Title of Invention: Child safety car seat with position-adjustable shoulder safety belts Abstract: A safety car seat for a child has a headrest vertical moving device, a shoulder belt position control device, a sleeping support position control device, a crotch belt position control device, a footrest step position control device and a moving device for changing the size or capacity of a support space for protecting the child. The shoulder belt position control device includes two holding plates that slide along two inclined elongated holes and are connected by two pivotable control arms to a control pin that slides along a vertical guide slot in the seat backrest. Upper portions of the shoulder belts pass through slit holes in the holding plates. The upper ends of the belts can be adjusted higher, wider apart and less inclined, or lower, closer together and more inclined. Brief Summary: 1. Field of the Invention The present invention relates to a technique for changing the capacity of a space for supporting a juvenile whose body is in the process of growth, and more particularly, it relates to a technique for enabling a bed state optimum for a baby based on medical criteria in a neonatal period, infancy or childhood. 2. Description of the Prior Art The most important factors of a child-care instrument are excellent safeness and comfortability for a juvenile or child. Among child-care instruments, particularly a child safety car seat employed in a car must be comfortable and assure a high safety in supporting a child in a proper state responsive to the growth of the child. A neonate grows into an infant, a child and a school child, and its habitus or growth changes in this process. Therefore, the juvenile safety car seat must change the space for supporting the juvenile in response to the change of its habitus for regularly providing an optimum space responsive to the growth of the child. Further, it is extremely important to protect the brain, the neck and respiration of the juvenile, particularly a neonate or an infant whose brain is in a developmental stage. An object of the present invention is to provide a juvenile safety car seat capable of providing optimum comfortability and safeness for a child with due regard to the growth stage of the child""s body. Another object of the present invention is to provide a child safety car seat improved for easy handling. Still another object of the present invention is to provide a safety car seat improved in safety on the basis of an improved attachability to a seat of a car. A further object of the present invention is to provide a protector capable of providing optimum comfortability and safeness for a child with due regard to the growth stage of the child""s body, particularly a protector enabling protection with a multilayer structure for a child whose brain is in a developmental stage. A further object of the present invention relates to a child-care instrument and a bed for a neonate enabling a bed state optimum for a baby based on medical criteria in a neonatal period, infancy or childhood. The child safety seat according to the present invention provides a child safety seat adapted to be secured to a car seat by a seat belt provided on said car seat, said child safety seat comprising a seat body including a backrest for supporting a child""s back, a headrest movably supported by said seat body, said headrest including a head guard wall rising from a plane of said headrest for protecting the top of the head of a child in said safety seat, and headrest moving means operatively connected to said headrest for controlling a position of said headrest including said head guard wall relative to said backrest. Thus, it is possible to protect the juvenile with a capacity responsive to its growth. Consequently, the child safety car seat has been improved for comfort and safety of the entire child. In the aforementioned aspect, the capacity-variable device preferably has a head space control device for changing the capacity of a head space that is part of the support space, in response to growth of the head of the child. Thus, it is possible to protect the head of the child with a capacity responsive to growth of the child. Consequently, the child safety car seat can be improved in comfortability and safeness for the head of the child. The term xe2x80x9cjuvenilexe2x80x9d is used herein as a synonym for xe2x80x9cchildxe2x80x9d. In order to implement the aforementioned aspect in a more preferable state, the following structures are employed: More preferably, the aforementioned head space control device includes a head guard for protecting the head of a juvenile and a head guard vertical position control device for controlling the vertical position of the head guard with respect to the head position of the juvenile. More preferably, the aforementioned head space control device includes a head guard provided substantially above a backrest portion of the aforementioned juvenile safety car seat and a head guard attachment angle control device for controlling the angle of attachment of the head guard with respect to the aforementioned backrest portion, in order to protect the head of the juvenile. More preferably, the aforementioned head space control device includes a pair of side guards for protecting the lateral surfaces of the head of the juvenile and a side guard vertical position control device for controlling the vertical positions of the aforementioned pair of side guards with respect to the head position of the juvenile. More preferably, the aforementioned head space control device includes a pair of side guards for protecting the lateral surfaces of the head of the juvenile and a side guard space control device changing the space between the aforementioned pair of side guards. More preferably, the aforementioned head space control device includes a pair of side guards for protecting the lateral surfaces of the head of the juvenile and a side guard attaching and/or detaching device rendering the aforementioned pair of side guards attachable to and/or detachable from the aforementioned juvenile safety car seat. More preferably, the aforementioned head space control device includes a head guard and a pair of side guards for protecting the head of the juvenile, a coupling member for coupling the aforementioned head guard and the aforementioned pair of side guards with each other, and a coupling member vertical position control device for controlling the vertical position of the aforementioned coupling member with respect to the head position of the juvenile. More preferably, the aforementioned head space control device includes a head protector arranged in a clearance defined between the aforementioned head space forming part of the aforementioned support space and the head of the juvenile for forming a head receiving space. In the aforementioned aspect, the aforementioned capacity-variable device has a shoulder space control device changing the capacity of a shoulder region of the aforementioned support space in response to growth of the shoulders of the juvenile. Thus, it is possible to protect the shoulders of the juvenile with a capacity responsive to growth of the juvenile. Consequently, the juvenile safety car seat can be improved in comfortability and safeness for the shoulders of the juvenile. In order to implement the aforementioned aspect in a more preferable state, the following structures are employed: More preferably, the aforementioned shoulder space control device includes a safety belt having a shoulder belt located on the shoulder of the juvenile and a shoulder belt vertical position control device for controlling the vertical position of the aforementioned shoulder belt with respect to the shoulder position of the juvenile. More preferably, the aforementioned shoulder space control device includes a safety belt having a shoulder belt located on the shoulder of the juvenile and a shoulder belt width position control device for controlling the position of the shoulder belt in the width direction with respect to the shoulder position of the juvenile. More preferably, the aforementioned shoulder space control device includes a safety belt having a shoulder belt located on the shoulder of the juvenile and a shoulder belt inclination control device for controlling inclination of the aforementioned shoulder belt with respect to the shoulder position of the juvenile. More preferably, the aforementioned shoulder space control device includes a shoulder protector arranged in a clearance defined between the aforementioned shoulder region of the aforementioned support space and the shoulder of the juvenile for forming a shoulder receiving space. In the aforementioned aspect, the aforementioned capacity-variable device preferably has an abdominal space control device changing the capacity of an abdominal region of the aforementioned support space in response to growth of the abdominal region of the juvenile. Thus, it is possible to protect the abdominal region of the child with a capacity responsive to growth of the juvenile. Consequently, the present child safety car seat is improved in comfortability and safety for the abdominal region of the juvenile. In order to implement the aforementioned aspect in a more preferable state, the following structures are employed: More preferably, the abdominal space control device includes a safety belt having a crotch belt located on the crotch of the juvenile and a crotch belt horizontal position control device for controlling the horizontal position of the aforementioned crotch belt with respect to the abdominal position of the juvenile. More preferably, the abdominal space control device includes a safety belt having a crotch belt located on the crotch of the juvenile and a crotch belt vertical position control device for controlling the vertical position of the aforementioned crotch belt with respect to the abdominal position of the juvenile. More preferably, the aforementioned abdominal space control device includes a safety belt having a crotch belt located on the crotch of the juvenile and a crotch belt inclination control device for controlling inclination-of the aforementioned crotch belt with respect to the abdominal position of the juvenile. More preferably, the aforementioned abdominal space control device includes an abdominal protector arranged in a clearance defined between the aforementioned abdominal region of the aforementioned support space and the abdomen of the juvenile for forming an abdomen receiving space. More preferably, the aforementioned abdominal space control device includes a crotch belt protector attached to the aforementioned crotch belt to fill up a clearance between the crotch of the juvenile and the aforementioned crotch belt. In the aforementioned aspect, the capacity-variable device preferably has a leg space control device changing the capacity of a leg region of the aforementioned support space in response to growth of the legs of the juvenile. Thus, it is possible to protect the legs of the juvenile with a capacity responsive to growth of the juvenile. Consequently, the present child safety car seat is improved in comfortability and safeness for the legs of the juvenile. In order to implement the aforementioned aspect in a more preferable state, the following structures are employed: More preferably, the aforementioned leg space control device includes a footrest step located under the feet of the juvenile and a footrest, located under the legs of the juvenile, provided to be horizontally slidable. More preferably, the aforementioned leg space control device includes a leg protector arranged in a clearance defined between the aforementioned leg region of the aforementioned support space and the legs of the juvenile for forming a leg receiving space. A juvenile safety car seat according to another aspect of the present invention, which is fixed to a seat of a car with a seat belt provided on the seat of the car, comprises a seat body receiving the juvenile, a base supporting the aforementioned seat body from below to be rotatable and backwardly inclinable, a rotational position locking device locking the aforementioned seat body to a rotational position with respect to the aforementioned base, a backward inclination angle locking device locking the aforementioned seat body at an angle of backward inclination with respect to the aforementioned base, and a locking release device supported by the aforementioned base to simultaneously release the seat body from locking by the aforementioned rotational position locking device and locking by the aforementioned backward inclination angle locking device. Thus, the rotational position locking device and the backward inclination angle locking device can be handled with the single locking release device. The position of the locking release device, which is provided on the seat body, remains unchanged after the juvenile safety car seat is attached to the seat of the car. Consequently, handleability of the rotational position locking device and the backward inclination angle locking device has been improved. In order to implement the aforementioned aspect in a more preferable state, the following structure is employed: More preferably, the aforementioned seat body has a seat portion, a backrest portion and a seat portion angle control device changing the angle formed by the aforementioned seat portion and the aforementioned backrest portion in response to change of the angle of backward inclination. Thus, it is possible to eliminate pressure against the abdomen of the child. Consequently, the present child safety car seat has been made more comfortable. A juvenile safety car seat according to still another aspect of the present invention, which is fixed to a seat of a car with a seat belt provided on the seat of the car, comprises an attachment angle control device for controlling the angle of attachment of the aforementioned juvenile safety car seat with respect to the aforementioned seat of the car. Thus, it is possible to attach the present child safety car seat to the seat of the car at a proper attachment angle regardless of the shape of the seat of the car. Consequently, the present child safety car seat has been made more comfortable. In order to implement the aforementioned aspect in a more preferable state, the following structure is employed: More preferably, the aforementioned child safety car seat has a seat body supporting a child and a base supporting the aforementioned seat body, and the aforementioned attachment angle control device is provided on a bottom surface portion of the aforementioned base with a leg member projectable and stowable with respect to the aforementioned bottom surface portion in order to control inclination with respect to the aforementioned seat of the car. A protector according to a further aspect of the present invention is employed for a child-care instrument having a support space for receiving a juvenile whose body is in the process of growth, and the aforementioned protector forms a receiving space for filling up a clearance defined between the aforementioned support space and the child while rendering the capacity of the aforementioned receiving space variable in response to the child""s growth. Thus, it is possible to protect the juvenile with a capacity responsive to growth of its body. Consequently, the child-care instrument employing this protector has been made more comfortable and safer for the entire body of the child. In the aforementioned aspect, the protector preferably includes a head protector protecting the head of the child. Thus, it is possible to protect the head of the child with a capacity responsive to the child""s growth. Consequently, the child-care instrument employing the protector has been improved and made safer for the child""s head. In order to implement the aforementioned aspect in a more preferable state, the following structures are employed: More preferably, the aforementioned head protector includes a pair of head side wall portions protecting the temporal regions of the child and a head side wall space control device for controlling the space between the pair of head side wall portions. More preferably, the aforementioned head protector includes an inner head protector and an outer head protector arranged to doubly enclose the temporal regions and the parietal region of the child. Further preferably, the aforementioned inner head protector is so provided that the position of the inner head protector is vertically controllable with respect to the aforementioned outer head protector. In the aforementioned aspect, the aforementioned protector preferably includes a shoulder protector protecting the shoulder region of the child. Thus, it is possible to protect the shoulder region of the child with a capacity responsive to growth of the child. Consequently, the child-care instrument employing the protector has been improved to be more comfortable and safer for the shoulder region of the child. In order to implement the aforementioned aspect in a more preferable state, the following structure is employed: More preferably, the aforementioned shoulder protector includes a shoulder side wall portion protecting the lateral surfaces of the shoulder of the neonate or the infant and a shoulder side wall position control device for controlling the vertical position of the shoulder side wall portion. In the aforementioned aspect, the aforementioned protector preferably includes an abdominal protector protecting the abdominal region of the child. In order to implement the aforementioned aspect in a more preferable state, the following structure is employed: More preferably, the aforementioned abdominal protector includes a crotch protector protecting the crotch region of the child. In the aforementioned aspect, the aforementioned protector preferably includes a leg protector for protecting the child""s legs with comfort and safety during the child""s growth. In the aforementioned aspect, the aforementioned protector preferably includes an upper protector protecting the head region and the shoulder region of the child, and a lower protector protecting the abdominal region and the leg region, and at least either the aforementioned upper protector or the aforementioned lower protector includes a length control device for controlling the length as the child grows taller. Thus, it is possible to protect the child with a capacity responsive to growth. Consequently, the child-care instrument employing the protector has been made more comfortable and safer. A protector for a child-care instrument according to a further aspect of the present invention, consisting of a flexible material, is arranged in a juvenile receiving space of the child-care instrument, and comprises an upper protector enclosing the upper half of the body of a juvenile, a lower protector enclosing the lower half of the child""s body, and a head protector arranged inside the upper protector for enclosing the head of the child, whereby the head, particularly the brain, is well protected in a way comfortable for the growing child. In order to implement the aforementioned aspect in a more preferable state, the following structures are employed: More preferably, the protector further comprises a coupling device for detachably coupling the aforementioned upper protector and the aforementioned lower protector with each other. More preferably, the protector further comprises a coupling device for detachably coupling the aforementioned head protector to the aforementioned upper protector. A child-care instrument according to a further aspect of the present invention has a space supporting a baby, and the aforementioned space is provided to be capable of selecting a neonatal bed mode suitable as a habitat of a baby in a neonatal period, an infantile bed mode suitable to the habits of a baby in infancy, and a child seat mode suitable for the habits of a baby in childhood. According to the aforementioned child-care instrument, it is possible to apply a bed mode or a seat mode most suitable for the baby on the basis of medical criteria for a baby in a neonatal period, infancy or childhood whose brain is in a developmental stage in particular, for protecting the brain, the neck and respiration of the baby in a proper state. In the aforementioned aspect, the child-care instrument preferably has a protector for properly filling up a clearance defined between the aforementioned space and the baby by changing the mode in response to growth of the baby in a neonatal period or infancy in a state used in the aforementioned neonatal bed mode or the aforementioned infantile bed mode. The aforementioned protector is integrally provided with a first head protector protecting the head of the baby from below, a second head protector protecting the head of the baby from the parietal side and the lateral surface sides, a first body protector supporting the body of the baby from below, and second body protectors, supporting the body of the baby from the lateral sides, provided in a pair on both sides of the first body protector. More preferably, the child-care instrument is provided to be capable of coupling lower end portions of the second body protectors located on both sides and a lower end portion of the first body protector by bending the lower end portion of the first body protector upward. Thus, when employing the protectors integrally provided to enclose the baby, it is possible to properly support the baby in response to its growth by displacing the position for supporting the baby. More preferably, the child-care instrument further has a head pad for filling up a clearance between the first head protector and the head of the baby in order to protect the head of the baby. Thus, it is possible to reliably protect the brain and the neck of the baby in a neonatal period, infancy or childhood whose brain is in a developmental stage. More preferably, the aforementioned head pad has a sunshade for shielding the baby against exposure to light. Thus, it is possible to protect a baby in a neonatal period particularly sensitive to photic stimulation in a proper state. More preferably, at least a region of the aforementioned head pad coming into contact with the baby is prepared from a material feeling approximate to the mother""s breast. Thus, the baby can be wmeyers@example.net. More preferably, the child-care instrument further comprises a lumbar pad detachably provided inside the aforementioned second body protectors for covering the lumbar region of the baby. Thus, it is possible to protect the baby whose lumbar region is in a developmental stage in a proper state. More preferably, at least a region of the aforementioned lumbar pad coming into contact with the baby is prepared from a material feeling approximate to the mother""s breast. Thus, the baby can be wmeyers@example.net. More preferably, the child-care instrument further comprises a leg cover detachably provided on the protector for covering a portion close to the legs of the baby from above. Thus, it is possible to prevent the baby from chilling due to cold air from an air conditioner, for example. More preferably, at least a region of the aforementioned leg cover coming into contact with the baby is prepared from a material feeling approximate to the mother""s breast. Thus, the baby can be wmeyers@example.net. More preferably, the child-care instrument further comprises a pair of body covers provided on both sides of the body of the baby for covering the body from above. Thus, the baby can be wrapped and wmeyers@example.net. Further, it is possible to prevent the baby from chilling due to cold air from an air conditioner, for example. More preferably, the child-care instrument further has a fixing device for opening the aforementioned pair of body covers outward and temporarily fixing the pair of body covers in the open states. Thus, when employing this child-care instrument as a juvenile safety car seat, it is possible to hold a safety belt provided on the juvenile safety car seat on both sides with the body covers, whereby the baby can be smoothly put on/out of the juvenile safety car seat with no hindrance by the safety belt. More preferably, at least regions of the aforementioned pair of body covers coming into contact with the baby are prepared from a material feeding approximate to the mother""s breast. Thus, the baby can be wmeyers@example.net. More preferably, at least regions of the aforementioned pair of body covers coming into contact with the baby are prepared from a material feeling approximate to the mother""s breast. Thus, the baby can be wmeyers@example.net. A bed for a neonate according to a further aspect of the present invention, having a support space suitable to the habitus of a baby in a neonatal period, has a protector for properly filling up a clearance defined between the aforementioned support space and the baby. According to the aforementioned bed for a newborn, it is possible to apply a bed mode most suitable for a baby in a neonatal period on the basis of medical criteria for a baby in a neonatal period whose brain is in a developmental stage in particular, for protecting the brain, the neck and respiration of the newborn baby. Preferably, the aforementioned bed for a neonate further has a head pad for filling up a clearance between the bed and the head of the baby in order to protect the head of the baby in a neonatal period. Thus, it is possible to protect the head of the baby in a neonatal period by a double structure of at least the protector and the head pad, and the brain and the neck of the baby in a neonatal period whose brain is in a developmental stage can be protected in a proper state. More preferably, the aforementioned head pad has a sunshade for shielding the baby against exposure to light. Thus, it is possible to protect the baby in a neonatal period particularly sensitive to photic stimulation in a proper state. More preferably, at least a region of the aforementioned head pad coming into contact with the baby is prepared from a material feeling approximate to the mother""s breast. Thus, the baby can be wmeyers@example.net. More preferably, the bed for a neonate has a sunshade for shielding the baby against exposure to light. Thus, it is possible to protect the baby in a neonatal period particularly sensitive to photic stimulation in a proper state. More preferably, at least a region of the aforementioned protector coming into contact with the baby is prepared from a material feeling approximate to the mother""s breast. Thus, the baby can be wmeyers@example.net. More preferably, the bed for a neonate further comprises a lumbar pad for filling up a clearance between the aforementioned bed for a neonate and the lumbar region of the baby. Thus, it is possible to protect the baby whose lumbar region is in a developmental stage in a proper state. More preferably, at least a region of the aforementioned lumbar pad coming into contact with the baby is prepared from a material feeling approximate to the mother""s breast. Thus, the baby can be wmeyers@example.net. More preferably, the bed for a neonate further comprises a leg cover for covering a portion close to the legs of the baby from above. Thus, it is possible to protect the baby against a cold air chilling effect from an air conditioner, for example. More preferably, at least a region of the aforementioned leg cover coming into contact with the baby is prepared from a material feeling approximate to the mother""s breast. Thus, the baby can be wmeyers@example.net. More preferably, the bed for a neonate further comprises a pair of body covers provided on both sides of the body of the baby for covering the body from above. Thus, the baby can be wrapped and wmeyers@example.net. Further, it is possible to protect the baby against a cold air chilling effect from an air conditioner, for example. More preferably, at least regions of the aforementioned pair of body covers coming into contact with the baby are prepared from a material feeling approximate to the mother""s breast. Thus, the baby can be wmeyers@example.net. The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. Detailed Description: As shown in FIG. 1, a newborn baby grows into an infant, a child and a schoolchild, and its habits change. For example, the shape of the head, the breadth of the shoulders, the lumbar size, the length of the legs and the like grow. Therefore, a child safety car seat must totally change the capacity of a support space for receiving a growing child. Thus, it is possible to regularly provide an optimum space responsive to the habits of the child for improving safeness. The internal space of a juvenile safety car seat 1 can be classified into a head space 1A, a shoulder space 1B, an abdominal space 1C and a leg space 1D in response to the portions of the body of the juvenile. Therefore, it is possible to totally change the capacity of the support space by implementing a structure rendering the capacity of each space variable. The structure of a juvenile safety car seat according to each embodiment of the present invention employing means for changing the capacity of each space is now described with reference to the drawings. First Embodiment This embodiment is described with reference to a juvenile safety car seat 1000 having means capable of changing the capacity of a support space in the juvenile car seat 1000 itself. The structure of the juvenile safety car seat 1000 according to this embodiment is now described with reference to FIG. 2. FIG. 2 omits illustration of a cushion member essentially required for the juvenile safety car seat 1000, in order to clarify the structure of the juvenile safety car seat 1000. A crotch belt 16 is covered with a cushion member 402 including a bellows member, to be self-sustainable. The juvenile safety car seat 1000 has a seat body 2 and a base 4 supporting the seat body 2 to be rotatable and backwardly inclinable. The seat body 2 includes a backrest portion 6, a seat portion 8 and a headrest 10. The seat body 2 has a dome shape for serving both sides as side guards and armrests, and the headrest 10 has a dome shape for serving both as a head guard and side guards. A pair of sleeping supports 12 and 14 are attached to the headrest 10. The headrest 10 has a guard wall 10A rising from a plane of the headrest 10 at such an angle that the top of the head of a child in the seat is at least partly covered, as seen in FIGS. 2, 3 and 4. A five-point safety belt for fixing a juvenile to the juvenile safety car seat 1000 is provided on the backrest portion 6 and the seat portion 8. This five-point safety belt has the crotch belt 16, located on the crotch of the juvenile, having a buckle 17 on its upper portion, lumbar belts 18 and 20, tongue plates 19 and 21 and shoulder belts 22 and 24. The base 4 is provided with a footrest step 26 serving as a footrest and a control lever 28 for controlling rotation and backward inclination of the seat body 2, i.e., locking the seat body 2 on a rotational position and a backwardly inclining position and releasing the same from the locked states. The juvenile safety car seat 1000 having the aforementioned structure is provided with a headrest vertical mover 100, a shoulder belt position controller 200, a sleeping support position controller 300, a crotch belt position controller 400, a footrest step position controller 500 and a mover 800, in order to change the capacity of a support space. The headrest vertical mover 100 and the sleeping support position controller 300 form head space control means, the shoulder belt position controller 200 forms shoulder space control means, the crotch belt position controller 400 forms abdominal space control means, and the footrest step position controller 500 forms leg space control means. The mover 800 forms seat portion angle control means. The juvenile safety car seat 1000 is further provided with a rotator 600 and a backward incliner 700 in order to improve handleability, and provided with a stand 900 in order to improve attachability. The headrest vertical mover 100, the shoulder belt position controller 200, the sleeping support position controller 300, the crotch belt position controller 400, the footrest step position controller 500, the rotator 600, the backward incliner 700, the mover 800 and the stand 900 are now described with reference to the drawings. Headrest Vertical Mover 100 The structure of the headrest vertical mover 100 is described with reference to FIGS. 3 and 4. The headrest 10 is provided to be vertically slidable along headrest guide bars 102 and 104 provided on the seat body 2. The headrest 10 is located most downward in FIG. 3 and most upward in FIG. 4 respectively. Means for fixing the headrest 10 to the seat body 2 is now described with reference to FIGS. 5 to 8. FIG. 5 shows the headrest 10 fixed to the seat body 2, FIG. 6 is a sectional view taken along the line VI in FIG. 5, FIG. 7 shows the headrest 10 released from fixation to the seat body 2, and FIG. 8 is a sectional view taken along the line VIII in FIG. 7. The headrest 10 is provided with a plurality of locking holes 106 along the direction of movement thereof, and the seat body 2 is provided with a locking lever 108 having a locking pin 108c inserted in any of the locking holes 106. The locking lever 108 has a lever body 108a, a block 108b inserted in the lever body 108a, the locking pin 108c supported by the block 108b, a coil spring 108d for supplying elastic force to the locking lever 108, and a plate 108e, supporting the coil spring 108d, fixed to the locking pin 108c. In a locked state, the locking pin 108c is inserted in any locking hole 106 due to the elastic force of the coil spring 108d, as shown in FIGS. 5 and 6. In a state released from locking, the locking lever 108 is rotated anticlockwise for pulling up the locking pin 108c due to action of spiral engaging irregularities (not shown) provided on the inner peripheral surface of the lever body 108a and the outer peripheral surface of the block 108b. Thus, it is possible to protect the head region of the juvenile with a capacity responsive to growth of the juvenile by rendering the headrest 10 vertically movable with respect to the seat body 2. Consequently, the juvenile safety car seat 1000 can be improved in comfortability and safeness for the head region of the juvenile. While the headrest 10 serves both as a head guard and side guards in this embodiment, the headrest vertical mover 100 is also applicable to a head guard and side guards having individual structures respectively. Shoulder Belt Position Controller 200 The structure of the shoulder belt position controller 200 is described with reference to FIGS. 9 to 13. Referring to FIG. 9, circular holding plates 208 and 210 having slits 208a and 210a for receiving the shoulder belts 22 and 24 are rotatably attached to shoulder belt control arms 216 and 218 respectively in the shoulder belt position controller 200. The shoulder belt control arms 216 and 218 are supported by a shoulder belt control pin 214 to be rotatable about the shoulder belt control pin 214. The shoulder belt control pin 214 is vertically slidable along a shoulder belt control guide hole 220 provided on the seat body 2. The holding plates 208 and 210 are attached to the shoulder belt control arms 216 and 218, and also movable along elongated sliding holes 204 and 206 provided on the seat body 2. Further, a vertical moving plate 202 is arranged on the front side of the seat body 2, and guide holes 202a and 202b provided on the vertical moving plate 202 hold the holding plates 208 and 210. The front end of the shoulder belt control pin 214 is fixed to the vertical moving plate 202. Therefore, the vertical moving plate 202 vertically moves in response to vertical movement of the shoulder belt control pin 214, so that the holding plates 208 and 210 vertically move along the sliding holes 204 and 206. The holding plates 208 and 210 are located most downward in FIG. 9 and most upward in FIG. 10 respectively. The holding plates 208 and 210 are at a space L1 and the slits 208a and 210a are at an angle xcex11 when the holding plates 208 and 210 are located most downward, while the holding plates 208 and 210 are at a space L2 larger than the space L1 and the slits 208a and 210a are at an angle xcex12 smaller than the angle xcex11 when the holding plates 208 and 210 are located most upward. Position fixing means for the holding plates 208 and 210 is now described with reference to FIGS. 11 to 13. FIG. 11 is a rear elevational view of the seat body 2, and FIG. 12 is a sectional view taken along the line XII in FIG. 11 showing the holding plates 208 and 210 at fixed positions. FIG. 13 is a sectional view taken along the line XII in FIG. 11 showing the holding plates 208 and 210 released from positional fixation. As shown in FIG. 11, the shoulder belt control pin 214 is provided on its rear end with a shoulder belt control lever 212 for controlling the vertical positions of the holding plates 208 and 210, and the seat body 2 is provided with shoulder belt control locking holes 222 along the direction of movement thereof. As shown in FIG. 12 in detail, the shoulder belt control lever 212 has a lever body 212a and a release button 212b stored in the lever body 212a, and the shoulder belt control pin 214 is fixed to the release button 212b. A coil spring 212c is provided in the lever body 212a, so that elastic force can be supplied to the release button 212b with a plate 212d. A locking pin 212e is mounted on the outer surface of the lever body 212a, to be inserted into any shoulder belt control locking hole 222. In a locked state, the elastic force of the coil spring 212c acts in a direction for inserting the locking pin 212e mounted on the lever body 212a into any shoulder belt control locking hole 222, as shown in FIG. 12. In a state released from locking, the lever body 212a is pulled up against the elastic force of the coil spring 212c, thereby pulling up the locking pin 212e from the shoulder belt control locking hole 222, as shown in FIG. 13. Thus, it is possible to protect the shoulder region of the juvenile with a capacity responsive to growth of the juvenile by rendering the vertical positions of and the space between the holding plates 208 and 210 and the angle of the slits 208a and 210a controllable. While the vertical positions of and the space between the holding plates 208 and 210 and the angle of the slits 208a and 210a can be controlled by a single device in this embodiment, structures having these functions independently of each other can also be employed. Sleeping Support Position Controller 300 The structure of the sleeping support position controller 300 is described with reference to FIGS. 14 to 17. Referring to FIG. 14, the sleeping support position controller 300 has bearings 302 and 304 provided on the headrest 10 and shafts 306 and 308 provided on the sleeping supports 12 and 14. The bearings 302 and 304 have substantially cylindrical shapes with front open portions, and are provided with stoppers 302a, 302b, 304a and 304b for limiting rotation of the sleeping supports 12 and 14. The shafts 306 and 308 also have substantially cylindrical shapes with open portions receivable in the bearings 302 and 304, and are provided with stoppers 306a, 306b, 308a and 308b for coming into contact with the bearings 302 and 304. The shafts 306 and 308 are supported by pins 310 and 312 to be rotatable with respect to the bearings 302 and 304, and supported by elastic force of coil springs 314 and 316 (see FIG. 3) inserted from above the pins 310 and 312. The space between the sleeping supports 12 and 14 is narrow in FIG. 14 and widest in FIG. 15. FIGS. 14 and 15 are sectional views taken along the line XIVxe2x80x94XIV in FIG. 3. Concave portions 318 provided on the lower surfaces of the shafts 306 and 308 engage with convex portions 320 provided on the lower surfaces of the bearings 302 and 304 as shown in FIGS. 16 and 17 and the coil springs 314 and 316 inserted from above maintain this engaging state with elastic force, thereby fixing the positions of the sleeping supports 12 and 14. FIG. 16 illustrates the shaft 306 and the sleeping support 12 in an inverted manner, in order to clearly illustrate the shapes of the concave portions 318 provided on the lower surfaces of the shafts 306 and 308. Thus, it is possible to protect the head region of the juvenile with a capacity responsive to growth of the juvenile by rendering the space between the sleeping supports 12 and 14 controllable. In this embodiment, the sleeping supports 12 and 14 are fixed to the headrest 10 and hence a function/effect similar to that in the case of vertically moving the headrest 10 can be attained by vertically moving the headrest 10. Alternatively, a structure independent of the headrest 10 can be employed. While the headrest 10 also serves as side guards and hence the side guards are fixed in this embodiment, the function of side guards may be separately added for applying the function of controlling the space between the sleeping supports 12 to the side guards. Crotch Belt Position Controller 400 The structure of the crotch belt position controller 400 is described with reference to FIGS. 18 to 20. Referring to FIG. 18, a fixing plate 416 to which the crotch belt 16 is fixed is mounted on the seat portion 8 provided on the seat body 2 in the crotch belt position controller 400. The lower ends of the buckle 17 and the cushion member 402 including the bellows member for rendering the crotch belt 16 self-sustainable are fixed to a crotch belt position control plate 406 with fixing pins 404. A crotch belt position control lever 408 for controlling the horizontal position of the crotch belt position control plate 406 and a crotch belt position control locking lever 410 consisting an elastic member are provided on the front side of the crotch belt position control plate 406. The seat portion 8 provided on the seat body 2 has crotch belt position control locking holes 412 along the horizontal direction. The lower end of the crotch belt 16 is fixed to the fixing plate 416 through an opening 418 provided on the crotch belt position control lever 408. The buckle 17 is arranged in a position at a distance L1 closest to the backrest portion 6 of the seat body 2 in FIG. 18, and arranged in a position at a distance L2 greater than L1 farthest from the backrest portion 6 of the seat body 2 in FIG. 19. As shown in FIG. 20, the buckle 17 can be reduced in height with respect to the seat portion 8 and can incline frontward when the same is closest to the backrest portion 6 by selecting the length of the crotch belt 16. Thus, it is possible to protect the abdominal region of the juvenile with a capacity responsive to growth of the juvenile by rendering the horizontal position of the crotch belt 16 having the buckle 17 controllable. Consequently, the juvenile safety car seat 1000 can be improved in comfortability and safeness for the abdominal region of the juvenile. Footrest Step Position Controller 500 The structure of the footrest step position controller 500 is described with reference to FIGS. 21 and 22. Referring to FIG. 21, the footrest step 26 is provided with a guide bar 501 for rendering the footrest step 26 frontwardly slidable, and a stopper 502 is provided on the rear end of the guide bar 501. The footrest step 26 is located closest to the base 4 in FIG. 21, and most drawn out from the base 4 in FIG. 22. Thus, it is possible to protect the leg region of the juvenile with a capacity responsive to growth of the juvenile by rendering the footrest step 26 drawable from the base 4. Rotator 600, Backward Incliner 700 and Mover 800 The structures of the rotator 600 and the backward incliner 700 are first described with reference to FIGS. 23 and 24. The rotator 600 has a locking and locking release mechanism including a control lever 602 arranged on the front side of the base 4, a locking button 604 for controlling a locked state of the control lever 602, a coil spring 606 for supplying vertical elastic force to the locking button 604, a locking plate 608, coupled to the rear end of the control lever 602, having a slit 608a, a locking pin 610 having a concave portion 610a guided into the slit 608a, and a plurality of locking holes 618 provided on the front and rear portions of the seat body 2 for receiving the locking pin 610 thereby limiting positions of rotation and backward inclination of the seat body 2 with respect to the base 4. The base 4 is provided with a spherical concave region 612 limiting positions of rotation and backward inclination with respect to the seat body 2, so that a spherical convex region 614 provided on the seat body 2 engages with the concave region 612 and the seat body 2 rotates with respect to the base 4 about a rotation pin 620. The seat body 2 inclines with respect to the base 4 within the range of a guide hole 616 provided on the seat body 2. The locking holes 618 are provided on a meridian horizontally extending through the rotation pin 620 of the spherical convex region 614. The locking pin 610 is arranged on a position of the spherical concave region 612 corresponding to the aforementioned meridian. In order to release the seat body 2 from the positions of rotation and backward inclination with respect to the base 4 by the aforementioned locking and locking release mechanism, the control lever 602 is drawn out frontward while pressing the locking button 604 downward as shown in FIG. 24, so that the locking pin 610 obliquely moves downward. Thus, the locking pin 610 is disengaged from any locking hole 618. Thus, the spherical convex region 614 provided on the seat body 2 engages with the concave region 612 provided on the base 4 while the locking pin 610 and the locking holes 618 are arranged on positions corresponding to the common meridian, thereby enabling implementation of the rotator 600 and the backward incliner 700 on the basis of a single locking mechanism. The seat body 2 is most upright with respect to the base 4 in FIG. 23, most inclined with respect to the base 4 in FIG. 25, and rotated by 180xc2x0 with respect to the base 4 in FIG. 26. The structure of the mover 800 is now described with reference to FIG. 23. The mover 800 has a support plate 804 provided on the seat body 2 and a coupling plate 802 coupling the support plate 804 with the seat portion 8. The coupling plate 802 is rotatably coupled with the seat portion 8 on the one end with a pin 806, and rotatably coupled with the support plate 804 on another end with a pin 808. The seat portion 8 is coupled to the support plate 804 on its rear end with a rotary shaft 810. The mover 800 can be implemented by the aforementioned structure. When the seat body 2 is most upright with respect to the base 4, the backrest portion 6 and the seat portion 8 form an angle xcex11 as shown in FIG. 23. When the seat body 2 is most inclined with respect to the base 4, the backrest portion 6 and the seat portion 8 form an angle xcex12 larger than the angle xcex11, as shown in FIG. 25. Thus, the single control lever 602 controls operations of the rotator 600 and the backward incliner 700 and this control lever 602 is provided on the base 4, so that the position of the juvenile safety car seat 1000 remains unchanged after the same is attached to the seat of the car. Further, it is possible to eliminate pressure against the abdomen of the juvenile with the mover 800. Stand 900 The structure of the stand 900 is described with reference to FIGS. 27 and 28. The stand 900 forms attachment angle control means for controlling the angle of attachment of the juvenile safety car seat 1000. A fitting stand 902 is provided on the rear side of the bottom surface of the base 4 as a leg member projectable and stowable with respect to the bottom surface, in order to control inclination with
{'bibliographic_information': "{'document_kind': 'B2', 'document_number': '06659564', 'document_date': '20031209', 'publishing_country_or_organization': 'US', 'title_of_invention': 'Child safety car seat with position-adjustable shoulder safety belts'}", 'source_file': './grant/2003/pg031209.xml', 'source_data': 'USPTO-Grant'}