JPS6325327B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an optical system for reading an original image of a copying machine;
The present invention relates to a scanning device that reciprocally drives an object to be scanned, such as a print head of a printer, and particularly relates to a scanning device that uses a ball screw rod and a ball nut.

In this type of scanning device, the object to be scanned and driven (hereinafter referred to as the driven object) is mounted on a carriage, the carriage is guided by a guide bar, and the carriage is screwed into a ball screw rod installed parallel to the guide bar. It is connected to a ball nut.

If the carriage is fixed to a ball nut, a radial load is applied to the ball screw in addition to the thrust load due to misalignment of the guide bar and ball screw rod, shape errors, etc., which shortens the life of the ball screw and There is a problem in that the rotational force applied to the rod must be increased. Therefore, as shown in FIG. 1a, an elongated hole 2a is formed in the connecting member 2 of the carriage 1, and a pin 4 set on a ball nut 3 is passed through the elongated hole 2a. Note that the first
In figure a, 5 is a ball screw rod, and 6 and 7 are guide bars. Figure 1b is a side view. As shown in FIG. 1b, the guide bar 6 passes through the carriage 1, but the guide bar 7 is located below the carriage 1, and the rollers 8 are mounted on it. Since the elongated hole 2a is formed in this manner, the carriage 1 can move relative to the ball nut 3 in a direction perpendicular to the ball screw rod 5. Therefore, no excessive force is applied between the ball nut 3 and the ball screw rod 5.

However, if the carriage 1 and ball nut 3 are made relatively movable in this way,
Play may occur between the carriage 1 and the ball nut 3, causing vibration while the carriage 1 is moving, or even if the rotational speed of the ball screw rod 5 is constant, the movement speed of the carriage 1 will fluctuate due to play. There is a problem.

The present invention prevents excessive force from being applied to the ball nut.
Moreover, it is an object of the present invention to provide a scanning mechanism with less fluctuation and vibration in the moving speed of the carriage.

FIG. 2a shows a plan view of an embodiment of the present invention, and FIG. 2b shows a side view. The connecting member 2 is sandwiched between pins 4 ₁ and 4 ₂ fixed to the ball nut 3, so that it can move in a direction perpendicular to the ball screw rod 5. The second enlarged perspective view of the top surface of the ball nut 3
Shown in Figure c. The following explanation will be given with reference to FIG. 2c. A click plate 9 is pivotally connected to the ball nut 3 via a pin 10, and the click plate 9 also has two pins 11 with the connecting member 2 sandwiched therebetween. ₁ and 1
1 ₂ is fixed. Pin 12 is placed exactly between pins 11 ₁ and 11 ₂ , and this pin 12
A coil spring 14 is stretched between the pin 13 and the ball nut 3. Since pin 10, which is the center of rotation of click plate 9, is located between pins 12 and 13, click plate 9 is located between pins 10 and 12.
The state in which and 13 are in a straight line is defined as an unstable state (dead center), and the force of the spring 14 causes the pin 10 to rotate clockwise or counterclockwise.
Leaf springs 15 ₁ and 15 ₂ are arranged at a position outside the steady scanning range of the carriage 1 and at a position that hits the pin 12.
The spring forces of ₁ and 15 ₂ are larger than the imitation force that the spring 14 is applying to the click plate 9.

Next, the operation will be explained. As shown in Figure 2a,
When the carriage 1 is driven in the direction of the thick arrow (leftward), the click plate 9 is set to rotate clockwise. When the nut 3 is being fed in the direction of the arrow (to the left) in this state, the pin 4 ₂ is pushing the connecting member 2 and the pin 4 ₁ is slightly separated from the connecting member 2 . If the nut 3 slides on the ball screw rod 5 or the carriage 1 slides on the guide bar 6 unevenly, the connecting member 2 tends to vibrate between the pins 4 ₁ and 4 ₂ . However, since the click plate 9 is rotating clockwise and the pin 11 ₁ presses the connecting member 2 in the direction of the pin 4 ₂ , vibrations are prevented. In other words, the coil spring 14 constantly presses the connecting member 2 against the pin ₄₂ . When the carriage 1 reaches near the left standby position in this state _, the pin 12 collides with the leaf spring 15 ₁ , causing the leaf spring 15 ₁ to bend clockwise. Moving to the left, the leaf spring ₁₅₁ returns to the straight state shown. When the ball nut 3 is reversely driven and begins to move in the direction opposite to the arrow (to the right), the pins 4 ₁ and 11 ₁ hit the connecting member 2 because the click plate is still rotating clockwise. When the pin 12 collides with the leaf spring 15 ₁ , the click plate 9 rotates counterclockwise, the pin 11 ₁ separates from the connecting member 2 , and the pin 11 ₂ comes into contact with the connecting member 2 . Then, the leaf spring 15 ₁ bends counterclockwise,
The pin 12 comes out of the leaf spring ₁₅₁ . In this way, when the carriage 1 enters the regular scanning range from the left, the pin ₄₁ hits the connecting member 2, and the pin ₁₁₂ presses the connecting member ₂ in the direction of the pin ₄₁ by the force of the spring 112. It's summery. From the right end inversion position to the right end of the regular scanning range, the click plate 9 rotates clockwise due to the action of the leaf spring ₁₅₂ , resulting in the state shown in FIG. 2a.

As described above, in the present invention, a spring is used in the click plate to perform a click operation with the dead center as the boundary, and the connecting member is held by the spring force while the driven body is in the normal scanning range. , not only can the carriage and nut move relative to each other in a direction perpendicular to the guide bar, but also in a direction parallel to the guide bar, since the connecting member is restrained by the nut by spring force, The driven body is less likely to vibrate or cause speed fluctuations.

[Brief explanation of the drawing]

FIG. 1a is a plan view showing the main parts of a conventional scanning mechanism, and FIG. 1b is a side view thereof. FIG. 2a is a plan view showing an embodiment of the present invention, FIG. 2b is a side view thereof, and FIG. 2c is a partially enlarged perspective view. 1: Carriage, 2: Connecting member, 3: Nut,
4, _{4 1} , 4 ₂ : Pin, 5: Threaded rod, 6, 7: Guide bar, 8: Roller, 9: Click plate, 10, 1
1 ₁ , 11 ₂ , 12, 13: pin, 14: coil spring.

Claims (1)

[Claims] 1. A guide bar that guides the movement of a driven body, a threaded rod installed parallel to the guide bar, and a nut that is screwed onto this threaded rod and connects the driven body, and the driven body is moved in the forward and reverse directions of the threaded rod. In a scanning device that reciprocates a driving body, a connecting member fixed to a driven body is held in a nut so as to be movable back and forth in a direction perpendicular to the reciprocating direction, and a click plate is provided with two pins that sandwich the member. A spring is pivotally attached to the nut and provides rotational force to the click plate in one direction and the opposite direction from the dead center, and a protrusion on the click plate is provided outside the normal movement range of the driven body. A scanning device characterized in that a member with a spring force is arranged to collide with a click plate, and the spring force of the member with a spring force is larger than the rotational force exerted by the spring on a click plate.