JPH02236540A - Film transfer mechanism - Google Patents

Abstract

PURPOSE:To hardly generate a static mark in a mechanism transferring a film by the rotation of rolls by forming a roll with a material electrified with positive charge by its friction against the film, and another roll with a material electrified with negative charge by its friction against the film. CONSTITUTION:When the film F is transferred in the direction of an arrow B and caught into between the driving roll 6 and the follower roll 7, charges are moved from the follower roll 7 to the film F and then from the film F to the driving roll 6. The positive charges on the follower roll 7, the negative charges on the surface of the film F in contact with the driving roll 6, and the positive charges on the surface of the film F in contact with the follower roll 7 are electrified. Although the film F is an insulating body, since it is as thin as 0.2mm in thickness, the charges which remain on its both surfaces are gradually neutralized as the film F comes away from the rolls 6 and 7, and only a small amount of charges for which the charges at a weakly electrified side are subtracted from the charges at the intensively electrified side remain in the film F. Thus, the electrifying amount of the film is decreased, and it is prevented that the static mark is generated due to discharging.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a film transport mechanism used in an X-ray film changer or the like. [Conventional Technique 11 Conventional. In an X-ray film changer, etc., the film is sandwiched between a pair of rollers, at least one of which is a drive roller, and the rotation of the rollers is used as a transfer means to transfer the film from the supply magazine to the shooting position and from the shooting position to the receive magazine. A film transport port is used to transport the film. FIG. 2 shows a conventional example, in which the driving roller l is fixed to a frame (not shown) and rotated by a driving means, and the driven roller 2 facing the driving roller l is rotated by a shaft 4.
The lever 3 is rotatably attached to the lever 3 and is biased in the direction of arrow A by a spring 5. The film F is sandwiched between the driving roller 1 and the subordinate a-roller 2, and is transported by the rotation of the driving roller 1. Rollers for transporting such films include rubber, metal,
Various materials such as synthetic resins are used, but rubber is especially used because it has a high coefficient of friction and is soft so it will not damage the film F. However, rubber has poor conductivity, and static electricity is generated when the film F is held and transferred. For example, as shown in Figure 2, the film F side is positively charged, and the driving roller l and driven roller 2 sides are negatively charged. Easy to do. When these potential differences exceed a certain value, a discharge occurs, and at this time, the film F is exposed to light, resulting in the formation of static marks. Therefore, in the past, by adding a conductive material such as carbon to rubber, 10"
In some cases, it has a conductivity of ~1010 Ωcm and is grounded to prevent static electricity from accumulating. [Problems to be Solved by the Invention] However, in a device such as an X-ray film changer that transports the film F at high speed, even if the charges of the driving roller 1 and the driven roller 2 are discharged, charges remain on the film F. Similarly, if the potential difference is large, discharge may occur and static marks may be created on the film F. SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional method and to provide a film transport mechanism in which static marks are less likely to occur even when the film is transported at high speed. [Means for Solving the Problems] In order to achieve the above object, in the film transport mechanism according to the present invention, the film is held between a pair of rollers, at least one of which is a drive roller, and the rotation of these rollers is In the film transport mechanism for transporting the film, one roller is made of a material that is positively charged by friction with the film, and the other roller is made of a material that is negatively charged by friction with the film. This is what we mean. [Function] In the film transport mechanism having the above configuration, both sides of the film are charged with charges of opposite signs, and the amount of charge on the entire film is canceled out and reduced. [Example] The present invention will be explained in detail based on the example shown in FIG. In FIG. 1, the same reference numerals as in FIG. 2 indicate the same members, and the drive roller 6 is made of a material that is negatively charged by friction with the film F, such as urethane rubber, aluminum, or stainless steel. The driven roller 7 is made of a material that is positively charged by friction with the film F, such as 66 nylon or Delrin.
Further, static elimination brushes 8 to 11, which are made of a large number of thin stainless steel wires bundled together, are arranged so as to be in sliding contact with the driving roller 6, the driven roller 7, and the upper and lower surfaces of the film F, and their ends are each grounded. There is. In the above configuration, the film F is transported in the direction of arrow B'
When the film is sandwiched between the driving roller 6 and the driven roller 7, the electric charge moves from the driven roller 7 to the film F and from the film F to the driving roller 6, and the negative electric charge is transferred to the driving roller 6, and the electric charge is transferred to the driven roller 6. 7 has a positive charge, and the film F
The contact surface of the driving roller 6 of the film F is charged with a positive charge, and the contact surface of the driven roller 7 of the film F is charged with a negative charge. Although film F is an insulator, it is extremely thin at about 0.2 mm, so the charges left on both sides of film F are low and
The film F is gradually neutralized as it moves away from A 6 and 7, and only a small amount of charge, which is obtained by subtracting the smaller charge from the larger charge, remains on the film F. In addition, the drive roller 6
The charge on the driven roller 7 is discharged by the static eliminating brushes 8 and 9. Note that the static eliminating brushes 10 and 11 are used to remove the film F during the pre-transfer stage.
This removes the electric charge left on the surface, and if the amount of electric charge is small, there is no need to install it. [Effects of the Invention] As explained above, the film transport mechanism according to the present invention has the following effects:
This has the effect of reducing the amount of charge on the film and preventing static marks from forming due to discharge.

[Brief explanation of drawings]

Figure 1 is a sectional view of an embodiment of the film transport mechanism according to the present invention, and Figure 2 is a sectional view of a conventional example. Reference numeral 6 is a driving roller, 7 is a driven roller, 8 to 11 are static eliminating brushes, and F is a film. 13791

Claims (1)

[Claims] 1. In a film transport mechanism in which a film is sandwiched between a pair of rollers, at least one of which is a driving roller, and the film is transported by the rotation of these rollers, one of the rollers is positively charged by friction with the film. A film transport mechanism characterized in that the other roller is made of a material that is negatively charged by friction with the film.