JPS62171266A - Color reading method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a color document reading device that uses multiple types of color separation filters and one line image sensor.
A control information table storing N product times and desired reference output levels is provided corresponding to the color separation filters, and a specific pixel on the reference white plate is read for each color separation filter according to the storage time to determine the output level of the line image sensor. is compared with the reference output level, and if the two do not match, the accumulation time is updated, and the comparison/update operation is repeated until the two match, thereby setting a desirable accumulation time for each color separation filter; Thereafter, the color original is read using the set storage time.

[Industrial application field]

The present invention relates to a color reading system using only one line image sensor, which is used as an image input device for facsimiles and electronic computers.

[Conventional technology]

The conventional color reading circuit has three
line image sensors 4a, 4b.

4c, the color original 1 was read for each color.

That is, the reflected light from the color original 1 illuminated by the white fluorescent lamp 2 is separated into colors (for example, R, G).

B) The light enters line image sensors 4a, 4b, 4c through filters 3a, 3b, 3c. The outputs of the line image sensors are input to amplifiers 5a, 5b, and 5c whose gains can be adjusted independently. The amplified three-color image signals are sent to an AD converter 6a.

The digital image signals inputted to 6b and 6c, AD converted and quantized here are connected to an external interface circuit.

The color reading method using image sensors 3a, 3b, and 3c reads three colors simultaneously, so high-speed reading is possible.
A color reading device using a prisoner's image sensor,
There are differences in characteristics between individual fluorescent lamps and filters, and this is absorbed by finely adjusting the gain of each amplifier circuit.
Alignment of three image sensors (main and sub-scanning directions)
This is not necessarily easy, and requires a reading circuit for each color, resulting in a complicated circuit configuration.

In order to overcome these drawbacks and make positioning easier, a color reading method has been proposed in which a single image sensor is used, lighting or color separation filters are sequentially driven, and colors are read in chronological order. , actually used.

[Problem that the invention seeks to solve]

However, with the reading method described above, only one set of reading circuits is required and costs can be reduced, but on the other hand, differences in characteristics between individual fluorescent lamps and filters immediately result in differences in characteristics between devices, so there is a problem in how to absorb them. It becomes.

Therefore, the present invention is a means for solving the C problem between fluorescent lamps and filters.] Fig. 1 is a diagram showing the configuration of the present invention, and 21 is a reference white plate;
22 is a control section, and 27 is a drive control section for the line image sensor 4. The control unit 22 is provided with a control main unit 23 that controls the entire system and a control information table 26. The control information table 26 includes a reference output level 24 and an accumulation time 2.
5 is stored.

The reference output level 24 is a desirable output level Lo.
is stored in advance.

Further, the accumulation time 25 is recorded corresponding to each color separation filter 3 used. The figure shows R (red), G
This is an example of using three types of color separation filters 3: (green) and B (blue), and in this case, as shown in FIG.
, G, B, respectively, the accumulation times Tr, Tg, Tb
Record it.

When reading a color original, before actual reading, the reference white plate 21 is read instead of the original to be read using each of the color separation filters R, G, and B.

For example, if color separation filters are used in the order of R, G, and B, first the color separation filter R is driven, and an image of a specific pixel of the reference white plate 21 is formed on the line image sensor 4 via this. On the other hand, the main control section 23 reads out the accumulation time Tr for the color separation filter R from the control information table 26 and sets it in the drive control section 27 . The drive control section 27 drives the line image sensor 4 during the accumulation time Tr.

The line image sensor 4 outputs an output signal with a level corresponding to the amount of charge accumulated between the TrOs, and sends it to the temporary storage section 29.

The control main unit 23 compares this L with the reference output level 24 Lo stored in the control information table 26, and if L is smaller, updates the storage time Tr to a larger value, and if larger, updates the accumulation time Tr to a smaller value. The above-mentioned operation is then performed again using this updated value.

This comparison/update operation is repeated until the output level L decreases and matches.

Next, by performing the above series of operations for each color separation filter 3, an accumulation time at which the output level matches Lo is set for each color separation filter 3 in the control information table 26.

By the above-described operation, the output level difference between the color separation filters 3 is corrected, and a color original is read.

[For production]

As described above, the present invention sets the accumulation time for each color separation filter so as to obtain the desired output levels I, o, so that output level differences not only within one device but also between devices can be corrected. .

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

As described above, the control information table 26 stores the reference output level 24 and the accumulation time 25. As a recording medium for such control information, it is convenient to use, for example, a RAM.

For the medium accumulation time, as shown in FIG. 2, columns are provided for color separation filter category 30 and accumulation time 25, and the accumulation time is recorded corresponding to each of the color separation filters 3 to be used. In the figure, three types of color separation filters 3, R, G, and H, are used, and the corresponding accumulation times are Tr, Tg,
The state in which Tb is stored is shown.

The color separation filter 3 is not limited to the above three types, and for example, a combination of W (white), Y (yellow), and R (red) can be used, and various selections can be made.

The drive control section 27 can be configured with a timer 31 and a sensor drive circuit 10, as shown in FIG. When the color separation filter 3 to be used is R, the timer 31 receives an accumulation time T'' corresponding to R, and sends a timing clock to the sensor drive circuit 10 for controlling the accumulation time according to the set Tr. The line image sensor 4 is driven by the sensor drive circuit and sends its output to the output temporary storage section 29 in accordance with the timing clock.

The control main unit 23 can be configured by, for example, a microprocessor and a memory storing a program for controlling the operation of the color reading device. Since this configuration is common, there is no need to describe it in detail.

The output temporary storage section 29 only needs to temporarily hold the output of the line image sensor 4, and can be configured using a register, for example.

With the above configuration, the accumulation time prior to document reading can be set for each color separation filter.

When reading a document, the accumulation time set as described above is read out in accordance with the color separation filter at the time of reading, and the document is read based on this value.

Therefore, it is possible to correct variations in characteristics among the nine color separation filters for fluorescent lamps. However, as is clear from the above explanation, the hardware and software used in this example are quite simple, and the reference output level and accumulation time can be changed arbitrarily, so it is possible to create color separations different from those at the time of design. Even if it becomes necessary to use a color reading device, the storage time can be adjusted without changing the hardware, and there is also the effect that the practical flexibility of the color reading device is increased.

〔Effect of the invention〕

According to the present invention, even in a color reading device using one line image sensor, variations in characteristics between individual fluorescent lamps and filters can be absorbed with simple hardware and software. Furthermore, since software is used, it is possible to flexibly deal with cases such as using color separation filters different from those used at the time of design.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the configuration of the present invention, FIGS. 2 and 3 are diagrams for explaining the configuration of one embodiment of the present embodiment, and FIG. 4 is a diagram showing a conventional configuration. In the figure, 1 is a color original, 2 is a fluorescent light, 3 is a filter for color separation, 4 is a line image sensor, 10 is a sensor drive circuit, 21 is a reference white plate, 22 is a control unit, 23
is the control main unit, 24 is the reference output level, 25 is the accumulation time,
26 is a control table, 27 is a drive control unit, 28 is an output level, 29 is an output temporary memory 1.0 part, 31 is a timer, R,
G and B indicate the types of color separation filters. ntlt D month 4 kidneys t49gm Wk 1 Figures 3o, 3b, 3c:f-zu>I'J? 7 (fly 7
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Claims (1)

[Scope of Claims] It has a plurality of types of color separation filters (3) and one line image sensor (4), and the luminous flux color-separated by the plurality of types of color separation filters (3) is transmitted to the line. In a color reading device that reads a document by entering an image sensor (4), the reference output level (2) of the line image sensor (4) is
4) and a control information table (26) for recording the accumulation time (25) of the line image sensor corresponding to each of the color separation filters (3);
2), and a drive control unit that drives the line image sensor (4) based on the accumulation time (25) instructed from 2), and sequentially drives the color separation filter (3) prior to reading the document, and The control unit (22) refers to the control information table (26) and instructs the accumulation time (25) corresponding to the driven color separation filter (3), and the drive control unit (27) The line image sensor (4) is driven to read specific pixels on the reference white plate (21), and the control section (22) adjusts the output (28) of the line image sensor (4) to the reference output level (24).
), and if the two do not match, the accumulation time (25
), and the comparison/update operation is performed so that the output level of the line image sensor (4) is the reference output level (24).
The color reading method is characterized in that the output of the line image sensor (4) for each of the color separation filters is made to be at substantially the same level until they match, and then the document is read.