This invention relates to a quotation marks or "comb teeth" pattern signal generating circuit of a video camera, and in particular to a zebra signal generating circuit of a video camera in which, an electronic view finder (which is abbreviated as E.V.F) is utilized and especially when taking photographs at a field location, the gain band of the video signal is divided into stages the user is able to see and by selecting the appropriate zebra pattern among these stages, an improved video image quality can be obtained.
In general, the zebra pattern means a comb teeth pattern, and this pattern is made to couple to the video signal by dividing the frequency down to a quarter of the 3.58 MHZ carrier which is the sub-carrier of the color signal, since the sub-carrier signal is inverted at every 1 Hz the comb teeth pattern appears in the picture screen. Accordingly, the visual status of the object becomes possible to observe in the electronic view finder of the video camera.
Therefore, when pressing the white balance of a video camera, the zebra signal appears and is produced up to the third stage from the white in the gray scale chart.
The zebra signal is conventionally produced when the video signal is a light quantity of over 100 IRE, the zebra signal can indicate the state and range of incident light quantity with regard to the surrounding environment during picture taking and is useful to check the state of the camera, and is used for making a pertinent video signal and photograph by controlling the lens iris in response to the zebra signal. However, the video camera using a conventional zebra pattern is structured to merely warn about the state or light quantity of the picture screen by inputting the zebra pattern when above a certain specific value i.e., only the portion of the light quantity being directed, and being designed not to be able to observe the state and light quantity of the picture screen when below the specific value, and therefore, when taking a picture of the field location with a video camera, because the state and scope of the light quantity is not possible to observe without a measuring instrument or master monitor, there is a problem that a picture of good quality is hard to obtain with only the electronic view finder scanned with black and white.