4. A thin slide unit, comprising:
a guide rail in which a rolling groove for balls is formed; and
a ball carriage equipped with a large number of balls rolling in the rolling groove, and including an endless circulation path for the balls, which is movable along the guide rail, wherein:
the ball carriage is formed such that two ball plates each formed with a ball groove are caused to face each other, and that the ball plates are directly connected;
the ball groove includes a load groove portion formed along peripheral portions of the ball plates, in which the balls roll while being applied with a load between the ball groove and the guide rail;
a loadless groove portion formed in parallel with the load groove portion, in which the balls roll in a loadless state;
a pair of direction switching groove portions for allowing the balls to come and go between the load groove portion and the loadless groove portion;
a bent portion formed in the peripheral portion of the ball plate in each load groove portion and continuously formed to curve along travelling directions of the balls entering into the direction switching groove portions at ends of the load groove portion;
peripheral sides of the two ball plates are opposed to each other, to thereby form a load opening portion causing the balls rolling in the load groove portion to contact the rolling groove of the guide rail, and form a scooping-up portion having a gap smaller than the diameter of each ball such that the bent portion oppose each other;
the scooping-up portion includes the bent portion curving along the travelling directions of the balls entering into the direction switching groove portions at ends of the load groove portion and guides the balls at the end of each load opening portion to enter into the direction switching groove portion without colliding with a location at which the ball plates meet at an entrance to the direction switching groove portion; and
wherein the scooping-up portion bends from the load opening portion to curve into the direction switching groove portions at a location different than the location at which the ball plates meet at the entrance to the direction switching groove portion.