GB2191061A

GB2191061A - Television film scanner

Info

Publication number: GB2191061A
Application number: GB08712335A
Authority: GB
Inventors: Dieter Poetsch
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1986-05-27
Filing date: 1987-05-26
Publication date: 1987-12-02
Anticipated expiration: 2007-05-26
Also published as: DE3617837A1; GB8712335D0; JP2540329B2; DE3617837C2; GB2191061B; JPS62287788A

Abstract

A television film scanner is described which may be used for producing high resolution video signals. For this purpose, the green colour signal is derived from two line sensors 14, 14' arranged for scanning the film on two adjacent lines of a television frame. Respective single line sensors 13, 15 for the red and blue colour signals are arranged for scanning a line between the two green line sensors. <IMAGE>

Description

SPECIFICATION Television film scanner This invention relates to a television film scanner having a plurality of semi-conductor line sensors for deriving red, blue and green colour signals by the line-by-line sequential scanning of a continuously moving film.

Such a television scanner is, for example, known from G.B. 1,597,504, with which it is possible to derive from a motion picture film colour television picture signals according to one of the presently used television standards. In order to improve these television pictures produced according to existing television standards, a considerable amount of development has taken place over the past few years in the field of high definition television (HDTV), particularly for studio equipment such as television cameras, film scanners, monitors, etc. If a television film scanner were designed in the conventional manner, for HDTV purposes, namely with three semi-conductor line sensors for red, green and blue respectively, several times the band width of existing television systems would be required.Apart from this difficulty, the additional problem occurs that semi-conductor line sensors with the large number of picture elements required for HDTV and which would have to be operated at a high picture element rate are not at present commercially available.

The object of the invention is therefore to provide a television film scanner of the aforementioned type, in which semi-conductor line sensors are able to produce high resolution television pictures with an only slightly increased picture element rate.

Accordingly, the invention provides a television film scanner having a plurality of semi-conductor line sensors for deriving red, blue and green colour signals by the line-by-line sequential scanning of a continuously moving film, wherein for deriving the green colour signal there are provided two line sensors arranged for scanning the film on two adjacent lines of a television frame.

The invention has the advantage that conventional semi-conductor line sensors can be used therewith.

In an embodiment of the invention it is particularly advantageous that by the provision of the two line sensors in one casing, it is possible to use conventional colour separators and imaging means.

An embodiment of the invention will now be described by way of example, with reference to the accompanying drawings, wherein: Figure 1 shows the optical position of a plurality of line sensors with respect to a television raster; Figure 2 shows a special design of a two-line sensor; Figure 3 are timing diagrams of some of the signals occurring in the television film scanner of Figure 4; and Figure 4 is a block circuit diagram of a television film scanner according to the invention.

On the left-hand side of Figure 1 are shown four positionally consecutive lines of a television raster frame by which a film is to be scanned, the dashed lines 2 and 4 belonging to the second (interlaced) field of the frame. The right-hand side diagrammatically shows a number of line sensors in their (optical) positions relative to the television raster frame. Thus, the first green line sensor G1 is arranged to scan the film on line 1 and the second green line sensor G2 on line 2 of the raster frame, whilst the line sensors for red Rand blue B are arranged to scan the film on a line between those scanned by the two green line sensors.Thus, by suitable control of the two green line sensors G1 and G2, the green signals of each line and its following interlaced line can be simultaneously scanned, which permits a doubling of the number of lines without increasing the picture element rate of the line sensor used. However, the red and blue video colour signals are only provided for a single line. The lines for the two interlaced fields corresponding to a frame must be produced electronically, e.g. by vertical filtering. Alternatively, it is possible to have two red and blue line sensors having the same optical positions relative to the television raster frame as the two green line sensors.

Figure 2 shows a special arrangement of the two line sensors for the green signal with picture element offset, i.e. relative to the television frame the picture elements of the line sensor 1 are horizontally offset with respect to those of the second line sensor 2 by one half of the picture element width. Thus, it is possible to reduce the number of picture elements by roughly a factor of 2, which contributes to reducing the data throughput to be processed. The corresponding green signals G1 and G2 can be taken at the outputs 3 and 4 of the associated shift registers 5,6 if the necessary pulse signal is applied to terminal 7 (Figure 3b). The two green line sensors are preferably housed in a common casing, and are integrated on a common semi-conductor substrate.However, the relative offset shown in Figure 2 is not necessarily achieved by physical positioning -- it can be achieved by optical means with the two green sensors actually at substantially different locations as shown in Figure 4. The same arrangement of picture element-offset line sensors is obviously also possible for the red and blue line sensors.

Figure 3 is a timing diagram showing some of the signals occurring in the block circuit diagram of Figure 4. The pulse signal shown in Figure 3a is used for timing the line sensors activated during time to, which is therefore the integration time during which optical signals can be recorded. Figure 3b shows the pulse signal for transmitting the charge resulting from recording in the photosensitive elements of the line sensors to the particular shift register of the line sensors. Figure 3c shows the video colour signal produced by the recording and which can be taken from the line sensors. The line time t1 of the video signal at the output of the line sensors is roughly twice as long as the line time t2 fixed in accordance with the particular television standard for the output video signal according to Figure 3d.

Line time t2 of the video signal in Figure 3d roughly corresponds to the pulse duration to.

Figure 4 shows the main parts of a television film scanner according to an embodiment of the invention. By means of a camera lens 10, the pictures of a motion picture film 11 are projected on to a beam splitting prism system 12, on which are arranged the line sensors 13 for red, 14 for green 1, 14' for green 2 and 15 for blue. Appropriate colour filters (not shown) are provided on the prism system 12 in front of each sensor. For adjusting the pictures, between each line sensor 13 to 15 and the beam splitting prism system 12 there is provided a respective plane-parallel plate, the drawing only showing one such plate 16 or 17 between the red sensor 13 and the blue sensor 15. By such plates it is possible to adjust or align the pictures both in the horizontal and vertical directions relative to the sensors.

The signals according to Figures 3a and 3b are supplied from a clock generator 18 to the line sensors 13 to 15 for timing purposes. Pre-amplifiers 19 to 22 and low-pass filters 23 to 26 are connected to the output of the line sensors 13 to 15. Video colour signals corresponding to Figure 3c are taken from the output of the low-pass filters 23 to 26 and these signals are then digitized in A/D converters 27 to 30. The A/D converters are supplied with a sampling frequency f1 by the block generator 18.

The digital video signals from the outputs of the AID converters 27 to 30 are converted in a following standard converter 31 into video signals appropriate for the desired television standard. When using only one line sensor 13 or 15, the red and blue video signals must first be converted by means of a vertical filter 32 or 33 into video signals with interlace lines, and in such a case a corresponding phase equalization of the green video signals is obtained by the transit phase elements 34, 35. When using two line sensors for red, green and blue, there is no need for the components 32 to 35. The sequentially occurring video signals are converted into interlaced video signals in the standard converter 31. In addition, the video signals according to Figure 3c are time-compressed by timing the converter 31 with the frequency f2 = k x f, (k = 2). The digital video signals R, G, B at the output of the standard converter 31 are then brought into analog form in D/A converters 36 to 38, so that it is possible to take from outputs 39 to 41 the output signals for red Ra, green Go and blue Ba in accordance with Figure 3d.

It is to be understood that where the two line sensors 14 and 14' for green are provided in a common casing, as described with reference to Figure 2, they are provided at a common face of the prism system 12.

Claims

1. Atelevision film scanner having a plurality of semi-conductor line sensors for deriving red, blue and green colour signals by the line-by-line sequential scanning of a continuously moving film, wherein for deriving the green colour signal there are provided two line sensors arranged for scanning the film on two adjacent lines of a television frame.

2. A television film scanner as claimed in Claim 1, wherein relative to the television frame the two green line sensors are mutually horizontally offset by half a picture element.

3. A television film scanner as claimed in Claim 1 or 2 wherein two line sensors arranged for scanning two adjacent lines of a television frame are also provided for deriving the red and/or blue colour signals.

4. A television film scanner as claimed in Claim 3, wherein relative to the television frame the two line sensors for red and/or blue are mutually horizontally offset by half a picture element.

5. Atelevision film scanner as claimed in Claim 1 or 2, wherein two single line sensors are provided for deriving the red and blue colour signals, such sensors being arranged to scan the film on a line intermediate the two adjacent lines scanned by the two green line sensors.

6. Atelevision film scanner as claimed in any preceding claim, comprising a beam splitting prism between the film and the semi-conductor line sensors, and wherein adjusting or aligning plates are arranged between the prism and the line sensors.

7. A television film scanner as claimed in Claim 6, wherein each adjusting plate is adjustable both horizontally and vertically.

8. A television film scanner as claimed in Claim 1 or 3, wherein the two line sensors for the green or each colour signal are integrated onto a common semi-conductor substrate.

9. A television film scanner as claimed in Claim 1 or 3, wherein the two line sensors for the green or each colour signal are housed in a common casing.

10. A television film scanner as claimed in Claim 5, wherein the colour signals derived from the red and blue line sensors are vertically filtered for producing interlaced television fields.

11. A television film scanner as claimed in any preceding claim, wherein high resolution transmission primaries corresponding to a desired colour television standard are produced by compression and time successive supply of the two colour television fields derived from the line sensors.

12. A television film scanner, substantially as described with reference to the accompanying drawings.