JP2000166690A - Headrest adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically adjust the position of a headrest to its precisely proper position by controlling a second driving means to move the headrest to a target moving position within a prescribed allowable moving position area based on an optional moving position signal by the operation of the first driving means. SOLUTION: The slide motor 71 of a first driving mechanism 7 and the headrest motor 81 of a second driving mechanism 8 are connected to the CPU 91 of a control means 9 through a forward rotation circuit 92 and a backward rotation circuit 93. A storing circuit 96 is connected to the CPU 91 and stores a characteristics range for setting the target vertical position (target moving position) of the headrest with respect to the present front/rear position of a vehicle seat and its allowable quantity (allowable moving position area) 1. The target vertical position of the headrest in this characteristics range is assumed from average body form data (height and sitting height) of people to take the vehicle seat and its allowable quantity is set vertically based on the target vertical position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a headrest adjusting device for a vehicle seat. More specifically, when the seat position is changed due to sliding of the vehicle seat in the longitudinal (front-back) direction, a headrest for moving the headrest to a height of the headrest of the seat suitable for the changed position. It relates to an adjusting device.

[0002]

2. Description of the Related Art Generally, a vehicle seat has a seat slide adjusting mechanism for changing its position with respect to a vehicle floor in a longitudinal direction, that is, a front-back direction. As a result, for example, when a tall person is seated, the tall occupant can operate the seat slide adjustment mechanism to move the seat backward in order to obtain a posture suitable for the occupant. At this time, the height of the headrest also needs to be changed so as to be suitable for the position of the occupant's head. That is, it is necessary to be able to select the height of the headrest according to the position of the seat. 2. Description of the Related Art Conventionally, as this type of headrest adjustment device, a device shown in German Utility Model No. 9421781 is known.

The first drive means moves a seat provided with a headrest to an arbitrary position along the longitudinal direction of the seat, and the second drive means moves the headrest to a target position along the seat height direction. And control means for controlling the movement of the headrest to the target movement position by the second drive means in accordance with the movement position of the sheet by the first drive means. There is storage means for setting a target movement position of the headrest based on the movement as a characteristic curve.

In this conventional apparatus, when a seated person operates a first driving means by a switch operation to move a seat to an arbitrary position along a longitudinal direction of a seat, a control means causes a headrest corresponding to an arbitrary moving position of the seat to be moved. The target movement position is retrieved from the storage means, and the second driving means is operated to move the headrest to the target movement position along the seat height direction.

[0005]

However, in the headrest adjusting device described above, the target movement position of the headrest is set as a characteristic straight line based on the movement of the seat to an arbitrary position. Is repeated, the headrest is also finely adjusted every time this fine adjustment movement is performed, which may cause the occupant to feel troublesome. Also, in order to prevent this, the conventional device
It is also disclosed that the characteristic straight line is stepped so that the headrest does not move unless a predetermined amount of seat movement occurs. However, when the characteristic straight line has a stepped shape, it is difficult to adjust the position of the headrest with respect to the moving position of the seat with high accuracy, and the position of the headrest may greatly differ from the target moving position.

[0006] Therefore, the present invention is to solve the above-mentioned problems, to provide a headrest adjustment device capable of preventing a small movement of a headrest due to a fine adjustment movement of a seat and performing more accurate position adjustment. Is a technical problem.

[0007]

SUMMARY OF THE INVENTION In order to solve the problems of the present invention, the present invention basically comprises a target position of a headrest before sliding of a seat in a front-rear direction, and an arbitrary position of a seat during sliding. When the target position of the headrest is separated from the target position by a predetermined dimension or more, the vertical movement of the headrest starts, and the headrest is moved up and down by the control means to a new target position corresponding to the seat position at that time. .
More specifically, the present invention relates to a headrest adjustment device for moving a headrest up and down in accordance with a forward and backward movement of a seat, wherein a storage means stores a target movement position of the headrest corresponding to an arbitrary position of the seat, and starts moving. When the target movement position of the headrest corresponding to the subsequent movement position of the seat is separated from the initial position of the headrest corresponding to the initial position of the sheet before the movement starts by a predetermined distance or more, the vertical movement of the headrest starts. And
A headrest adjustment device is provided, comprising: a control unit that moves the headrest to a target movement position set as a characteristic line that changes according to the position of the seat being moved.

Further, the present invention provides a first driving means for moving a seat provided with a headrest to an arbitrary position along a longitudinal direction of the seat, and a second driving means for moving the headrest along a height direction of the seat. Means, and control means for controlling movement of the headrest by the second drive means in accordance with movement of the seat by the first drive means, wherein the control means comprises: A target movement position of the headrest corresponding to an arbitrary position of the seat is stored, and a target movement position of the headrest corresponding to the movement position of the sheet after the movement starts corresponds to an initial position of the sheet before the movement starts. When moving away from the initial position of the headrest by a predetermined distance or more, the headrest starts moving up and down, and Providing headrest adjusting device, characterized in that the set target movement position as a characteristic line which varies in accordance with the bets position moving the headrest.

According to this technical means, when the headrest is moved up and down in accordance with the forward and backward movement of the seat, the target movement position of the headrest corresponding to the seat position after the start of movement corresponds to the seat position before the start of movement. The movement of the headrest is not started until the headrest is separated from the initial position by a predetermined distance or more, so that the headrest is prevented from moving slightly according to the fine adjustment movement of the seat. In addition, the headrest after the start of movement moves to a target movement position set as a characteristic line that changes according to the position of the moving sheet, thereby performing high-precision position adjustment of the headrest according to the seat position. be able to.

According to the preferred technical means, when the occupant operates the first driving means by a switch operation to move the seat to an arbitrary position along the longitudinal direction of the seat, the control means moves the seat to an arbitrary moving position of the seat. The target movement position of the headrest is retrieved from the storage means, and when the seat is moved to an arbitrary position outside the movement position area permitted by the height of the headrest, the second driving means is operated to move the headrest in the seat height direction. To the target movement position along. When the seat moves to an arbitrary movement position within the movement position area permitted by the height of the headrest, the headrest does not move, and when the sheet moves to any movement position outside the allowable movement position area. The headrest can be reliably moved to the target movement position, and the position of the headrest can be adjusted with higher precision than before.

[0011] More preferably, said second driving means includes:
The headrest may be moved to an arbitrary position along a seat height direction, and the control unit may move the headrest to the arbitrary position independently of the allowable movement position area or independently of the allowable movement position area. It is preferable to operate the second driving means so as to be moved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a vehicle seat 1 is composed of a seat cushion 2, a seat back 3 and a headrest 4, and the vehicle seat 1
Is supported on a vehicle floor (not shown) via a well-known slide adjusting mechanism 5 arranged at a lower portion of the seat section 2 so as to be movable in a longitudinal direction of the seat, which is a longitudinal direction of the vehicle. The seat back 3 is disposed at a rear portion of the seat cushion 2, and the headrest 4 is supported on an upper portion of the seat back 3 via a well-known adjustment mechanism 6 so as to be movable in a seat height direction which is a vehicle vertical direction. I have.

The seat slide adjusting mechanism 5 includes a lower rail 51 fixed to the vehicle floor and an upper rail 52 fixed to the seat cushion 2 and slidably supported by the lower rail 51. The upper rail 52 includes a screw shaft and a nut. The sliding operation is performed on the lower rail 51 by the operation of the well-known drive mechanism 7 including the members, the reduction gear structure, and the slide motor 71.
Moves to an arbitrary position along the longitudinal direction of the seat, and the front and rear positions of the vehicle seat 1 are adjusted.

The headrest adjusting mechanism 6 has a stay 61 slidably supported by a holder attached to the headrest 4 and attached to the seat back 3.
The stay 61 slides with respect to the holder by the operation of a well-known drive mechanism 8 including a screw shaft, a nut member, a reduction gear structure, and a headrest motor 81, whereby the headrest 4 moves along the seat height direction. The headrest 4 moves and the vertical position of the headrest 4 is adjusted.

[0015] As shown in FIG.
The slide motor 71 of the first drive mechanism 7 and the headrest motor 81 of the second drive mechanism 8 are connected to U91 via a forward rotation circuit 92 and a reverse rotation circuit 93. CP
A slide manual switch 72 for driving and operating the slide motor 71 and a headrest manual switch 82 for driving and operating the headrest motor 81 are connected to U91 via an input processing circuit 94. The slide manual switch 72 includes a front (forward) adjustment switch (hereinafter, referred to as a slide FrSW) 72a and a rear (reverse) adjustment switch (hereinafter, referred to as a slide RrSW) 72b. This slide FrSW72a and slide RrSW72b
Each of the switches is a normally-open type switch, which is normally off and turned on only while being pressed. The headrest manual switch 82 includes an up (up) adjustment switch (hereinafter, referred to as a headrest UpSW) 82a and a down (down) adjustment switch (hereinafter, headrest Dow).
82b). The headrest UpSW82a and the headrest DownSW82
b is a normally open switch, which is normally off and turned on only while being pressed.

When the slide FrSW 72a is turned on, the CPU 91 outputs a slide drive signal to the forward rotation circuit 92 to drive the slide motor 71 in the forward direction so as to move the vehicle seat 1 forward.
A slide drive signal is output to the reversing circuit 93 to drive the slide motor 71 in the reverse direction in order to move the vehicle seat 1 backward when the 2b is on, and to move the headrest 1 upward when the headrest UpSW 82a is on. A headrest drive signal is output to the normal rotation circuit 92 to drive the headrest motor 81 in the normal direction, and the headrest motor 81 is rotated in the reverse direction to move the headrest 1 downward when the headrest DownSW 82b is on. A headrest drive signal is output to the circuit 93.

A slide position sensor 73 and a headrest position sensor 83 are connected to the CPU 91 via a position detection circuit 95. Slide position sensor 73
Is a pulse counting type that includes a Hall element and counts driving pulses as the slide motor 71 is driven.
3. The current front-rear position (arbitrary movement position) of the vehicle seat 1 is recognized based on the pulse signal from the controller 3 (absolute position based on the front most position as shown in FIG. 3).

The headrest position sensor 83 has a Hall element and is of a pulse counting type which counts the number of driving pulses in accordance with the driving of the headrest motor 81.
Then, the current vertical position (arbitrary position) of the headrest 4 is calculated based on the pulse signal from the controller (the absolute position based on the downmost position as shown in FIG. 3).

Further, a storage circuit 96 is connected to the CPU 91. The storage circuit 96 has a target vertical position (a target movement position) of the headrest 4 with respect to the current front-rear position of the vehicle seat 1 as shown in FIG. ) And a map (characteristic range) for setting the allowable amount (allowable movement position area). The target vertical position of the headrest 4 in this map is assumed from average body shape data (height, sitting height, etc.) of a person sitting on the vehicle seat 1, and the allowable amount is set up and down based on the target vertical position. (Specifically, as shown in FIG. 3, each is 12 mm above and below). Although the diagram showing the boundary of the allowable amount is directly proportional to the diagram showing the target vertical position, it is not always necessary to be directly proportional, and the current front-rear position of the vehicle seat 1 is the rear most position (specifically, FIG. As shown in FIG. 3, the headrest 4 approaches the reference front most position or 240 mm from the reference front most position, or, as shown in FIG. As the position gradually approaches (position), the allowable amount may gradually decrease.

Next, the processing of the control circuit 9 will be described with reference to FIGS.

In the steps S1 and S2, the CPU 91 determines whether or not the slide manual switch 72 has been operated. If the slide FrSW 72a is on, the process proceeds from step S1 to step S3, where a slide drive signal is output to the forward rotation circuit 92 to drive the slide motor 71 of the drive mechanism 7 in the forward direction. As a result, the slide adjustment mechanism 5 operates to move the vehicle seat 1 forward. Also, slide RrSW
If the switch 72b is turned on, the steps S2 to S4
In step S4, a slide drive signal is output to the reverse rotation circuit 93, and the slide motor 71 of the drive mechanism 7 is driven.
Is driven in the reverse direction. As a result, the slide adjustment mechanism 5 operates to move the vehicle seat 1 backward.

During adjustment of the front / rear position of the vehicle seat 1, the CPU 9
In step 1, the process proceeds from steps S3 and S4 to step S6,
In step S6, the current front and rear position of the vehicle seat 1 is recognized and stored based on a signal from the position detection circuit 95 by the slide position sensor 73. In step S7, the headrest 4 with respect to the recognized and stored current front and rear position of the vehicle seat 1 is stored. Is calculated from the map stored in the storage circuit 96. Subsequently, in step S8, the current vertical position of the headrest 4 is recognized based on a signal from the position detection circuit 95 by the headrest position sensor 83.

Thereafter, the CPU 91 proceeds from step S8 to step S9. In steps S9 and S10, a comparison is made between the current vertical position of the headrest 4 recognized in step S8 and the target vertical position calculated in step S7. I do. If it is determined in steps S9 and S10 that the current vertical position of the headrest 4 is outside the calculated target vertical position and the allowable amount, the adjustment start flag of the headrest 4 is turned on in step S11, and the flag is turned on and off in step S12. The process proceeds to steps S13 and S14 via the determination.

In steps S13 and S14, it is determined whether the current vertical position of the headrest 4 is higher or lower than the target vertical position. If it is determined that the current vertical position is lower than the target vertical position, the process proceeds from step S14 to step S15. In step S15, a headrest drive signal is output to the normal rotation circuit 92 to drive the headrest motor 81 of the drive mechanism 8 in the normal rotation direction. Thereby, the adjusting mechanism 6
Operates to move the headrest 4 upward.

If it is determined that the current vertical position is higher than the target vertical position, the process proceeds from step S13 to step S16. In step S16, a headrest drive signal is output to the reversing circuit 93 and the headrest motor 81 of the drive mechanism 8 is driven. Is driven in the reverse direction. As a result, the headrest adjusting mechanism 6 operates to move the headrest 4 downward. Thereafter, in the CPU 1, steps S15, S16
From step S17, the current vertical position of the headrest 4 is recognized and stored in step S17 based on the signal from the position detection circuit 95 by the headrest position sensor 83, and the process returns to step S1. And the vehicle seat 1
The above-described steps are repeated during the front-back position adjustment.

When the current vertical position of the headrest 4 falls within the target vertical position, the CPU 91 proceeds from step S14 to step S18. In step S18, the CPU 91 outputs a headrest drive stop signal to the normal rotation circuit 92 and the reverse rotation circuit 93 to output the headrest The motor 81 is stopped and the process proceeds to step S19 to turn off the headrest adjustment start flag. Then, from step S19 to step S1
The process proceeds to step S7 and returns to step S1.

When the operation of the slide manual switch 72 is stopped, the CPU 91 proceeds to step S5 from steps S1 and S2, stops outputting the slide drive signal to the normal rotation circuit 92 and the reverse rotation circuit 93, and stops the slide motor 71.

As described above, the vehicle seat 1 can be adjusted to a desired front-rear position, and the headrest 4 is automatically adjusted to an appropriate vertical position according to the body shape of the seated person according to the desired front-rear position of the vehicle seat 1. Can be done.

If the CPU 91 determines in step S9 or S10 that the current vertical position of the headrest 4 is within the calculated target vertical position and its permissible amount, the CPU 91 does not proceed to step S11, and proceeds from step S10 to step S11. Proceeding to S12, the process proceeds to step S20 via the flag OFF determination in step S12, and stops outputting the headrest drive signal to the normal rotation circuit 92 and the reverse rotation circuit 93 to stop the headrest motor 81.
Then, the process proceeds to step S17 and returns to step S1.

This prevents the height of the headrest 4 from being adjusted as long as the vehicle seat 1 is located within the allowable amount. Specifically, as shown in FIG.
While the vehicle seat 1 moves back and forth from the position A to the position B or D, the headrest 4 does not move up and down. When the vehicle seat 1 moves back and forth to the position C or the position E exceeding the position B or D, the headrest 4 moves up and down. . Thereby, the vehicle seat 1
Even if the fine adjustment is repeated, the headrest 4 is not automatically adjusted up and down every time the fine adjustment is performed, and there is no fear that the occupant feels annoying.

In the CPU 91, steps S21 and S22
In, it is determined whether or not the headrest manual switch 82 has been operated.

If the headrest UpSW 82a is ON, the process proceeds from step S21 to step S23. In step S23, the target vertical position of the headrest 4 with respect to the current front-rear position of the vehicle seat 1 recognized and stored in step S6 from the map is determined in step S24. , The current vertical position of the headrest 4 is recognized based on the signal from the position detection circuit 95 by the headrest position sensor 83, and the process proceeds to step S25.

In step S25, the headrest 4
It is determined whether the current vertical position is higher or lower than the target vertical position calculated in step S23 and the allowable amount above the target vertical position. If it is determined that the driving force is low, the process proceeds from step S25 to step S26.
Is driven in the normal rotation direction. As a result, the headrest adjusting mechanism 6 operates to move the headrest 4 upward. On the other hand, if it is determined to be high, the process proceeds from step S25 to step S27, and step S27
, The output of the headrest drive signal to the forward rotation circuit 92 and the reverse rotation circuit 93 is stopped, and the headrest motor 8 is stopped.

Thereafter, the CPU 91 determines in step S2
6. The process proceeds from step S27 to step S28, where step S28
In step, the headrest adjustment start flag is turned off, and the process proceeds to step S17. In step S17, the current vertical position of the headrest 4 is recognized and stored based on a signal from the position detection circuit 95 by the headrest position sensor 83, and the process returns to step 1. , Headrest UpSW82a
While the operation is being performed, that is, during the upward movement adjustment (manual) of the headrest 4, the above-described steps are repeated. When the operation of the headrest UpSW82a is stopped, the process proceeds to step S12.

As described above, when the headrest UpSW 82a of the headrest manual switch 82 is operated to move the headrest 4 upward, step S25 is performed.
The headrest 4 can move upward only within the target vertical position and the allowable amount, and the upward movement of the headrest 4 automatically stops when the headrest 4 becomes higher than the target vertical position and the allowable amount. Specifically, as shown in FIG. 9, the headrest 4 can be manually adjusted upward only between the H position and the G position, so that the headrest 4 does not largely deviate from an appropriate position, and Is very safe for

If the headrest DownSW 82b is on, the process proceeds from step S22 to step S29. In step S29, the target vertical position of the headrest 4 with respect to the current position of the vehicle seat 1 recognized and stored in step S6 from the map is determined in step S30. Then, based on the signal from the position detection circuit 95 by the headrest position sensor 83, the current vertical position of the headrest 4 is recognized, and the process proceeds to step S31.

In step S31, the headrest 4
It is determined whether the current vertical position is lower than the target vertical position calculated in step S29 and the allowable amount below the target vertical position.
Then, when it is determined to be high, the process proceeds from step S31 to step S32, and in step S32, a headrest drive signal is output to the reverse rotation circuit 93 to drive the headrest motor 81 of the drive mechanism 8 in the reverse rotation direction. As a result, the headrest adjusting mechanism 6 operates and the headrest 4
Moves down. On the other hand, if it is determined to be low, the process proceeds from step S31 to step S33. In step S33, the output of the headrest drive signal to the normal rotation circuit 92 and the reverse rotation circuit 93 is stopped, and the headrest motor 8 is stopped.

Thereafter, the CPU 91 determines in step S3
2. The process proceeds from step S33 to step S34 and proceeds to step S34.
In step, the headrest adjustment start flag is turned off, and the process proceeds to step S17. In step S17, the current vertical position of the headrest 4 is recognized and stored based on a signal from the position detection circuit 95 by the headrest position sensor 83, and the process returns to step 1. , Headrest DownSW8
The above-described steps are repeated during the operation of 2b, that is, during the downward movement adjustment (manual) of the headrest 4. When the operation of the headrest DownSW82b is stopped, the process proceeds to step S12.

As described above, when the headrest DownSW 82b of the headrest manual switch 82 is operated to move the headrest 4 downward, the headrest 4 is moved downward only within the target vertical position and its allowable amount by the judgment in step S31. When the headrest 4 becomes lower than the target vertical position and the allowable amount, the downward movement of the headrest 4 automatically stops. Specifically, as shown in FIG. 9, the headrest 4 can be adjusted downward by manual operation only between the G position and the H position, so that the headrest 4 does not largely deviate from an appropriate position, and Is very safe for the elderly.

In the above-described embodiment, the control circuit is such that the headrest 4 can be moved up and down independently to an arbitrary position within the allowable movement position area by the headrest motor 81 in accordance with the operation of the headrest manual switch 82. The present invention was implemented in the headrest adjustment device that constituted No. 9. However, according to the present invention, a headrest adjustment circuit configured such that the headrest 4 can be moved up and down to an arbitrary position independently of the allowable movement position area by the headrest motor 81 in accordance with the operation of the headrest manual switch 82. The same can be applied to the apparatus. In this modification, the control circuit has the configuration shown in FIG. 2 in the same manner as in the above-described embodiment, but the operation thereof is changed as follows. That is, if the headrest UpSW is turned on in step S21 of FIG. 4, the control circuit rotates the headrest motor forward without executing the flowchart of FIG. 6, and then proceeds to step S17. Headrest DownSW
Is ON, the headrest motor is reversed without executing the flowchart of FIG.
It operates to proceed to 7. According to this modification, the position of the headrest can be adjusted to any position outside the allowable movement position area, so that the position can be adjusted to an optimal position for the seated person regardless of individual differences in the body shape of the seated person. Very secure.

[0041]

According to the present invention, the headrest is moved to the target moving position within the predetermined allowable moving position area by the second driving means based on the arbitrary moving position signal by the operation of the first driving means. Since the control means is configured to operate as desired, the automatic adjustment of the position of the headrest to the appropriate position can be performed with higher accuracy than in the past.

[Brief description of the drawings]

FIG. 1 is a perspective view of a vehicle seat employing a headrest adjustment device according to the present invention.

FIG. 2 is a circuit diagram showing control means of the headrest adjusting device according to the present invention.

FIG. 3 is a schematic view showing the operation of the headrest adjustment device according to the present invention.

FIG. 4 is a flowchart showing the operation of the control means of the headrest adjusting device according to the present invention.

FIG. 5 is a flowchart showing the operation of the control means of the headrest adjusting device according to the present invention.

FIG. 6 is a flowchart showing the operation of the control means of the headrest adjusting device according to the present invention.

FIG. 7 is a flowchart showing the operation of the control means of the headrest adjusting device according to the present invention.

FIG. 8 is a schematic view showing the operation of the headrest adjusting device according to the present invention.

FIG. 9 is a schematic view showing the operation of the headrest adjusting device according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 vehicle seat (seat) 4 headrest 7 drive mechanism (first drive means) 8 drive mechanism (second drive means) 9 control circuit (control means) 96 storage circuit (storage means)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Koji Aoki 2-1-1 Asahi-cho, Kariya-shi, Aichi Prefecture Inside Aisin Seiki Co., Ltd. (72) Inventor Toshimitsu Oka 2-1-1 Asahi-cho, Kariya-shi, Aichi Prefecture Aisin Within Seiki Co., Ltd. (72) Inventor Tsuyoshi Aso 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yuki Hasegawa 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Invention Kentaro Morishita 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (5)

[Claims] 1. A headrest adjustment device for moving a headrest up and down in accordance with a forward and backward movement of a seat, wherein a storage means stores a target movement position of the headrest corresponding to an arbitrary position of the seat, and the seat after the start of movement. When the target movement position of the headrest corresponding to the movement position of the headrest is separated from the initial position of the headrest corresponding to the initial position of the seat before the movement starts by a predetermined distance or more, the headrest starts moving up and down and moving A headrest adjusting device comprising: a control unit that moves the headrest to a target movement position set as a characteristic line that changes according to the position of the seat. 2. A first driving means for moving a seat provided with a headrest to an arbitrary position along a longitudinal direction of the seat, a second driving means for moving the headrest along a height direction of the seat, Control means for controlling the movement of the headrest by the second drive means in accordance with the movement of the seat by the first drive means, wherein the control means is configured to store any of the sheets by a storage means A target movement position of the headrest corresponding to a position is stored, and a target movement position of the headrest corresponding to a movement position of the seat after the movement starts is an initial movement of the headrest corresponding to an initial position of the seat before the movement starts. When separated from the position by more than a predetermined dimension,
A headrest adjustment device, wherein the headrest starts moving up and down, and moves the headrest to a target movement position set as a characteristic line that changes according to the position of the moving seat. 3. The headrest adjusting device according to claim 2, wherein the second driving unit has a configuration for moving the headrest to an arbitrary position. 4. The storage means stores a target movement position of the headrest corresponding to an arbitrary position of the seat as a characteristic range having a predetermined allowable movement position area based on the target movement position. Controlling the headrest to be moved into the allowable movement position area when the target movement position of the headrest is out of the limit or outside the allowable movement position area due to the movement of the seat. The headrest adjusting device according to claim 1, wherein 5. The headrest adjusting device according to claim 4, wherein the second driving means has a configuration for moving the headrest to an arbitrary position within the allowable movement position area.