JPH04199969A - Image reader - Google Patents

Abstract

PURPOSE:To prevent the color fading at the time color original reading by comparing the read images by plural light emitting diode arrays which vary in light emission frequency and selectively controlling the lighting points of the light emitting diode arrays. CONSTITUTION:This device has the plural light emitting diode arrays 23a, 23b which vary in light emission frequency, a comparing means 207 which radiates the respective light emitting diode arrays 23a, 23b and compares the read images, a detecting means 22 which detects the color fading components obtd. by the comparing means 207, a memory means 206b which stores the color fading components, and a lighting control means 211 which controls the lighting points of the light emitting diode arrays 23a, 23b in accordance with the color fading components obtd. from the memory means 206b. The color fading components are known by comparing the read images by the plural light emitting diode arrays 23a, 23b which vary in light emission frequency and the lighting points of the light emitting diode arrays 23a, 23b are controlled in accordance therewith. The color fading at the time of the reading of color originals is prevented in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device having a light emitting diode array as a light source.

[Conventional technology]

In an image reading device having a conventional close-contact image sensor, when a light-emitting tie auto array is used as a light source, the light emission distribution of the light-emitting tie auto array or the monochromatic light as shown in Fig. Reading the color may cause discoloration. To prevent this, conventionally, yellow or orange light emitting diode arrays with intermediate emission distribution characteristics have been used.

[Invention or problem to be solved]

However, as long as a light emitting diode array is used as a light source, the emission distribution is very narrow as shown in Figure 5.
Conventional image reading devices cannot avoid color fading when reading color originals.

The present invention has been made to solve these conventional problems, and it is an object of the present invention to provide an image reading device that can prevent color fading when reading a color document.

[Means to solve the problem]

The image reading device provided by the present invention includes a device that irradiates a document with a light emitting diode array and reads the reflected light using a photoelectric conversion element. a comparison means for comparing images read by irradiating with a light source, a detection means for detecting a fading component obtained by the comparison means, a storage means for storing the fading component, and a method for detecting a fading component obtained from the storage means. The light-emitting device also includes lighting control means for controlling lighting locations of the light-emitting tie auto array.

[Effect]

This image reading device learns the fading components by comparing images read by multiple light emitting tie auto arrays with different light emission frequencies, and based on this, controls the lighting locations of the light emitting tie auto arrays to detect color originals. This helps prevent color fading during reading.

〔Example〕

The present invention will be explained in detail below.

FIG. 1 is a sectional view showing an image reading device according to an embodiment. This image reading device 1 includes a contact type image sensor 3, a document leading edge detection sensor 7, and one of the image sensors 3 in a body 2.
It has a reading roller 5 which is placed on the side and presses the sheet original 4 against the sensor 3, and a sheet original discharge device 6 which is arranged downstream of the image sensor 3.

In the image sensor 3, 21 is a lot lens array, 22 is a sensor, 23a is a green LED array, 23b
is a red LED array.

The sheet document discharge device 6 includes a sheet discharge roller 9 that constitutes an inner guide surface of the reversing path 12, and a flexible clamping plate that presses the sheet document 4 against the sheet discharge roller 9 and holds it therebetween. 10.

11. 13 is a paper discharge port provided in the machine body 2, 8 is a paper feed section, and ■ is a reading section.

FIG. 2 is a block diagram showing the electrical configuration of the image reading device according to the embodiment. This image reading device is always connected to an external device 209 (a digital printer, a personal computer, etc.), and the interface circuit 210 is used to send and receive control signals to and from the external device 209 and to output images to the external device 209. It is done through.

The CPU 207 outputs a control signal to the timing signal generation circuit 208 in advance to perform initial settings. In this state, when a document reading start command is input from the external device 209, the original sheet M4 is conveyed from upstream, held between the reading roller 5 and the image sensor 3, and conveyed to the discharge roller 9.

At this time, the image analog signal read by the sensor 22 on the image sensor 3 is compared and amplified by the amplifier 202 and input to the A/D converter 203.

The A/D converter 203 converts the image signal into an 8-hit digital signal. This digital signal is subjected to image processing in the binarization circuit 205, and either the binarization mode or the multi-value mode is selected, and the image data of the first read is stored in RAMa.
206a. The CPU 207 compares the stiffness with the image data of the second reading, and stores the fading components in RAMb.
206b and transferred to the external device 209 through the interface circuit 210. 211 is an LED array 23a under the CPU 207.

This is a light source lighting control circuit that controls lighting of the light source 23b. Third
The figure shows an example of the light source lighting control circuit.

In the figure, 101 is a decoder circuit, 102 is a port circuit, and 10
3 is a latch circuit, and 104 is a resistor array.

Next, the operation will be explained with reference to FIGS. 1 to 4.

First, it is determined whether the sheet original 4 is full color or not, and settings are made from the external device 209 accordingly. If it is full color (step 1), CPU20 according to the settings
7 sets data in the port circuit 102 via the decoder circuit 101 so that only all the green LED arrays 23a are lit. After lighting the green LED array 23a, a first reading of the sheet original 4 is performed (step 2), and multivalued image data is stored in the RAMa 206a (step 3).

Next, after the first reading is completed, the user sets the sheet document 4 again in the paper feed section 8 (FIG. 1), and the document leading edge detection sensor 7
When the seat ring M44 is detected, the CPU 207 sets data in the port circuit 102 so as to light only the red LED array 23b, and lights the red LED array 23b. When the leading edge of the document is sent to the reading section V (FIG. 1), second reading is started (step 4). When you start reading,
For each line, read data when only the green LED array 23a is lit is read out from the RAMa 206a (step 5). Then, the logical sum (G+R) of the image data of each address of one main scanning line and the image data read with only the red LED array 23b lit is taken (step 6), and if the logical sum is "true", it is white data. to black data,
If it is “false”, leave it as white data in RAM2.
Rewrite the contents of 06 (step 7). At the same time, R.A.
The green LED array 23a and the red LED are attached to M206b.
The operation 10.R is performed on both image data in the array 23b, and if it is "true", rlJ is written, and if it is "false", "o" is written (step 8).

Next, if the number of scans is one according to the initial setting, the external device 209 is caused to perform the transfer via the interface circuit 210. If the number of scans is multiple, RAMa206
Based on the contents of a, the CPU 207 controls the light source lighting control circuit for each line so that the main scanning address "0" part lights up the green LED array 23a and the "1" part lights up the red LED array 23b. Reading is performed before data is set in the boat circuit 102 in 211, and thereafter, by repeating the scanning until the set number of scans is exhausted, it is possible to perform reading without fading (steps 9 to 12).

Further, if the seat ring M4 is not in full color (step 1), the external device 209 is set depending on whether it is in a single green color (step 13). The CPU 207 is
Based on the stiffness, if the seat ring M44 is a single green color, the red LED array 23b is turned on, and if not, the green LED array 23a is turned on and read (step 14.15). To prevent image information from being bleached and to read with good resolution.

In the above embodiment, two types of light-emitting tie auto arrays with different light emission frequencies were used, but fading can also be eliminated by using a plurality of light-emitting tie auto arrays with different light emission frequencies using the same reading method.

In addition, for originals containing a mixture of color and monochrome,
If the reading range is set from an external device, it is possible to read with good resolution in the monochrome original reading range by using a light source with a high emission center energy key such as a green LED array, and in the color original reading range, By using multiple light sources, it is possible to read documents faithfully to the original by preventing color fading.

[Effects of the Invention] As explained above, according to the present invention, in an image reading device having a light emitting diode array with a narrow emission spectrum as a light source, images read by a plurality of light emitting diode arrays having different emission frequencies can be compared. So, I decided to selectively control the lighting locations of the light-emitting tie auto array.
It is possible to prevent color fading when reading color originals.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the mechanical configuration of an image reading device according to an embodiment of the present invention, FIG. 2 is a block diagram showing an electric circuit of the image reading device shown in FIG. 1, and FIG. FIG. 4 is a block diagram of a light source lighting control circuit, FIG. 4 is a flowchart showing the operation of the image reading device of the embodiment, and FIG. 5 is a diagram showing the emission spectrum characteristics of the light emitting diode array. 1... Image reading device 3... Image sensor 4... Sheet original 5... Reading roller 6... Original ejection device 7... ...Document leading edge detection sensor 21-...Lot lens array 22...
・Sensor 23 a -==-Green LED array 23 b--・
-・Red LED array

Claims (1)

[Claims] An image reading device that illuminates a document with a light emitting diode array and reads the reflected light using a photoelectric conversion element, and compares images read by illuminating each light emitting diode array with multiple light emitting diode arrays with different emission frequencies. a comparison means, a detection means for detecting a fading component obtained by the comparison means, a storage means for storing the fading component, and a lighting point of the light emitting diode array based on the fading component obtained from the storage means. An image reading device comprising a lighting control means for controlling lighting.