Dentistry – Apparatus – Having intra-oral dispensing means
Reexamination Certificate
2000-04-17
2001-10-02
Wilson, John J. (Department: 3732)
Dentistry
Apparatus
Having intra-oral dispensing means
C222S391000
Reexamination Certificate
active
06296484
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dispenser for dental viscous material which is not only cable of discharging a desired amount of a dental viscous material contained in a cartridge but also free from a “after flow” phenomenon in which even after the discharge operation has been stopped, the dental viscous material is continued to be discharged out due to a residual pressure in the cartridge (the dispenser for dental viscous material will be sometimes simply referred to as “dispenser” in some cases).
2. Description of the Conventional Art
Dental viscous materials to be used in a field of the dental treatment are commercially available depending upon an object of use thereof, including impression material, filling material, and adhering material (the dental viscous material will be sometimes simply referred to as “viscous material”). Some typical examples of the use thereof are explained below.
For example, in case where a viscous material is formed by a combination of two or more kinds of materials, just before the use, necessary amounts of the materials are taken out from the respective containers (in almost all cases, the materials are weighted and used in equivalent amounts or in equal lengths) and placed on a mixing pad, etc., which are then mixed with each other and put into use. Also, there are an example in which a powder and a liquid, each of which has been previously weighted in a capsule, are mixed with each other to form a paste (in a viscous state), which is then put into use; and an example in which a viscous material as previously contained in a container is directly filled into a dental cavity for which the preparation in an oral cavity has been made, from the container (the container will be sometimes simply referred to as “cartridge).
In the case where the viscous materials are weighted and put into use, tubes are generally used for the containers, and a mixing pad on which a scale mark for measuring the length has been previously printed is used. And, in case where it is required that the amounts of the respective viscous materials are different, there is a measure that apertures of the tube outlets are different while the lengths are equal. Operators, such as dentists and dental hygienists, mixed these materials on a mixing pad and put them into use. At this time, since they must take care that air bubbles or the like are not entrained, while paying attention that these materials are thoroughly mixed, the mixing works relatively required skill and were annoying.
As instruments that are provided for the purpose of liberating the operators from the works that require skill and are annoying, there are devices (applicators) as disclosed in Japanese Patent Publication No. 55195/1993, Japanese Patent Publication No. 30762/1995 and International Patent Publication No. 502464/1999. In these applicators, one or two cartridges containing the viscous material are installed in a device having a pistol-like shape for use. A discharge outlet of the cartridge is installed with a mixing tool as disclosed in Japanese Patent Publication No. 8290/1969 (the mixing tool will be sometimes referred to as “nozzle”). By using such a nozzle, the material to be discharged from the opening at a tip of the nozzle is thoroughly mixed during the step of passing through the nozzle and is in a state that it can be immediately put into use. At this time, as a driving source of this device is used a human power or compressed air.
In addition, examples of devices for discharging the viscous material as the contents from the capsule or cartridge include devices as disclosed, for example, in Japanese Patent Laid-Open No. 276550/1986, Japanese Patent Laid-Open No. 253095/1997, and Japanese Patent Laid-Open No. 43206/1998. These devices mainly have an appearance like a pistol and are arranged with an installation portion (e.g., a concave of the connector portion) for installing the capsule or cartridge in a predetermined position at the front of the device. And, any of these devices are provided with a piston rod for pressing and extruding the viscous material in the capsule or cartridge. As a driving source for advancing the piston rod to the extrusion direction of the viscous material, a human power is used in any of the cases.
In various devices as described above, as to those in which a human power is used as the driving source are roughly classified into the following two groups according to the mechanism for advancing the piston rod in the extrusion direction of the viscous material.
One of the two groups is of a ratchet mechanism type for obtaining advancing and braking (stopping) effects by a combination of a rack and a claw; and the other is of a jamming mechanism type for obtaining advancing and braking (stopping) effects by inclining a plate bored with a hole through which the piston rod is to be penetrated and which has a size slightly larger than that of an outer diameter of the piston rod, against the axis of the piston rod and bringing the piston rod into contact with an edge of the hole.
Examples of the former ratchet mechanism type include devices as disclosed in Japanese Patent Publication No. 55195/1993 and International Patent Publication No. 502464/1999. Also, examples of the latter jamming mechanism type include devices (applicators) as disclosed in Japanese Patent Laid-Open No. 276550/1986 and Japanese Patent Laid-Open No. 43206/1998. The both mechanisms have merits and demerits, respectively.
First of all, the outline of the mechanism of the ratchet mechanism type is explained. What the piston rod is advanced in the extrusion direction of the viscous material is effected by an engagement of a row of rack formed on the piston rod with a claw. And, to impart a movement to the claw is effected by a human power through handle operation (in some cases, a motor is used). The ratchet mechanism type has the following merits. That is, the piston rod can be surely advanced in a constant distance by a single handle operation (hence, the measurement of the material to be discharged is accurate); and a cartridge containing a relatively highly viscous material can also be used. Further, from the mechanical viewpoint, restrictions in designing is decreased, so that a relatively thin piston rod can be used, leading to realizing decrease in size.
On the other hand, the ratchet mechanism type involves the following demerits. That is, from the operational viewpoint, the piston rod must be advanced in the extrusion direction after blank shots of the handle until the material in the cartridge has reached a certain position (a position of an inner lid functioning to press the material in the cartridge); measurement of the material to be discharged at a first handle operation is inaccurate (due to the fact that at the first handle operation, a tip of the piston rod cannot be brought into contact with a rear portion of the inner lid functioning to press the material in the cartridge to cause the material to be throw away, and such is wasteful); the movement of the piston rod is restricted by the size or position of the rack; and even after the handle operation has been stopped, the material is discharged due to the residual pressure in the cartridge (such phenomenon is called as “afterflow”). Also, from the processing viewpoint, a relatively high processing precision is required (leading to high costs); and when a safety is taken into consideration, the mechanism inevitably becomes complicated, thereby increasing the number of component members.
Next, the outline of the mechanism of the jamming mechanism type is explained. The movement in the extrusion direction and braking (stopping) of the piston rod are effected by inclining at least one of two plates bored with a hole through which the piston rod is to be penetrated and which has a size slightly larger than that of an outer diameter of the piston rod, against the axis of the piston rod (in order to impart a force to the inclined plate, an elastic member such as a coil spring is generally
Ishida Kazuya
Nihei Tsutomu
GC Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Wilson John J.
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