JP7837205B2 - Developing apparatus and image forming apparatus - Google Patents

Description

This invention relates to a developing apparatus with a filter, and an image forming apparatus using the same.

In image forming apparatuses, the developing unit has an opening opposite the photoreceptor drum, exposing the developing roller through this opening to develop the electrostatic latent image on the surface of the photoreceptor drum. However, if the internal pressure of the developing unit is high, air leaks from the gap between the opening and the developing roller, resulting in the release of excessive toner, preventing desired development, or causing toner to scatter outside the developing unit (inside the image forming apparatus). Therefore, exhaust ports (pressure relief holes) are provided in the housing of the developing unit to reduce the internal pressure and prevent toner scattering. Furthermore, in such developing units, filters are provided at the exhaust ports to prevent toner leakage (for example, Patent Document 1).

Japanese Patent Publication No. 2012-189787

In Patent Document 1, the filter installed in the exhaust port reduces its effectiveness in lowering the internal pressure of the developing unit when it becomes clogged with toner. Therefore, this filter is designed to be detachably attached to the developing unit, making replacement and maintenance easy. However, a detachable filter presents the problem of forgetting to install it. If the image forming apparatus is operated without the filter installed, a large amount of toner may leak from the exhaust port of the developing unit, potentially severely contaminating the inside of the image forming apparatus.

To prevent toner leakage due to a missing filter, a common method involves using detection devices such as sensors or switches to detect the filter's absence and preventing the image forming machine from operating if the filter is not installed. However, this method requires a detection device, which complicates the structure and leads to increased parts and higher costs in the image forming machine.

This invention was made in view of the above-mentioned problems, and aims to provide a developing apparatus and an image forming apparatus that can prevent toner leakage due to forgetting to install a filter with a simple structure.

To solve the above problems, a developing apparatus according to a first aspect of the present invention is used in an image forming apparatus and comprises an exhaust port for discharging air from inside the developing tank and a filter detachably provided to the exhaust port. The developing apparatus is characterized by having a movable member on the front end side when the developing apparatus is mounted on the image forming apparatus. This member is held in a first position when the filter is not mounted and moves from the first position to a second position during the mounting operation when the filter is mounted.

According to the above configuration, when a filter is not installed in the developing device, the movable member is held in the first position. When a filter is installed, the movable member moves from the first position to the second position. Therefore, a simple structure that utilizes the change in the position of the movable member (a structure that does not use a detection device to detect filter installation) allows the user to easily recognize if a filter has been forgotten.

Furthermore, in the above-described developing apparatus, the movable member can be configured to be held in the first position by gravity when the developing apparatus is mounted on the image forming apparatus and the filter is not installed.

According to the above configuration, an elastic member or the like is not required to hold the movable member in the first position when the filter is not attached, thus simplifying the structure of the developing apparatus.

Furthermore, in the above-described developing apparatus, the direction in which the filter is attached and detached is parallel to the rotation axis direction of the developing roller, and the filter can be configured to be attached and detached while the developing apparatus is mounted on the image forming apparatus.

According to the above configuration, the direction in which the filter is attached to and detached from the developing unit can be the same as the direction in which the developing unit is attached to and detached from the image forming apparatus (usually parallel to the rotation axis of the developing roller), allowing the filter to be attached and detached independently while the developing unit is mounted on the image forming apparatus.

Furthermore, in the above-described developing apparatus, the movable member is displaceable between the first and second positions by rotational movement and has a guide boss. The filter can be configured to have a guide groove that guides the guide boss during attachment and detachment to the developing apparatus, causing the movable member to rotate between the first and second positions.

According to the above configuration, the rotational movement of the movable member can be linked to the attachment and detachment of the filter with a simple structure.

Furthermore, in order to solve the above problems, a second aspect of the present invention is an image forming apparatus comprising a developing apparatus, wherein the developing apparatus has an exhaust port for discharging air from inside the developing tank, a filter detachably provided to the exhaust port, and a movable member on the front end side when the developing apparatus is mounted on the image forming apparatus, which is held in a first position when the filter is not mounted and moves from the first position to a second position in conjunction with the mounting operation when the filter is mounted, and an opening/closing member is provided on one end side of the developing apparatus, characterized in that the opening/closing member cannot be closed by interfering with the movable member when the movable member of the developing apparatus is in the first position, and can be closed without interfering with the movable member when the movable member is in the second position.

According to the above configuration, if a filter is not installed in the developing device, that is, if the movable member is in the first position, the opening/closing member cannot be closed due to interference from the movable member. The user can easily recognize that a filter has been forgotten in the developing device because the opening/closing member cannot be closed, thus preventing the image forming apparatus from being operated without a filter.

The developing apparatus and image forming apparatus of the present invention utilize a simple structure that takes advantage of the change in the position of a movable member depending on whether or not a filter is installed in the developing apparatus, thereby enabling the user to easily recognize if a filter has been forgotten.

This is an explanatory diagram showing the basic configuration of the image forming section in an image forming apparatus to which the present invention is applied. This is a perspective view showing the external appearance of a developing unit according to Embodiment 1, which is one embodiment of the present invention. This is a longitudinal cross-section of the developing unit. This is a disassembled perspective view of the filter removed from the developing unit. This is an enlarged perspective view showing the front end of the developing unit, with the filter not attached. This is an enlarged perspective view showing the front end of the developing unit, with the filter attached. This is a magnified view of the back surface at the front end of the filter. This diagram shows the process of attaching a filter to the developing unit, and is a view of the front end of the developing unit from a diagonal downward direction. This diagram shows the process of attaching a filter to the developing unit, and is a view of the front end of the developing unit from a diagonal downward direction. This diagram shows the process of attaching a filter to the developing unit, and is a view of the front end of the developing unit from a diagonal downward direction. This diagram shows the process of attaching a filter to the developing unit, and is a view of the front end of the developing unit from a diagonal downward direction. This is a front view showing the area around the developing unit inside the image forming apparatus, with a filter attached to the developing unit. This is a front view showing the area around the developing unit inside the image forming apparatus, with the developing unit without a filter installed. This is a side view illustrating the rotational movement of the movable lever during the filter mounting process in the developing unit according to Embodiment 2. This is a side view illustrating the rotational movement of the movable lever during the filter mounting process in the developing unit according to Embodiment 2. This is a perspective view showing the external appearance of the developing unit according to Embodiment 3.

[Embodiment 1]
Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 is an explanatory diagram showing the basic configuration of the image forming section in an image forming apparatus to which the present invention is applied.

In the image forming unit shown in Figure 1, the charging unit 11, exposure unit 12, developing unit (developing device) 13, transfer roller 14, static elimination lamp 15, and cleaning unit 16 are arranged around the photoreceptor drum 10 along the rotational direction of the photoreceptor drum 10 (direction of arrow R in the figure).

The charging unit 11 charges the surface of the photoreceptor drum 10 to a predetermined potential; for example, a scorotron charger is used. An output voltage (charging bias) from a charging bias power supply (not shown) is applied to the charging unit 11. The exposure unit 12 exposes the uniformly charged surface of the photoreceptor drum 10 by irradiating it with light corresponding to the image data output from an image processing unit (not shown). This forms an electrostatic latent image on the surface of the photoreceptor drum 10 corresponding to the image data.

The developing unit 13 visualizes the electrostatic latent image formed on the photoreceptor drum 10 using toner, and includes a developing roller 131 positioned opposite the photoreceptor drum 10. The developing roller 131 is positioned opposite the photoreceptor drum 10, exposed through an opening 133 (see Figure 3) provided in the housing of the developing unit 13. In the developing unit 13, developer (toner, or toner and carrier) is supplied from inside the developing unit 13 to the outer circumference of the developing roller 131, and the electrostatic latent image formed on the photoreceptor drum 10 is visualized by the toner (a toner image is formed on the photoreceptor drum 10). At this time, an output voltage (developing bias) from a developing bias power supply (not shown) is applied to the developing roller 131.

The transfer roller 14 has a paper transport path (not shown in Figure 1) between it and the photoreceptor drum 10, allowing it to transport the incoming paper while pressing it against the photoreceptor drum 10. Furthermore, an output voltage (transfer bias) from a transfer bias power supply (not shown) is applied to the transfer roller 14, transferring the toner image on the photoreceptor drum 10 to the recording paper. The recording paper with the transferred toner image is then transported to a fuser unit (not shown) where the transferred toner image is fixed.

The static elimination lamp 15 irradiates the surface of the photoreceptor drum 10 with static elimination light to remove residual charge from the surface of the photoreceptor drum 10. The cleaning unit 16 removes residual toner from the surface of the photoreceptor drum 10 using the cleaning blade 161.

Figure 2 is a perspective view showing the external appearance of the developing unit 13 according to this embodiment 1. Figure 3 is a longitudinal cross-sectional view of the developing unit 13. Figure 4 is an exploded perspective view of the filter 132 removed from the developing unit 13. In the figures, arrow A indicates the vertical direction when mounted on the image forming apparatus. The developing unit 13 has an opening 133 opposite the photoreceptor drum 10, exposing the developing roller 131 through the opening 133. Furthermore, the developing unit 13 is configured to reduce internal pressure in order to prevent unwanted toner scattering from the gap between the opening 133 and the developing roller 131. Specifically, the developing unit 13 is provided with an exhaust port 134, and the internal pressure is reduced by exhausting air from the exhaust port 134. In addition, a filter 132 is provided for the exhaust port 134 to prevent toner leakage along with the exhaust from the exhaust port 134.

The filter 132 is designed to be detachable from the developing unit 13 for easy replacement and maintenance. In the developing unit 13 according to this embodiment 1, the filter 132 can be attached to and detached from the developing unit 13 by sliding it in a direction parallel to the rotation axis of the developing roller 131 (direction of arrow B in the figure). Normally, the developing unit 13 can also be attached to and detached from the image forming apparatus body by sliding it, but the direction of attachment/detachment (sliding direction) is the same as the direction of attachment/detachment of the filter 132. Therefore, the filter 132 can be attached and detached while the developing unit 13 is mounted on the image forming apparatus. Both the filter 132 and the developing unit 13 can be attached and detached from the front side of the image forming apparatus.

As shown in Figure 4, the filter 132 is configured to hold the filter member 132b with a holder member 132a. The filter cover 135, shown in Figures 2 and 3, serves to guide the sliding movement of the filter 132 during attachment and detachment, to hold the attached filter 132, and to act as a duct for the air discharged from the exhaust port 134. In Figure 3, the airflow through the filter cover 135 as a duct is indicated by a thick arrow.

As described above, if the image forming apparatus is operated without the filter 132 installed in the developing unit 13, a large amount of toner will leak from the exhaust port 134, contaminating the inside of the image forming apparatus. Therefore, the image forming apparatus in this embodiment 1 has a structure that prevents operation when the filter in the developing unit 13 is not installed. This structure will be described in detail below.

Figures 5A and 5B are enlarged perspective views showing one end of the developing unit 13, specifically the upstream end in the insertion direction of the filter 132 (hereinafter referred to as the front end). Figure 5A shows the developing unit 13 without the filter 132 installed, while Figure 5B shows the developing unit 13 with the filter 132 installed.

A movable lever 136 is provided on the side of the front end of the developing unit 13. The movable lever 136 can rotate around a rotation axis parallel to the direction of attachment and detachment of the filter 132, and its range of rotation is between the first position shown in Figure 5A and the second position shown in Figure 5B. That is, the movable lever 136 is in the first position when the filter 132 is not attached to the developing unit 13, and moves to the second position in conjunction with the attachment operation when the filter 132 is attached. Furthermore, a restricting projection 137 may be provided on the side of the front end of the developing unit 13, which contacts the movable lever 136 in the first position and restricts the movable lever 136 from rotating beyond the first position.

Preferably, the movable lever 136 is held in a first position by gravity when the filter 132 is not mounted on the developing unit 13. When the filter 132 is mounted on the developing unit 13, it receives a pressing force due to contact with the filter 132, and this pressing force causes it to rotate towards the second position against gravity. However, the present invention is not limited to this configuration; the movable lever 136 may also be biased towards the first position by an elastic member such as a spring, and rotate towards the second position against the biasing force of the elastic member when the filter 132 is mounted.

Furthermore, it is preferable that the movable lever 136 has a holding mechanism that ensures its secure retention when the filter 132 is not attached to the developing unit 13 and it is held in the first position. A specific example of such a holding mechanism is a configuration in which, for example, a convex portion is provided on the movable lever 136 side and a concave portion on the developing unit 13 side at the mutual sliding surfaces of the movable lever 136 and the body of the developing unit 13. These convex and concave portions engage with each other when the movable lever 136 is in the first position, thereby holding the movable lever 136. By providing such a holding mechanism, it is possible to suppress the rotation of the movable lever 136 from the first position due to vibration or other factors when the filter 132 is not attached to the developing unit 13.

Next, we will explain the configuration that allows the movable lever 136 to rotate in conjunction with the attachment and detachment of the filter 132. Figure 6 is an enlarged view of the back surface at the front end of the filter 132. Figures 7A to 7D show the process of attaching (inserting) the filter 132 into the developing unit 13, and are views of the front end of the developing unit 13 from a diagonally downward direction. Note that Figure 7A shows the state in which the filter 132 has been removed from the developing unit 13, and the filter 132 is not shown.

As shown in Figure 6, a guide groove 132c is provided on the back surface of the front end of the filter 132. On the other hand, as shown in Figure 7A, the movable lever 136 has a guide boss 136a at one end and a lever boss 136b at the other end. The axis of rotation of the movable lever 136 is located between the guide boss 136a and the lever boss 136b. That is, both the guide boss 136a and the lever boss 136b are displaceable by the rotation of the movable lever 136.

When inserting the filter 132 into the developing unit 13, the guide boss 136a of the movable lever 136 engages with the guide groove 132c of the filter 132, and is guided by the guide groove 132c as the filter 132 is inserted. Specifically, the guide groove 132c is composed of two ribs erected downward from the back surface of the filter 132, and the guide boss 136a is positioned in the groove between the ribs to guide it. The entrance side of the guide boss 136a in the guide groove 132c is wide open so that the guide boss 136a can be reliably inserted into the groove when the movable lever 136 is in the first position. The end end side of the guide boss 136a is designed to hold the guide boss 136a when the movable lever 136 is in the second position. The section of the guide groove 132c between the inlet and end points is formed at an angle (inclined with respect to the direction of insertion/removal of the filter 132) to allow the guide boss 136a to move smoothly as the filter 132 is inserted.

In this manner, the connection between the guide groove 132c of the filter 132 and the guide boss 136a of the movable lever 136 causes the movable lever 136 to rotate from the first position to the second position as the filter 132 is inserted into the developing unit 13 (movement from Figure 7A to Figure 7D). When the filter 132 is mounted in the developing unit 13, the movable lever 136 is held in the second position. Conversely, when the filter 132 is removed from the developing unit 13, the movable lever 136 rotates from the second position back to the first position (movement from Figure 7D to Figure 7A).

The developing unit 13, mounted in the image forming apparatus, requires the rotation axis of its rotating members, such as the developing roller 131, to be positioned. Therefore, the image forming apparatus is equipped with a positioning cover (opening/closing member) 17, as shown in Figures 8A and 8B. Figures 8A and 8B are front views showing the area around the developing unit 13 inside the image forming apparatus, with the front housing cover removed. Figure 8A shows the developing unit 13 with the filter 132 mounted, while Figure 8B shows the developing unit 13 without the filter 132 mounted.

The positioning cover 17 is positioned on the front side of the image forming apparatus so as to be openable and closable relative to the developing unit 13. The developing unit 13 or filter 132 is attached to or detached from the image forming apparatus with the positioning cover 17 open. The positioning cover 17 is closed when the image forming apparatus is in operation.

When the filter 132 is attached to the developing unit 13, that is, when the movable lever 136 is in the second position, the lever boss 136b of the movable lever 136 is in a position that does not interfere with the positioning cover 17, as shown in Figure 8A. Therefore, the positioning cover 17 can be closed, and the image forming apparatus can be made operational.

On the other hand, if the filter 132 is not installed in the developing unit 13, that is, if the movable lever 136 is in the first position, as shown in Figure 8B, the lever boss 136b of the movable lever 136 is in a position to interfere with the positioning cover 17. Therefore, even if one attempts to close the positioning cover 17, the interference of the lever boss 136b prevents the positioning cover 17 from being closed. If the positioning cover 17 cannot be closed, the user can easily recognize that the filter 132 has been forgotten to be installed in the developing unit 13, and this prevents the image forming apparatus from being operated with the filter 132 missing. Furthermore, the image forming apparatus may be equipped with a sensor that detects the opening and closing of the positioning cover 17, and if the sensor detects that the positioning cover 17 is open, the image forming apparatus may be electrically controlled to prevent operation. In this case, it is possible to reliably prevent the image forming apparatus from being operated with the filter 132 missing.

[Embodiment 2]
In the above embodiment 1, the direction in which the filter 132 is attached to and detached from the developing unit 13 is the direction of rotation of the developing roller 131. However, the present invention is not limited thereto, and the direction in which the filter 132 is attached to and detached from the developing unit 13 may be other directions. For example, the direction in which the filter 132 is attached to and detached may be a direction perpendicular to the rotation axis of the developing roller 131 (for example, the up and down direction).

If the attachment/detachment direction of the filter 132 is vertical, for example, as shown in Figures 9A and 9B, a contact portion 132d can be provided on the filter 132. During the process of attaching the filter 132 (Figure 9A → Figure 9B), the contact between the guide boss 136a of the movable lever 136 and the contact portion 132d causes the movable lever 136 to rotate from a first position to a second position. That is, the contact surface of the contact portion 132d with respect to the attachment/detachment direction of the filter 132 is an inclined surface, allowing the guide boss 136a to move along the inclined surface as the filter 132 is attached or detached. The contact portion 132d is provided at a position corresponding to the guide boss 136a in the rotation axis direction of the developing roller 131.

Furthermore, the mechanism that rotates the guide boss 136a in the filter 132 is not limited to the contact portion 132d described above, but may also be a guide groove. However, when the filter 132 is attached or detached in the vertical direction, the guide groove differs from the guide groove 132c in Embodiment 1. It is formed on a surface perpendicular to the rotation axis of the developing roller 131 and parallel to the vertical direction (a portion having such a surface is provided at the front end of the filter 132).

Furthermore, if the filter 132 is to be attached and detached in the vertical direction, the presence of a filter cover 135 on the developing unit 13 would interfere with the attachment and detachment of the filter 132. In this case, the filter cover 135 may be omitted in the developing unit 13, or the filter 132 may be configured to have a filter cover 135.

[Embodiment 3]
In the above embodiment 1, an example was given in which the filter cover 135 has the function of serving as a duct for the air discharged from the exhaust port 134. However, the present invention is not limited thereto, and the filter cover 135 may be configured without a duct function. Figure 10 is a perspective view showing the external appearance of the developing unit 13' according to embodiment 3. The developing unit 13' is configured to have a filter cover 135' instead of the filter cover 135 in embodiment 1.

The filter cover 135' has a vent 135a on its upper surface. In the developing unit 13', air is exhausted through the exhaust port 134, the filter member 132b (see Figure 3), and the vent 135a to reduce the internal pressure of the unit.

The embodiments disclosed herein are illustrative in all respects and are not intended to be restrictive. Therefore, the technical scope of the present invention is not construed solely by the embodiments described above, but is defined by the claims. This includes all modifications within the meaning and scope of the equivalents of the claims.

10 Photoreceptor drum 11 Charging unit 12 Exposure unit 13, 13' Developing unit (developing device)
131 Developing roller 132 Filter 132a Holder member 132b Filter member 132c Guide groove 132d Contact portion 133 Opening 134 Exhaust port 135, 135' Filter cover 135a Vent 136 Movable lever (movable member)
136a Guide boss 136b Lever boss 137 Restricting projection 14 Transfer roller 15 Static elimination lamp 16 Cleaning unit 17 Positioning cover (opening/closing member)

Claims (7)

A developing apparatus used in an image forming apparatus, comprising an exhaust port for discharging air from inside the developing tank, and a filter detachably provided to the exhaust port,
A developing apparatus characterized in that, when the developing apparatus is mounted on the image forming apparatus, it is provided with a movable member on the front end side surface that is held in a first position when the filter is not mounted, and moves from the first position to a second position in conjunction with the mounting operation when the filter is mounted. A developing apparatus according to claim 1,
The developing apparatus is characterized in that the movable member is held in the first position by gravity when the developing apparatus is mounted on the image forming apparatus and the filter is not mounted. A developing apparatus according to claim 1 or 2,
The direction in which the filter is attached and detached is parallel to the rotation axis direction of the developing roller.
The developing apparatus is characterized in that the filter can be attached to and detached while the developing apparatus is mounted on the image forming apparatus. A developing apparatus according to claim 1 or 2,
The movable member is displaceable between the first position and the second position by rotational movement and has a guide boss.
The developing apparatus is characterized in that the filter has a guide groove that guides the guide boss during attachment and detachment to the developing apparatus and rotates the movable member between the first position and the second position. An image forming apparatus equipped with a developing device,
The developing apparatus is
An exhaust port for discharging air from inside the developing tank, and a filter detachably provided to the exhaust port,
When the developing device is mounted on the image forming apparatus, the front end side surface has a movable member that is held in a first position when the filter is not mounted, and moves from the first position to a second position in conjunction with the mounting operation when the filter is mounted.
The image forming apparatus is equipped with an opening/closing member on the front side relative to the developing apparatus.
The opening and closing member is characterized in that it cannot be closed by interfering with the movable member when the movable member of the developing apparatus is in the first position, and can be closed without interfering with the movable member when the movable member is in the second position. An image forming apparatus according to claim 5,
The movable member is characterized in that, when the developing device is mounted on the image forming apparatus and the filter is not mounted, it is held in the first position by the action of gravity. An image forming apparatus according to claim 5 or 6,
The direction in which the filter is attached and detached is parallel to the rotation axis direction of the developing roller.
The filter can be attached and detached while the developing device is mounted on the image forming apparatus.
The movable member is displaceable between the first position and the second position by rotational movement and has a guide boss.
The image forming apparatus is characterized in that the filter has a guide groove that guides the guide boss during attachment and detachment to the developing apparatus and rotates the movable member between the first position and the second position.