DE2063884C3 - Device in a color television camera with multiple image pickup tubes - Google Patents

Description

The invention relates to a device in a color television camera with at least three image pickup tubes and an optical beam splitter, which is such that the incident light from the pickup optics is split and on emerges from the color divider in different places, each with a different proportion of color.

In a color television camera with multiple image pickup tubes, difficulties often arise are caused by the fact that the physical behavior of the image pick-up tubes in the individual color channels is different; among others are those caused by inertia and other physical ones Characteristics-related trailing phenomena in the individual color channels different. One tried to compensate for this by electrical switching measures in the amplifier circuits connected to the image pickup tubes, so that no

ίο disturbing phenomena become visible. In the practical operation of color television recording cameras has However, this is not fully satisfied. The invention is based on the consideration that by approximation of the signal generated in the individual image pick-up tubes ^r > flows a reduction of the disturbing phenomena is possible

It is already known to reduce or equalize trailing symptoms on the light-sensitive layers of image pick-up tubes to guide additional light (DE-OS 15 97 218). This results in a reduction in the trailing phenomena, especially at low exposure levels achieved; at high illuminance levels and high color temperatures, the blue component is in the incident light so large that the image pickup tube for the blue channel is overdriven, unless it is the incident one Light would be reduced accordingly by a tine aperture, which in turn leads to a poor signal-to-noise ratio leads in the red channel

In a device of the type mentioned at the outset, according to the invention, there is therefore between at least an exit point of the color splitter for the blue light component and the light-sensitive layer of the image pickup tube reproducing blue color separation

i ¹ ) a transparent filter disc is movably arranged in such a way that it can either be switched into or removed from the beam entrance.

As a result, it is very practical with the image pickup tubes currently in use Operation sufficiently possible with a universal adjustment of the operating parameters below the usual lighting conditions both in the studio and during outdoor broadcasts, e.g. B. on Sports fields to receive satisfactory television pictures.

In particular, it is then not necessary to laboriously readjust the operating parameters when the floodlights of a sports field are switched on. It is useful if the filter disc is a neutral gray filter.

In a preferred embodiment, at least two, preferably three, filter disks are arranged directly next to one another and each of these filters can optionally be switched into or removed from the beam path, with at least one of these

V ' filter discs are made of clear glass in order to keep the optical path length constant regardless of whether a filter is switched on. It is advantageous here if the device for moving the filters into or out of the optical device in order to carry out a fine adjustment

μ beam path mechanically with a switch to Gain control is coupled. In some cases it can be useful if between the A first filter and exit point for the blue light component and the associated image pick-up tube

b ^r > a second filter can be switched on between the exit point for the red light component and the associated image pickup tube and the devices for using these filters are coupled to one another,

such that in one operating state only the first filter and in another operating state only the second The filter is in the associated beam path.

In the following, the invention is described in connection with the figures representing an exemplary embodiment described. Here, all details not necessary for understanding the invention are better ones Has been omitted for the sake of clarity. Corresponding to each other? Parts are the same in the figures Way labeled It shows

F i g. 1 the optical system of a color television camera with the device according to the invention,

2 shows, on an enlarged scale, a structural detail of this device.

In the arrangement according to FIG. 1 is that of the taking lens 1 (which for the sake of simplicity only indicated by a simple lens) incident luminous flux from prisms 2, 3 and 4 existing, known per se optical beam splitter supplied. The light emerging from the prism 1 is the photo-sensitive layer of the TV receiver tube 5 supplied, soft the so-called 'Äfeißsignal The light emerging from the prism 4 is generated in an analogous manner by the tube that generates the red signal 6 and the light emerging from the prism 3 via a roof prism 7 and relay optics 8 of the das The pick-up tube 9 supplying the blue signal is supplied. In the blue channel, this is shown in FIG. 2 illustrated filter wheel 10 switched on with a clear glass pane 11 and a neutral gray filter pane 12. The filter wheel is shown in FIG. 1 indicated only by the disks 11 and 12 and the axis 13

In an analogous manner, a further filter wheel is provided for the red channel, which has a clear glass pane 15 and has a neutral gray filter disk 16 and is rotatable about the indicated axis 17. The establishment is taken in such a way that at a relatively low color temperature of the scene lighting

the clear glass pane 11 is located in the blue channel, while the neutral gray filter disk 16 is in the red channel. This makes the red signal selective weakened; the signal current in the image pickup tube 9 supplying the red signal is reduced and thereby approximated the signal streams in the other image channels in the desired manner.

If television recordings at relatively high

κι color temperature of the scene lighting, so z. B. are made corresponding to 8000 ° Kelvin, then it can be useful in the blue channel neutral gray filter disk 12, but switch on the clear glass disk 15 in the red channel.

In a preferred embodiment, the filter wheel 10 carrying the filter disk is also at the edge provided with a toothing, in which a pinion 20 engages via the shaft 21 of the motor 22 is driven. By means of a switch 23, the filter setting can either be for a temperature of e.g. 3000 ° or 8000 ° Kelvin can be sprinkled. to For this purpose, the switch is connected to a so-called follow-up control 25 via a connecting cable 24 connected which of the one with the filter wheel

α coupled actual value transmitter 26 is controlled in such a way that the filter wheel assumes the respectively pre-planned position. The filter wheel can also be equipped with several filter discs of different densities; in this case the switch 23 is designed for correspondingly several operating positions.

If there are two filter wheels in the television camera, then it is recommended> to couple these two filter wheels together. This coupling, which in Fig. 1 by the dashed line 27

) - that is indicated can either be electrical or mechanical take place.

1 sheet of drawings

Claims (8)

Patent claims: 1. Apparatus in a color television camera having at least three image pickup tubes and one optical beam splitter which is designed in such a way that the light incident from the receiving optics is divided and in different places with a different proportion of color from the color divider exits, characterized in that between at least one exit point for the blue light component and the light-sensitive layer that reproduces the blue color separation Image pickup tube (9) a transparent filter disc (12) is movably arranged so that it can optionally be switched into or removed from the beam path. 2. Apparatus according to claim 1, characterized in that the filter disc is a neutral one Neutral density filter is 3. Priority according to one of the preceding Claims, characterized in that at least two, preferably three filter discs directly are arranged next to each other and each of these filter discs optionally in the beam path can be switched on or removed from this, and at least one of these filter discs made of clear glass consists 4. Apparatus according to claim 1 to 3, characterized in that the immediately next to each other arranged filter discs have different optical density (transparency). 5. Apparatus according to claims 1-4, characterized in that the filter disks have a transparency of 95 or 50%. 6. Device according to Ansprucu 1, characterized in that the device for moving the Filter discs in or out of the optical beam path is mechanically coupled to a switch for gain control. 7. The device according to claim 1, characterized in that between the exit point for the blue light component and the associated image pickup tube (6) a first filter (11) and between Exit point for the red light component and the associated image pick-up tube (9) a second filter (16) is switched on and the device for using these filters are coupled together such that in one operating state only the first filter (11) and in another operating state only that second filter (16) is located in the associated beam path. 8. Apparatus according to claim 1, characterized in that the first filter is a clear glass pane (15) and the second filter is a neutral gray filter disc (16).