The present invention relates to camcoders, more particularly to an on-screen display for displaying a zooming position of zoom lens in the camcorders on the screen of a CRT (cathode ray tube) in order to quickly and accurately control the zooming operation of zoom lens in the camcorders.
Conventionally, the focusing operation, that is the zooming operation of the zoom lens in camcoders has been carried out by in/out movement of the zoom lens, which zooming operation has been generally controlled by means of zooming controllers.
FIG. 1 is a schematic view showing an example of the conventional zooming controllers for camcorders, which controller comprises a zoom motor 1 adapted to generate normal/reverse driving powers in response to zooming control signals, a zoom motor gear 2 for transmitting the driving power from the motor 1 to a zoom gear 3, and the zoom gear 3 engaged with said zoom motor gear 2 to simultaneously therewith, thereby causing a zoom lens 4 to do in/out movement.
In the conventional zooming controller, the zoom motor 1 rotates in a normal or a reverse direction in response to zooming control signals in order to generate driving power by which the zoom motor gear 2 is driven, then the zoom gear 3 engaged with the zoom motor gear 2 rotates, thereby causing the zoom lens 4 to move in/out.
On the other hand, FIG. 2 is a block diagram showing an operation of a conventional on-screen display (OSD) for the camcorder according to prior art, which conventional on-screen display operates individually with the zooming controller of FIG. 1. The on-screen display of FIG. 2 comprises a microcomputer 5, an on-screen display character signal generator 6, and a luminance/color processing circuit 7. The conventional on-screen display device operates as follows.
Once the microcomputer 5 outputs on-screen display data with a clock at its output ports (P5-P8) in synchronization with a vertical synchronizing signal (Vsync), the on-screen display character signal generator 6 then generates an on-screen display character signal (OSD) in accordance with the on-screen display data from the microcomputer 5 in synchronization with the vertical synchronizing signal (Vsync) and a horizontal synchronizing signal (Hsync), and also the luminance/color processing circuit 7 processes a video signal in accordance with video information obtained from the zoom lens 4 (video in), so that it outputs the vertical synchronizing signal (Vsync) and the horizontal synchronizing signal (Hsync) to the microcomputer 5 and the on-screen display signal generator 6 and then composes the on-screen display character signal (OSD) with the processed video signal to output a composite video signal (video out).
As described above, the conventional camcorder includes the zooming controller and the on-screen display which operate individually with each other without any relationship therebetween, thus it has not any function for supplying the information for the present zooming position. Therefore, the correct information for the present zooming position can not be obtained, and thus focusing of the zoom lens (zooming operation) can not help being roughly accomplished by user's guess. As a result, there is a limit in zooming operation when the object moves quickly in backward or forward direction, and thus the pickup may interrupt. Otherwise, the user has to mvoe quickly with the moving object, but such a moving pickup may result in missing the important scene or obtaining bad pictures of image shaken or out of focus.