SU59238A1 - A device for determining the response speed of photographic shutters - Google Patents

Description

Currently, devices for determining the response speed of photographic shutters are widely known (made in the form of a uniformly rotating screen, the surface of which is covered with photosensitive material, such as photographic paper. Such a screen is placed in a light-permeable camera and directed through the lens and the test shutter the light from the light source; while the screen itself: rotate with the help of an electric motor with a known speed of 1. S screen scrapping speed is chosen in this way, during the exposure time n povorachivals on part revolution. In this case, the arc produced on the screen, the magnitude of which gives vO31mozhn Arista determine the velocity of actuation I1spyt :: uemogo shutter.

These instruments have the significant disadvantage that during the testing of the closures, a considerable amount of Time is required to process photographic paper associated with wet processes.

The subject of the present invention is a device for determining the response speed of photographic

gates, in which the disk surface is covered with: a phosphorescent substance, due to which it does not possess the above disadvantages.

The light from the arc, after its magnitude has been measured, disappears, as the illumination ceases and the screen is again ready for the next measurement. From the number of phosphorus-containing substances, zinc sulfide, activated by copper, gives a bright light-green luminescence with a short duration of luminescence of about one minute, quite satisfactory (meaning that the phosphorus is most prominent).

An exemplary embodiment of the device is shown in FIG. -1, -2 and 3 of the attached drawing. FIG. 1 and shows a diagram of the device, in FIG. 2 is a section through the apparatus chamber, and in FIG. 3 - view of the disk from the end with a light arc.

The light from the light source L (volt arc, a-kalivan lamp with a H-beam approach of the form) passes through the i-trigger shutter R (Fig. 1) and is collected by the lens O on a uniformly rotated phosphorescent screen E in the form of light Under the action of the light falling on the rotating screen, a glow appears in the places of the screen passing through the point S (fig. 3), i.e. we will see in the dark on the screen stopped (the motor M rotating the screen, after the test gate lever R is pressed, is stopped) the arc (/. TIME ONE-revolution of phosphorus The screen is always larger than the measured time, so that the arc (I) is not closed, the shutter opening time is found from the size of the arc and the screen rotation speed.

A disk D, which sits on the axis of motor M, is half-inserted into a round box K with a diameter MiM. On the disk, a phosphorescent screen E is fastened.

On the part of the disk D protruding from the box K, ring B with a scale sits on the friction. A short-focus lens O is fixed on the wall in front of it. After the shutter lever R is pressed and the screen appears with a light from the arc (/) (Fig. 3), the motor M, which rotates the screen E, is stopped. In the opening of the tube F (the eye is located at some distance from the opening of the tube), the light of a narrow arc, coming opposite the prism, and the bar crossing the arc, is visible.

The arc is measured as follows: turning the disk D with a hand, bring one of the ends of the arc light to the bar. Then, rotating the ring B freely sitting on the disk D with the scale, combine the zero of this scale with the index I. Finally, bring the other end of the arc to the line and read on the scale of the ring B, against index I, the value of the luminous arc IB degrees.

The opening time of the shutter T will be equal to

T-- n.36J

T - shutter open time in seconds. / - magnitude of the light of the arc in degrees

n - the number of screen revolutions in seconds.

You can choose the screen rotation speed to be constant; then the scale of ring B can be directly calibrated for opening times. In this case, it will be convenient to use a synchronous motor.

Drive D with screen E is driven by a DC motor M. Uniform screen rotation is achieved with a strobe light. The stroboscope consists of a small disk with a white line on a black background and a neon light bulb N, powered by an ordinary AC network. If a rotating disk is illuminated with a neon light bulb, then when the number of revolutions of the screen is equal to n -,.

where f is the current frequency

K 1, 2, 3. . ., watching, looking at a rotating disk, fixed white lines. With a slight deviation of the number of revolutions from the numbers given by the above formula, such a pattern consisting of several lines begins to rotate. With the help of a rheostat included in the motor chain M, before pressing the shutter lever R, the picture is fixed, WHAT is done very easily. The position of the photographic shutter and the path of the rays to the lens O are determined by the type of the tested shutter.

FIG. 2, a lens is added in front of the shutter R, directing light from the source L through the center of the shutter.

The subject matter of the invention.

Claims (3)

1. An instrument for determining the speed of operation of photographic shutters using a uniformly rotating screen with a surface covered with photosensitive material, to which the subject is directed. The shutter has a light beam, characterized in that a phosphorescent substance is used as the photosensitive material. 2. The form of the instrument according to claim 1, is determined by the fact that for measuring the length of an illuminated arc on the phosphorescent surface of the screen E in front of the screen E there is a prism P with a stroke on the surface facing the screen E, and on disk D carrying the screen E, is located on the friction ring B, equipped with a scale. 3. In the device on PP. 1-2 use a stroboscapic disk mounted on an electric motor shaft to control the rotational speed of the latter. S j FIG 3