Patent Description:
A child safety seat is typically used in an automobile vehicle to properly restrain a child in the event of accidental collision. The child safety seat usually has a backrest provided with a headrest that is movable along the backrest for height adjustment in accordance with the size of the child. Unfortunately, this conventional construction can only provide a limited range of height adjustment that may not be suitable for children of all sizes.

Document <CIT>describes a child safety seat with a seatback, a cartridge that can be located at discrete vertical positions relative to the seatback, and an adjustable headrest.

Therefore, there is a need for an improved child safety seat that can offer a larger range of height adjustment and address at least the foregoing issues.

The present invention describes a child safety seat including a backrest assembly that has multiple stages of height adjustment adapted to children of different sizes and ages.

According to the invention, the child safety seat includes a seat portion, a backrest assembly connected with the seat portion, and a backrest adjusting system. The backrest assembly includes a first backrest portion, a second backrest portion slidably connected with the first backrest portion, and a headrest slidably connected with the second backrest portion. The backrest adjusting system is carried with the backrest assembly and is configured to provide a first stage of height adjustment where the first and second backrest portions are locked with each other and the headrest is movable relative to the first and second backrest portions for adjustment between a plurality of first positions, and a second stage of height adjustment where the second backrest portion is locked with the headrest and unlocked from the first backrest portion so that the second backrest portion and the headrest are movable in unison relative to the first backrest portion for adjustment between a plurality of second positions. The backrest adjusting system includes an adjustment latch carried with the headrest, the adjustment latch being operable to engage with the second backrest portion for locking the headrest in any one of the first positions in the first stage of height adjustment and to engage with the first backrest portion for locking the headrest in any one of the second positions in the second stage of height adjustment.

<FIG> are various schematic views illustrating an embodiment of a child safety seat <NUM>. Referring to <FIG>, the child safety seat <NUM> includes a seat portion <NUM>, a backrest assembly that is connected with the seat portion <NUM> and includes two backrest portions <NUM> and <NUM> and a headrest <NUM>, and a backrest adjusting system <NUM>.

The backrest portion <NUM> is connected with the seat portion <NUM>. According to an example of construction, the backrest portion <NUM> may be pivotally connected with the seat portion <NUM> about a pivot axis extending transversally (i.e., direction shown with arrow C in <FIG>) from a left to a right side of the seat portion <NUM>. The backrest portion <NUM> can thereby rotate relative to the seat portion <NUM> for adjustment: for example, the backrest portion <NUM> can be forwardly folded toward the seat portion <NUM> so that the overall size of the child safety seat <NUM> is reduced for convenient storage and/or transport. It will be appreciated that the backrest portion <NUM> may also be fixedly attached to the seat portion <NUM> without rotational adjustability.

According to an example of construction, the backrest portion <NUM> may be fixedly attached to the seat portion <NUM> via a connection that is detachable or not detachable. For example, a lower end of the backrest portion <NUM> can include one or more catches <NUM> having a semicircular recess 204a (as shown in <FIG> and <FIG>) that can engage with a corresponding structure on the seat portion <NUM> for pivotally assembling the backrest portion <NUM> with the seat portion <NUM> in a detachable manner.

Referring to <FIG>, the backrest portion <NUM> is slidably connected with the backrest portion <NUM> for sliding movement along a lengthwise axis D of the backrest assembly, whereby the backrest portion <NUM> can be adjusted upward and downward relative to the backrest portion <NUM> and the seat portion <NUM> according to the size of a child. According to an example of construction, the backrest portions <NUM> and <NUM> may be disposed one in front of the other for a compact assembly, e.g., the backrest portion <NUM> be placed in front of or behind the backrest portion <NUM>.

The headrest <NUM> is slidably connected with the backrest portion <NUM> for sliding movement along the lengthwise axis D of the backrest assembly, whereby the headrest <NUM> can be adjusted upward and downward relative to the backrest portions <NUM> and <NUM> and the seat portion <NUM> according to the size of a child. According to an example of construction, the headrest <NUM> may include a head support portion 40A, and a mount panel 40B that is fixedly connected with and projects downward from the head support portion 40A, the mount panel 40B being slidably disposed through a channel provided in the backrest portion <NUM> for slidably assembling the headrest <NUM> with the backrest portion <NUM>.

The backrest adjusting system <NUM> is disposed on the backrest assembly, and is configured to provide multiple stages of height adjustment. According to an embodiment, two stages of height adjustment can be provided: a first stage where the backrest portions <NUM> and <NUM> are locked with each other and cannot move relative to each other while the headrest <NUM> is movable relative to the backrest portions <NUM> and <NUM> for adjustment, and a second stage where the backrest portion <NUM> is unlocked from the backrest portion <NUM> and is locked with the headrest <NUM> so that the headrest <NUM> and the backrest portion <NUM> are movable in unison relative to the backrest portion <NUM> for adjustment. The first stage can exemplary correspond to a configuration where the backrest portion <NUM> is locked with the backrest portion <NUM> in a predetermined anchor position and the headrest <NUM> is movable relative to the backrest portions <NUM> and <NUM> for adjustment within a first height range. The second stage can exemplary correspond to a configuration where the backrest portion <NUM> and the headrest <NUM> locked with each other are movable in unison relative to the backrest portion <NUM> to adjust the headrest <NUM> within a second height range lower than the first height range.

In conjunction with <FIG>, <FIG> are various schematic views illustrating construction details of the backrest adjusting system <NUM>. Referring to <FIG>, the backrest adjusting system <NUM> can include a release actuator <NUM>, two adjustment latches <NUM>, a lock <NUM>, a spring <NUM> and a switching actuator <NUM>. The release actuator <NUM> and the two adjustment latches <NUM> are assembled with the headrest <NUM>, and are movable along with the headrest <NUM> during adjustment of the headrest <NUM>.

Referring to <FIG>, each of the two adjustment latches <NUM> can engage with any of the backrest portion <NUM> and the backrest portion <NUM> for locking the headrest <NUM> at a desirable height in any of the first and second stages of height adjustment, and disengage from any of the backrest portion <NUM> and the backrest portion <NUM> to unlock the headrest <NUM> for adjustment. According to an example of construction, the two adjustment latches <NUM> can be connected with the mount panel 40B of the headrest <NUM> for sliding transversally relative to the headrest <NUM>, i.e., along an axis extending from a left to a right side of the headrest <NUM>. For example, the two adjustments latches <NUM> can be assembled with the mount panel 40B respectively adjacent to two opposite side edges of the mount panel 40B, and are operable to slide transversally in opposite directions relative to the mount panel 40B. The two adjustment latches <NUM> can slide away from each other so that each adjustment latch <NUM> can protrude sideways from the mount panel 40B and engage with any of the backrest portion <NUM> and the backrest portion <NUM> for locking the headrest <NUM> in position, and can slide toward each other to disengage from any of the backrest portion <NUM> and the backrest portion <NUM> and thereby unlock the headrest <NUM> for adjustment.

Referring to <FIG> and <FIG>, the backrest portion <NUM> can include a plurality of height locking sites <NUM> associated with the first stage of height adjustment of the backrest assembly. The height locking sites <NUM> may exemplary include openings, recesses, slots or the like, and may be disposed in two symmetric rows parallel to the lengthwise axis D at a left and a right side of the backrest portion <NUM>. When the headrest <NUM> is assembled with the backrest portion <NUM>, the mount panel 40B of the headrest <NUM> is disposed between the two rows of the height locking sites <NUM>. The number of height locking sites <NUM> provided at each of the left and right side of the backrest portion <NUM> may vary depending on the desirable number of settable positions for the first stage of height adjustment. For example, each of the left and right side of the backrest portion <NUM> may respectively include <NUM>, <NUM>, <NUM>, <NUM> or more height locking sites <NUM> so that the first stage of height adjustment may correspondingly include <NUM>, <NUM>, <NUM>, <NUM> or more settable positions. The headrest <NUM> may be locked in any of the settable positions in the first stage of height adjustment by engaging each adjustment latch <NUM> with a corresponding one of the height locking sites <NUM>. For example, the two adjustment latches <NUM> can slide away from each other so that each adjustment latch <NUM> can protrude sideways from the mount panel 40B of the headrest <NUM> and engage with a corresponding one of the height locking sites <NUM> for locking the headrest <NUM> in position, and can slide toward each other to disengage from the height locking sites <NUM> and thereby unlock the headrest <NUM> for adjustment.

The backrest portion <NUM> can include a plurality of height locking sites <NUM> associated with the second stage of height adjustment of the backrest assembly. The height locking sites <NUM> may exemplary include openings, recesses, slots or the like, and may be disposed in two symmetric rows parallel to the lengthwise axis D at a left and a right side of the backrest portion <NUM>. The number of height locking sites <NUM> provided at each of the left and right side of the backrest portion <NUM> may vary depending on the desirable number of settable positions for the second stage of height adjustment. For example, each of the left and right side of the backrest portion <NUM> may respectively include <NUM>, <NUM>, <NUM>, <NUM> or more height locking sites <NUM> so that the second stage of height adjustment may correspondingly include <NUM>, <NUM>, <NUM>, <NUM> or more settable positions. The headrest <NUM> may be locked in any of the settable positions in the second stage of height adjustment by engaging each adjustment latch <NUM> with a corresponding one of the height locking sites <NUM>. For example, the two adjustment latches <NUM> can slide away from each other so that each adjustment latch <NUM> can protrude sideways from the mount panel 40B of the headrest <NUM> and engage with a corresponding one of the height locking sites <NUM> for locking the headrest <NUM> and the backrest portion <NUM> in position, and can slide toward each other to disengage from the height locking sites <NUM> and thereby unlock the headrest <NUM> and the backrest portion <NUM> for adjustment.

The two row regions of the height locking sites <NUM> on the backrest portion <NUM> may overlap at least partially with the two row regions of the height locking sites <NUM> on the backrest portion <NUM> when the backrest portion <NUM> moves in the second stage of height adjustment. According to an example of construction, the two rows of the height locking sites <NUM> may be located between the two rows of the height locking sites <NUM> in the second stage of height adjustment, and the two adjustment latches <NUM> may also respectively engage with two ones of the height locking sites <NUM> (e.g., the lowest ones) on the backrest portion <NUM> when the headrest <NUM> and the backrest portion <NUM> are locked in any positions in the second stage of height adjustment.

Referring to <FIG>, the release actuator <NUM> is movably coupled to the two adjustment latches <NUM>, whereby the release actuator <NUM> is operable to urge the adjustment latches <NUM> in movements for unlocking the headrest <NUM>. According to an example of construction, the release actuator <NUM> can be respectively coupled to the two adjustment latches <NUM> via two linking members <NUM>. Each linking member <NUM> can have an elongate shape respectively affixed to one adjustment latch <NUM> and the release actuator <NUM> at two opposite ends, whereby the release actuator <NUM>, the linking members <NUM> and the two adjustment latches <NUM> are movable in unison during operation.

According to an example of construction, the release actuator <NUM> may be provided as a handle, and may be disposed at a central region of the headrest <NUM>, e.g., at a central region adjacent to a top of the head support portion 40A. The release actuator <NUM> can be slidably connected with the headrest <NUM> for sliding movements along the lengthwise axis D of the backrest assembly. Each linking member <NUM> connecting the release actuator <NUM> to one adjustment latch <NUM> can include a curved shape and can be elastically deformable. For example, each linking member <NUM> can include a first portion <NUM> that extends generally parallel to the lengthwise axis D of the backrest assembly and upwardly connects with the release actuator <NUM>, and a second portion <NUM> having a curved shape that connects with one adjustment latch <NUM>. The headrest <NUM> may further include a guiding structure <NUM> configured to guide sliding movements of the linking members <NUM> during operation. For example, the guiding structure <NUM> may include ribs and/or slots provided on the mount panel 40B that are in sliding contact with the linking members <NUM>. Once assembled, the adjustment latches <NUM> and the linking members <NUM> may be at least partially concealed between the mount panel 40B of the headrest <NUM> and the backrest portion <NUM>.

With the aforementioned construction, the release actuator <NUM>, the adjustment latches <NUM> and the linking members <NUM> are linked with one another, and are movable in unison for locking and unlocking the headrest <NUM>. For example, the release actuator <NUM> can slide downward when the two adjustment latches <NUM> slide away from each other to engage with the backrest portion <NUM> and/or the backrest portion <NUM> for locking the headrest <NUM>, and the release actuator <NUM> can be pulled upward to draw the two adjustment latches <NUM> to slide toward each other and disengage from the backrest portion <NUM> and/or the backrest portion <NUM> for unlocking the headrest <NUM>.

Referring to <FIG>, the backrest adjusting system <NUM> can further include a spring <NUM> configured to apply a biasing force for urging the adjustment latches <NUM> toward a locking state in engagement with any of the backrest portion <NUM> and the backrest portion <NUM>. For example, the spring <NUM> can be respectively connected with the release actuator <NUM> and the headrest <NUM>, and can apply a downward biasing force on the release actuator <NUM>.

Referring to <FIG>, the release actuator <NUM> may include a protrusion <NUM> that is restricted to slide within a limiting slot <NUM> provided on the headrest <NUM> (e.g., on the head support portion 40A of the headrest <NUM>) for limiting the course of the release actuator <NUM> and the two adjustment latches <NUM>. For example, the travel of the release actuator <NUM> and the two adjustment latches <NUM> in an unlocking direction may be stopped by a contact between the protrusion <NUM> and an upper end of the limiting slot <NUM>, and the travel of the release actuator <NUM> and the two adjustment latches <NUM> in a locking direction may be stopped by a contact between the protrusion <NUM> and a lower end of the limiting slot <NUM>.

Referring to <FIG>, the lock <NUM> is assembled with the backrest portion <NUM>, and can be operable independently of the release actuator <NUM> and the adjustment latches <NUM>. More specifically, the lock <NUM> is movable along with the backrest portion <NUM>, and can have two locking states: a first locking state where the lock <NUM> is engaged with the backrest portion <NUM> and disengaged from the headrest <NUM> corresponding to the first stage of height adjustment, and a second locking state where the lock <NUM> is engaged with the headrest <NUM> and disengaged from the backrest portion <NUM> corresponding to the second stage of height adjustment. According to an example of construction, the lock <NUM> can include two latching parts <NUM> and <NUM> and a spring <NUM>, the latching part <NUM> being provided for locking engagement with the headrest <NUM>, and the latching part <NUM> being provided for locking engagement with the backrest portion <NUM>. The lock <NUM> may be exemplary disposed in a central region of the backrest portion <NUM> that extends between the two rows of the height locking sites <NUM>, e.g., the lock <NUM> may be disposed centrally and close to a lower transversal edge of the backrest portion <NUM>.

Referring to <FIG>, the latching part <NUM> can unlock the headrest <NUM> from the backrest portion <NUM> when the lock <NUM> is in the first locking state corresponding to the first stage of height adjustment, and can lock the headrest <NUM> with the backrest portion <NUM> when the lock <NUM> is in the second locking state corresponding to the second stage of height adjustment. According to an example of construction, the latching part <NUM> can be disposed in a central region of the backrest portion <NUM> between the two rows of the height locking sites <NUM>. According to an example of construction, the latching part <NUM> can be pivotally connected with the backrest portion <NUM> about a pivot axis L extending transversally relative to the backrest portion <NUM>, and can include two side protrusions <NUM> eccentric from the pivot axis L that protrude from two opposite sides of the latching part <NUM>. The side protrusions <NUM> can be fixedly connected with the latching part <NUM>. For example, the latching part <NUM> including the side protrusions <NUM> may be formed integrally as a single part. The latching part <NUM> can rotate about the pivot axis L in a first direction to respectively engage the two side protrusions <NUM> with two anchoring portions <NUM> provided on the headrest <NUM> for locking the headrest <NUM> with the backrest portion <NUM>, and can rotate in a second direction opposite to the first direction to respectively disengage the two side protrusions <NUM> from the two anchoring portions <NUM> for unlocking the headrest <NUM> from the backrest portion <NUM>.

According to an example of construction, the two anchoring portions <NUM> can be provided on the mount panel 40B of the headrest <NUM>, and can be grooves, slots, recesses or the like. For example, each anchoring portion <NUM> may be a curved slot that has a center of curvature on the pivot axis L of the latching part <NUM> and is adapted to receive the engagement of a corresponding side protrusion <NUM>. The latching part <NUM> can exemplary rotate in a first direction to displace the two side protrusions <NUM> forward for engagement with the two anchoring portions <NUM> of the headrest <NUM>, and can rotate in a second direction opposite to the first direction to displace the two side protrusions <NUM> rearward for disengagement from the two anchoring portions <NUM> of the headrest <NUM>. The backrest portion <NUM> may include two receiving slots <NUM> (better shown in <FIG> and <FIG>) adapted to receive the two side protrusions <NUM> when the latching part <NUM> is fully disengaged from the headrest <NUM>, which can ensure proper placement of the latching part <NUM> when the lock <NUM> is in the first locking state. For example, each receiving slot <NUM> may be a curved slot that has a center of curvature on the pivot axis L of the latching part <NUM>.

Referring to <FIG>, <FIG>, <FIG> and <FIG>, the latching part <NUM> can lock the backrest portion <NUM> with the backrest portion <NUM> when the lock <NUM> is in the first locking state corresponding to the first stage of height adjustment, and can unlock the backrest portion <NUM> from the backrest portion <NUM> when the lock <NUM> is in the second locking state corresponding to the second stage of height adjustment. According to an example of construction, the latching part <NUM> can be carried by the latching part <NUM>, so that the latching parts <NUM> and <NUM> may move in unison during a rotation of the latching part <NUM> about the pivot axis L. For example, the latching part <NUM> and the side protrusions <NUM> may be placed at two opposite sides of the latching part <NUM> relative to the pivot axis L, whereby the latching part <NUM> may be rotatable to concurrently displace the latching part <NUM> and the side protrusions <NUM> in opposite directions.

Moreover, the latching part <NUM> can be movably connected with the latching part <NUM> so as to allow relative movement between the latching parts <NUM> and <NUM>. For example, the latching part <NUM> can be slidably connected with the latching part <NUM> for sliding along a front-rear axis E (better shown in <FIG>) of the backrest portion <NUM>. The latching part <NUM> can thereby slide relative to the latching part <NUM> between a first position where an abutting portion <NUM> of the latching part <NUM> (better shown in <FIG>) can contact with or lie adjacent to without contacting an abutting portion <NUM> of the latching part <NUM> (better shown in <FIG>), and a second position where the abutting portion <NUM> is displaced away from the abutting portion <NUM>. According to an example of construction, the latching part <NUM> can have a protuberant portion 32A (better shown in <FIG>) that can project forward at a front of the latching part <NUM> to facilitate locking engagement with the backrest portion <NUM> when the latching part <NUM> is in the first position relative to the latching part <NUM>. The spring <NUM> is respectively connected with the latching parts <NUM> and <NUM>, and can bias the latching part <NUM> toward the first position adapted to provide locking engagement.

With the aforementioned construction, the latching part <NUM> can move in one direction to engage with an anchoring portion <NUM> provided on the backrest portion <NUM> for locking the backrest portion <NUM> with the backrest portion <NUM>, and can move in an opposite direction to disengage from the anchoring portion <NUM> for unlocking the backrest portion <NUM> from the backrest portion <NUM>. For example, a rotation of the latching part <NUM> for disengaging the side protrusions <NUM> and unlocking the headrest <NUM> can displace the latching part <NUM> in one direction for engagement with the anchoring portion <NUM> of the backrest portion <NUM>, and an external force can be applied on the latching part <NUM> to cause the latching part <NUM> to move relative to the latching part <NUM> in an opposite direction for disengaging from the anchoring portion <NUM> of the backrest portion <NUM>. The spring <NUM> can be compressed when the latching part <NUM> moves for disengaging from the anchoring portion <NUM> of the backrest portion <NUM>.

According to an example of construction, the anchoring portion <NUM> can include an opening provided on a front wall 20A of the backrest portion <NUM>, and the protuberant portion 32A of the latching part <NUM> can engage with the anchoring portion <NUM> for locking the backrest portion <NUM> with the backrest portion <NUM>. The anchoring portion <NUM> may be exemplary disposed in a central region on the front wall 20A of the backrest portion <NUM>. More specifically, the anchoring portion <NUM> may be exemplary disposed in a recessed region <NUM> of the front wall 20A (better shown in <FIG>) having a suitable depth so that the latching part <NUM> (in particular, the protuberant portion 32A thereof) engaged with the anchoring portion <NUM> would not protrude outward from a major surface of the front wall 20A. This may prevent a child resting against the backrest assembly from feeling discomfort when the latching part <NUM> is engaged with the anchoring portion <NUM> of the backrest portion <NUM>. With the aforementioned placement of the anchoring portion <NUM> on the front wall 20A of the backrest portion <NUM>, the latching part <NUM> can exemplary move forward to engage the protuberant portion 32A with the anchoring portion <NUM> of the backrest portion <NUM> for locking the backrest portion <NUM> with the backrest portion <NUM>, and can move rearward to disengage the protuberant portion 32A from the anchoring portion <NUM> of the backrest portion <NUM> for unlocking the backrest portion <NUM> from the backrest portion <NUM>. For unlocking the backrest portion <NUM> from the backrest portion <NUM>, a caregiver can press the protuberant portion 32A exposed through the anchoring portion <NUM> at the front of the backrest portion <NUM> so as to cause the latching part <NUM> to slide relative to the latching part <NUM> and disengage from the anchoring portion <NUM> of the backrest portion <NUM>.

Referring to <FIG>, the spring <NUM> is configured to bias the lock <NUM> toward the second locking state. According to an example of construction, the spring <NUM> can be respectively connected with the latching part <NUM> and the backrest portion <NUM>, and is arranged to bias the latching part <NUM> to rotate about the pivot axis L for engagement with the headrest <NUM>. The spring <NUM> may be compressed when the lock <NUM> is in the first locking state.

Referring to <FIG> and <FIG>, the switching actuator <NUM> is operable to cause the lock <NUM> to switch from the second locking state (i.e., wherein the backrest portion <NUM> is locked with the headrest <NUM> and unlocked from the backrest portion <NUM>) to the first locking state (i.e., wherein the backrest portion <NUM> is unlocked from the headrest <NUM> and locked with the backrest portion <NUM>) when a movement of the backrest portion <NUM> and the headrest <NUM> locked with each other moves the backrest portion <NUM> to a predetermined anchor position relative to the backrest portion <NUM>. According to an embodiment, the switching actuator <NUM> can be configured to contact and urge the latching part <NUM> to move and disengage from the headrest <NUM> so that the latching part <NUM> can engage with the backrest portion <NUM>, when a movement of the backrest portion <NUM> and the headrest <NUM> locked with each other by the latching part <NUM> moves the backrest portion <NUM> to the anchor position relative to the backrest portion <NUM>.

According to an example of implementation, the anchor position of the backrest portion <NUM> relative to the backrest portion <NUM> may correspond to a most extended position of the backrest portion <NUM> relative to the backrest portion <NUM>, which may be exemplary when the backrest portion <NUM> is at a highest position relative to the backrest portion <NUM> with the adjustment latch <NUM> on each of the and right side located above or at the same level as a highest one of the height locking sites <NUM> on the backrest portion <NUM>. However, it will be appreciated that the anchor position of the backrest portion <NUM> relative to the backrest portion <NUM> may be set at other locations. For example, the anchor position of the backrest portion <NUM> relative to the backrest portion <NUM> may be any lower position where the adjustment latch <NUM> on each of the and right side is located above or at the same level as any height locking site <NUM> that is higher than the lowest height locking site <NUM> and lower than the highest height locking site <NUM> on the backrest portion <NUM>.

According to an example of construction, the switching actuator <NUM> can be fixedly connected with the backrest portion <NUM>, and the lock <NUM> can move toward or away from the switching actuator <NUM> when the backrest portion <NUM> slides relative to the backrest portion <NUM> in the second stage of height adjustment. The switching actuator <NUM> may be a single part fixedly attached to the backrest portion <NUM>, or may be a part integrally formed with the backrest portion <NUM>. As the backrest portion <NUM> locked with the headrest <NUM> by the latching part <NUM> slides upward and reaches the anchor position relative to the backrest portion <NUM>, the switching actuator <NUM> can contact and urge the lock <NUM> to switch from the second locking state to the first locking state. More specifically, the switching actuator <NUM> can contact and urge the latching part <NUM> to rotate for disengaging the side protrusions <NUM> from the anchoring portions <NUM> of the headrest <NUM> and for engaging the latching part <NUM> with the anchoring portion <NUM> of the backrest portion <NUM>. For example, a ramp surface <NUM> provided on the switching actuator <NUM> may contact and push against a ramp surface <NUM> provided on the latching part <NUM> to urge the latching part <NUM> in rotation for disengaging from the headrest <NUM> as the backrest portion <NUM> slides upward and reaches the anchor position.

Exemplary operation of the backrest adjusting system <NUM> is described hereinafter with reference to <FIG>. Suppose that the backrest assembly is in the first stage of height adjustment. The lock <NUM> is in the first locking state, and the backrest portions <NUM> and <NUM> are locked with each other by the engagement of the latching part <NUM> with the anchoring portion <NUM> of the backrest portion <NUM> while the headrest <NUM> is unlocked from the backrest portion <NUM>. In this first stage of height adjustment, the backrest portions <NUM> and <NUM> are not movable relative to each other and are affixed to the seat portion <NUM>, and the headrest <NUM> can slide upward or downward relative to the backrest portions <NUM> and <NUM> for adjusting the headrest <NUM> within a first height range. Once the headrest <NUM> reaches a desired position, the adjustment latches <NUM> can engage with two corresponding ones of the height locking sites <NUM> on the backrest portion <NUM> for locking the headrest <NUM> in position.

When the backrest assembly is to be switched from the first stage of height adjustment to the second stage of height adjustment for adjusting the headrest <NUM> within the second height range lower than the first height range, a caregiver can operate the release actuator <NUM> to cause the adjustment latches <NUM> to disengage from the backrest portion <NUM>, which thereby unlocks the headrest <NUM> from the backrest portion <NUM>. While the backrest portions <NUM> and <NUM> are locked with each other by the latching part <NUM> and remain stationary, the unlocked headrest <NUM> then can be moved downward until the headrest <NUM> reaches a proper position relative to the backrest portion <NUM> and the lock <NUM> that enables locking engagement of the lock <NUM> with the anchoring portions <NUM> of the headrest <NUM>. This proper position may be, for example, a lowest position of the headrest <NUM> relative to the backrest portion <NUM> corresponding to the lowest ones of the height locking sites <NUM>. Once the headrest <NUM> is in the proper position relative to the backrest portion <NUM>, the caregiver can release the release actuator <NUM> so that the adjustment latches <NUM> can engage with the corresponding ones of the height locking sites <NUM> so as to lock the headrest <NUM> with the backrest portion <NUM>. Then the protuberant part 32A can be pressed inward so as to cause the latching part <NUM> to slide relative to the latching part <NUM> and the backrest portion <NUM> and disengage from the anchoring portion <NUM> of the backrest portion <NUM>, whereby the backrest portions <NUM> and <NUM> are unlocked from each other. As the latching part <NUM> moves to disengage from the backrest portion <NUM>, the abutting portion <NUM> of the latching part <NUM> can move away from the abutting portion <NUM> of the latching part <NUM>. Subsequently, the headrest <NUM> and the backrest portion <NUM> locked with each other by the adjustment latches <NUM> can move downward in unison relative to the backrest portion <NUM>, which also causes the latching part <NUM> to move downward along with the backrest portion <NUM>. As a result, the latching part <NUM> can move away and disengage from the switching actuator <NUM>, and can rotate and engage with the anchoring portions <NUM> of the headrest <NUM> owing to the biasing force applied by the spring <NUM>. The lock <NUM> can be thereby switched to the second locking state, and the backrest portion <NUM> and the headrest <NUM> can be locked with each other by the latching part <NUM> for the second stage of height adjustment. Once the headrest <NUM> and the backrest portion <NUM> are adjusted to a desired position, the adjustment latches <NUM> can engage with two corresponding ones of the height locking sites <NUM> on the backrest portion <NUM> for locking the headrest <NUM> and the backrest portion <NUM> in position with respect to the backrest portion <NUM>.

When the backrest assembly is to be switched from the second stage of height adjustment to the first stage of height adjustment for adjusting the headrest <NUM> within the first height range, a caregiver can operate the release actuator <NUM> to cause the adjustment latches <NUM> to disengage from the backrest portion <NUM> and thereby unlock the headrest <NUM> and the backrest portion <NUM> from the backrest portion <NUM>, wherein the the headrest <NUM> and the backrest portion <NUM> remain locked with each other by the latching part <NUM>. Then the headrest <NUM> and the backrest portion <NUM> can be moved upward in unison until the backrest portion <NUM> reaches the predetermined anchor position relative to the backrest portion <NUM>, which can exemplary correspond to a most extended position of the backrest portion <NUM> relative to the backrest portion <NUM>. This upward movement of the backrest portion <NUM> can move the latching part <NUM> toward the switching actuator <NUM>. When the backrest portion <NUM> reaches the anchor position relative to the backrest portion <NUM>, the latching part <NUM> can engage with the anchoring portion <NUM> of the backrest portion <NUM> under the biasing action of the spring <NUM>, and the switching actuator <NUM> can contact and urge the latching part <NUM> to rotate about the pivot axis L for disengaging the side protrusions <NUM> of the latching part <NUM> from the anchoring portions <NUM> of the headrest <NUM>. In an embodiment, the relative positions of the anchoring portion <NUM> and the switching actuator <NUM> are properly set related to the locations of the latching parts <NUM> and <NUM>, so that as the latching part <NUM> rotates for disengaging from the headrest <NUM>, the latching part <NUM> can move concurrently under the biasing action of the spring <NUM> for engaging with the anchoring portion <NUM> of the backrest portion <NUM>. In other words, the locking status of the latching parts <NUM> and <NUM> can be switched at a same time. Accordingly, the latching parts <NUM> and <NUM> are movable in a concurrent manner for switching the lock <NUM> from the second locking state to the first locking state so that the backrest portion <NUM> is locked with the backrest portion <NUM> in the anchor position by the latching part <NUM>, and the headrest <NUM> is unlocked from the backrest portion <NUM> and can slide relative to the backrest portions <NUM> and <NUM> for adjustment. Once the headrest <NUM> is adjusted to a desired position, the adjustment latches <NUM> can engage with two corresponding ones of the height locking sites <NUM> on the backrest portion <NUM> for locking the headrest <NUM> in position with respect to the backrest portion <NUM>.

Advantages of the child safety seat described herein include a backrest assembly that has multiple stages of height adjustment adapted to children of different sizes and ages. Accordingly, the child safety seat may offer an extended service life.

Although the embodiments described herein provide a particular construction of the lock <NUM> having the aforementioned latching parts <NUM> and <NUM> that can respectively engage with the headrest <NUM> and the backrest portion <NUM>, it will be appreciated that other constructions may be possible. For example, another construction may provide a lock that is slidably connected with the backrest portion <NUM> and can slide to selectively attach either of the backrest portion <NUM> and the headrest <NUM> to the backrest portion <NUM>, the switching actuator <NUM> contacting with the lock to cause displacement of the lock for switching from the second locking state to the first locking state. Another exemplary construction may provide a lock that is movably connected with the backrest portion <NUM> via a resilient arm and can be moved to selectively attach either of the backrest portion <NUM> and the headrest <NUM> to the backrest portion <NUM>, the switching actuator <NUM> being configured to push against the resilient arm so as to cause an elastic deformation of the resilient arm that displaces the lock for switching from the second locking state to the first locking state. Other possible constructions can provide a lock including magnetic and/or electromagnetic elements capable of selectively attaching either of the backrest portion <NUM> and the headrest <NUM> to the backrest portion <NUM>, a lock including elastic elements capable of selectively attaching either of the backrest portion <NUM> and the headrest <NUM> to the backrest portion <NUM>, or any combinations thereof.

Claim 1:
A child safety seat (<NUM>) comprising:
a seat portion (<NUM>);
a backrest assembly connected with the seat portion (<NUM>), the backrest assembly including a first backrest portion (<NUM>), a second backrest portion (<NUM>) slidably connected with the first backrest portion (<NUM>), and a headrest (<NUM>) slidably connected with the second backrest portion (<NUM>); and
a backrest adjusting system (<NUM>) carried with the backrest assembly and configured to provide a first stage of height adjustment where the first and second backrest portions (<NUM>, <NUM>) are locked with each other and the headrest (<NUM>) is movable relative to the first and second backrest portions (<NUM>, <NUM>) for adjustment between a plurality of first positions, and a second stage of height adjustment where the second backrest portion (<NUM>) is locked with the headrest (<NUM>) and unlocked from the first backrest portion (<NUM>) so that the second backrest portion (<NUM>) and the headrest (<NUM>) are movable in unison relative to the first backrest portion (<NUM>) for adjustment between a plurality of second positions;
characterised in that the backrest adjusting system (<NUM>) includes an adjustment latch (<NUM>) carried with the headrest (<NUM>), the adjustment latch (<NUM>) being operable to engage with the second backrest portion (<NUM>) for locking the headrest (<NUM>) in any one of the first positions in the first stage of height adjustment and to engage with the first backrest portion (<NUM>) for locking the headrest (<NUM>) in any one of the second positions in the second stage of height adjustment.