JP4960015B2 - Liquid toner amount detection apparatus and wet image forming apparatus - Google Patents

Description

  The present invention relates to a liquid toner amount detection device and a wet image forming apparatus provided with the liquid toner amount detection device.

In an electrophotographic image forming apparatus, it is a mainstream to transfer an electrostatic latent image on a photosensitive drum using powder toner. However, liquid toner obtained by diluting a concentrated toner liquid with a carrier liquid is used. A liquid developing device for developing an electrostatic latent image has been proposed (for example, Patent Document 1).
In the liquid developing device, liquid toner is stored in a container. Since the liquid toner is used for developing the electrostatic latent image, it must be monitored so that the storage amount of the liquid toner in the container is larger than the lower limit amount. For this reason, it is necessary to detect that the amount of liquid toner stored in the container reaches the lower limit.

As a method of detecting the amount of liquid stored in the container, as shown in Patent Document 2, a float is floated on the liquid surface, and the position of the float that moves up and down as the liquid amount changes is detected. What performs quantity detection is known.
JP 2005-315948 A Japanese Patent Publication No. 6-23898

By the way, the carrier liquid which is a medium of the liquid toner is a high viscosity liquid such as liquid paraffin or silicone oil. The high-viscosity liquid does not move well, and the float does not work well with the vertical movement of the carrier liquid. Therefore, the liquid amount detection using the float is not suitable for the liquid amount detection of the liquid toner.
Although it is conceivable to detect the liquid level by detecting the liquid level using an optical sensor, the liquid level of the liquid cannot be accurately detected because the toner particles of the liquid toner adhere to the detection surface. There is also a fear.

The present invention has been made based on such a background, and an object thereof is to provide a liquid toner amount detection device capable of appropriately detecting the amount of liquid toner.
Another object of the present invention is to provide a wet image forming apparatus capable of stably obtaining a good image.

The invention described in claim 1 is a liquid toner amount detection device (100) for detecting that the amount of liquid toner stored in the storage container (27) has reached a predetermined amount. A shaft (40) that extends in a substantially vertical direction in the container and is rotatably provided, a drive motor (42) that rotationally drives the shaft at a predetermined speed, and a buoyancy that rotates as the shaft rotates. Detecting means for detecting that a predetermined amount of liquid toner is stored based on the fact that the rotating body (43) rising in the liquid toner and the rising rotating body has reached a predetermined height position (44, 45) and only contains, the rotating body includes a cylindrical (46) covering the outer periphery of the shaft, the lower end of the cylinder and a screw provided in (46A) (47), in the cylindrical In the direction in which the shaft extends What extending elongated hole (49) is formed on the outer peripheral surface of the shaft (40A), the liquid amount detection of the liquid toner, wherein a projection fitted into the elongated hole (50) is formed Device.

The numbers in parentheses indicate corresponding components in the embodiments described later. The same applies hereinafter .

According to a second aspect of the present invention, the detection means is provided at an upper end of the cylinder, and the detected portion (44) that moves up and down as the rotating body moves up and down, and a height position that the detected portion determines in advance. upon reaching a liquid amount detecting device of the liquid toner according to claim 1, characterized in that it comprises a sensor (45) for outputting to that effect.
The invention described in claim 3 includes a photosensitive drum (2C, 2M, 2Y) and a liquid developing device (6C, 6M, 6Y) for visualizing an electrostatic latent image using liquid toner. The apparatus is provided with a storage container for storing liquid toner, and the storage container is provided with the liquid toner amount detection device according to claim 1 or 2. ).

  According to the first aspect of the present invention, when the shaft rotates at a constant speed, the rotating body balances buoyancy and gravity at a certain height position in the vertical direction, and this balance position reaches a predetermined height position. By detecting whether or not the liquid toner stored in the container has reached a predetermined amount, it is detected. Since the rotating body is raised using the rotational driving force of the drive motor, the rotating body can be smoothly moved up and down even in a liquid having a high viscosity such as liquid toner. Thereby, it is possible to appropriately detect whether or not the storage amount of the liquid toner has reached a predetermined amount.

Further, since the amount of storage can be detected by moving the rotating body in the vertical direction, it is sufficient if there is a space in the vertical direction. Thereby, the whole liquid quantity detection apparatus can be made compact.
In addition , a rotating body that is allowed to move in the axial direction while being restricted from moving in the rotational direction with respect to the shaft can be realized with a simple configuration. Therefore, it is possible to detect whether or not the storage amount of the liquid toner has reached a predetermined amount with a simple configuration.

According to invention of Claim 2 , the height position of a rotary body is detectable with a simple structure. Thereby, it is possible to detect whether or not the storage amount of the liquid toner has reached a predetermined amount with a simple configuration.
In the third aspect of the invention, since the liquid toner amount detection device according to the first or second aspect is employed, the liquid toner is applied to the photosensitive drum without causing the toner to run out. Thereby, a wet image forming apparatus capable of stably obtaining a good image can be provided.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a schematic view showing a configuration of a wet image forming apparatus according to an embodiment of the present invention.
The wet image forming apparatus 1 forms a color image, and includes a first image forming mechanism 11, a second image forming mechanism 12, and a third image forming mechanism 13. In the wet image forming apparatus 1, each of the image forming mechanisms 11 to 13 is configured for cyan (C), magenta (M), and yellow (Y) in order from the top in FIG. Yes. Although the black (BK) image forming mechanism is not illustrated in FIG. 1, the wet image forming apparatus 1 may include a black (BK) image forming mechanism.

  Each of the image forming mechanisms 11 to 13 includes cylindrical photosensitive drums 2C, 2M, and 2Y, chargers 3C, 3M, and 3Y for charging the surfaces of the photosensitive drums 2C to 2Y, and chargers 3C to 3Y. Exposure units 4C, 4M, and 4Y for exposing the surfaces of the charged photosensitive drums 2C to 2Y corresponding to the image to be created, and supplying liquid toner of each color to the surfaces of the photosensitive drums 2C to 2Y The liquid developing devices 6C, 6M, and 6Y that develop the electrostatic latent images formed by the exposure, and the toner images remaining on the surfaces of the photosensitive drums 2C to 2Y after the toner images are transferred to the intermediate transfer belts 10C, 10M, and 10Y. Cleaning devices 7C, 7M, and 7Y for removing the liquid toner to be removed, and neutralizers 8C, 8M, and 8Y for neutralizing the surface of the photosensitive drum 2 after the toner image is transferred.

The toner images of the respective colors developed on the surfaces of the photosensitive drums 2C to 2Y are temporarily transferred to the endless intermediate transfer belts 10C, 10M, and 10Y, and the toner images are transferred to a sheet by a secondary transfer roller (not shown). . The sheet on which the toner image has been transferred is heated and pressed by a fixing device (not shown), whereby the full-color toner image is fixed on the sheet.
Each of the liquid developing devices 6C to 6Y has a configuration that is substantially common to each other. However, the cyan liquid developing device 6C will be described as an example, and the description of the configurations of the other liquid developing devices 6M and 6Y will be omitted.

  The liquid developing device 6 </ b> C includes a supply pot 20 in which liquid toner is stored, a supply roller 21 that draws liquid toner from the supply pot 20, and a liquid drawn by the supply roller 21 in contact with the peripheral surface of the supply roller 21. An application roller 22 that applies toner to the peripheral surface of the developing roller 23 and a developing roller 23 that is in contact with the surface of the photosensitive drum 2 and supplies liquid toner to the photosensitive drum 2 as a liquid toner carrier. Yes.

  The supply roller 21 enters the supply pot 20 and is immersed in the liquid toner stored in the supply pot 20. The liquid toner in the supply pot 20 has high wettability, so that the liquid toner is taken up by the rotation of the supply roller 21 and is applied to the surface of the photosensitive drum 2 via the application roller 22 and the developing roller 23. The developing roller 23 is provided with a cleaning blade 24 that scrapes off the liquid toner remaining on the surface of the developing roller 23 after the image is formed on the surface of the photosensitive drum 2.

Further, the liquid developing device 6C stores a liquid pot 26 that stores liquid toner to be supplied to the supply pot 20 while adjusting the particle concentration within an appropriate range, and a toner pot 27 that stores the liquid toner supplied to the liquid pot 26. And a collection pot 28 for storing the liquid toner scraped and collected by the cleaning blade 24.
Liquid toner is supplied to the blending pot 26 from the toner pot 27 through the transport path 29. The liquid toner is obtained by dispersing powder toner in a carrier liquid. However, a high-viscosity liquid is used as the carrier liquid, and thus the liquid toner also has a high viscosity. A valve 30 is interposed in the transport path 29, and the liquid toner is applied from the toner pot 27 to the preparation pot 26 by opening the valve 30.

In the liquid developing device 6C, the recovered liquid toner is used again for development, and the liquid toner is supplied to the preparation pot 26 from the recovery pot 28 via the transport path 31. A valve 32 is interposed in the transport path 31, and when this valve 32 is opened, the liquid toner in the collection pot 28 is applied to the preparation pot 26.
A carrier liquid tank 34 is connected to the blending pot 26 via a carrier liquid transport path 33 and a branch path 33C. The carrier liquid tank 34 stores a transparent carrier liquid for diluting the liquid toner. As the carrier liquid, one having a high viscosity such as liquid paraffin or silicone oil is used.

  A stirring blade 36 for stirring the liquid toner is installed at the bottom of the blending pot 26. The liquid toner supplied from the toner pot 27, the liquid toner supplied from the recovery pot 28, and the carrier liquid supplied from the carrier liquid tank 34 are stirred by the stirring blade 36 and stored in a mixed state. A concentration sensor 37 for measuring the particle concentration of the liquid toner is attached to the blending pot 26. The particle concentration of the liquid toner in the blending pot 26 is monitored and maintained within an appropriate range by feedback control.

The blending pot 26 is connected to the supply pot 20 via the transport path 38. A valve 39 is interposed in the middle of the conveyance path 38, and the liquid toner adjusted to an appropriate concentration is supplied to the supply pot 20 by opening the valve 39.
The carrier liquid tank 34 supplies the carrier liquid to the preparation pots 26 of all the liquid developing devices 6C to 6Y, and branches for each color branched from the carrier liquid transport path 33 connected to the carrier liquid tank 34. The carrier liquid is supplied to the preparation pots 26 of the liquid developing devices 6C to 6Y through the paths 33C, 33M, and 33Y. A valve 35C is interposed in the cyan branch path 33C. When the valve 35C is opened, the carrier liquid is supplied to the preparation pot 26 of the liquid developing device 6C. Further, a valve 35M is interposed in the magenta branch path 33M. When the valve 35M is opened, the carrier liquid is supplied to the preparation pot 26 of the liquid developing device 6M. Further, a valve 35Y is interposed in the yellow branch path 33M. When the valve 35Y is opened, the carrier liquid is supplied to the preparation pot 26 of the liquid developing device 6Y.

The liquid toner stored in the toner pot 27 should not fall below the lower limit amount (for example, 200 ml). The toner pot 27 is provided with a liquid amount detection device 100 for detecting whether or not the liquid toner stored in the toner pot 27 has reached the lower limit amount.
FIG. 2 is a schematic diagram showing the configuration of the liquid amount detection device. For convenience of explanation, the toner pot 27 is partially cut away.

A shaft 40 extending in a substantially vertical direction is erected at the right rear corner of the bottom surface 27 </ b> A of the toner pot 27. The shaft 40 is attached to the bottom surface 27A of the toner pot 27 so as to be rotatable in the direction of an arrow 41 in the drawing.
A drive motor 42 is disposed above the shaft 40. The drive motor 42 is fixed to a wall or the like (not shown) outside the toner pot 27, and an output shaft (not shown) is coupled to the shaft 10 so as to be integrally rotatable. The drive motor 42 is connected to the control unit 60, and the shaft 40 is rotated at a constant speed (for example, 60 r / min) in the direction of the arrow 41 in the figure by the drive force of the drive motor 42.

  A cylindrical rotating body 43 is fitted on the outer periphery of the shaft 40 so as to be movable up and down. As the shaft 40 rotates, a buoyancy is generated in the rotator 43, and the rotator 43 moves up in the liquid toner by the action of the buoyancy. A detected object 44 is disposed above the rotating body 43. The detected body 44 is placed above the rotating body 43, and the detected body 44 moves up and down as the rotating body 43 moves up and down.

A position sensor 45 is disposed on the shaft 40 above the detection target 44. The position sensor 45 outputs the fact to the control unit 60 when the detected object 44 reaches a predetermined height position described later.
The control unit 60 is configured by a CPU, RAM, ROM, and the like. The control unit 60 may be provided separately from the main control unit of the image forming apparatus 1 or may be included in the main control unit.

  FIG. 3 is a front view for explaining the configuration of the rotating body. With reference to FIG. 3, the rotating body 43 includes a cylinder 46 fitted to cover the outer periphery of the shaft 40, and a screw 47 provided at a lower end portion 46 </ b> A of the cylinder 46. The screw 47 includes, for example, six blades 48, 48,... Arranged around the cylinder 46. The screw 47 rotates as the cylinder 46 rotates. When the cylinder 46 rotates in the direction of the arrow 41 in the figure, the buoyancy is generated in the rotating body 43 by the rotation of the screw 47, and the rotating body 43 rises.

  The cylinder 46 is formed with a pair of long holes 49 and 49 (only one is shown in FIG. 3) at positions that are separated from each other. Each long hole 49 extends along the direction in which the shaft 40 extends, and the length of the long hole 49 is set to about 2/3 of the length of the cylinder 46. On the other hand, a pair of pins 50, 50 project from the outer peripheral surface 40 </ b> A of the shaft 40 at positions away from each other. Each pin 50 of the shaft 40 is fitted in each elongated hole 49. For this reason, the rotating body 43 is allowed to move in the axial direction with respect to the shaft 40, but is not allowed to move in the rotating direction. For this reason, when the shaft 40 rotates, the rotating body 43 also rotates in conjunction with it.

  FIG. 4 is a perspective view of relevant parts for explaining the configuration of the detection target and the sensor. The detected body 44 includes a cylindrical portion 51 that surrounds the outer peripheral surface 40 </ b> A of the shaft 40, and a plate-shaped detected plate 52 that projects from the cylindrical portion 51 outward in the radial direction. Although omitted in FIG. 2, a U-shaped guide rail 53 extending in a substantially vertical direction is provided upright on the bottom surface 27 </ b> A of the toner pot 27. The guide rail 53 is disposed to face the shaft 40. The guide rail 53 is in contact with the detected plate 52 of the detected body 44 and restricts the rotation of the detected body 44 while allowing the detected body 44 to move up and down. A position sensor 45 is attached to a predetermined height position of the guide rail 53.

  The position sensor 45 is a known transmissive optical sensor. The position sensor 45 includes a light emitting unit 54 and a light receiving unit 55 that face each other, and the light emitted from the light emitting unit 54 is received by the light receiving unit 55. The position sensor 45 is attached to the guide rail 53 so as to straddle from the outside. When the detection plate 52 of the detection target 44 is detected, the fact is output to the control unit 60.

FIG. 5 is a schematic diagram illustrating the movement of the rotating body when the storage amount is detected. (A) is the state at the start of the storage amount detection, and (b) shows the state after 30 seconds from the start of the storage amount detection.
The amount of storage is detected when the power is turned on. As shown in FIG. 5A, initially, the rotating body 43 is positioned at the lowest position (a state where the lower end 43A of the rotating body 43 is in contact with the bottom surface 27A). From this state, when the drive motor 42 rotationally drives the shaft 40, the rotating body 43 also rotates in conjunction with the shaft 40, buoyancy is generated in the rotating body 43 by the rotation of the screw 47, and the rotating body 43 rises. Along with the rotating body 43, the detected object 44 also rises. The shaft 40 is rotated for 30 seconds at a rotation speed of 60 r / min, for example.

  When the shaft 40 continues to rotate at a constant speed and the lower end 43A of the rotating body 43 reaches the liquid level S, the gravity acting on the rotating body 43 and the buoyancy acting on the rotating body 43 balance, and the rotating body 43 is displaced in the vertical direction. Disappear. At the latest, when 30 seconds have elapsed from the start of rotation of the shaft 40, the rotating body 43 is not displaced in the vertical direction. As shown in FIG. 5B, when the position sensor 45 detects the detection target 44, it is determined that the storage amount of the liquid toner has reached the lower limit amount.

There is a certain correlation between the balance position of the rotating body 43 and the height H1 of the liquid surface S. Similarly, between the height position H2 of the detected body 44 and the amount of liquid toner stored in the balance state. Also have a certain correlation.
The height position H0 of the position sensor 45 is set to the height of H2 of the detected body 44 when the liquid toner storage amount is the lower limit amount. Therefore, when the detected object 44 is detected by the position sensor 45, it can be seen that the amount of liquid toner stored in the toner pot 27 is equal to or greater than the lower limit amount. Thereby, it is possible to detect whether or not the storage amount of the liquid toner has reached the lower limit amount.

  The balance position of the rotating body 43 depends on the rotation speed of the shaft 40. Accordingly, the height position H0 of the position sensor 45 is also determined based on the rotational speed of the shaft 40. On the other hand, the liquid toner is a high-viscosity fluid as described above. For this reason, the rotation speed of the shaft 40 is set to an optimum rotation speed based on the viscosity and specific gravity of the liquid toner stored in the toner pot 27. Is set.

  When the detected object 44 is detected by the position sensor 45, the control unit 60 determines that the amount of liquid toner in the toner pot 27 has reached the lower limit amount. On the other hand, as shown in FIG. 6, when the storage amount of the liquid toner does not reach the lower limit amount, the height position H2 of the detected body 44 is the height of the position sensor 45 when the rotating body 43 is in the balanced position. The position H0 is not reached. If the detected object 44 is not detected by the position sensor 45 even after 30 seconds, the control unit 60 determines that the amount of liquid toner stored in the toner pot 27 has not reached the lower limit amount, that is, the storage amount is insufficient. To do. In this case, new toner liquid flows into the toner pot 27 from a toner cartridge (not shown) connected to the toner pot 27, and the storage amount of the liquid toner stored in the toner pot 27 is increased.

According to this embodiment, since the rotating body 43 is raised using the driving force of the driving motor 42, the rotating body 43 can be smoothly moved up and down even in a liquid having a high viscosity such as liquid toner. Thereby, it is possible to appropriately detect whether or not the storage amount of the liquid toner has reached the lower limit amount.
Further, since the amount of storage is detected by moving the rotating body 43 in the vertical direction, it is sufficient if there is a space in the vertical direction, and the rotating body 43 is disposed at the right back corner of the bottom surface 27 </ b> A of the toner pot 27. Thereby, the liquid amount detection apparatus 100 can be made into a compact structure.

The present invention is not limited to the embodiment described above.
In the above description, the position sensor 45 is described as an optical sensor, but an actuator may be used as the sensor.
In addition, the storage amount detection is performed when the wet image forming apparatus 1 is turned on. However, the storage amount detection may be performed every predetermined number of image forming sheets (for example, 10,000 sheets).

Furthermore, although the liquid amount detection device 100 has been described as being provided in the toner pot 27, it can also be provided in the preparation pot 26, the supply pot 20, and further the recovery pot 28.
Further, the liquid amount detection device 100 is not limited to the one that detects the liquid amount of the liquid toner in which the powder toner is dispersed in the carrier liquid. The liquid amount detection device 100 is incorporated in the toner tank 34 that stores the carrier liquid. It is also possible to detect the amount of liquid.

  In addition, various modifications can be made within the scope of the claims.

1 is a schematic diagram showing a configuration of a wet image forming apparatus according to an embodiment of the present invention. It is a schematic diagram which shows the structure of a liquid quantity detection apparatus. It is a front view for demonstrating the structure of a rotary body. It is a principal part perspective view for demonstrating the structure of a to-be-detected body and a sensor. It is a schematic diagram showing the motion of the rotary body at the time of storage amount detection. (A) is the state at the start of the storage amount detection, and (b) shows the state after 30 seconds from the start of the storage amount detection. It is a schematic diagram showing the motion of a rotary body in the case of storage amount shortage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wet image forming apparatus 100 Liquid quantity detection apparatus 2C, 2M, 2Y Photosensitive drum 6C, 6M, 6Y Liquid developing device 11, 12, 13 Development forming mechanism 40 Shaft 42 Drive motor 43 Rotating body 44 Detected object (detected part) )
45 Position sensor (sensor)
46 Cylinder 48 Screw 49 Long hole 50 Pin (protrusion)
60 Control unit

Claims (3)

A liquid toner amount detection device for detecting that the amount of liquid toner stored in a storage container has reached a predetermined amount,
A shaft that extends in the vertical direction in the container and is rotatably provided;
A drive motor for rotating the shaft at a predetermined speed;
A rotating body that rotates with the rotation of the shaft to generate buoyancy and rises in the liquid toner;
Based on the increased rotational body reaches the height position predetermined, saw including a detection means for detecting that the liquid toner of a predetermined amount is stored,
The rotating body has a cylinder that covers the outer periphery of the shaft, and a screw provided at the lower end of the cylinder,
The cylinder has a long hole extending along the direction in which the shaft extends,
A liquid toner amount detecting device, wherein a projection that fits into the elongated hole is formed on an outer peripheral surface of the shaft . The detection means is provided at the upper end of the cylinder, and a detected part that moves up and down as the rotating body moves up and down, and a sensor that outputs that when the detected part reaches a predetermined height position preparative liquid amount detecting device of the liquid toner according to claim 1, characterized in that it comprises a. A photosensitive drum;
A liquid developing device for visualizing an electrostatic latent image using liquid toner,
The liquid developing unit is provided with a container for containing a liquid toner, characterized in that the liquid toner in the liquid volume sensing device is provided according to claim 1 or 2 in the container Wet image forming apparatus.

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