JPH0411065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to an apparatus for reading document information, and more particularly to a reading device that has two modes: color reading that separates the information into color signals, and black and white reading that does not separate the information into color signals.

<Prior art> Conventionally, in a color reading device such as a drum scanner, color reading is performed by providing red, green, and blue filters and three photoelectric conversion elements that receive the transmitted light of each filter. Many devices provide a fourth photoelectric conversion element that receives transmitted light to perform black-and-white and halftone reading.
However, according to such a conventional example, not only is it extremely difficult to relatively align the three color photoelectric conversion elements, but also another set of filters and photoelectric conversion elements are required for the black and white mode. There was a drawback that I had to prepare for.

<Object of the invention> The object of the invention is to achieve the following by using a single photoelectric conversion element:
To provide a color reading device equipped with a monochrome mode that can use both color reading and monochrome reading modes and executes reading in the monochrome mode at a higher speed than in the color mode.

In order to achieve the above object, the present invention provides three fluorescent lamps each having a peak value in the red, green, and blue wavelength bands for illuminating a color original to be read, and a lighting circuit for each of the fluorescent lamps. , an optical system for obtaining a real image of the document, a single photoelectric conversion element disposed at the real image position, a mode selection means for selectively selecting a color mode and a black and white mode, and a mode selection means for obtaining the above-mentioned image by the mode selection means. When a color mode is selected, each lighting signal that causes each fluorescent lamp to sequentially switch and emit light is transmitted to the lighting circuit at a constant cycle at a ratio of the light emission time at which each output of the photoelectric conversion element due to the light emission of each fluorescent lamp is at the same level. In addition to sequentially outputting in synchronization with the pulse, when the black and white mode is selected, each lighting signal with a time width of 1/3 of the lighting time of each fluorescent lamp due to each lighting signal in the color mode is simultaneously output for each transfer pulse. The invention is characterized in that it includes a light emission control means.

<Function> When the color mode is selected, each lighting signal output from the light emission control means to the lighting circuit causes red, red,
Each of the green and blue fluorescent lights is sequentially and repeatedly emitted in a predetermined time width determined individually, and the photoelectric conversion element outputs red, green, and blue color separation signals for each period separated by transfer pulses. .

On the other hand, when the monochrome mode is selected, each fluorescent lamp is turned on at the same time for each transfer pulse. The light emitting time of each fluorescent lamp is determined by the ratio of the light emitting time at which each output of the photoelectric conversion element due to the light emission of each fluorescent lamp is at the same level. Since each light emission time is 1/3, by emitting fluorescent lamps at the same time with this light emission time ratio, it becomes a white light source and can read black and white originals, and the output of the photoelectric conversion element when reading a white original. Since the level can be set to the same level as when reading a color original, the output signal of the photoelectric conversion element can be processed in common, and the scanning speed of the original can be increased three times compared to when color mode is selected. .

<Example> FIG. 1 shows an overall configuration diagram of the present invention. Three fluorescent lights 2, 3, and 4 of red, green, and blue are arranged to illuminate the document 1 to be read, and an optical system consisting of a mirror 5 and a convex lens 6 illuminates a single image on the image plane of the document. A CCD sensor 7 is provided. The output signal of the CCD sensor 7 is amplified by an amplifier circuit 8 and introduced into a white balance control circuit 9. Control circuit 9
outputs a lighting signal, which will be described later with reference to FIGS. 2 and 3, to the fluorescent lamp lighting circuit 10 at a predetermined timing synchronized with the control of the CCD sensor. The lighting circuit 10 pulses each fluorescent lamp. A mode selection button 11 is connected to the control circuit 9.

Next, the effect will be explained.

FIG. 2 shows a time chart when selecting the color mode. The charges in the light receiving section are transferred in parallel to each bit of the analog shift register by the transfer pulse Φ _T to the CCD, and then serially led out by the shift register, and the CCD output signal is read out via the amplifier circuit 8. In synchronization with this transfer pulse Φ _T , a red lighting signal T _R , a green lighting signal T _G , and a blue lighting signal
The three fluorescent lights 2, 3, 4 of red, green, and blue are repeatedly output from the control circuit 9 in the order of T _B.
will emit light in sequence. The output time widths Tron, Tgon, and Tbon of each of the lighting signals T _R , T _G , and T _B are the red signal and green signal of the CCD sensor 7 caused by the lighting of each fluorescent lamp 2, 3, and 4 when reading a white original, respectively. The output levels of the signal and the blue signal are determined to be constant. By sequentially switching light emission like this,
For each period separated by the transfer pulse Φ _T , the CCD
Outputs red, green, and blue separated color signals.

FIG. 3 shows a time chart when black and white mode is selected. The difference in this mode from the color mode described above is that the lighting signals T _R , T _G , and T _B for the three fluorescent lamps 2, 3, and 4 are the same transfer pulses Φ _T as in the color mode. The output time width tr of each lighting signal T _R , T _G , T _B is
tg, tb are each lighting progress T _R , T _G , in color mode
The output time widths of T _B are set to 1/3 of each of Tron, Tgon, and Tbon. That is, tr=Tron/3, tg=Tgon/3, tb=Tbon/
3. As a result, the output level of the CCD sensor 7 when reading a white original can be the same as when reading a color original, so the output signal of the CCD sensor 7 can be processed without changing the constants of the analog processing circuit. By performing these steps in common, the scanning speed of the document can be increased three times compared to when the color mode is selected.

<Effects of the Invention> As described above, according to the present invention, a single CCD
Both color and black-and-white reading can be done just by using a sensor, and a single
Since CCD sensors are used, there is no need to align the CCD sensors with each other, and there is no need to provide special parts for black and white mode, simplifying both the configuration and manufacturing process. In addition, the scanning speed when monochrome mode is selected is three times faster than when color mode is selected, and the output level of the CCD sensor when monochrome mode is selected can be the same as when color mode is selected.
Signal processing circuits can be shared.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operation when selecting a color mode in the above embodiment.
FIG. 3 is an explanatory diagram of the operation when black and white mode is selected. 1... Original, 2... Red fluorescent light, 3... Green fluorescent light, 4... Blue fluorescent light, 6... Convex lens (optical system), 7... CCD sensor (photoelectric conversion element) ), 9...
...Control circuit (light emission control means), 10...Lighting circuit,
11...Mode selection button (mode selection means).

Claims (1)

[Claims] 1. 3 with peak values in the red, green, and blue wavelength bands for illuminating the color original to be read.
fluorescent lamps, a lighting circuit for each fluorescent lamp, an optical system for obtaining a real image of the document, a single photoelectric conversion element placed at the position of the real image, and a color mode and a monochrome mode. a mode selection means for selecting the color mode; and a mode selection means for sequentially switching each fluorescent lamp to emit light at a ratio of a light emission time at which each output of the photoelectric conversion element due to light emission from each fluorescent lamp becomes the same level when the color mode is selected by the mode selection means. Each lighting signal is sequentially outputted to the lighting circuit in synchronization with a fixed cycle transfer pulse, and when the monochrome mode is selected, the lighting time of each fluorescent lamp is 1/3 of each lighting time by each lighting signal during the color mode. 1. A color reading device having a monochrome mode, comprising: a light emission control means for simultaneously outputting each lighting signal having a time width of .