Television – Special applications – Film – disc or card scanning
Reexamination Certificate
1997-12-02
2002-09-24
Garber, Wendy R. (Department: 2612)
Television
Special applications
Film, disc or card scanning
C348S096000, C348S102000, C348S105000
Reexamination Certificate
active
06456319
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image sensing apparatus represented by a video camera and, more particularly, to an image sensing apparatus having a function of reading an image from a negative film, a slide film, or the like.
Along with rapid improvements of the techniques of personal computers and their peripheral devices, for example, it has now become easy for an operator to capture and edit a taken picture on a memory in a personal computer, and to create a unique postcard or poster. Under this circumstance, the market demand in this technical field is increasing year by year.
When an image on a picture is input into a personal computer, image information on the picture must be converted into an electrical signal using a video camera or an electronic still video camera. Since pictures on photographic paper sheets have various sizes, it is troublesome for an operator to set the field angle and to determine how to illuminate each picture upon taking the picture using such camera. Also, a large-scale, dedicated image sensing apparatus such as a fixing base of a video camera, or the like is required.
To solve such problems, an adapter for mounting a negative (or positive) film is attached to an image sensing lens of the video camera, and an image projected via the adapter is sensed by the video camera. The sensed image is converted into a video signal, which is recorded on a magnetic tape or a memory in a personal computer, or is output to a monitor. This adapter is called a “film adapter” (this specification uses this name) or “film carrier holder”, and a camera system with this adapter is called a photo video camera system or the like.
The film adapter is merely attached to the lens of a camera, and has only a function of allowing the user to mount a film. For this reason, when the film adapter is used, various setup processes are required. For example, image signal processing inside the camera must be switched in correspondence with a negative or positive image. If this setup process is ignored, a negative image is directly displayed on a monitor. Also, the frame of a film must be positioned accurately. If this setup process is neglected, an image on a film frame, which is moving in the adapter, or an image on a frame which is not set at a predetermined position, is displayed.
Hence, when the film adapter is attached to the conventional video camera and images on a negative film are taken as still images, various switch operations for attaining the above-mentioned setup processes (to be referred to as a “film image sensing mode” hereinafter) are required, resulting in meticulous operations.
However, when a switch for detecting attachment of the adapter is arranged on the video camera main body, the number of parts increases and results in a large camera size and high cost, the video camera main body must be drastically modified, and so on. Such problems are the first problems in the conventional camera attached with the film adapter.
On the other hand, some conventional cameras that can set the film image sensing mode often have two modes, i.e., “sequential shot mode” and “single shot mode”. With these cameras, the photographer selects one of such image sensing modes in correspondence with his or her purpose at that time. The sequential shot mode has as its principal object to avoid a loss of an image sensing chance when a moving subject is captured as still images. When a still image is taken using the film adapter, the film as a subject completely stands still integrally with the camera, and identical still images are repetitively taken unless the sequential shot mode is canceled. That is, the switching function of the sequential and single shot modes, which function is convenient for the user, requires extra user operations. Such problem is the second problem of the prior art.
Problems posed when the film adapter is attached to the video camera or the like are not limited to those concerning the operability mentioned above.
More specifically, when the film adapter is not attached to a conventional camera that can mount a film adapter (when the camera is not in the film image sensing mode), the camera must be able to optimally take images of a normal subject as a normal video camera (i.e., the one without any film image sensing function), as a matter of course. For this reason, the signal processing circuit of the camera is set to assure a broad dynamic range, which is not so required in the film image sensing mode. That is, signals input to the video camera normally have a large level difference (dynamic range) depending on the subject to be taken, i.e., a film set in the film adapter or a normal subject. In order to execute normal video image sensing prior to the film image sensing mode and to optimally take images of a subject in the normal video image sensing, the dynamic range of the signal processing circuit of the video camera is set to cover a very broad range from a subject in a dark room to a very bright subject such as a seashore under direct sunlight. On the other hand, in the film image sensing mode using the film adapter, since illumination light coming from a backlight serves as a light source, changes in lightness (luminance level) of a subject (film) are very smaller than those in a normal image sensing mode (ranging from a bright seashore to a dark room). If the signal processing circuit is fixedly set in both the film image sensing mode and normal subject image sensing mode that have a large dynamic range difference, the performance of the signal processing circuit cannot be fully used especially in the film image sensing mode.
When images on a film are taken using a camera which sets an A/D converter in this manner, such A/D converter is not suitable for the film image sensing mode with a narrow input dynamic range, and the quality of images to be recorded or displayed on the monitor deteriorates. This is a problem (third problem) arising from circuit setups.
Another problem (fourth problem) arising from circuit setups will be explained below. This problem is posed since the conventional camera that can mount the film adapter has moving image-priority circuit setups.
The conventional camera that can mount the film adapter will be explained below with reference to
FIGS. 1 and 2
.
Referring to
FIG. 1
, reference numeral
2001
denotes a film adapter;
2002
, a film;
2003
, an imaging lens;
2004
, an image sensing element for photoelectrically converting incoming light;
2005
, a signal processing circuit for generating luminance and chrominance signals based on signals generated by the image sensing element
2004
;
2006
, a reversing circuit for converting a negative image into a positive image;
2007
, a switching circuit for selecting whether or not that negative/positive reversing is to be done;
2008
, a noise reduction circuit (N.R.) for reducing noise components in an image signal; and
2009
, an encoder circuit for converting the luminance and chrominance signals into a video signal.
The film adapter
2001
has a light source for illuminating the film
2002
. Light transmitted through the film
2002
is imaged on the image sensing element
2004
via the lens
2003
. An optical signal incident on the image sensing element
2004
is photoelectrically converted, and the signal processing circuit
2005
generates luminance and chrominance signals based on the converted signals. In this case, when the film
2002
to be sensed is a positive film, the outputs from the signal processing circuit
2005
are directly input to the noise reduction circuit
2008
by the switching circuit
2007
. On the other hand, when the film
2002
is a negative film, the outputs from the signal processing circuit
2005
are converted into those for a positive image by the reversing circuit
2006
, and the converted signals are input to the noise reduction circuit
2008
.
FIG. 2
is a block diagram showing the arrangement of the frame correlation noise reduction circuit
2008
. In
FIG. 2
, reference numeral
2031
denotes a frame memor
Hirasawa Masahide
Kurobe Masakazu
Nakayama Satoshi
Garber Wendy R.
Morgan & Finnegan , LLP
White Mitchell
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