall surface of the side plate 27.

The cleaning member 38 for cleaning the detection surface 36 of the magnetic sensor 34 is formed of a polyacetal resin having excellent slidability as a material, and is provided so as to be fitted into one end of the agitator 32 on the magnetic sensor 34 arrangement side.
<Cleaning member>
4 and 5 show a cleaning member of the developing device according to the first embodiment of the present invention.

  As shown in FIGS. 4 and 5, the cleaning member 38 has a cylindrical base portion 42 that rotates mechanically in synchronization with the agitator 32, and six cleaning members 38 at an angle of 60 ° from the base portion 42 to the rotation center. Radially arranged cross section: φ4 mm, length: 16.4 mm rod-shaped arm portion 40, the tip of arm portion 40 is provided perpendicular to detection surface 36, and tip 44 </ b> A is substantially in contact with detection surface 36. It is comprised from the wiper part 44 used as the position to perform.

In this embodiment, as shown in FIG. 4, six rod-like arm portions 40 having a cross section of φ4 mm and a length of 16.4 mm are arranged radially every sixty degrees perpendicular to the detection surface 36 and 60 ° with respect to the rotation center. ing. The shortest dimension from the rotation center of the agitator 32 to the detection surface 36 of the magnetic sensor 34 is set to 16.4 mm, and the longest dimension is set to 26.4 mm. The rotation radius of the six cleaning members is [R (n) = ( n-1) * (longest dimension-shortest dimension) / (number of divisions-1) + shortest dimension] was set stepwise as follows. Ie
No.1 (40-1) member radius R1: 16.4mm [R1 = (1-1) * (26.4-16.4) / (6-1) +16.4 = shortest dimension]
No.2 (40-2) member radius R2: 18.4mm [R2 = (2-1) * (26.4-16.4) / (6-1) +16.4]
No. 3 (40-3) member radius R3: 20.4mm [R3 = (3-1) * (26.4-16.4) / (6-1) +16.4]
No.4 (40-4) member radius R4: 22.4mm [R4 = (4-1) * (26.4-16.4) / (6-1) +16.4]
No.5 (40-5) member radius R5: 24.4mm [R5 = (5-1) * (26.4-16.4) / (6-1) +16.4]
No.6 (40-6) member radius R6: 26.4mm [R6 = (6-1) * (26.4-16.4) / (6-1) +16.4 = longest dimension)
With the above set dimensions, as the agitator 32 rotates, the detection surface 36 with a diameter of 10 mm is cleaned while being shifted by a difference of 2 mm by dividing the cleaning member 6 with a cross section of φ4 mm, so that almost the entire detection surface 36 can be cleaned. Become.

  The dimension setting of the cleaning member 38 is an example, and the number of divisions and the member radius should be set and changed in accordance with the toner detection characteristics of the magnetic sensor 34. Further, since the tip 44A of the wiper portion 44 of the cleaning member 38 is formed in a spherical shape with respect to the cross-sectional dimension: φ4 mm, the tip 44A is in contact with the detection surface 36 when the cleaning member 38 stops. The contact of 44A to the detection surface 36 can be substantially a point contact shape and the contact area can be minimized, and even if the cleaning member 38 stops in contact with the detection surface 36 of the magnetic sensor 34 during toner replenishment. The detection of replenishing toner is not hindered.

In addition, since the adjacent arm portions 40 are arranged at an interval of 60 °, a sufficient space for the toner to flow in the vicinity of the detection surface 36 is ensured. The flow is good, and the toner does not come into contact with the detection surface 36 at the time of toner replenishment, and there is no possibility of hindering detection of toner replenishment. The shape of the tip 44A is not limited to a spherical shape, and an alternative shape such as a conical shape that reduces the contact area can be applied.
<Toner supply position>
FIG. 6 shows a toner replenishment position of the developing device according to the first embodiment of the present invention.

  As described above, when the toner 24 in the housing 26 is consumed and “no toner” is detected by the magnetic sensor 34, the toner 24 is supplied from the toner cartridge 25 shown in FIG.

  At this time, in the developing device 18 according to the present embodiment, the toner cartridge 25 is set at a position closer to the magnetic sensor 34 than the center of the width direction (arrow x in the drawing) of the paper P which is the longitudinal direction as shown in FIG. Replenish.

  FIG. 7 shows the toner replenishment position and toner distribution of the developing device according to the first embodiment of the present invention.

  As shown in FIG. 7A, when the toner cartridge 25 is set at the center position in the width direction (arrow x in the figure) of the paper P, particularly when the bottle shaking (stirring) before setting is insufficient, the toner 24 Therefore, the toner cartridge 25 is biased to a high mountain shape immediately below the set position.

  At this time, if the toner 24 does not reach the detection position 35 where the magnetic sensor 34 detects “no toner”, the toner 24 is replenished correctly (the agitator 32 rotates to smooth the toner 24). May be detected without toner).

  FIG. 8 shows the toner replenishment height / toner replenishment amount and toner distribution of the developing device according to the first embodiment of the present invention.

  As shown in FIG. 8B, the mounting position of the toner cartridge 25 is 35 mm higher than the standard (120 mm) (= the toner 24 is dropped from a high place) or the replenishment amount of the toner 24 is increased. It is difficult to solve the problem. In particular, increasing the height of the toner cartridge 25 has an adverse effect such as an increase in the size of the entire apparatus. Even if the replenishment amount of the toner 24 is increased, the height just below the set position of the toner cartridge 25 becomes a higher mountain shape. In the vicinity of the side plate 27 provided with the magnetic sensor 34 (horizontal axis = position in the width direction of the developing device 18), the height of the toner 24 when the fluidity is low cannot be earned.

  Therefore, in this embodiment, as shown in FIG. 7B, the toner cartridge 25 is set at a position closer to the magnetic sensor 34 than the center of the width direction (arrow x in the figure) of the paper P, which is the longitudinal direction, and the toner 24 is replenished. . Specifically, the mounting position 23 of the toner cartridge 25 is changed to 23 'close to the magnetic sensor 34. In this embodiment, when the toner replenishing port of φ48.4 mm is provided in the 936 mm wide housing 26, the detection position 35 is cleared by moving the side plate 27 on the side where the magnetic sensor 34 is provided to an offset position of 90 mm. I was able to.

  As a result, as shown in FIG. 7B, the distribution of the toner 24 (in the longitudinal direction) is shifted to the magnetic sensor 34 side, so that the toner 24 does not reach the detection position 35 after the toner 24 is replenished. Even though the toner is replenished, it is possible to prevent a situation where the toner is erroneously detected.

  Since the present invention is configured as described above, even when the tip 44A of the wiper portion 44 stops on the detection surface 36 of the magnetic sensor 34 (toner empty detection sensor) during toner replenishment, the contact area is small, so the replenished toner Therefore, it is possible to reliably detect toner replenishment. Further, the divided cleaning by the plurality of wiper portions 44 can compensate for the small contact area of the tip 44A per wiper portion 44.

  Since the toner 24 adhering to the vicinity of the detection surface 36 of the magnetic sensor 34 can be surely removed by the divided cleaning by the plurality of wiper portions 44, the toner 24 is removed even though the toner 24 in the developing device 18 has already disappeared. It can solve the problem of false detection when it still remains.

  Further, it is not necessary to apply a flexible material such as polyester film or polyurethane rubber to the cleaning member 38, and the problem that the cleaning effect is deteriorated due to deterioration with time such as sag can be solved. Furthermore, since the cleaning member 38 can be applied with a relatively inexpensive (hard) resin material molded product for the above reason, it is possible to provide a low-cost apparatus.

  In the above embodiment, the developing device using the magnetic one-component toner has been described as an example. However, since the configuration includes the magnetic sensor 34 and the rotating cleaning member 38, toner density detection using a toner / carrier two-component developer. It can also be applied to sensors.

  Further, in the above-described embodiment, it is assumed that the magnetic sensor 34 (permeability sensor: detecting the magnetic powder contained in the toner to determine the presence or absence of toner) is used as the toner empty detection sensor. Although means for cleaning by contacting the cleaning member 38 is described, a vibration sensor (an oscillation body is built in the sensor and the vibration level is changed by contact of the toner 24 with the detection surface 36 as a toner empty detection sensor. This may be used to detect the presence of toner 24).

  When a vibration sensor is used as the sky detection sensor, placing the cleaning member 38 in contact with the detection surface 36 affects the vibration level of the sensor and causes erroneous detection. In this case, the influence of the cleaning member 38 on the vibration level of the sensor can be avoided by disposing the tip 44A of the cleaning member 38 about 0.5 mm away from the detection surface 36. Even when the tip 44A does not contact the detection surface 36, since the tip 44A is not a surface shape but a small area such as a sphere or a cone, the toner 24 is not pressed into the detection surface 36 and pressed and hardened. A sufficient cleaning effect is obtained.

It is a figure which shows the image recording device which concerns on the 1st form of this invention. It is a figure which shows the developing device which concerns on the 1st form of this invention. It is a figure which shows the developing device which concerns on the 1st form of this invention. It is a figure which shows the cleaning member of the developing device which concerns on the 1st form of this invention. It is a figure which shows the cleaning member of the developing device which concerns on the 1st form of this invention. It is a figure which shows the developing device which concerns on the 1st form of this invention. It is a figure which shows the developing device which concerns on the 1st form of this invention. It is a figure which shows the relationship of the toner fall position of the conventional developing device, a toner amount, and a toner height.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image recording device 12 Photosensitive drum 18 Developing device 25 Toner cartridge 32 Agitator 34 Magnetic sensor 35 Detection position 36 Detection surface 38 Cleaning member 40 Base part 42 Arm part 44 Wiper part 44A Tip

Claims (3)

In a developing device having a sensor for detecting a toner remaining amount in a housing and a cleaning unit for cleaning a toner detection surface of the sensor,
It said cleaning means comprises a cleaning rod-shaped member provided more substantially perpendicular to the toner detection surface,
The cleaning member, which is provided radially from the rotating base and is provided at the tip of the rotating arm having a different length , contacts the toner detection surface along the rotating direction of the rotating arm and performs divided cleaning. ,
Until the cleaning member provided at the tip of one rotating arm cleans the toner detection surface until the cleaning member provided at the tip of the next rotating arm cleans the toner detection surface The developing device is characterized in that there is a time during which the cleaning member does not contact the toner detection surface . The developing apparatus according to claim 1, comprising six rotating arms having different lengths . 3. The developing device according to claim 1, wherein the tip of the cleaning member has a shape in which a cross-sectional area decreases as the tip approaches the tip. 4.

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