WO2008018667A1

WO2008018667A1 - A dental unit chair's cleaning water process system

Info

Publication number: WO2008018667A1
Application number: PCT/KR2007/000499
Authority: WO
Inventors: Tae Woo Kim
Original assignee: E-Woo Technology Co., Ltd
Priority date: 2006-08-08
Filing date: 2007-01-29
Publication date: 2008-02-14

Abstract

A dental unit chair is provided with a plurality of pipes, which supply clean water to respective parts of the unit chair. If the unit chair is not operated for a long time period, clean water in the pipes does not flow and remains therein for a long time period, so that a biofilm is formed on the inside wall of the pipes. This contaminates the inside of the pipes, and such contamination can secondarily infect a patient. Accordingly, the invention provides a clean water processing system for the dental unit chair, which can automatically drain or circulate clean water in the pipes of the unit chair, so that clean water does not remain in the water supply pipe for a long time period.

Description

A DENTAL UNIT CHAIR'S CLEANING WATER PROCESS

SYSTEM

Technical Field

[1] The present invention relates to a clean water processing system for a dental unit chair. More particularly, the invention relates to a clean water processing system for a dental unit chair, which can prevent a biofilm from forming on the inside wall of a water supply pipe of the dental unit chair by draining or circulating clean water, which remains in the water supply pipe. Background Art

[2] Generally, water supplied to dental unit chairs is used to cool heat generated in dental treatment devices such as dental handpieces and to remove powder and sediment generated when grinding teeth, or is supplied to dental treatment assistant devices such as a spittoon or an auto-cup with which patients gargle. Because water supplied to such a dental unit chair directly contacts a wound region in the mouth of a patient or a region in which treatment is required, it is very important to maintain the water in a sanitary and clean condition.

[3] Therefore, typically, clean water, from which impurities have been removed using a water purifier, is used as water to be supplied to the dental unit chair, rather than directly using tap water.

[4] However, when the dental unit chair is not in use, for example, during lunch time, when dental treatment is stopped for a while, during the evening and at night, after dental treatment time is over, or when the hospital is closed, clean water remains in a water supply pipe connected to the dental treatment assistant device of the dental unit chair, with the result that a biofilm may be formed on the inner surface of the water supply pipe.

[5] The biofilm is composed of an organic substance or an inorganic substance.

Harmful microbes such as bacilli or mildew may be created around the biofilm. Therefore, if water enters the mouth of the patient through the water supply pipe, in which the biofilm is formed, there is the possibility of secondary infection. Disclosure of Invention

Technical Problem

[6] The present invention has been made to solve the foregoing problems with the prior art, and therefore an object of the present invention is to provide a clean water processing system for a dental unit chair, which drains clean water from a water supply pipe through a handpiece while the dental unit chair is not used, thereby preventing a biofilm from forming on the inside wall of the water supply pipe.

[7] Another object of the present invention is to provide a clean water processing system for a dental unit chair, which drains clean water from a water supply pipe through a handpiece and fills the water supply pipe with compressed air when the dental unit chair is not being used, thereby preventing a biofilm from forming on the inside wall of the water supply pipe, which leads from a clean water pipe to the handpiece.

[8] A further object of the present invention is to provide a clean water processing system for a dental unit chair, which circulates clean water in a water supply pipe portion, drains clean water from a water supply portion connected to a handpiece and fills the water supply portion connected to the handpiece with compressed air when the dental unit chair is not being used, thereby preventing a biofilm from forming on the inside wall of the water supply pipe, which leads from a clean water pipe to the handpiece. Technical Solution

[9] According to an aspect of the invention for realizing the object, the invention provides a clean water processing system for a dental unit chair, which includes a handpiece for draining clean water, which is supplied from a water purifier, and air; a water supply pipe for supplying clean water from a clean water pipe to the handpiece; a master block provided on the water supply pipe, the master block supplying clean water from the clean water pipe to the handpiece; a valve provided on the water supply pipe and connected to an air supply pipe; and a control unit for controlling the valve and the handpiece when clean water supplied into the water supply pipe from the water purifier has not been drained for a predetermined time period, so that clean water is drained through the handpiece from the water supply pipe.

[10] Preferably, the valve is a three-way valve, which, in a turned-on state, prevents compressed air from being introduced from the air supply pipe while introducing clean water from the water purifier into the water supply pipe, and, in a turned-off state, prevents clean water from being introduced from the clean water pipe while introducing compressed air from the air supply pipe into the water supply pipe.

[11] According to another aspect of the invention for realizing the object, the invention provides a method of processing clean water in a dental unit chair, which includes a first step of recording a time and a duration of handpiece-opening means (33), which are inputted by an input unit (180) in a timer of a control unit; a second step of comparing the time, recorded in the timer, with the current time, and if the time is the same as the current time, transmitting an operation start signal to a unit controller; a third step in which, when the operation start signal is received, the unit controller turns off a three-way valve (170) to introduce compressed air while operating the handpiece- opening means (33) to open the handpiece (130), thereby draining clean water from a water supply pipe (140) through the handpiece (130); a fourth step of comparing the duration, recorded in the timer, with a time that has elapsed since the operation start signal was transmitted, and, if they are equal, transmitting an operation end signal to the unit controller; and a fifth step in which, when the operation end signal is received, the unit controller operates the handpiece-opening means (33) to close the handpiece (130), thereby finishing the draining of clean water.

[12] According to a further aspect of the invention for realizing the object, the invention provides clean water processing system for a dental unit chair, which includes a water supply pipe connected to a clean water pipe; a master block connected to a downstream end of the water supply pipe; a first valve provided on the water supply pipe and connected to an air supply pipe; a subsidiary block provided on the water supply pipe, at a position between the first valve and the master block; a water drain pipe diverging from the subsidiary block; a second valve provided on the water drain pipe; a third valve provided on the water supply pipe, at a position between the subsidiary block and the master block; and a control unit for controlling the first to third valves. The control unit controls the first to third valves to introduce compressed air from the air supply pipe into the water supply pipe, thereby draining clean water from the water supply pipe through the water drain pipe.

[13] Preferably, the valve is a three-way valve, which, in a turned-on state, prevents compressed air from being introduced from the air supply pipe while introducing clean water from the clean water pipe into the subsidiary block, and in a turned-off state, prevents clean water from being introduced from the clean water pipe while introducing compressed air from the air supply pipe into the subsidiary block.

[14] According to another aspect of the invention for realizing the object, the invention provides a method of processing clean water in a dental unit chair, which includes a first step of recording a time and a duration of a draining operation, inputted through an input unit, in a timer of a control unit; a second step of comparing the time of the draining operation, recorded in the timer, with a current time, and, if the time of the draining operation is the same as the current time, transmitting a draining operation start signal to a unit controller of the control unit; a third step in which, when the draining operation start signal is received, the unit controller turns off a first valve, opens a second valve, and closes a third valve, thereby draining clean water from a water supply pipe through a water drain pipe; a fourth step of comparing the duration of the draining operation, recorded in the timer, with a time that has elapsed since the draining operation start signal was transmitted, and, if they are equal, transmitting a draining operation end signal to the unit controller; and a fifth step in which, when the draining operation end signal is received, the unit controller closes the second valve to finish the draining operation.

[15] According to a further aspect of the invention for realizing the object, the invention provides a method of processing clean water in a dental unit chair, which includes a first step of recording a time and a duration of a draining operation, inputted through an input unit, in a timer of a control unit; a second step of comparing the time of the draining operation, recorded in the timer, with a current time, and, if the time of the draining operation is the same as the current time, transmitting a draining operation start signal to a unit controller of the control unit; a third step in which, when the draining operation start signal is received, the unit controller turns off a first valve and opens a third valve and a handpiece, thereby draining clean water from a water supply pipe through the handpiece; a fourth step of comparing the duration of the draining operation, recorded in the timer, with a time that has elapsed since the draining operation start signal was transmitted, and, if they are equal, transmitting a draining operation end signal to the unit controller; and a fifth step in which, when the draining operation end signal is received, the unit controller closes the hand piece, thereby finishing the draining operation.

[16] According to another aspect of the invention for realizing the object, the invention provides a clean water processing system for a dental unit chair, which includes a water supply pipe connected to a clean water pipe; a subsidiary block provided on the water supply pipe; a circulation pipe diverging from the subsidiary block and connected to the water supply pipe, at a position between the clean water pipe and the subsidiary block; a fourth valve connecting the water supply pipe to the circulation pipe; a circulation pump provided on the circulation pipe; and a control unit for controlling a fourth valve and the circulation pump. The control unit controls the fourth valve and the circulation pump, so that clean water introduced from the clean water pipe circulates through the water supply pipe and the circulation pipe.

[17] Preferably, the fourth valve is a three-way valve, which, in a turned-on state, prevents clean water from being introduced from the circulation pipe while introducing clean water from the clean water pipe into the subsidiary block, and, in a turned-off state, prevents clean water from being introduced from the clean water pipe while introducing clean water from the circulation pipe into the subsidiary block.

[18] Preferably, the clean water processing system further includes a master block provided on a downstream end of the water supply pipe; a first pipe diverging from the master block; a handpiece connected to the first pipe and held by a handpiece holder, the handpiece holder including opening means; a fifth valve provided on the water supply pipe, at a position between the subsidiary block and the master block; and an air pipe connected to the fifth valve. The control unit controls the fifth valve and the opening means in order to drain clean water from the water supply pipe and the first pipe through the handpiece using compressed air, which is introduced from the air supply pipe.

[19] Preferably, the fifth valve is a three-way valve, which, in a turned-on state, prevents compressed air from being introduced from the air supply pipe while introducing clean water from the subsidiary block to the master block, and in a turned-off state, prevents clean water from being introduced from the subsidiary block while introducing compressed air from the air supply pipe into the master block.

[20] According to yet another aspect of the invention for realizing the object, the invention provides a method of processing clean water in a dental unit chair, which includes a first step of recording a time and a duration of a circulating operation, inputted through an input unit, in a timer of a control unit; a second step of comparing the time of the circulating operation, recorded in the timer, with a current time, and if the time of the circulating operation is the same as the current time, transmitting a circulating operation start signal to a unit controller of the control unit; a third step in which, when the circulating operation start signal is received, the unit controller turns off a fourth valve and operates a circulation valve, thereby enabling the circulating operation, so that clean air in the water supply pipe and the circulation pipe circulates therethrough; a fourth step of comparing the duration of the circulating operation, recorded in the timer, with a time that has elapsed since the circulating operation start signal was transmitted, and if they are equal, transmitting a circulating operation end signal to the unit controller; and a fifth step in which, when the circulating operation end signal is received, the unit controller turns on the fourth valve and stops the circulation pump, thereby finishing the circulating operation.

Advantageous Effects

[21] According to the invention as set forth above, when the dental unit chair is not used for a long time period, the clean water processing system for a dental unit chair drains clean water from a water supply pipe of the dental unit chair through the water supply pipe or a handpiece at a specific time for a specific duration by using a three-way valve and handpiece-opening means, and fills the water supply pipe with compressed air, so that a biofilm is not formed on the inside wall of the water supply pipe connected to the handpiece of the unit chair.

[22] Furthermore, the clean water processing system for a dental unit chair of the present invention circulates clean water in the dental unit chair using a three-way valve and a circulation pump but drains clean water from a water supply pipe connected to a handpiece using the three-way valve and handpiece-opening means, so that a biofilm is not formed on the inside wall of the water supply pipe inside the dental unit chair or the water supply pipe connected to the handpiece. Brief Description of the Drawings

[23] FIG. 1 is a schematic view illustrating the construction of a clean water processing system for a dental unit chair according to a first embodiment of the invention;

[24] FIGS. 2 and 3 are a perspective view illustrating handpiece holders of the clean water processing system for the unit chair according to the first embodiment of the invention;

[25] FIG. 4 is a schematic view illustrating the construction of a clean water processing system for a dental unit chair according to a second embodiment of the invention;

[26] FIG. 5 is a schematic view illustrating the construction of a clean water processing system for a dental unit chair according to a third embodiment of the invention;

[27] FIG. 6 is a schematic view illustrating the construction of a clean water processing system for a dental unit chair according to a fourth embodiment of the invention;

[28] FIG. 7 is a perspective view illustrating a handpiece holder of the clean water processing system for the dental unit chair according to any of the second to fourth embodiments of the invention; and

[29] FIGS. 8 and 9 are schematic views illustrating a clean water processing system and a clean water processing method of a dental unit chair according to a fifth embodiment of the invention.

[30] <Major Reference Numerals of the Drawings>

[31] 100, 200, 300, 400, 700, 800: clean water processing system for a dental unit chair

[32] 110: water purifier 120: clean water pipe

[33] 130: handpiece 140: water supply pipe

[34] 145: air supply pipe 150: unit chair

[35] 160: master block

[36] 170, 270, 370, 375: three-way valve

[37] 180: input unit 190: control unit

[38] 191: timer 192: unit controller

[39] 30: handpiece holder 33: handpiece-opening means

Best Mode for Carrying Out the Invention

[40] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The present invention is not limited to the following embodiments, and may be realized by other embodiments. Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

[41] FIG. 1 is a schematic view illustrating the construction of a clean water processing system for a dental unit chair according to a first embodiment of the invention, and FIGS. 2 and 3 are a perspective view illustrating handpiece holders of the clean water processing system for the unit chair according to the first embodiment of the invention.

[42] Referring to FIGS. 1 to 3, the construction and operation of the clean water processing system for the dental unit chair according to the invention will be described below.

[43] The clean water processing system 100 for dental chairs includes a water purifier

110, a clean water pipe 120, handpieces 130, water supply pipes 140 and a unit chair 150. In addition, the clean water processing system 100 according to the present invention also has three-way valves 170, each of which is provided in a respective water supply pipe 140 of the unit chair 150, and handpiece holders 30, each of which has handpiece-opening means 33.

[44] The water purifier 110 purifies supply water drawn from an inlet pipe 10 and supplies purified water into the clean water pipe 120 through an outlet thereof. Here, the water purifier 110 serves to remove impurities (for example, rusty water, bacilli, microbes, etc.) from supply water. Preferably, the water purifier 110 includes a plurality of filters, a motor pump and a purification tank, and a typical purifier may be used as the water purifier 110.

[45] The clean water pipe 120 is connected to the outlet side of the water purifier 120.

Various dental treatment devices of the unit chair 150, particularly, the water supply pipes 140, for supplying water to the handpieces 130, are connected to the clean water pipe 120. The manner in which the water supply pipes 140 are connected corresponding clean water pipes 120 can be determined according to the number of unit chairs.

[46] Inside the unit chair 150, a master block 160, an input unit 180 and a control unit

190 are provided. In particular, each of the three-way valves 170 is provided on the respective water supply pipe 140.

[47] The master block 160 supplies clean water, introduced through the water supply pipe 140, to the handpiece 130. In this case, the master block 160 may be connected to an air supply pipe (not shown) to be supplied with air therefrom, so that clean water and air can be suitably regulated and supplied through the water supply pipe 140 and the air supply pipe connected to the handpiece 130.

[48] The three-way valve 170 is provided on the water supply pipe 140 inside the unit chair 150, between the master block 160 and the handpiece 130.

[49] The first and second ports of the three-way valve 170 are connected to the water supply pipe 140, and the third port of the three-way valve 170 is connected to the air supply pipe 145. That is, when the three-way valve 170 is on, the first and second ports are connected to each other to supply clean water into the water supply pipe 140. When the three-way valve 170 is off, the second and third ports are connected to each other to supply compressed air into the water supply pipe 140. When the three-way valve 170 is turned off, compression is actuated to supply compressed air into the water supply pipe 140. Here, compressed air, introduced into the water supply pipe 140, is exhausted to the outside through the handpiece 130. Thus, clean water can be drained from the water supply pipe 140, which is connected to the handpiece 130 of the unit chair 150.

[50] The air supply pipe 145, connected to the third port of the three-way valve 170, can be an air supply pipe that is connected to the master block 160.

[51] The control unit 190 controls the three-way valve 170 and the handpiece-opening means 33.

[52] Furthermore, in the present invention, the input unit 180 is connected to the control unit 190, such that a user or a manufacturer is able to input data for controlling the clean water processing system 100 using the input unit 180. The input unit 180 may be provided on the outer surface of the unit chair 150 or, alternatively, may be provided in a separate body. As a further alternative, the input unit 180 may be integrated with a central controller, such as a computer, rather than being provided in a separate body.

[53] Here, the control unit 190 can include a timer 191 and a unit controller 192. The timer 191 has functions of storing data (e.g., operation time and period of the handpiece-opening means), inputted into the input unit 180, and comparing an internal clock with the input data to transmit an operation start signal or an operation end signal to the unit controller 192. The unit controller 192 also serves to control the operation of the three-way valve 170 and the handpiece-opening means 33 in response to the operation start signal or the operation end signal of the timer 191.

[54] With specific reference to FIG. 2, the handpiece 130 connected to the unit chair 150 by a guide pipe is held in the handpiece holder 30. The water supply pipe 140 and the air supply pipe are provided inside the guide pipe.

[55] The handpiece holder 30 includes a body 31 , a plurality of holding portions 32, for holding handpieces, and the handpiece-opening means 33.

[56] When the three-way valve 170 is turned off and the handpiece-opening means 33 is operated to open the handpiece 130 under the control of the control unit 190, as mentioned above, compressed air is introduced into the water supply pipe 140, so that clean water is drained from the water supply pipe 140 through the handpiece 130. Thus, no biofilm is formed inside the water supply pipe 140, which is connected to the handpiece 130 of the unit chair 150.

[57] Meanwhile, as well as having the above-mentioned components, the clean water processing system 100 may further include a subsidiary power supply (not shown), having a battery, which operates when the supply of power to the system 100 is interrupted. Furthermore, the clean water processing system 100 may further include a water drain state indicating lamp (not shown) for indicating the state of the operation of draining clean water. The water drain state indicating lamp indicates the state in which the clean water processing system 100 is draining clean water or the state in which clean water has been completely drained from the unit chair 150.

[58] The operation of draining clean water using the clean water processing system 100 of the dental unit chair will be explained herein below.

[59] The user, that is, a dentist or a dental assistant, inputs the time at which the operation of the handpiece-opening means 33 is to be conducted and the duration for which it is operated using the input unit 180. The input data is recorded in the timer 191 of the control unit 190 (step 1). Here, the operation duration may be a period during which the dental unit chair is not in operation. Typically, the operation duration may be at lunch time, in the evening, at night, after the hospital is closed, or on a holiday of the hospital, when medical instruments are not used.

[60] Then, the timer of the control unit 190 compares the input time, at which the operation begins, with the current time. When the time of the internal clock of the timer, that is, the current time, corresponds to the operation beginning time, the timer 191 transmits an operation start signal to the valve controller 192 of the control unit 190 (step 2).

[61] When the operation start signal is received, the unit controller 192 turns on the three-way valve 170, and operates the handpiece-opening means 33 to open the handpiece 130. Here, compressed air is introduced into the water supply pipe 140 from the connected air supply pipe, thereby draining clean water from the water supply pipe 140 through the handpiece 130 (step 3).

[62] Subsequently, the timer 191 of the control unit 190 compares the input operation duration with the amount of time that has passed since the time at which the operation began. When the operation duration becomes equal to the amount of passed time, the timer 191 transmits an operation end signal to the valve controller 192 of the control unit 190 (step 4).

[63] Finally, when the operation end signal is received, the unit controller 192 operates the handpiece-opening means 33 to close the handpiece 130, thereby stopping clean water from being drained from the water supply pipe 140 (step 5). Here, clean water is completely drained from the water supply pipe 140, in which only compressed air remains. Therefore, the clean water processing system 100 can keep the inside of the water supply pipe 140 clean after the draining operation is ended, so that clean water can be supplied to a patient in a subsequent operation.

[64] The dental clean water processing system 100 can also perform step 6 and step 7. In step 6, the unit controller turns on the three-way valve 170, and operates the handpiece-opening means 33 to open the handpiece 130, thereby supplying clean water to the water supply pipe 140. In step 7, after the operation duration exceeds a predetermined period, the unit controller 192 operates the handpiece-opening means 33 to close the handpiece 130, thereby preventing clean water from being supplied to the water supply pipe 140. That is, the unit controller 192 receives a count signal through the timer 191, and, when it is time to use the unit chair (i.e., when it is the time that was inputted and stored by the user), fills the water supply pipe 140, connected to the handpiece 130 of the unit chair 150, with clean water. This results in a standby state, in which clean water is ready to be used in a medical treatment. In this case, the operation times and the operation durations in step 6 and step 7 above are already inputted in the control unit 190.

[65] FIG. 4 is a schematic view illustrating the construction of a clean water processing system for a dental unit chair according to a second embodiment of the invention.

[66] The clean water processing system 200 for a dental unit chair according to the second embodiment of the invention includes a three-way valve 270, which is provided in the water supply pipe 140 in the dental unit chair 150, between the clean water pipe 120 and the master block 160. Thus, when the three-way valve 270 is turned off, and the handpiece-opening means is operated to open the handpiece 130, clean water can be drained through the handpiece 130 from a predetermined section of the water supply pipe 140 that spans from a portion of the water supply pipe 140 connected to the three-way valve 270 to another portion of the water supply pipe 140 connected to the handpiece 130 of the unit chair 150. That is, in comparison with the first embodiment, the second embodiment of the invention makes it easier to drain clean water from the section of the water supply pipe 140 spanning from the portion connected to the clean water pipe 120 to the portion connected to the master block 160 inside the unit chair 150.

[67] Except for the above-mentioned features, the clean water processing system of this embodiment is substantially the same as the clean water processing system 100 of the first embodiment.

[68] FIG. 5 is a schematic view illustrating the construction of a clean water processing system for a dental unit chair according to a third embodiment of the invention.

[69] The clean water processing system 300 of a dental unit chair according to the third embodiment of the invention includes a first three-way valve 370 on the water supply pipe 140, between the clean water pipe 120 and the master block 160, and a second three-way valve 375 on the water supply pipe 140, between the master block 160 and the handpiece 130. Thus, when the first and second three-way valves 370 and 375 are turned off, and the handpiece-opening means 33 is operated to open the handpiece 130, clean water can be drained through the handpiece 130 from a predetermined section of the water supply pipe 140 that spans from a portion of the water supply pipe 140 connected to the first three-way valve 370 to another portion of the water supply pipe 140 connected to the handpiece 130 of the unit chair 150. That is, the third embodiment of the invention can drain a larger amount of clean water from the water supply pipe 140 using a greater amount of compressed air, in comparison to the first embodiment.

[70] Except for the above-mentioned features, the clean water processing system of this embodiment is substantially the same as the clean water processing system 100 of the first embodiment. Mode for the Invention

[71] FIG. 6 is a schematic view illustrating the construction of a clean water processing system for a dental unit chair according to a fourth embodiment of the invention.

[72] The construction of the clean water processing system 400 for a dental unit chair will be described with reference to FIG. 6. The clean water processing system 400 of the invention includes a clean water pipe 401 connected to a water purifier, which purifies raw water, a water supply pipe 410 connected to the clean water pipe 401, a master block 420 connected to the downstream end of the water supply pipe 410 (i.e., the end opposite the upstream end of the water supply pipe 400 connected to the clean water pipe 401), a first valve 430 provided in a predetermined portion of the water supply pipe (preferably, at a position near the upstream end of the water supply pipe 410), an air supply pipe 440 connected to the first valve 430, a subsidiary block 450 provided in a predetermined portion of the water supply pipe 410, positioned between the first valve 430 and the mater block 420, a water drain pipe 460 provided in the subsidiary block 450 and diverging from the water supply pipe 410, a second valve 470 provided in a predetermined portion of the water drain pipe 460, a third valve 480 provided in a portion of the water supply pipe 460 positioned between the subsidiary block 450 and the master block 420, and a control unit 490 for controlling the first, second and third valves.

[73] The clean water processing system 400 for a dental unit chair can also include a first pipe 510, which diverges from the water supply pipe 410 connected to the master block 420, and a handpiece 520 connected to the first pipe 510.

[74] As shown in FIG. 7, a handpiece holder 40 for holding the handpiece 520 can also be provided. The handpiece holder 40 includes a body 41, a plurality of holding portions 32, each of which holds a handpiece, and handpiece-opening means 43 for opening and closing the handpiece 520.

[75] The handpiece 520 is provided with its own opening means, such as a button, so that the handpiece 520 can be opened when the opening means 43 of the handpiece holder 40 pushes the button of the handpiece 520. [76] In the clean water processing system 400 for a dental unit chair, a division block

530 can also be provided in a predetermined portion of the water supply pipe 410, positioned between the first valve 430 and the subsidiary block 450. A second pipe 540, which diverges from the water supply pipe 410, can also be provided in the division block 530. The second pipe 540 serves to supply clean water to a three-way syringe (not shown), a dental appliance for receiving spittle (not shown) and an auto cup (not shown).

[77] The clean water processing system 400 for a dental unit chair can also include an input unit 550 and a display unit 560. Using the input unit 550, a user or a manufacturer can input the time when the clean water-draining operation of the dental unit chair is to be conducted, the duration of the draining operation, the time when the clean water- filling operation of the dental unit chair is to be conducted and the duration of the filling operation. The display unit 560 includes an indicator lamp, which indicates the draining state of the dental unit chair.

[78] Here, the time when the clean water-draining operation is to be conducted and the duration of the draining operation may be a period during which the dental unit chair is not used for a long time period. Typically, the draining operation may be at lunch time, in the evening, at night, after the hospital is closed, or on a holiday of the hospital, during which the dental unit chair is not used. In addition, the time when the filling operation is to be conducted and the duration of the filling operation can be the time after the time when the draining operation is to be conducted and the draining operation is completed, or a time period that it takes to completely fill the water supply pipe 410 with clean water.

[79] The time when the draining operation is to be conducted, the duration of the draining operation, the time when the filling operation is to be conducted and the duration of the filling operation can be set in advance by the manufacturer of the dental unit chair or can be inputted by the user as desired. In the case where the clean water- draining operation starts and ends and the clean water-filling operation starts and ends at the time when the filling operation is to be conducted, the display unit 560 can have a clean water drain state indicating lamp, which indicates the progress of the clean water-draining operation and the clean water-filling operation. (The clean water drain state indicating lamp can indicate the state in which clean water is being drained, the state in which clean water has been completely drained and the state in which clean water has been completely filled.)

[80] In addition, the clean water processing system 400 can further include a subsidiary power supply (not shown), which is separated from a main power supply of the unit chair. Since the draining operation of the dental unit chair is to be conducted when the dental unit chair has not been used for a long time, the subsidiary power supply can be used instead of the main power supply in order to prevent unnecessary power consumption. In addition, the clean water processing system can be freely operated even if main power is not supplied.

[81] The control unit 490 can also include a timer 492 for measuring time and a unit controller 494 for controlling the turning on and off of respective valves.

[82] The timer 492 can record the time when the draining operation is to be conducted, the duration of the draining operation, the time when the filling operation is to be conducted and the duration of the filling operation, which are inputted in the input unit 550. The timer 492 functions to transmit a clean water-draining operation start signal and a clean water-filling operation start signal to the unit controller 494 by comparing the current time with the time when the draining operation is to be conducted and the time when the filling operation is to be conducted. The timer 492 also functions to compare the time that has elapsed since the clean water-draining operation start signal was transmitted with the duration of the clean water-draining operation and the time that has elapsed since the clean water-filling operation start signal was transmitted with the duration of the clean water- filling operation, and if the corresponding durations are equal, transmits a clean water-draining operation end signal or a clean water-filling operation end signal to the unit controller 494. Preferably, at the same time, the timer 492 also transmits the above-mentioned signals to the indicator lamp of the display unit 560, and thereby controls the display unit 560, so that the indicator lamp indicates the current clean water draining state.

[83] When the clean water-draining operation start signal, the clean water-draining operation end signal, the clean water-filling operation start signal and the clean water- filling operation end signal are received from the timer, the unit controller 494 controls the state of the first valve 430, the second valve 470 and the third valve 480.

[84] The first valve 430 is a three-way valve, and in the turned-on state, acts to cut off compressed air, which is introduced from the air supply pipe 440, and provides a flow passage through which clean water is supplied from the clean water pipe 401 to the water supply pipe 410, which is connected to the subsidiary block 450. In the turned- off state, the first valve 430 acts to cut off clean water, which is introduced from the clean water pipe 401, and provides a flow passage through which compressed air is introduced from the air supply pipe 440 to the water supply pipe 410, which is connected to the subsidiary block 450. The first valve 430 can stay turned on while the dental unit chair operates normally (i.e., clean water is normally used by means of the handpiece or the like, and thus does not remain in the water supply pipe 410). At the time when the clean water-draining operation is to be conducted, which is recorded in the timer 492 of the control unit 490, the first valve 430 can be turned off by the unit controller 494 of the control unit 490, which received the clean water-draining operation start signal from the timer 492 of the control unit 490. Then, the first valve 430 can be turned on by the unit controller 494 of the control unit 490, which received the clean water-filling operation start signal, at the start of the clean water-filling operation.

[85] The second valve 470 can be provided in a predetermined portion of the water drain pipe 460, and can be used to drain clean water, through the water drain pipe 460, from a predetermined section of the water supply pipe 410 inside the unit chair (i.e., from a portion of the water supply pipe 410, where the first valve 440 is located, to another portion of the water supply pipe 410, where the subsidiary block 450 is located).

[86] The second valve 470 stays in a closed state while the dental unit chair is operating normally. When the clean water-draining operation or the clean water-filling operation is to be conducted, upon the arrival of the respective operation time, which is recorded in the control unit 490, the second valve 470 can be opened by the unit controller 494 of the control unit 490, which received the clean water-draining operation start signal or the clean water-filling operation start signal from the timer 492 of the control unit 490. Then, the second valve 470 can be closed by the unit controller 494 of the control unit 490, which received the clean water-draining operation end signal or the clean water- filling operation end signal, upon the completion of the duration of the clean water-draining operation or the duration of the clean water-filling operation.

[87] The third valve 480 is provided in a predetermined portion of the water supply pipe

410, positioned between the subsidiary block 450 and the master block 420. The third valve 480 can be used to drain clean water from substantially the entire water supply pipe 410 inside the dental unit chair (i.e., the entire water supply pipe 410 except for a predetermined section thereof, ranging from a portion connected to the clean water pipe 401 to another portion connected to the first valve 430), and be used to drain clean water from the first pipe 510, which diverges from the master block 420 and is connected to the handpiece 520.

[88] The third valve 480 can remain in an opened state in the case where the dental unit chair normally operates, or exit the opened state in the case where the clean water- draining operation or the clean water-filling operation is to be conducted at the arrival of the respective operation time, which is recorded in the timer 492 of the control unit. The third valve 480 can be closed by the unit controller 494 of the control unit 490, which received the clean water-draining operation end signal or the clean water-filling operation end signal, at the completion of the clean water-draining operation or the clean water- filling operation, which is recorded in the timer 492 of the control unit 490. (Alternatively, the unit controller 494, which received the clean water-draining operation end signal or the clean water-filling operation end signal, may keep the third valve 180 open because the third pipe 510 can be closed by the handpiece 520, which is located downstream of the water supply pipe 410.)

[89] Here, the opening means 43 of the handpiece holder 40, which holds the handpiece

520, can operate to open the handpiece 520 when the clean water-draining operation or the clean water-filling operation is to be conducted at the arrival of the respective operation time. The opening means 43 can also close the handpiece 520 under the control of the unit controller 494 of the control unit 490, which received the clean water-draining operation end signal or the clean water-filling end signal, at the termination of the respective operation time, which is recorded in the timer 492 of the control unit 490.

[90] Several embodiments of the operation of the clean water processing (draining) system will be described with reference to FIG. 7.

[91] As a first embodiment, a method of draining clean water from a predetermined section of the water supply pipe 410 using the first valve 430 and the second valve 470 will be described. Here, the predetermined section of the water supply pipe 410 ranges from a portion of the water supply pipe 410, where the first valve 430 is located, to another portion of the water supply pipe 410, where the subsidiary block 450 is located (or where the third valve is located).

[92] First of all, a user or a manufacturer inputs the time when the clean water-draining operation is to be conducted, the duration of the clean water-draining operation, the time when the clean water- filling operation is to be conducted and the duration of the clean water-filling operation, using the input unit 550.

[93] The inputted times and durations are recorded in the timer 492 of the control unit

490, and the current time is compared with the time when the clean water-draining operation is to be conducted or the time when the clean water-filling operation is to be conducted. If the current time corresponds to the time when the clean water-draining operation is to be conducted, a draining operation start signal is transmitted. If the current time corresponds to the time when the clean water-filling operation is to be conducted, a filling operation start signal is transmitted.

[94] After the transmission of the above-mentioned signals, if the time that has elapsed since the draining operation start signal was transmitted corresponds to the duration of the clean water-draining operation, which is recorded in the timer 492 of the control unit 490, a draining operation end signal is transmitted. If the time that has elapsed since the filling operation start signal was transmitted corresponds to the duration of the clean water-filling operation, recorded in the timer 492 of the control unit 490, a filling operation end signal is transmitted. Here, when the timer 492 of the control unit 490 transmits the draining operation start signal to the unit controller 494 of the control unit 490, it can also transmit a signal, indicating that the pipe is being cleaned, to the display unit 560, so that the indicator lamp of the display unit 560, which indicates the draining state of clean water, is turned on. This informs the user that clean water is being drained from the water supply pipe 410 of the dental unit chair, so that the handpiece 520 and the like of the dental unit chair are not used in the state in which clean water is being drained from the water supply pipe 410.

[95] These signals are sequentially transmitted in the order of the clean water-draining operation start signal, the clean water-draining operation end signal, the clean water- filling operation start signal and the clean water-filling operation end signal. This is because clean water is required to be drained from the water supply pipe 410 in the case where the dental unit chair will not be used for a predetermined time period, and then to be filled into the water supply pipe 410 when the dental unit chair is to be used again.

[96] When the unit controller 494 of the control unit 490 receives the draining operation start signal, it turns off the first valve 430 (which is in the turned-on state in the case where the dental unit chair is used normally) and opens the second valve 470 (which is in the closed state in the case where the dental unit chair is used normally), thereby draining clean water from the water supply pipe 410 through the water drain pipe 460.

[97] When the draining operation has been carried out for a predetermined period, the duration of the draining operation, recorded in the timer 492 of the control unit 490, is compared with the time that has elapsed since the draining operation start signal was transmitted. If the duration of the draining operation corresponds to the time that has elapsed since the draining operation start signal was transmitted, the timer 492 of the control unit 490 transmits a draining operation end signal to the unit controller 494.

[98] The unit controller 494 of the control unit 490, which received the draining operation end signal, closes the second valve 470, thereby finishing the draining operation. Here, it is required that the first valve 430 stay in the turned-off state because clean water can be introduced into the water supply pipe 410 from the clean water pipe 401 if the first valve 430 is turned on.

[99] Accordingly, the control unit 490 compares the current time with the time when the clean water- filling operation is to be conducted, recorded in the timer 492, and if the current time corresponds to the time when the clean water-filling operation is to be conducted, transmits a filling operation start signal to the unit controller 494 of the control unit 490.

[100] The unit controller 494, which received the filling operation start signal, carries out the clean water-filling operation by turning on the first valve 430 and opening the second valve 470, so that clean water flows through the water supply pipe 410.

[101] When the clean water-filling operation has been carried out for a predetermined period, the unit controller 494 receives the filling operation end signal, and then finishes the clean water-filling operation by closing the second valve 470 and opening the third valve 480.

[102] Accordingly, when the dental unit chair is not used for a predetermined period, the invention can carry out the clean water-draining operation and the clean water-filling operation as above in order to drain clean water from the water supply pipe 410, thereby preventing clean water from remaining therein, so that a biofilm is not formed on the inside wall of the water supply pipe 410.

[103] As a second embodiment, a method of draining clean water from a predetermined section of the water supply pipe 410 and the first pipe 510 will be described. Here, the predetermined section of the water supply pipe 410 ranges from a portion of the water supply pipe 410, where the first valve 430 is located, to another portion of the water supply pipe 410, where the subsidiary block 450 is located (or where the third valve is located), and the first pipe 510 diverges from the master block 420 and is connected to the handpiece 520.

[104] First of all, a user or a manufacturer inputs the time when the clean water-draining operation is to be conducted, the duration of the clean water-draining operation, the time when the clean water- filling operation is to be conducted and the duration of the clean water-filling operation, using the input unit 550.

[105] The inputted times and durations, inputted by the user or the manufacturer, are recorded in the timer 492 of the control unit 490, and the timer, which stores the inputted times and durations, compares the current time with the time when the clean water-draining operation is to be conducted or the time when the clean water-filling operation is to be conducted. If the current time corresponds to the time when the clean water-draining operation is to be conducted, a draining operation start signal is transmitted. If the current time corresponds to the time when the clean water-filling operation is to be conducted, a filling operation start signal is transmitted.

[106] After the transmission of the above-mentioned signals, if the time that has elapsed since the draining operation start signal was transmitted corresponds to the duration of the clean water-draining operation, which is recorded in the timer 492 of the control unit 490, a draining operation end signal is transmitted. If the time that has elapsed since the filling operation start signal was transmitted corresponds to the duration of the clean water-filling operation, recorded in the timer 492 of the control unit 490, a filling operation end signal is transmitted. Here, when the timer 492 of the control unit 490 transmits the draining operation start signal to the unit controller 494 of the control unit 490, it also transmits a signal, indicating that the pipe is being cleaned, to the display unit 560, so that the indicator lamp of the display unit 560, which indicates the draining state of clean water, is turned on. This informs the user that clean water is being drained from the water supply pipe 410 of the dental unit chair, so that the handpiece 520 and the like of the dental unit chair are not used in the state in which clean water is being drained from the water supply pipe 410.

[107] Typically, these signals are sequentially transmitted in the order of the clean water- draining operation start signal, the clean water-draining operation end signal, the clean water-filling operation start signal and the clean water-filling operation end signal. This is because clean water is required to be drained from the water supply pipe 410 in the case where the dental unit chair will not be used for a predetermined time period, and then to be filled into the water supply pipe 410 when the dental unit chair is to be used again.

[108] When the unit controller 494 of the control unit 490 receives the draining operation start signal, it turns off the first valve 430, opens the third valve 480, and opens the handpiece 520 using the opening means 43 of the handpiece holder 40, thereby draining clean water from the water supply pipe 410 and the first pipe 510 through the handpiece 520.

[109] When the draining operation has been carried out for a predetermined period, the duration of the draining operation, recorded in the timer 492 of the control unit 490, is compared with the time that has elapsed since the draining operation start signal was transmitted. If the duration of the draining operation corresponds to the time that has elapsed since the draining operation start signal was transmitted, the timer 492 of the control unit 490 transmits a draining operation end signal to the unit controller 494.

[110] The unit controller 494 of the control unit 490, which received the draining operation end signal, closes the second valve 470, thereby finishing the draining operation. (While the third valve 480 may be closed or not, it is preferably kept open so as to minimize the operation of the valve.) Here, it is required that the first valve 430 stay in the turned-off state because clean water can be introduced into the water supply pipe 410 from the clean water pipe 401 if the first valve 430 is turned on.

[I l l] In the dental unit chair, the handpiece 520 can be used only when the water supply pipe 410 and the first pipe 510 are filled with clean water.

[112] Accordingly, the control unit 490 compares the current time with the time when the clean water- filling operation is to be conducted, recorded in the timer 492 of the control unit 490, and if the current time corresponds to the time when the clean water- filling operation is to be conducted, transmits a filling operation start signal to the unit controller 494 of the control unit 490.

[113] The unit controller 494, which received the filling operation start signal, carries out the clean water-filling operation by turning on the first valve 430 and opening the handpiece 520, so that clean water flows through the water supply pipe 410 and the first pipe 510. (Here, it is required that the third valve 480 be opened if it is closed when the clean water-draining operation is finished.)

[114] When the unit controller 494 receives the filling operation end signal after the clean water-filling operation has been carried out for the predetermined period, it applies an operation signal to the opening means to close the handpiece 520, thereby finishing the clean water-filling operation.

[115] Accordingly, when the dental unit chair is not used for a predetermined period, the invention can carry out the clean water-draining operation and the clean water-filling operation as above in order to drain clean water from the water supply pipe 410 and the first pipe 510, thereby preventing clean water from remaining therein, so that a biofilm is not formed on the inside wall of the water supply pipe 410 or the first pipe 510.

[116] Furthermore, the invention can carry out the clean water-draining operation and the clean water-filling operation by combining the first and second embodiments. That is, the clean water-draining operation can be carried out by turning off the first valve 440, opening the first and third valves 470 and 480, and opening the hand piece 520, thereby draining clean water from the water supply pipe 410 and the first pipe 510 through the water drain pipe 460 and the handpiece 520. Then, the clean water- draining operation can be finished by closing the second valve 470 and the handpiece 520.

[117] The clean water-filling operation can be carried out by turning on the first valve 430 and opening the second valve 470 and the handpiece 520, so that clean water flows through the water supply pipe 410 and the first pipe 510. Then, the clean water- filling operation can be finished by closing the handpiece 520 and the second valve 470.

[118] The above-mentioned embodiments have been described only with respect to the operations of draining clean water from and filling clean water into the water supply pipe 410, which is connected to the master block 420, and the first pipe 510. When these embodiments are slightly modified, clean water can be drained from or filled into the second pipe 540 connected to the division block 530. That is, the division block 530 can be connected to a three-way syringe, a tap of a dental appliance for receiving spittle (not shown) and an auto cup, an auto cup tap or the like. An intermediate valve, which controls the opening or closing of the second pipe 540, can be provided in an intermediate portion of the second pipe 540, so that clean water can be drained from or charged into the second pipe 540.

[119] That is, the clean water-draining operation is carried out by turning off the second valve 430 and opening the intermediate valve of the second pipe 540, and is finished by closing the intermediate valve of the second pipe 540. Conversely, the clean water- filling operation is carried out by turning on the first valve 430 and opening the intermediate valve of the second pipe 540, and is finished by closing the intermediate valve. Accordingly, the invention can realize operations similar to those of the first and second embodiments in order to prevent a biofilm from forming on the inside wall of the second pipe 540 as in the water supply pipe 410. [120] FIGS. 8 and 9 are schematic views illustrating a clean water processing system and a clean water processing method of a dental unit chair according to a fifth embodiment of the invention.

[121] The construction of the clean water processing system 800 of the invention will be described with reference to FIGS. 8 and 9. The clean water processing system 800 of the invention includes a clean water pipe 701 connected to a water purifier, which purifies raw water, a water supply pipe 710 connected to the clean water pipe 701, and a master block 720 connected to the downstream end of the water supply pipe 710 (i.e., the end opposite the upstream end of the water supplying pipe 710, connected to the water supply pipe 701). In the clean water processing system 800, a subsidiary block 730 is provided in a predetermined portion of the water supply pipe 710, positioned between the master block 720 and the starting point of the water supply pipe 710. A circulation pipe 740, which diverges from the water supply pipe 710, is provided in the subsidiary block 730. A fourth valve 750 is connected to the circulation valve 740, and is provided in a predetermined portion of the water supply pipe 710, positioned between the subsidiary block 730 and the starting point of the water supply pipe 710. A circulation pump 760 is provided at a predetermined position on the circulation pipe 740. In the clean water processing system 800, a control unit 770 controls the fourth valve 750 and the circulation pump 760.

[122] The clean water processing system 800 can also include a fifth valve 780, which is provided at a predetermined position on the water supply pipe 710, located between the subsidiary block 730 and the master block 720, and an air supply pipe 790 connected to the fifth valve 780.

[123] Here, the clean water processing system 800 can also include a first pipe 810, which diverges from the water supply pipe 710 connected to the master block 720, and a handpiece 820 connected to the first pipe 810. Although not shown in FIG. 8 or 9, a handpiece holder for holding the handpiece 820 can be provided. The handpiece holder can have opening means, which can open and close the handpiece 820.

[124] In the clean water processing system 800, a division block 830 can be provided in a predetermined portion of the water supply pipe 710, positioned between the fourth valve 750 and the subsidiary valve 730. A second pipe 840, which diverges from the water supply pipe 710, can also be provided in the division block 830. The second pipe 840 serves to supply clean water to a three-way syringe (not shown), a dental appliance for receiving spittle (not shown) and an auto cup (not shown).

[125] The clean water processing system 800 for a dental unit chair can also include an input unit 850 and a display unit 860. Using the input unit 850, a user or a manufacturer can input the time when the clean water-circulating operation of the dental chair is to be conducted, the duration of the circulating operation, the time when the clean water-draining operation of the dental unit chair is to be conducted, the duration of the draining operation, the time when the water- filling operation of the dental unit chair is to be conducted and the duration of the filling operation. The display unit 860 includes an indicator lamp, which indicates the clean water processing state of the dental unit chair.

[126] Here, the time when the clean water-circulating operation is to be conducted, the duration of the circulating operation, the time when the clean water-draining operation of the dental unit chair is to be conducted and the duration of the draining operation may be a period when the dental unit chair is not used for a long time. Typically, the draining operation may be at lunch time, in the evening, at night, after the hospital is closed, or on a holiday of the hospital, during which the dental unit chair is not used. In addition, the time when the filling operation is to be conducted and the duration of the filling operation can be a time after the time when the draining operation is to be conducted and the draining operation are completed, or a period during which the first pipe 810 is completely filled with clean water.

[127] The time when the circulating operation is to be conducted, the duration of the circulating operation, the time when the draining operation is to be conducted, the duration of the draining operation, the time when the filling operation is to be conducted and the duration of the filling operation can be previously set by the manufacturer of the dental unit chair, or can be desirably inputted by the user. In the case where the clean water-circulating operation starts and ends at the time when the circulating operation is to be conducted, and the clean water-draining operation starts and ends at the time when the filling operation is to be conducted, the display unit 860 can have a clean water drain state indicating lamp, which can indicate the progress of the clean water-circulating operation, the clean water-draining operation and the clean water-filling operation. (The clean water drain state indicating lamp can indicate the state in which clean water is being circulated, the state in which clean water is being drained, the state in which clean water has been completely drained and the state in which clean water has been completely supplied.)

[128] The control unit 770 can include a timer 772 and a unit controller 774.

[129] The timer 772 can record the time when the circulating operation is to be conducted, the duration of the circulating operation, the time when the draining operation is to be conducted, the duration of the draining operation, the time when the filling operation is to be conducted and the duration of the filling operation, which are inputted in the input unit 850. The timer 772 has a function of transmitting a clean water-circulating operation start signal, a clean water-draining operation start signal and a clean water-filling operation start signal to the unit controller 774 by comparing the current time with the time when the circulating operation is to be conducted, the time when the draining operation is to be conducted and the time when the filling operation is to be conducted. The timer 772 also functions to by compare the time that has elapsed since the clean water-circulating operation start signal was transmitted with the duration of the clean water-circulating operation, the time that has elapsed since the clean water-draining operation start signal was transmitted with the duration of the clean water-draining operation, and the time that has elapsed since the clean water- filling operation start signal was transmitted with the duration of the clean water- filling operation, and if the time spans are equal to the corresponding durations, to transmit a clean water-circulating operation end signal, a clean water-draining operation end signal or a clean water-filling operation end signal, respectively, to the unit controller 774. At the same time, the timer 772 also transmits the above- mentioned signals to the indicator lamp of the display unit 860, and thereby controls the display unit 860, so that the indicator lamp indicates the current processing state.

[130] When the clean water-circulating operation start signal, the clean water-draining operation start signal, the clean water-draining operation end signal, the clean water- filling operation start signal and the clean water-filling operation end signal are received from the timer 772, the unit controller 774 controls the state and the operation of the fourth valve 750, the fifth valve 780 and the circulation pump 760.

[131] The fourth valve 750 is a three-way valve, and, in the turned-on state, acts to cut off clean water, which is introduced from the circulation pipe 740, and provides a flow passage through which clean water is supplied from the clean water pipe 701 to the water supply pipe 710, which is connected to the subsidiary block 730. In the turned- off state, the fourth valve 750 acts to cut off the flow of clean water, which is introduced from the clean water pipe 701, and provides a flow passage by which clean water is introduced from the air circulation pipe 740 to the water supply pipe 710, which is connected to the subsidiary block 730. The fourth valve 750 can stay in the turned-on state while the dental unit chair operates normally (i.e., clean water is normally used by means of the handpiece or the like, and thus does not remain in the water supply pipe 710). When the clean water-circulating operation is to be conducted at the corresponding time, which is recorded in the timer 772 of the control unit 770, the fourth valve 750 can be turned off by the unit controller 774 of the control unit 770, which received the clean water-circulating operation start signal from the timer 492 of the control unit 490, or can be turned on by the unit controller 774 of the control unit 770, which received the clean water-circulating operation end signal from the timer 492 of the control unit 490.

[132] The fourth valve 780 is provided in a predetermined portion of the water supply pipe 710, positioned between the subsidiary block 730 and the master block 720, and is used to drain clean water from the first pipe 810, which diverges from the master block 720 and is connected to the hand piece.

[133] The function of the fifth valve 780 and a method of draining clean water using the fifth valve 780 are substantially the same as the method of draining clean water through the handpiece, which was explained in the fourth embodiment of the invention.

[134] Referring to FIG. 8, an embodiment for processing clean water in the pipe of the dental unit chair by performing the clean water-circulating operation will be described below.

[135] This embodiment relates to a method of processing clean water from a predetermined section of the water supply pipe 710 using the fourth valve 750 and the circulation pump 760, so that a biofilm is not formed on the inside wall of the pipe of the dental unit chair. Here, the predetermined section of the water supply pipe 710 ranges from a portion of the water supply pipe 710, where the fourth valve 750 is located, to another portion of the water supply pipe 710, where the subsidiary block 730 is located.

[136] First of all, a user or a manufacturer inputs the time when the clean water- circulating operation is to be conducted and the duration of the circulating operation using the input unit 850.

[137] The time and the duration are recorded in the timer 772 of the control unit 770, and the current time is compared with the time when the clean water-circulating operation is to be conducted. If the current time corresponds to the time when the clean water- circulating operation is to be conducted, a circulating operation start signal is transmitted.

[138] After the transmission of the circulating operation start signal, if the time that has elapsed since the circulating operation start signal was transmitted corresponds to the duration of the clean water-circulating operation, which is recorded in the timer 772 of the control unit 770, a circulating operation end signal is transmitted. Here, when the timer 772 of the control unit 770 transmits the circulating operation start signal to the unit controller 774 of the control unit 770, it also transmits a signal, indicating that clean water is being circulated, to the display unit 860, so that the indicator lamp of the display unit 860, which indicates the processing state of clean water, is turned on. This informs the user of the clean state of water in the water supply pipe 710 of the dental unit chair, meaning that clean water is being circulated in the water supply pipe 710 of the dental unit chair.

[139] When the unit controller 774 of the control unit 770 receives the circulating operation start signal, it turns off the fourth valve 750 (which is in the turned-on state in the case where the dental unit chair is used normally) and operates the circulation pump 760 (which is stopped in the case where the dental unit chair is used normally), thereby circulating clean water through the water supply pipe 710 and the circulation pipe 740.

[140] When the circulating operation has been carried out for a predetermined period, the duration of the circulating operation, recorded in the timer 772 of the control unit 770, is compared with the time that has elapsed since the circulating operation start signal was transmitted. If the duration of the circulating operation corresponds to the time that has elapsed since the circulating operation start signal was transmitted, the timer 772 of the control unit 770 transmits a circulating operation end signal to the unit controller 774.

[141] When the circulating operation end signal is received, the unit controller 774 of the control unit 770 turns on the fourth valve 770 and stops the circulation valve 760, thereby finishing the clean water-circulating operation.

[142] Accordingly, when the dental unit chair is not used for a predetermined period, the invention enables the clean water-circulating operation to be carried out as described above in order to prevent clean water from remaining in the water supply pipe 710, so that a biofilm is not formed on the inside wall of the water supply pipe 710.

[143] Referring to FIG. 9, an embodiment of processing clean water in the pipe of the dental unit chair by performing the clean water-circulating operation and the clean water-draining operation will be described below.

[144] This embodiment relates to a method of processing clean water using the fourth valve 750, the fifth valve 780 and the circulation pump 760, so that a biofilm is not formed on the inside wall of the pipe of the dental unit chair. Here, this method circulates clean water in a predetermined section of the water supply pipe 710, which ranges from a portion of the water supply pipe 710, where the fourth valve 750 is located, to another portion of the water supply pipe 710, where the subsidiary block 730 is located, but drains clean water from the first pipe 810, which diverges from the master block 720.

[145] Here, since the method of circulating clean water in the section of the water supply pipe 710, which ranges from the fourth valve 750 to the subsidiary block 730, is substantially the same as that of the former embodiment, which was explained with reference to FIG. 8, a detailed description thereof will be omitted. Accordingly, the method of processing clean water, that is, the operation of draining clean water from the first pipe 810, which diverges from the master block 720, will be mainly described.

[146] First of all, a user or a manufacturer inputs the time when the clean water-draining operation is to be conducted and the duration of the circulating operation using the input unit 850. (Here, the time when the clean water-circulating operation is to be conducted and the duration of the circulating operation in the former embodiment can also be inputted at the same time.) [147] The time(s) and the duration(s) are recorded in the timer 772 of the control unit 770, and the current time is compared with the time when the clean water-draining operation is to be conducted. If the current time corresponds to the time when the clean water-draining operation is to be conducted, a draining operation start signal is transmitted. (The circulating operation start signal, explained in the former embodiment, can also be transmitted at the same time.)

[148] After the transmission of the draining operation start signal, if the time that has elapsed since the draining operation start signal was transmitted corresponds to the duration of the clean water-draining operation, which is recorded in the timer 772 of the control unit 770, a draining operation end signal is transmitted. (The clean water- circulating operation end signal explained in the former embodiment of FIG. 8 can also be transmitted at the same time.)

[149] Here, when the timer 772 of the control unit 770 transmits the draining operation start signal to the unit controller 774 of the control unit 770, it can also transmit a signal, indicating that clean water is being drained, to the display unit 860, so that the indicator lamp of the display unit 860, which indicates the processing state of clean water, is turned on. This informs the user of the state of clean water in the water supply pipe 710 of the dental unit chair, in which clean water has been drained from the water supply pipe 710 of the dental unit chair.

[150] When the unit controller 774 of the control unit 770 receives the draining operation start signal, it turns off the fifth valve 780 (which is in the turned-on state when the dental unit chair is used normally) and operates the opening means of the handpiece holder, by which the handpiece 820 is held, thereby opening the handpiece 820. This interrupts clean water, which is introduced from the water supply pipe 710, adjacent to the subsidiary block 730 connected to the fifth valve 780, to the master block 720, but compressed air is introduced from the air supply pipe 790 to the master block 720, so that clean water is drained from the first pipe 810 through the handpiece 820. (Clean water in the section of the water supply pipe 710 ranging from the fourth valve 750 to the subsidiary block 730 can be circulated by the clean water-circulating operation, which was explained in the former embodiment with reference to FIG. 8.)

[151] After the draining operation has been carried out for a predetermined period, the duration of the draining operation, recorded in the timer 772 of the control unit 770, is compared with the time that has elapsed since the draining operation start signal was transmitted. If the duration of the draining operation corresponds to the time that has elapsed since the draining operation start signal was transmitted, the timer 772 of the control unit 770 transmits a draining operation end signal to the unit controller 774.

[152] When the draining operation end signal is received, the unit controller 774 of the control unit 770 finishes the clean water-draining operation by closing the handpiece 820 (but the fifth valve 780 remains in the turned-off state). (The clean water- circulating operation, which was explained with reference to FIG. 8, can also be finishe d by turning on the fourth valve 770 and stopping the circulation valve 760 in response to the received circulating operation end signal.)

[153] Accordingly, when the dental unit chair is not used for a predetermined period, the invention enables the clean water-draining operation to be carried out as described above in order to prevent clean water from remaining in the first pipe 810, so that a biofilm is not formed on the inside wall of the first pipe 810.

[154] Since clean water is drained from the first pipe 810, on which the clean water- draining operation is completely performed, it is required that the first pipe 810 be filled with clean water again so that the dental unit chair can be used again.

[155] Accordingly, the current time is compared with the time when the clean water- filling operation is to be conducted, recorded in the timer 772 of the control unit 770, and if the current time corresponds to the time when the clean water- filling operation is to be conducted, a filling operation start signal is transmitted to the unit controller 774 of the control unit 770.

[156] When the filling operation start signal is received, the unit controller 774 carries out the clean water-filling operation by turning on the fifth valve 780 and opening the handpiece 820, so that clean water flows through the first pipe 810.

[157] When a filling operation end signal is received after the clean water-filling operation has been carried out for a predetermined period, the unit controller 774 of the control unit 770 finishes the clean water-filling operation by closing the handpiece 820.

[158] Accordingly, when the dental unit chair has not been used for a predetermined period, the fifth embodiment of the invention can carry out both the circulating operation and the draining operation. The circulating operation is carried out in the section of the water supply pipe 710, ranging from the fourth valve 750 to the subsidiary block 730, using the fourth valve 750, the circulation valve 740 and the circulation pump 760. The draining operation is carried out in the section of the water supply pipe 710, ranging from the fifth valve 780 to the master block 720, and the first pipe 810 using compressed air, which is introduced from the fifth valve 780 and the air supply pipe 790. As a result, a biofilm or the like is not formed on the inside wall of the pipe of the dental unit chair.

[159] While the present invention has been described with reference to the particular illustrative embodiments and the accompanying drawings, it is not to be limited thereto, but will be defined by the appended claims. It is to be appreciated that those skilled in the art can substitute, change or modify the embodiments in various forms without departing from the scope and spirit of the present invention. Industrial Applicability The invention can be used for dental surgery, in which a clean water processing system for a dental unit chair is used. The invention drains clean water from the unit chair or circulates clean water in the unit chair using the three-way valve or the like, so that a biofilm is not formed on the inside wall of the water supply pipe portion in the unit chair or the water supply pipe portion connected to the handpiece.

Claims

[1] A clean water processing system for a dental unit chair, comprising: a handpiece for draining clean water, which is supplied from a water purifier, and air; a water supply pipe for supplying clean water from a clean water pipe to the handpiece; a master block provided on the water supply pipe, the master block supplying clean water from the clean water pipe to the handpiece; a valve provided on the water supply pipe and connected to an air supply pipe; and a control unit for controlling the valve and the handpiece when clean water supplied into the water supply pipe from the water purifier is not drained for a predetermined time period, so that clean water is drained through the handpiece from the water supply pipe. [2] The clean water processing system according to claim 1, wherein the valve is a three-way valve, which, in a turned-on state, prevents compressed air from being introduced from the air supply pipe while introducing clean water from the water purifier into the water supply pipe, and in a turned-off state, prevents clean water from being introduced from the clean water pipe while introducing compressed air from the air supply pipe into the water supply pipe. [3] The clean water processing system according to claim 2, wherein the handpiece is opened when the valve is in the turned-off state. [4] The clean water processing system according to claim 2, wherein the valve is provided on the water supply pipe at a position between the master block and the handpiece. [5] The clean water processing system according to claim 2, wherein the valve is provided on the water supply pipe at a position between the clean water pipe and the master block. [6] The clean water processing system according to claim 2, wherein the valve is provided on the water supply pipe at a position between the clean water supply pipe and the master block and between the master block and the handpiece. [7] The clean water processing system according to claim 1, further comprising a handpiece holder for holding the handpiece, the handpiece holder including opening means for opening or closing the handpiece. [8] The clean water processing system according to claim 7, wherein the control unit includes: a timer for comparing a previously-inputted time with a current time; and a unit controller for controlling operation of the valve and the opening means of the handpiece holder in response to a signal from the timer.

[9] The clean water processing system according to claim 8, further comprising an input unit connected to the control unit, wherein the input unit allows a user or a manufacturer to input a time and a duration.

[10] The clean water processing system according to claim 8 or 9, further comprising an indicator lamp connected to the control unit, the indicator lamp displaying a clean water-draining state of the water supply pipe.

[11] A method of processing clean water in a dental unit chair, comprising: a first step of recording a time and a duration of handpiece-opening means (33), which are inputted by an input unit (180) in a timer of a control unit; a second step of comparing the time, recorded in the timer, with a current time, and if the time is the same as the current time, transmitting an operation start signal to a unit controller; a third step in which, when the operation start signal is received, the unit controller turns off a three-way valve (170) to introduce compressed air while operating the handpiece-opening means (33) to open the handpiece (130), thereby draining clean water from a water supply pipe (140) through the handpiece (130); a fourth step of comparing the duration, recorded in the timer, with a duration that has elapsed since the operation start signal was transmitted, and if the durations are equal, transmitting an operation end signal to the unit controller; and a fifth step in which, when the operation end signal is received, the unit controller operates the handpiece-opening means (33) to close the handpiece

(130), thereby finishing the draining clean water.

[12] The method according to claim 11, further comprising: a sixth step in which the unit controller turns on the three-way valve (170) and operates the handpiece-opening means (33) to open the handpiece (130), thereby supplying clean water into the water supply pipe (140); and a seventh step in which the unit controller operates the handpiece-opening means to close the handpiece (130), thereby stopping the supplying clean water into the water supply pipe (140).

[13] A clean water processing system for a dental unit chair, comprising: a water supply pipe connected to a clean water pipe; a master block connected to a downstream end of the water supply pipe; a first valve provided on the water supply pipe and connected to an air supply pipe; a subsidiary block provided on the water supply pipe, in a position between the first valve and the master block; a water drain pipe diverging from the subsidiary block; a second valve provided on the water drain pipe; a third valve provided on the water supply pipe at a position between the subsidiary block and the master block; and a control unit for controlling the first to third valves, wherein the control unit controls the first to third valves to introduce compressed air from the air supply pipe into the water supply pipe, thereby draining clean water from the water supply pipe through the water drain pipe. [14] The clean water processing system according to claim 13, wherein the valve is a three-way valve, which, in a turned-on state, prevents compressed air from being introduced from the air supply pipe while introducing clean water from the clean water pipe into the subsidiary block, and in a turned-off state, prevents clean water from being introduced from the clean water pipe while introducing compressed air from the air supply pipe into the subsidiary block. [15] The clean water processing system according to claim 14, wherein clean water is drained in a state where the first valve is turned off, the second valve is opened, and the third valve is closed. [16] The clean water processing system according to claim 14, wherein clean water is drained in a state where the first valve is turned off, the second valve is closed, and the third valve is opened. [17] The clean water processing system according to claim 13 or 14, further comprising: a handpiece diverging from and connected to the master block; and a handpiece holder for holding the handpiece, the handpiece holder including opening means for opening or closing the handpiece. [18] The clean water processing system according to claim 13 or 14, further comprising an input unit connected to the control unit, wherein the input unit allows a user or a manufacturer to input a time and a duration. [19] The clean water processing system according to claim 13 or 14, further comprising an indicator lamp connected to the control unit, the indicator lamp displaying a clean water-draining state of the water supply pipe. [20] The clean water processing system according to claim 13 or 14, wherein the control unit includes: a timer for comparing a previously-inputted time with a current time; and a unit controller for controlling operation of the first to third valves in response to a signal from the timer. [21] A method of processing clean water in a dental unit chair, comprising: a first step of recording a time and a duration of a draining operation, inputted through an input unit, in a timer of a control unit; a second step of comparing the time of the draining operation, recorded in the timer, with a current time, and if the time of the draining operation is the same as the current time, transmitting a draining operation start signal to a unit controller of the control unit; a third step in which, when the draining operation start signal is received, the unit controller turns off a first valve, opens a second valve, and closes a third valve, thereby draining clean water from a water supply pipe through a water drain pipe; a fourth step of comparing the duration of the draining operation, recorded in the timer, with a duration that has elapsed since the draining operation start signal was transmitted, and if the durations are equal, transmitting a draining operation end signal to the unit controller; and a fifth step in which, when the draining operation end signal is received, the unit controller closes the second valve to finish the draining operation.

[22] The method according to claim 21, further comprising: a sixth step of recording a time and a duration of a filling operation, received through the input unit, in the timer of the control unit; a seventh step of comparing the time of the filling operation, recorded in the timer, with a current time, and if the time of the filling operation is the same as the current time, transmitting a filling operation start signal to the unit controller of the control unit; an eighth step in which, when the filling operation start signal is received, the unit controller turns on the first valve and opens the second valve, thereby enabling the filling operation, so that clean water flows through the water supply pipe; a ninth step of comparing the duration of the filling operation, recorded in the timer, with a duration that has elapsed since the filling operation start signal was transmitted, and if the durations are equal, transmitting a filling operation end signal to the unit controller; and a tenth step in which, when the filling operation end signal is received, the unit controller closes the second valve and opens the third valve, thereby finishing the filling operation.

[23] A method of processing clean water in a dental unit chair, comprising: a first step of recording a time and a duration of a draining operation, inputted through an input unit, in a timer of a control unit; a second step of comparing the time of the draining operation, recorded in the timer, with a current time, and if the time of the draining operation is the same as the current time, transmitting a draining operation start signal to a unit controller of the control unit; a third step in which, when the draining operation start signal is received, the unit controller turns off a first valve and opens a third valve and a handpiece, thereby draining clean water from a water supply pipe through the handpiece; a fourth step of comparing the duration of the draining operation, recorded in the timer, with a duration that has elapsed since the draining operation start signal was transmitted, and if the durations are equal, transmitting a draining operation end signal to the unit controller; and a fifth step in which, when the draining operation end signal is received, the unit controller closes the hand piece, thereby finishing the draining operation.

[24] The method according to claim 23, further comprising: a sixth step of recording a time and a duration of a filling operation, inputted through the input unit, in the timer of the control unit; a seventh step of comparing the time of the filling operation, recorded in the timer, with a current time, and if the time of the filling operation is the same as the current time, transmitting a filling operation start signal to the unit controller of the control unit; an eighth step in which, when the filling operation start signal is received, the unit controller turns on the first valve and opens the third valve and the handpiece, thereby enabling the filling operation, so that clean water flows through the water supply pipe; a ninth step of comparing the duration of the filling operation, recorded in the timer, with a duration that has elapsed since the filling operation start signal was received, and if the durations are equal, transmitting a filling operation end signal to the unit controller; and a tenth step in which, when the filling operation end signal is received, the unit controller closes the handpiece, thereby finishing the filling operation.

[25] A clean water processing system for a dental unit chair, comprising: a water supply pipe connected to a clean water pipe; a subsidiary block provided on the water supply pipe; a circulation pipe diverging from the subsidiary block and connected to the water supply pipe at a position between the clean water pipe and the subsidiary block; a fourth valve connecting the water supply pipe to the circulation pipe; a circulation pump provided on the circulation pipe; and a control unit for controlling a fourth valve and the circulation pump, wherein the control unit controls the fourth valve and the circulation pump, so that clean water introduced from the clean water pipe circulates through the water supply pipe and the circulation pipe.

[26] The clean water processing system according to claim 25, wherein the fourth valve is a three-way valve, which, in a turned-on state, prevents clean water from being introduced from the circulation pipe while introducing clean water from the clean water pipe into the subsidiary block, and in a turned-off state, prevents clean water from being introduced from the clean water pipe while introducing clean water from the circulation pipe into the subsidiary block.

[27] The clean water processing system according to claim 25 or 26, further comprising: a master block provided on a downstream end of the water supply pipe; a first pipe diverging from the master block; a handpiece connected to the first pipe and held by a handpiece holder, the handpiece holder including opening means; a fifth valve provided on the water supply pipe at a position between the subsidiary block and the master block; and an air pipe connected to the fifth valve, wherein the control unit controls the fifth valve and the opening means in order to drain clean water from the water supply pipe and the first pipe through the handpiece using compressed air, which is introduced from the air supply pipe.

[28] The clean water processing system according to claim 27, wherein the fifth valve is a three-way valve, which, in a turned-on state, prevents compressed air from being introduced from the air supply pipe while introducing clean water from the subsidiary block to the master block, and in a turned-off state, prevents clean water from being introduced from the subsidiary block while introducing compressed air from the air supply pipe into the master block.

[29] The clean water processing system according to claim 25 or 26, further comprising an input unit connected to the control unit, wherein the input unit allows a user or a manufacturer to input a time and a duration.

[30] The clean water processing system according to claim 29, wherein the control unit includes: a timer for comparing a previously-inputted time with a current time; and a unit controller for controlling the fourth valve, the fifth valve and the circulation pump in response to a signal from the timer.

[31] The clean water processing system according to claim 25 or 26, further comprising an indicator lamp connected to the control unit, the indicator lamp displaying a clean water-draining state of the water supply pipe. [32] A method of processing clean water in a dental unit chair, comprising: a first step of recording a time and a duration of a circulating operation, inputted through an input unit, in a timer of a control unit; a second step of comparing the time of the circulating operation, recorded in the timer, with a current time, and if the time of the circulating operation is the same as the current time, transmitting a circulating operation start signal to a unit controller of the control unit; a third step in which, when the circulating operation start signal is received, the unit controller turns off a fourth valve and operates a circulation valve, thereby enabling the circulating operation, so that clean air in the water supply pipe and the circulation pipe circulates therethrough; a fourth step of comparing the duration of the circulating operation, recorded in the timer, with a duration that has elapsed since the circulating operation start signal was transmitted, and if the durations are equal, transmitting a circulating operation end signal to the unit controller; and a fifth step in which, when the circulating operation end signal is received, the unit controller turns on the fourth valve and stops the circulation pump, thereby finishing the circulating operation.