초록 ▼

A radiation device, such as an instrument for gauging a property of moving sheet materials, has a surface including window means in the path of radiation affecting the output of a radiation detector. The radiation transmission characteristics of the portion of the radiation path including the window

A radiation device, such as an instrument for gauging a property of moving sheet materials, has a surface including window means in the path of radiation affecting the output of a radiation detector. The radiation transmission characteristics of the portion of the radiation path including the window means are maintained substantially constant so as to reduce the probability of error in the detector output response resulting from the presence of an unpredictable amount of extraneous radiation-absorbing or scattering material in the path or at the window means. A jet of fluid, such as compressed air, is formed in a manner such that the jet is attached to the surface by implementation of the Coanda effect and directed to flow over the window means. Typically the jet is initially directed away from the portion of the surface adjoining the window means. The jet is typically formed between an abruptly terminating wall and an attachment wall which gradually turns into the direction of the window location and effectively forms a continuation of the surface, whereby the jet is guided into a curved path to the location of the window means. This arrangement allows the jet-forming structure to be placed in a location, such as in a sunken area below the main portion of the surface, where it cannot interfere with the movement of the sheet material. Likewise it has been found not to interfere with the operation of a high-volume, constant temperature air blower which may be used concurrently to maintain constant atmospheric conditions in the radiation path adjacent to the window means.

대표청구항 ▼

In the use of a radiation device having a surface including window means in the path of radiation affecting the output response of a radiation detector, the method of maintaining substantially constant the radiation transmission characteristics of the portion of the radiation path including the wind

In the use of a radiation device having a surface including window means in the path of radiation affecting the output response of a radiation detector, the method of maintaining substantially constant the radiation transmission characteristics of the portion of the radiation path including the window means and thereby reducing the probability of error in the detector output response resulting from the presence of an unpredictable amount of extraneous radiation-absorbing or scattering material in the path or at the window means, comprising forming a jet of fluid in a manner such that the jet is attached to the surface by implementation of the Coanda effect and thereby directed to flow over the window means.