RU1830510C - Two-step system of automatic focusing an objective - Google Patents

Description

comparison 5; a driver of a control signal of a second channel 9, electrically connected to a signal level analyzer 8: a frame frame drive 10, electrically connected to a driver of a control signal of a second channel 9; a frame frame 11 located on the optical axis of the lens, having the ability to move along this axis and mechanically associated with the actuator 10.

The work of the proposed system is as follows.

The luminous flux from the lens 1 enters the beam splitter 2, which: divides it into two parts. The first part of the light flux falls on the first photodetector 3, the second on the second photodetector 4. Depending on the magnitude of the incident light flux, each photodetector generates an electric signal of the corresponding magnitude. The electrical signals of the photodetectors 3 and 4 go to a comparison device 5, which compares these signals and, depending on the results of the comparison, generates an electrical signal depending on the defocusing of the system; This signal enters two control channels.

Depending on the magnitude of the electrical signal of the comparison device 5, the driver 6 generates a control signal and supplies it to the actuator 7, which moves the lens 1 by an appropriate amount, roughly eliminating the defocusing of the optical system of the camera. Moreover, if the signal of the first photodetector is greater than the signal of the second photodetector, then the lens moves in one direction, if less - in the other.

The second control channel is more accurate. It only works, starting with defocusings that do not exceed a predetermined value, which is ensured by channel tuning. When the signal level of the comparison device 5 becomes small, the signal level analyzer 8 is activated and the second control channel is activated. From this moment on, both channels (first and second) are working simultaneously.

The electrical signal from the comparison device 5 through the signal level analyzer 8 is fed to the driver 9 of the control signal of the second channel, which

generates a control signal of a certain value and feeds it to the actuator 10, which moves the frame frame 11 in order to more accurately eliminate defocusing.

Thus, the proposed device has, compared with the prototype, greater accuracy and a wider range of practiced defocuses and allows using it to create

cameras with higher image quality.

The use of the proposed system is especially advisable in cameras with multiple lenses. In this case

for all lenses, the second control channel will be the same.

Claims (1)

SUMMARY OF THE INVENTION A two-stage system for automatically focusing a camera lens, comprising a beam splitter, the first and second phthoreceptors installed in the optical channels formed by the beam splitter with an equal amount offset relative to the focal plane of the lens in the opposite directions, series-connected photodetector signal comparison device, the first and second inputs of which are connected to the outputs of the first and second photodetectors, a driver of the control signal and a lens drive, characterized in that, in order to increase the accuracy of focusing the lens and expand the range of eliminated defocusing yok, the second channel is introduced into the system adjusting the focus of the lens, including a series-connected comparison signal level analyzer. the input of which is connected to the output of the device for comparing signals of photodetectors, a driver of the control signal and a frame frame drive of the camera to move it along the optical axis of the lens.