JPH0131340B2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field This invention arranges a plurality of optical fibers, shines light onto an image original, receives the reflected light with each optical fiber, and adjusts the amount of light received by each optical fiber. The present invention relates to an optical image reading device that reads an image recorded on an image original based on the image.

Prior Art Conventionally, this type of optical image reading device, in principle, irradiates light output from a light emitting element L to a reading point D on the surface of a document using an optical fiber T on the light emitting side, as shown in FIG. The reflected light is received by the light-receiving optical fiber R, and the photoelectric conversion element P converts the light into an electrical signal proportional to the amount of light, and then the image information at that reading point is determined by the value (level) of the electrical signal. It is for reading.

In a specific reading device, as shown in FIG. 2, a plurality of light emitting side optical fibers T1
~ Tn are arranged in a row, and each optical fiber T1
The light emitted from the light emitting elements L1 to Ln provided at the base end of ~Tn is irradiated to each reading point D1 to Dn on the front document surface, respectively, and the optical fibers are arranged in a line corresponding to the optical fibers T1 to Tn. The light-receiving side optical fibers R1 to Rn each receive the reflected light from each of the reading points D1 to Dn.
It is configured to receive the reflected light of the light irradiated to ~Dn. Then, the receiving side optical fiber R1~
The light received by Rn is transmitted to photoelectric conversion element P1,
After being converted into an electric signal proportional to the amount of light by the conversion element P1, it is amplified by the next stage amplifier A1 and output to the microcomputer M.

On the other hand, each drive control circuit C1 to Cn of each light emitting element L1 to Ln turns on a transistor 2 based on a drive control signal from a microcomputer M via a resistor 1, as shown in FIG. The light emitting diode 3 was configured to emit light.

However, if the operating characteristics of each of the light emitting elements L1 to Ln change due to changes over time, for example, each light emitting element L under the same conditions (for example, the same applied voltage)
Even if 1 to Ln are emitted, the amount of light emitted will be different. For example, when each of the reading points D1 to Dn on a document with a white background on which nothing is recorded is irradiated with each light, the reading points D1 to Dn will be different. The level of the electrical signal based on the reflected light at Dn is not the same level h1 as shown in Figure 4a, but is different from the amount of light irradiated to each reading point D1 to Dn as shown in Figure 4b. There will be variations in the level of the electrical signals, and even if the reading points D1 to Dn are under the same conditions, electrical signals of different levels will be output, making it difficult for the microcomputer M to read each reading point D1 to Dn accurately. I was having trouble reading it. Therefore, when the light output from each light emitting element L1 to Ln illuminates each corresponding reading point D1 to Dn, the same level of electrical signal is obtained if each reading point D1 to Dn is under the same conditions. As shown in Fig. 3, a variable resistor 4 is connected in series to a diode 3 as a light emitting element, and the voltage applied to each light emitting element L1 to Ln is selected by adjusting with the variable resistor 4. Ta.

However, this adjustment work requires time to be adjusted one by one, and even if the adjustment is made once, there may be changes over time in the light emitting elements L1 to Ln, photoelectric conversion element P1, or amplifier A1, or the light emitting side relative to the reading point. There was a problem that the conditions had to be adjusted again due to relative positional deviation between the optical fiber and the light-receiving optical fiber.

Purpose This invention was made to solve the above-mentioned problems, and its purpose is to control the amount of light of each light emitting element without adjusting the operating conditions of the light emitting elements one by one, so that the reading point is always the same under the same condition. The object of the present invention is to provide an optical image reading device that can perform identical reading and can read images accurately and reliably.

Embodiment Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings.

In FIG. 5, a driver shaft 11 whose both ends are supported by a frame (not shown) of an optical reading device is disposed parallel to a support drum 13 that controls the feeding of a document 12, and whose end protruding from the frame is a direct current It is drivingly connected to a motor 14, and has a spiral cam groove 15 carved on its outer peripheral surface. As shown in FIG. 6, the holder 16 has its base end movably supported by a guide shaft 17 disposed below and in front of the driver shaft 11 in parallel with the support drum 13, and its distal end rear surface. A locking piece 18 formed in the spiral cam groove 1
5 is fitted and supported. When the driver shaft 11 is rotated by the DC motor 14, the holder 16 reciprocates in the left-right direction along the guide shaft 17 based on the engagement between the spiral cam groove 15 and the locking piece 18.

An optical image reading device (hereinafter referred to as reading device) 19 is attached to the front surface of the tip of the holder 16, and its front surface is connected to the document surface 12 on the support drum 13.
It is facing a. Therefore, the reading device 19
As the holder 16 moves, images recorded on the document 12 are sequentially read in the horizontal direction.

Next, the reading device 19 will be explained with reference to FIG. It should be noted that each member disposed in the reading device 19 is the same as the member described in the conventional example, and therefore will be described below using the same reference numerals for convenience of explanation.

Inside the reading device 19, first to n-th light emitting elements L1 to Ln such as light emitting diodes as light sources are provided at the base end.
The first to n-th light emitting optical fibers T1 to Tn are arranged, and the tips thereof are arranged in order from the first light emitting optical fiber T1 in a direction perpendicular to the moving direction of the reading device 19. , and each irradiation surface thereof is inclined at approximately 60 degrees with respect to the original surface 12a, as shown in FIG. And each light emitting element L1~
The light from Ln is transmitted through each optical fiber T1 to Tn, respectively.
The light is irradiated onto the original surface 12a through the rays, and the irradiated points are defined as first to nth reading points on the original surface 12a.

The first to nth light emitting side optical fibers T1 to Tn
The first to n light-receiving optical fibers R1 to Rn provided on opposite sides of the light-receiving-side optical fibers R1 to Rn are arranged so that their tips are parallel to the tips of the light-emitting-side optical fibers T1 to Tn, starting from the first light-receiving optical fiber R1. The light receiving surface at the tip thereof is tilted at 60 degrees with respect to the irradiation surface of each of the light emitting side optical fibers T1 to Tn. The light irradiated to each of the reading points D1 to Dn becomes reflected light and is received by the corresponding first to nth light receiving side optical fibers R1 to Rn.

The base ends of the first to nth light-receiving side optical fibers R1 to Rn are respectively connected to a photoelectric conversion element P1 such as a phototransistor provided in the reading device 9, and the received reflected light is transmitted to the conversion element. do. The photoelectric conversion element P1 converts the reflected light transmitted from each light-receiving side optical fiber R1 to Rn into an electric signal proportional to the amount of light, and sends a detection signal to the central processing unit 21 (described later) via the next stage amplifier A1. Output as SG1.

A central processing unit (hereinafter referred to as CPU) 21 serving as each means operates based on a control program stored in a read-only memory (hereinafter referred to as ROM) 22, and controls the light emission operation timing of each of the light emitting elements L1 to Ln. While outputting the operation control signal to the multiplexer 23, each light emitting element L1~
A data signal (digital amount) for controlling the amount of light emitted from Ln is output to a D/A converter 24 as a digital-to-analog conversion means. The D/A converter 24 connects each light emitting element L1 to
It controls the amount of light emitted by Ln, and converts the data signal into an analog signal with a voltage proportional to the digital amount and outputs it.

Each drive control circuit C1 for each light emitting element L1 to Ln
A predetermined one is selected at each time based on the operation of the multiplexer 23 based on the operation control signal from the CPU 21, and when Cn is selected, the D/A
An analog signal output from converter 24 is input. Each drive control circuit C1 to Cn is composed of a portage follower operational amplifier 25 as shown in FIG. 8, and is proportional to the analog value of the input analog signal, that is, the digital value of the data signal output from the CPU 21 to the D/A converter 24. The voltage thus obtained is applied to a light emitting diode 27 as a light emitting element via a resistor 26. Therefore, the light emitting diode 27
That is, the amount of light emitted from each of the light emitting elements L1 to Ln increases in proportion to the applied voltage value.

The data signal input to the D/A converter 24 may be various test data stored in advance in the ROM 22 or suitable light amount data stored in a readable and rewritable memory (hereinafter referred to as RAM) 28 as a storage device. On the basis of
Output from CPU21. The test data stored in the ROM 22 is transferred to the D/A converter 24.
As shown in FIG. L1~
It is used when selecting the optimum light amount of Ln, that is, when creating appropriate light amount data for each light emitting element L1 to Ln. Further, the proper light amount data stored in the RAM 28 is stored in the number corresponding to each of the light emitting elements L1 to Ln.
In order to emit light with the optimum amount of light, the D/
This is data that determines the voltage value of the analog signal output from the A converter 24.

Further, the CPU 21 determines whether the detection signal SG1 output from the amplifier A1 is based on irradiation of light onto the background color of the document or on irradiation of light onto an image recorded on the document. When the level of the detection signal SG1 is higher than a preset reference value k, it means that no image is recorded at the reading point on the document surface 12a, and conversely, when it is lower than that, the image is recorded at the reading point on the document surface 12a. It is determined that an image is recorded at the upper reading point. Note that the reference value k is stored in advance in the ROM 22 and is read out every time a determination is made.

The working memory 29 stores read data of image information at each reading point D1 to Dn on the document surface 12a from time to time based on the detection signal SG1 output from the amplifier A1. Display device 3
0 indicates that when the CPU 21 detects that each light emitting element L1 to Ln does not emit an appropriate amount of light, the CPU 2
The number of the light emitting element that has failed is displayed based on the control signal output from 1.

Next, the operation of the reading device 19 configured as described above will be explained.

Now, the original 1 with an image recorded on the original surface 12a
2 on the support drum 13, the power switch (not shown) of the reading device 19 is turned on, and the CPU 21 starts operating according to the flowchart shown in FIG. For convenience of explanation, the number of reading points is 16, and the number of drive control circuits for that purpose is 16, and the ROM 22 is
It is assumed that 13 types of data are stored.

First, the CPU 21 uses the N
After initially setting the contents of the M register to "1" for specifying each of the 13 types of test data stored in the register and ROM 22, the DC motor 14 is driven and controlled to move the reading device 19 onto the document surface 12a. Move it so that it is located at a place with a background color where nothing is recorded.

Next, the CPU 21 outputs an operation control signal to the multiplexer 23 based on the content "1" of the N register to specify the first drive control circuit C1, and also specifies the ROM 2 based on the content "1" of the M register.
2 and outputs the data signal to the D/A converter 24. The analog signal that the D/A converter 24 outputs to the first drive control circuit C1 based on this data signal is 0 volts as shown in FIG.
The light emitting element L1 does not emit light. On the other hand, at the same time as this data signal is output, the CPU 21 receives a detection signal SG1 from the amplifier A1. At this time, the light emitting element L1
Since is not emitting light, there is no reflected light transmitted to the photoelectric conversion element P1, and as a result, the detection signal SG is output from the photoelectric conversion element P1 and amplified by the amplifier A1.
1 becomes 0 volts.

CPU21 detects the level of this detection signal SG1.
It is determined whether it matches the reference value k stored in the ROM 22. Then, the CPU 21 determines that they do not match at this point, immediately determines that the content of the M register is not "13", and then changes the content of the M register from "1" to "2".
The CPU 21 reads out the second test data stored in the ROM 22 based on the contents of "2" in the M register and outputs the data signal to the D/A converter 24. The D/A converter 24 converts the analog signal based on this new data signal into a first
The output signal is output to the drive control circuit C1. From then on, this operation is repeated until the content of the M register becomes "13" or until the level of the detection signal SG1 matches the reference value k during the process, and the analog signal is added to the content of the M register by "1". Each time the voltage is applied, the voltage value increases stepwise as shown in FIG. 9 and is applied to the light emitting element L1.

Then, as the applied analog signal increases, the amount of light emitted from the light emitting element L1 increases, and the light is irradiated via the light emitting side optical fiber L1 to the reading point D1 of the background color where nothing is recorded. Ru. Therefore, since the amount of received reflected light of the light irradiated onto the reading point D1, which is received by the light-receiving side optical fiber L1, also increases in proportion to the amount of light emitted, that is, in proportion to the analog signal, the photoelectric conversion element P1 After being converted into an electrical signal at , the level of the detection signal SG1 output from the amplifier A1 also becomes relatively large.

Then, when the level of the detection signal SG1 matches the reference value k during the process, the CPU 21 reads out the data based on the contents of the register at that time.
The test data stored in the ROM 22 is stored in the RAM 28 as appropriate light amount data for the first light emitting element L1, and the process proceeds to the next processing operation for determining appropriate light amount data for the second light emitting element L2.

On the other hand, if the output detection signal SG1 does not reach the reference value k even if all the analog signals based on the test data in the ROM 22 are applied to the first light emitting element L1, the CPU 21 determines that there is a failure. immediately displays the corresponding first
The number of the light emitting element L1 is displayed, and an alarm device (not shown) is activated to generate an alarm and perform maintenance work thereon.

The appropriate light amount data of the first light emitting element L1 is stored in the RAM
28, the CPU 21 then determines whether the content of the N register is "16", that is, whether the appropriate light amount data for all the light emitting elements L1 to L16 has been obtained, and then stores the content of the N register as "16". 2”. The CPU 21 outputs an operation control signal to the multiplexer 23 based on the content "2" of this N register, and outputs an operation control signal to the second drive control circuit C2.
is specified, and analog signals shown in FIG. 9 are again sequentially output to the second drive control circuit C2 via the D/A converter 24 based on the test data stored in the ROM 22 in the same manner as described above.

Then, the same operation as above is repeated, and the appropriate light amount data in the second light emitting element L2 is stored in the ROM2.
RAM28 was selected from each test data of 2.
is memorized. Thereafter, similarly, the 16th light emitting element L16
Appropriate light amount data is determined individually for each
It is stored in RAM28.

The appropriate light amount data for the last 16th light emitting element L16 is selected from among the test data in the ROM22.
When output to the RAM 28, the CPU 21 determines that the content of the N register is "16", that is, that it has been determined from the appropriate light amount data for all light emitting elements L1 to L16, and records it on the document surface 12a. After waiting for the ON operation of a start switch (not shown) for image reading, the operation of creating the appropriate light amount data is completed.

Therefore, for example, even if the operating characteristics of the light emitting elements L1 to Ln differ due to changes over time, analog signals based on the appropriate light amount data are sent to the corresponding drive control circuits C1 to C1 through the D/A converter 24.
C16, each light emitting element L1 to L1
The light emitted from 6 corresponds to each reading point D1 to D16.
If each reading point is under the same condition, all the reading points are converted into detection signals SG1 having the same constant level.

Then, when the start switch is turned on to start reading the image on the document surface 12a, the CPU
At step 21, the DC motor 14 is moved to move the reading device 19 onto the document surface 12a on which an image is recorded, and a reading operation is started. And the CPU
21 specifies time-divisionally from the first drive control circuit C1 to the 16th drive control circuit C16 in a predetermined order, and sequentially reduces the points of each of the light emitting elements L1 to L16. At this time, CPU21 is RAM2
8 and outputs a data signal based on the appropriate light amount to the D/A converter 24. The D/A converter 24 is connected to each light emitting element L1 to L1.
Light emitting elements L1 to L1 respectively corresponding to 6
An analog signal based on the appropriate light amount data of No. 6 is outputted to cause each of the light emitting elements L1 to L16 to emit light.

Therefore, when each reading point D1 to D16 is irradiated with light with a controlled amount of light from each light emitting element L1 to L16, if each reading point D1 to D16 is under the same condition, Since the detection signal SG1 of the same constant level is always output for both, accurate and reliable image reading can be performed within the CPU 21.

In this way, each reading point D1 to D16
Each detection signal SG1 in is output to the CPU 21, which compares the detection signal SG1 with the reference value K to determine the presence or absence of an image, converts the result into numerical values, and sequentially stores them in the working memory 29.

In this example, one light-receiving optical fiber is used for one light-emitting optical fiber, but even if there are m light-receiving optical fibers for one light-receiving fiber, the same light-emitting element can be used. On the other hand, even if m pieces of appropriate light amount data are created and the same light emitting element is driven M times based on the appropriate light amount data, image reading can be performed in the same manner as described above.

Effects As detailed above, the present invention provides a digital-to-analog conversion means for controlling the light intensity of a plurality of light sources based on input data, and sequentially changes the light emission intensity of each light source in advance. When the output from the photoelectric conversion element reaches a predetermined reference value as the light intensity of the light source changes, the digital
The light intensity of the light source is adjusted one by one by storing the data input to the analog conversion means in a storage device and using the stored data as data to be output to the digital-to-analog conversion means when reading the image on the document surface. The light amount of each light emitting element is controlled based on the data without any problem, and the same reading can be performed under the same conditions at all times at the reading point, which has an excellent effect that accurate and reliable image reading can be performed.

[Brief explanation of drawings]

Fig. 1 is a principle diagram showing the principle of image reading, Fig. 2 is an electric block circuit diagram of a conventional optical image reading device, Fig. 3 is a conventional drive control circuit diagram, and Fig. 4 a and b are from an amplifier. 5 is a plan view of an optical image reading device embodying the present invention; FIG. 6 is a side view; FIG. 7 is an electric block circuit diagram; FIG. 9 is a drive control circuit diagram, FIG. 9 is an output waveform diagram showing the output waveform of an analog signal output from the D/A converter based on test data, and FIG. 10 is a flowchart diagram showing the operation of the central processing unit. be. Optical image reading device...19, Central processing unit (CPU) as means...21, Multiplexer...23, D/A converter as digital/analog conversion means...24, Readable and rewritable as storage device Memory (RAM)...
...28, Light emitting element as a light source...L1 to Ln,
Light emitting side optical fiber...T~Tn, photoelectric conversion element...P1, reading points D1~Dn, light receiving side optical fiber...R1~Rn, amplifier...A1.

Claims (1)

[Claims] 1. A plurality of light sources L1 based on input data.
~Ln; a plurality of light emitting side optical fibers T1~Tn provided facing each of the light sources L1~Ln; and the light emitting side optical fibers T1~ A plurality of light-receiving side optical fibers R1-- which are provided opposite to Tn and for receiving light emitted from the light-emitting-side optical fibers T1-Tn and reflected from the document surface 12a.
Rn, a photoelectric conversion element P1 connected to the light-receiving side optical fibers R1 to Rn, and data input to the digital-to-analog conversion means 24 to cause each of the light sources L1 to Ln to emit light from each of the light sources L1 to Ln. means 21 for sequentially changing the amount of light emitted; detecting the output from the photoelectric conversion element P1, and detecting that the output reaches a certain reference value (k) as the amount of light from the light sources L1 to Ln changes; The data inputted to the digital-to-analog conversion means 24 at the time is transferred to the plurality of light-receiving side optical fibers R1 to
Means 2 for storing information in the storage device 28 for each Rn
1, means 21 for sequentially reading data stored in the storage device 28 and inputting the read data to the digital-to-analog conversion means 24 when reading the image on the document surface 12a; An optical image reading device comprising: