COLOR-PICTURE ANALYZING APPARATUS FOR CONTINUOUSLY SWITCHING-ON GREEN LAMP AND FOR ALTERNATIVELY SWITCHING-ON BLUE AND RED-PURPOSE LAMPS

Abstract: A color-picture analyzing apparatus comprises a blue, green, and red-pupose lamps, preferably, fluorescent lamps, a sharp-cut filter in front of the red-purpose lamp for solely passing the red radiation, an infrared-cut filter interposed between a document having a color-picture to be analyzed and a reading sensor for cutting an infrared zone radiation, and a first circuit for continuously switching on the green lamps, a second circuit for alternatively switching on the blue and the red-purpose lamps. The red-purpose lamp can provide wide radiations covering the red spectral zone. It may be a cool white fluorescent lamp having a short afterglow time.

Description: The present invention relates to a color picture analyzing apparatus with an image signal sensor, such as a charge coupled device, that analizes color components of an original color document, comprising: green lamp means; blue lamp means; red purpose lamp means; and switching means for controlling the operation of said lamp means. Such apparatuses, comprising two or three fluorescent lamps, are described for example in US-A-4 318 122 ( published on 02.03.1982 ) or in US-A-4 375 647 ( published on 01.03.1983 ). Conventionally, a color-picture reading apparatus is provided in a color facsimile machine, color copying machine, and color scanner for analyzing the color-picture into the red component, green component, and blue component by optically scanning the color-picture, so that they are electrically converted and outputted. To analyze the red, green, and blue components from the color-picture, various types of filters are presented through which reflected radiations from the color-picture are passed to pick-up picture information for a specific wavelength zone. Some conventional blue fluorescent lamp can respond speedily and has a short afterglow time while the conventional red and green fluorescent lamps inevitably have relatively long afterglow times (several-about 10 msec). It may, therefore, be difficult to provide a superior reading apparatus for rapidly analyzing the color-picture. Accordingly, it is an object of the present invention to provide an improved color-picture analyzing apparatus for analyzing a color-picture rapidly. The color picture analyzing apparatus according to the present invention is characterized in that: said red-purpose lamp means is of the type for propagating light having broad band spectral characteristics that include within red spectral characteristics, so as to have a short afterglow time; the switching means are such that said green lamp stays ON at all times, while said red-purpose lamp means and said blue lamp means are turned ON and OFF such that their respective ON times do not overlap; and a sharpcut filter is interposed between said red-purpose lamp means and the document to be analyzed for filtering said light having broad band spectral characteristics so as to illuminate the document with light having red spectral characteristics when said switching means turns ON said red-purpose lamp means. The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein: FIG. 1 is a side view of a color-picture analyzing apparatus according to the present invention; FIG. 2 is a graph showing the spectral characteristics of an infrared-cut filter used for the present invention; FIG. 3 is a graph showing the spectral emission characteristics of a red-purpose fluorescent lamp used in the apparatus of FIG. 1; FIG. 4 is a graph showing the spectral characteristics of a sharp-cut filter used for the present invention; FIG. 5 is a graph showing the spectral emission characteristics of the red-purpose fluorescent lamp of FIG. 3 with the help of the sharp-cut filter of FIG. 4, and the infrared-cut filter of FIG. 2; and FIG. 6 is a time chart of switching the three flurescent lamps according to the present invention. FIG. 1 is a side view of a color-picture analyzing apparatus of the present invention. It is applicable to a color facsimile, color copying machine, and color scanner. With reference to FIG. 1, a document 1 having thereon a color-picture to be readout is constantly transported along the direction of the arrow "A" by transport means comprising two pairs of rollers 2. "B" point of the document 1 denotes an analyzing position for analyzing the color-picture on the document 1. To emit tight toward the document 1, three tight emitting sources 3,4, and 5 are provided. The reflected light from the document 1 is reflected by two reflection mirrors 7 and 8. An infrared-cut filter 9 is provided for enabling the reflected light to pass through to thereby be incident upon a reading lens 10. The light passing through the reading lens 10 is applied to a charge coupled device (CCD) image sensor 11, so that it provides signals corresponding to the light into a processing circuit 12 calculating the color-signals. The circuit 12 may comprise a subtraction circuit. In connection with the three light sources 3, 4, and 5, the light source 3 is a green fluorescent lamp for propagating the light having the green spectral characteristics. It has a conventional long afterglow time of several-about 10 msec. The term "afterglow time" is referred to as the interval when the lamp continus to propagate some radiation after the power supply to itself has been shut off. During the afterglow time, the spectral characteristics of all the fluorescent lamps as used for the present invention is unchanged although its emission level is relatively small. The source 4 is a blue fluorescent lamp for propagating the light having the blue spectral emission characteristics. It has a short afterglow time. The source 5 is a red-purpose fluorescent lamp for propagating the light having the red spectral emission zone in that the spectral characteristics are wide as shown in FIG. 3 and that a short afterglow time can be provided. For example, the red-purpose fluorescent lamp 5 may be composed of a fluorescent material of trade name, "SPD-103A", available from Toshiba Corporration, Japan. The "SPD-103A" can provide a short afterglow time of about 10 micro sec. The red-purpose fluorescent lamp 5 can be called a cool white type although should not limited to this type so long as it can emit the light covering the red spectral zone. FIG. 2 shows a graph showing the spectral characteristics of the infrared-cut filter 9 for cutting light in the infrared zone so as to improve the resolution of analyzing the color. A sharp-cut filter 6 is interposed between the red-purpose fluorescent lamp 5 and the document 1. The sharp-cut filter 6 has the spectral transmission characteristics as shown in FIG. 4 characterized in that it shows a high transmission factor in a specific zone. Therefore, the light emitted from the red-purpose fluorescent lamp 5 and passing through the sharp-cut filter 6 results in having the red spectral characteristics. Since the infrared-cut filter 9 serves to cut the light in the infrared zone, the passing light has the emission spectrum for the red radiation as shown in FIG. 5, eventually. FIG. 6 shows a timing chart for switching on and off the three fluorescent lamps 3, 4, and 5 according to the feature of the present invention. More specifically, FIG. 6-(a) is a timing according to which the green fluorescent lamp 3 propagates the green light. FIG. 6-(b) is a timing by which the blue lamp 4 propagates the blue light. FIG. 6-(c) is a timing by which the red-purpose lamp 5 propagates the light, which becomes the red light in combination with the sharp-cut filter 6 and the infrared-cut filter 9. As indicated in FIG. 6, the green lamp 3 is continuously switched on as long as the other lamps 4 and 5 are switched on. A first means is provided for continuously switching on the lamp 3 over analyzing the red, blue, and green components. A second means is provided for alternatively switching on the blue lamp 4 and the red-purpose lamp 5. That is, the blue lamp 4 is switched on, being prevented from being overlapped with the switching on timing of the red-purpose lamp 5. FIG. 6-(d) is a timing for the CCD image sensor 11 to analyze the respective color components. FIG. 6-(e) is a timing for the CCD image sensor 11 to output the respective signals. The green components of the color-picture are analyzed in the first timing of the timing of FIG. 6-(d) so that the processing circuit 11 provides the signals corresponding to the green components. Just after the circuit 12 provides the green components signals, the blue lamp 4 is started to be switched on. At this timing, the green lamp 3 and the blue lamp 4 are both switched on. In synchronization with the switching off timing of the blue lamp 4, the sensor 11 starts to read-out the color-picture so that it provides into the circuit 12 the signals representative of the green components plus the blue components. The circuit 12 serves to cancel the green components signals from the mixed signals of the green components plus the blue components to get the proper blue components signals. Second, the red-purpose lamp 5 is started to be switched on, so that it is continued to be switched on together with the green lamp 3. With the help of the sharp-cut filter 6 and the infrared-cut filter 9, as stated, the red-purpose lamp 5 enables the propagation of the light of the red spectral characteristics with a sufficient light amount. In synchronization with the switching off timing of the red-purpose lamp 5, the sensor 11 starts to read-out the color-picture, so that it provides the signals for the green components plus the red components. Similarily, the circuit 12 subtracts the green components signals from the green components signals plus the red components signals to obtain the proper red components signals. These operations are repeated to subsequently analyze the color information from the picture on the document 1. In the embodiment of FIG. 1, the infrared-cut filter 9 is provided. To eliminate the filter 9, either the reflected mirror 7 or 8 should serve to cut the infrared radiation by comprising a filter named "cold filter". With the blue fluorescent lamp having a conventional short afterglow time and the green fluorescent lamb having a conventional long afterglow time, according to the present invention, because a good red-light emitting source can be provided by the red-purpose fluorescent lamp 5 having a short afterglow time in combination with the sharp-cut filter 6 and the infrared-cut filter 9, the switching on and off of all the fluorescent lamps can be accelerated to make it possible to rapidly analyze the blue, green, and red components.

Claims: A color picture analyzing apparatus with an image signal sensor, such as a charge coupled device, that analyzes color components of an original color document, comprising: green lamp means; blue lamp means ; red-purpose lamp means; and switching means for controlling the operation of said lamp means, characterized in that: said red-purpose lamp means is of the type for propagating light having broad band spectral characteristics that include red spectral characteristics, and having a shorter afterglow time than the green lamp means; the switching means are such that said green lamp stays ON at all times, while said red-purpose lamp means and said blue lamp means are turned ON and OFF such that their respective ON times do not overlap; and a sharpcut filter is interposed between said red-purpose lamp means and the document to be analyzed for filtering said light having broad band spectral characteristics so as to illuminate the document with light having red spectral characteristics when said switching means turns ON said red-purpose lamp means. The apparatus of claim 1, further comprising an infrared-cut filter interposed between the document and the image signal sensor for cutting the radiation in the infrared band from the reflection signal. The apparatus of claim 1, wherein said red-purpose means is a flurorescent lamp for propagating the light covering the red spectral band. The apparatus of claim 3, wherein the fluorescent lamp is of a cool white type.

Inventors: NAGANO, FUMIKAZU, URAKAWA,TOSHIO
Applicants: SHARP KABUSHIKI KAISHA
Application year: 1985
Main classification: H04N1
IPC codes: H04N1