Diagnosis and treatment chair with balance armrests

Abstract

The invention provides a diagnosis and treatment chair with a balance armrest. The diagnosis and treatment chair comprises a chair body and a balance armrest device arranged on the chair body. The chair body comprises a base and a seat arranged on the base, and the seat comprises a cushion unit and a backrest unit. The backrest unit is arranged in cooperation with a pivoting device and turns over relative to the cushion unit with a rotating shaft of the pivoting device as the axis. The balance armrest device is arranged on the backrest unit, and when the backrest unit turns over relative to the cushion, the balance armrest device keeps the armrest unit in a horizontal state in a mechanical or motor manner. According to the balance armrest design provided by the invention, in the structure that the armrest unit is connected to the backrest unit, the angle of the armrest unit can be prevented from being changed when the backrest is turned over, and the problem that the armrest unit interferes with the operation of a doctor or is inconvenient to use by a patient when turned over is solved.

Description

Technical Field

[0001] The present invention relates to a dental chair, and more particularly to a dental chair with balanced armrests. Background Art

[0002] A dental chair is a special chair for patients to sit or lie on when dentists perform dental treatments. Generally speaking, dental chairs are designed to be both comfortable and convenient for surgeries. They not only enable the operator to maintain a fixed posture during surgeries but also provide dentists with sufficient space and perspectives for dental treatments. Most advanced dental chairs on the market are also equipped with many other tools and devices, such as lighting, suction devices, water nozzles, etc., to facilitate doctors' treatments.

[0003] Most dental chairs can adjust their heights and tilt angles, allowing doctors to perform surgeries or treatments from the best angles and heights. To ensure the comfort of patients during treatments, these chairs are usually equipped with cushions and good supports to avoid discomfort caused by long sitting during surgeries. All in all, dental chairs are indispensable equipment in dental clinics, with multiple functions, and require a certain degree of professionalism to know how to adjust the seats. Summary of the Invention

[0004] The main object of the present invention is to provide a dental chair with balanced armrests, including a chair body and a balanced armrest device disposed on the chair body. The chair body includes a base and a seat disposed on the base. The seat includes a cushion unit and a backrest unit. The backrest unit is disposed in cooperation with a pivoting device and pivots relative to the cushion unit with the axis of the pivoting device as the center. The balanced armrest device is disposed on the backrest unit. When the backrest unit pivots relative to the cushion, the balanced armrest device includes mechanical means or motor means to maintain the armrest unit in a horizontal state.

[0005] Further, the mechanical means of the balanced armrest device includes a seat body pivotally disposed on the backrest unit, the armrest unit disposed on the seat body, and a connecting rod pivotally connected to the seat body and the base at both ends. The connection line between the axis of the pivoting device and the axis of the seat body pivotally disposed on the backrest unit is parallel and equal in length to the connecting rod to form a parallelogram.

[0006] Further, the armrest unit includes a horizontal rotating seat disposed on the seat body and a handrail disposed on the horizontal rotating seat to rotate horizontally through the horizontal rotating seat.

[0007] Further, the horizontal rotating seat includes a bushing fixed on the seat body and a rotating shaft pivotally disposed in the bushing.

[0008] Further, a positioning hole is provided on the rotating shaft, and the support rod is locked to the positioning hole through the positioning hole and a lateral locking unit on one side.

[0009] Further, a limiting cross bar is provided on the lower side of the rotating shaft. The limiting cross bar is horizontally arranged on the shaft rod of the rotating shaft, thereby protruding laterally on the shaft rod for clamping into a bidirectional groove on the upper surface of the shaft sleeve. The bidirectional groove corresponds to and coincides with the shaft rod on the rotating shaft at the first angular position and the second angular position respectively, for the shaft rod to be embedded in the bidirectional groove when pivoting to the corresponding angle.

[0010] Further, the limiting cross bar protrudes from both sides of the shaft rod. Limiting blocks are provided on the peripheral wall surface of the shaft sleeve on one side facing the rotating shaft in the axial direction. When the support rod is lifted, the limiting cross bar disengages from the bidirectional groove, and the protruding sides of the limiting cross bar will interfere with the limiting blocks to limit the pivoting stroke of the rotating shaft.

[0011] Further, a relief groove is provided on the rotating shaft. The relief groove includes a first limiting wall provided at the first angular position, a second limiting wall provided at the second angular position, and a limiting track provided between the first limiting wall and the second limiting wall. A limiting block is provided on the shaft sleeve and is embedded in the limiting track to limit the rotational stroke of the support rod in the horizontal direction by restricting the rotation of the limiting block between the first angular position and the second angular position.

[0012] Further, the motor means of the balanced armrest device includes another pivoting device provided on the backrest unit, a seat body provided on the another pivoting device, and the armrest unit provided on the seat body. The another pivoting device receives a control instruction when the pivoting device rotates, and rotates relative to the pivoting device to keep the armrest unit horizontal.

[0013] Further, the base includes a base, a lifting unit provided on the base, and a bracket provided on the lifting unit. The bracket is for setting the seat cushion unit and the backrest unit.

[0014] Further, the lifting unit raises or lowers the bracket according to a control instruction.

[0015] Further, bearing units are respectively provided on both sides of the backrest unit on the bracket. The pivoting device includes a motor, and the shaft rod of the motor passes through the two bearing units for support and is combined with the backrest unit.

[0016] Therefore, in the structure where the armrest unit is connected to the backrest unit, the balanced armrest design provided by the present invention can avoid the armrest unit changing its angle when the backrest flips, and avoid the problem that the armrest unit interferes with the doctor's operation or causes inconvenience to the patient during flipping. Description of the Drawings

[0017] Figure 1 This is a schematic diagram of the appearance of the dental chair in the present invention.

[0018] Figure 2 This is a side schematic diagram of the dental chair in the first state of the present invention.

[0019] Figure 3 This is a side schematic diagram of the dental chair in the second state of the present invention.

[0020] Figure 4 This is a partial exploded schematic diagram of the dental chair in the present invention.

[0021] Figure 5 This is a partially enlarged side schematic diagram of the balance armrest device in the present invention.

[0022] Figure 6 This is a partially transparent isometric view schematic diagram of the balance armrest device in the present invention.

[0023] Figure 7 This is a partially transparent top view schematic diagram of the balance armrest device in the present invention.

[0024] Figure 8A This is the actuation schematic diagram (one) of the balance armrest device in the present invention.

[0025] Figure 8B This is the actuation schematic diagram (two) of the balance armrest device in the present invention.

[0026] Figure 9 This is a partially enlarged side schematic diagram of another embodiment of the balance armrest device in the present invention.

[0027] The labels in the figure are as follows:

[0028] 100 Dental chair

[0029] 10 Chair body

[0030] 11 Base

[0031] 111 Base

[0032] 112 Lifting unit

[0033] 113 Bracket

[0034] 1131 Bearing unit

[0035] 1132 Bearing unit

[0036] 12 Seat

[0037] 121 Cushion unit

[0038] 122 Footrest unit

[0039] 123 Backrest unit

[0040] 124 Headrest unit

[0041] 13 Pivoting device

[0042] 131 Rotating shaft

[0043] 20 Balanced armrest device

[0044] 21 Seat body

[0045] 22 Armrest unit

[0046] 221 Horizontal rotating seat

[0047] S2 Limit block

[0048] 221A Bush

[0049] 2211A Bidirectional groove

[0050] 2212A Sleeve

[0051] 2213A Hollow space

[0052] 2214A Return spring

[0053] 2215A Compression rod

[0054] 2216A Limit piece

[0055] 2217A Wall surface

[0056] 221B Rotating shaft

[0057] 2211B Positioning hole

[0058] 2212B Shaft rod

[0059] S1 Limit cross bar

[0060] WA1 First protruding part

[0061] WA2 Second protruding part

[0062] S3 Relief groove

[0063] P1 First angular position

[0064] P2 Second angular position

[0065] 222 Armrest rod

[0066] 23 Connecting rod

[0067] 30 Control device

[0068] Axis of A1

[0069] Axis of A2

[0070] Connection line of L1

[0071] Axis of A3

[0072] Axis of A4

[0073] Connection line of L2

[0074] Lateral locking unit of D1

[0075] Balanced armrest device of 20A

[0076] Backrest unit of 123A

[0077] Pivoting device of 21A

[0078] Seat body of 22A

[0079] Armrest unit of 23A

[0080] Arrow of B1

[0081] Arrow of B2 Specific implementation manner

[0082] The detailed description and technical content of the present invention will be described below in conjunction with the accompanying drawings. For the convenience of description and to facilitate understanding of the technical content of the present invention, some contents are not necessarily drawn according to the actual proportion, and such proportions and shapes are not intended to limit the scope of the present invention, which is hereby stated in advance.

[0083] In the present invention, the "one side" mentioned may be, for example but not limited to, the "left side", "right side", "front side", "rear side", "upper side" or "lower side" of the target object or any other position close to the target object, which is hereby stated in advance.

[0084] The following is a specific embodiment of the present invention described in conjunction with the accompanying drawings. Please refer to Figure 1 , which is a schematic external view of the dental chair in the present invention. As shown in the figure: The dental chair 100 of this embodiment mainly includes a chair body 10, a balanced armrest device 20 provided on the chair body 10, and a control device 30 for generating control instructions to control the working modes of various devices of the chair body 10. In the present invention, the "dental chair" is described by taking the dental chair as an example, but is not limited to the dental chair. The dental chair described may be, for example but not limited to, an ophthalmic chair, an otolaryngology chair, a plastic surgery chair, an obstetrics / gynecology chair, a urology chair, a rehabilitation treatment chair, a general dental chair or other similar dental and surgical seats, which are not limited in the present invention.

[0085] Regarding the detailed structure of the treatment chair in the present invention, please also refer to the following in conjunction with Figure 2 and Figure 3 , which are the side schematic diagrams of the first state and the second state of the treatment chair in the present invention. As shown in the figure: In this embodiment, the chair body 10 mainly includes a base 11 and a seat 12 disposed on the base 11. In one embodiment, the seat 12 can be mainly divided into four parts, namely a seat cushion unit 121, a footrest unit 122, a backrest unit 123, and a headrest unit 124.

[0086] In one embodiment, in order to adjust the height of the seat 12, the base 11 mainly includes a base 111, a lifting unit 112 disposed on the base 111, and a bracket 113 disposed on the lifting unit 112. The lifting unit 112 is connected to the control device 30 and raises or lowers the bracket 113 according to the control instruction received by the control device 30, thereby adjusting the height of the seat 12. The bracket 113 is provided for the seat cushion unit 121 and the backrest unit 123 to support the seat cushion unit 121 and the backrest unit 123 through the bracket 113. The headrest unit 124 is disposed on the backrest unit 123 so that the headrest position of the headrest unit 124 is located on the upper side of the backrest unit 123. The footrest unit 122 is connected to the seat cushion unit 121, and the footrest unit 122 is supported by the seat cushion unit 121. In other embodiments, the headrest unit 124 and the seat cushion unit 121 may also be directly connected to the bracket 113, with the bracket 113 serving as the backbone of the entire treatment chair. The variations of these embodiments are not limited in the present invention.

[0087] In order to adjust the angle of the backrest unit 123, the backrest unit 123 is provided in cooperation with a pivoting device 13 and pivots relative to the seat cushion unit 121 about the rotation axis 131 of the pivoting device 13. The balanced armrest device 20 is disposed on the backrest unit 123. When the backrest unit 123 pivots relative to the seat cushion unit 121, regardless of the angle to which the backrest unit 123 pivots, the balanced armrest device 20 maintains the armrest unit 22 in a horizontal state by mechanical means or motor means. Herein, the "mechanical means" refers to a method that does not directly use an electric motor, but simply maintains the balance state of the armrest unit 22 in various working states through pure mechanical actuation; the "motor means" refers to a method that involves using electricity or electromagnetic effects to perform operations or functions, such as an electric motor. It should be noted here that the "maintaining in a horizontal state" does not necessarily mean a completely horizontal state. In the present invention, the armrest unit 22 can be modified to be in a substantially horizontal state for ergonomic or comfort considerations. Such variations also fall within the scope of protection of the present invention and are hereby described in advance.

[0088] Regarding the design of the balanced armrest device 20 maintaining balance by mechanical means, please also refer toFigure 4 and Figure 5 , which are the partial structural decomposition diagram of the treatment chair in the present invention and the partial enlarged side view of the balance armrest device in the present invention. As shown in the figure: In an embodiment, the mechanical means of the balance armrest device 20 includes a seat body 21 pivotally provided on the backrest unit 123, an armrest unit 22 provided on the seat body 21, and a connecting rod 23 with two ends pivotally connected to the seat body 21 and the base 11 respectively. In an embodiment, bearing units 1131 and 1132 are respectively provided on both sides of the backrest unit 123 by the bracket 113. The pivoting device 13 includes a motor, and the shaft of the motor passes through the two bearing units 1131 and 1132 for support and is combined with the backrest unit 123. In an embodiment, the motor described above can be, for example, a DC motor, an AC motor, a stepper motor, a servo motor, an electromagnetic motor or other similar devices.

[0089] In order to keep the armrest unit 22 balanced at various angles, in the side view direction (such as Figure 5 's perspective), the connecting line L1 connecting the axis A1 of the pivoting device 13 and the axis A2 where the seat body 21 is pivotally provided on the backrest unit 123, and the connecting line L2 between the axis A3 where the connecting rod 23 is pivotally provided on the seat body 21 and the axis A4 where the connecting rod 23 is pivotally provided on the base 11 are parallel and equal in length to form a parallelogram. Through the configuration of the parallelogram, no matter what angle the backrest unit 123 is adjusted to, the armrest unit 22 on the seat body 21 can generally maintain a horizontal state. In an embodiment, the axis A4 where the connecting rod 23 is pivotally provided on the base 11 is provided on one side of the bearing units 1131 and 1132. This part depends on the requirements of the mechanism configuration. This position only needs to determine the relative position with the axis A1 of the pivoting device 13 to be fixed, and it is not limited to be set on a specific device or mechanism. It is hereby described in advance.

[0090] The following is an explanation of one embodiment of the present invention. Please refer to Figure 6 and Figure 7, which is a partially transparent schematic diagram of the balancing armrest device in the present invention in the side view direction and a partially transparent schematic diagram in the top view direction, as shown in the figure: In one embodiment, in order to facilitate the patient to get up from the side when leaving the seat, the armrest unit 22 includes a horizontal rotating seat 221 disposed on the seat body 21 and a handrail 222 disposed on the horizontal rotating seat 221 to rotate in the horizontal direction through the horizontal rotating seat 221. Specifically, the horizontal rotating seat 221 mainly includes a sleeve 221A fixed on the seat body 21 and a rotating shaft 221B pivoted on the sleeve 221A. In order to fix the handrail 222 on the horizontal rotating seat 221, a positioning hole 2211B is provided on the rotating shaft 221B, and the handrail 222 passes through the positioning hole 2211B and is locked on the positioning hole 2211B through the lateral locking unit D1. In one embodiment, the lateral locking unit D1 can be, for example, but not limited to, screws and bolts, screws, positioning pins, rivets or other similar mechanisms, which are not limited in the present invention.

[0091] In one embodiment, a limit cross bar S1 is disposed on the lower side of the rotating shaft 221B, and the limit cross bar S1 is horizontally disposed on the shaft 2212B of the rotating shaft 221B, thereby protruding laterally on the shaft 2212B to form a bidirectional groove 2211A for clamping on the upper surface of the sleeve 221A. The bidirectional groove 2211A corresponds to and overlaps with the limit cross bar S1 on the rotating shaft 221B at the first angle position P1 and the second angle position P2, respectively, so that the limit cross bar S1 is embedded in the bidirectional groove 2211A when the shaft 2212B is pivoted to the corresponding angle, and the limit cross bar S1 interferes with the wall around the bidirectional groove 2211A at other relative pivoting angles, thereby fixing the rotating shaft 221B at two corresponding pivoting angles. The above-mentioned pivoting angle refers to the rotating shaft 221B relative to the sleeve 221A, which is first described in the present invention. In this embodiment, the bidirectional groove 2211A is cross-shaped, and the limiting cross bar S1 protrudes from both sides of the shaft 2212B. Through such a configuration, the rotation angle of the handrail 222 is fixed within the range of 0 to 90 degrees; in other embodiments, the angle between the two grooves of the bidirectional groove 2211A is not limited to 90 degrees, and the angle between the two grooves can be adjusted according to needs to change the stay angle of the handrail 222. In other embodiments, the limiting cross bar S1 can protrude from one side of the shaft 2212B, and the bidirectional groove 2211A can be cross-shaped or L-shaped, which is not limited in the present invention.

[0092] To limit the rotation angle of the handrail 222, in an embodiment of the present invention, the limiting crossbar S1 protrudes from both sides of the shaft rod 2212B. The sleeve 221A is provided with a limiting block S2 on the peripheral wall surface facing the rotating shaft 221B in the axial direction. When the handrail 222 is lifted, the limiting crossbar S1 disengages from the bidirectional groove 2211A. Interference will occur between the two protruding sides of the limiting crossbar S1 and the limiting block S2, restricting the pivoting stroke of the rotating shaft 221B and further restricting the rotation angle of the handrail 222. The rotation angle of the handrail 222 depends on the angle between the first protruding portion WA1 (at the first angular position P1) protruding from the first side of the shaft rod 2212B and the second protruding portion WA2 (at the second angular position P2) protruding from the second side of the shaft rod 2212B. Thereby, the horizontal rotating base 221 is interfered with each other through the limiting crossbar S1 and the limiting block S2 at a fixed position, so that the horizontal rotating base 221 can only move within the range defined by the first angular position P1 and the second angular position P2. In addition, a relief groove S3 is provided on the limiting crossbar at the position corresponding to the limiting block S2 of the rotating shaft 221B, so that when the limiting crossbar S1 is inserted into the bidirectional groove 2211A, the limiting block S2 can be received in the relief groove S3 to avoid interference between the limiting block S2 and the rotating shaft 221B.

[0093] Specifically, the "first angular position" and the "second angular position" mentioned herein refer to the positions defined by the radial angle (or polar angle). That is, with the axis of the rotating shaft 221B as the center, the position passed by the radial extension at the first radial angle is the first angular position P1, and the position passed by the radial extension at the second radial angle is the second angular position P2.

[0094] In an embodiment, the included angle A1 defined between the first angular position P1 and the second angular position P2 (i.e., between the first protruding portion WA1 and the second protruding portion WA2) is between 90 degrees and 120 degrees, which is not limited in the present invention.

[0095] Please refer to Figure 8A and Figure 8B, is the schematic diagram (1) and schematic diagram (2) of the actuation of the balance handrail device in the present invention. As shown in the figure: In an embodiment, in order to provide appropriate elasticity when the handrail 222 is lifted, when the handrail 222 rotates to the coincidence position of the limit crossbar S1 and the bidirectional groove 2211A, it automatically resets (is embedded in the bidirectional groove 2211A). The bottom side of the bushing 221A has a sleeve 2212A. A hollow space 2213A is provided inside the sleeve 2212A for the bottom of the shaft rod 2212B to pass through. A compression rod 2215A is provided on the bottom of the shaft rod 2212B. A limit piece 2216A is provided at one end of the compression rod 2215A. A return spring 2214A is sleeved outside the sleeve 2212A and is arranged between a wall surface on the bottom side of the bushing 221A and the limit piece 2216A. One end of the return spring 2214A is fixed to the limit piece 2216A. When the handrail 222 is lifted, as Figure 8A shown, the rotating shaft 221B moves relatively away from the bushing 221A. At this time, the compression rod 2215A moves upward and compresses the return spring 2214A therebetween, so that the return spring 2214A is compressed. When the limit crossbar S1 moves to the coincidence position with the bidirectional groove 2211A, as Figure 8B shown, the return spring 2214A is released, and the limit crossbar S1 is reset to the inside of the bidirectional groove 2211A by the acting force of the return spring 2214A.

[0096] Regarding the design of the balance handrail device to maintain balance by means of a motor, please refer to Figure 9, which is a partially enlarged schematic view of the side of another embodiment of the balance armrest device in the present invention, as shown in the figure: In another embodiment, the motor means of the balance armrest device 20A includes a pivot device 21A provided on the backrest unit 123A, a seat body 22A provided on the pivot device 21A, and an armrest unit 23A provided on the seat body 22A. Specifically, the pivot device 21A is configured to receive a control instruction from the control device 30 when the pivot device 13 rotates, and trigger the pivot device 21A to rotate relative to the pivot device 13 through the control instruction to keep the armrest unit 23A horizontal; More specifically, the control device 30 synchronizes the pivot device 13 and the pivot device 21A by transmitting corresponding control instructions to the pivot device 13 and the pivot device 21A respectively, so that the armrest unit 23A remains balanced. The "synchronization" mentioned here does not mean that the strokes of the pivot device 13 and the pivot device 21A are the same, but that the stroke of the pivot device 21A has a corresponding relationship with the stroke of the pivot device 13, and the stroke that the pivot device 21A should rotate is found through the rotation stroke of the pivot device 13, so that the armrest unit 23A remains balanced. In one embodiment, the control device 30 can calculate the stroke that the pivot device 21A should rotate; In another embodiment, the control device 30 can directly map the rotation stroke of the pivot device 13 to the rotation stroke of the pivot device 21A (such as a look-up table) through mapping, and the changes in these embodiments are not limited in the present invention.

[0097] As Figure 9 shown, in order to keep the armrest unit 23A balanced at various angles, when the control device 30 outputs a control instruction to make the backrest unit 123A tilt backward, the pivot device 21A drives the rotating shaft to rotate counterclockwise (as shown by arrow B1) when receiving the first control instruction from the control device 30, and the control device 30 simultaneously sends out a second control instruction to operate the pivot device 13 to rotate clockwise (as shown by arrow B2) to control the armrest unit 23A to remain balanced. In one embodiment, the control device 30 can include, for example, but not limited to, PID control (Proportional-Integral-Derivative Control), master-slave control, model predictive control (Model Predictive Control, MPC), adaptive control, synchronous control or other similar methods to control the synchronization relationship between the pivot device 21A and the pivot device 13.

[0098] In summary, in the structure where the armrest unit is connected to the backrest unit in the balanced armrest design provided by the present invention, it is possible to prevent the armrest unit from changing its angle when the backrest flips, and avoid the problem that the armrest unit interferes with the doctor's operation or causes inconvenience to the patient during flipping.

[0099] The present invention has been described in detail above. The above description is only one preferred embodiment of the present invention. It should not be used to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the scope of the patent application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. A treatment chair with a balanced armrest, characterized in that, Comprising: A chair body, including a base and a seat disposed on the base. The seat includes a cushion unit and a backrest unit. The backrest unit is disposed in cooperation with a pivoting device and pivots relative to the cushion unit with the axis of the pivoting device as the center; and A balanced armrest device, disposed on the backrest unit. When the backrest unit pivots relative to the cushion, the balanced armrest device includes mechanical means or motor means to maintain the armrest unit in a horizontal state.

2. The treatment chair with a balanced armrest according to claim 1, characterized in that, The mechanical means of the balanced armrest device includes a seat body pivotally disposed on the backrest unit, the armrest unit disposed on the seat body, and a connecting rod pivotally connected to the seat body and the base at both ends. The first connecting line between the axis of the pivoting device and the axis where the seat body is pivotally disposed on the backrest unit is parallel and equal in length to the second connecting line between the axes of both ends of the connecting rod to form a parallelogram.

3. The treatment chair with a balanced armrest according to claim 2, characterized in that, The armrest unit includes a horizontal rotating seat disposed on the seat body and a handrail disposed on the horizontal rotating seat and rotatable horizontally through the horizontal rotating seat.

4. The treatment chair with a balanced armrest according to claim 3, characterized in that, The horizontal rotating seat includes a sleeve fixed on the seat body and a rotating shaft pivotally disposed in the sleeve.

5. The treatment chair with a balanced armrest according to claim 4, characterized in that, Positioning holes are provided on the rotating shaft, and the handrail passes through the positioning holes and is locked to the positioning holes through a lateral locking unit.

6. The examination and treatment chair with a balanced armrest according to claim 4, characterized in that, A limiting cross bar is provided on the lower side of the rotating shaft. The limiting cross bar is horizontally disposed on the shaft rod of the rotating shaft and protrudes laterally on the shaft rod to be clamped in a bidirectional groove on the upper surface of the sleeve. The bidirectional groove corresponds to and coincides with the shaft rod on the rotating shaft at a first angular position and a second angular position respectively, for the shaft rod to be embedded in the bidirectional groove when pivoting to the corresponding angle.

7. The examination and treatment chair with a balanced armrest according to claim 6, characterized in that, The limiting cross bar protrudes from both sides of the shaft rod. Limiting blocks are provided on the peripheral wall surface of the sleeve on the side facing the rotating shaft in the axial direction. When the handrail is lifted, the limiting cross bar disengages from the bidirectional groove, and the two protruding sides of the limiting cross bar will interfere with the limiting blocks to limit the pivoting stroke of the rotating shaft.

8. The treatment chair with a balanced armrest according to claim 1, characterized in that, The motor means of the balanced armrest device includes another pivoting device disposed on the backrest unit, a seat body disposed on the another pivoting device, and the armrest unit disposed on the seat body. The another pivoting device receives a control command when the pivoting device rotates and rotates relative to the pivoting device to keep the armrest unit horizontal.

9. The treatment chair with a balanced armrest according to claim 1, characterized in that, The base includes a base, a lifting unit disposed on the base, and a bracket disposed on the lifting unit. The bracket is for the cushion unit and the backrest unit to be disposed.

10. The examination and treatment chair with a balanced armrest according to claim 9, characterized in that, Bearing units are respectively disposed on both sides of the backrest unit of the bracket. The pivoting device includes a motor, and the shaft rod of the motor passes through the two bearing units to provide support and is combined with the backrest unit.

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