JPH04142865A - Image reading device - 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 [Field of Industrial Application] The present invention relates to an image reading device such as a facsimile or an image scanner.

[Prior Art] Conventionally, in an image reading device using a rod-shaped light source such as a fluorescent lamp, in order to stabilize the light intensity level and light distribution of the light source, the light source is kept in standby for a certain period of time before starting to read an original. After the light source is turned on or the light intensity level of the light source is detected and it is confirmed that the light intensity of the light source reaches a certain level, reading is started.

[Problem to be solved by the invention] However, in a document reading device that preliminarily lights up the light source for a certain period of time before starting to read a document, the light source preliminarily turns on for a certain period of time before starting to read the document. Even if the ambient temperature is high and the light intensity of the light source does not take that long to stabilize, the user may have to wait longer than necessary to start reading. It will become.

In addition, for image reading devices that detect the light intensity level of the light source and start reading after the light intensity reaches a certain level, it is possible to start reading immediately without placing emphasis on the gradation reproducibility of the output image information. However, reading does not start until the amount of light from the light source reaches the set light amount level, resulting in a disadvantage that the time required to read the original image becomes longer.

[Means for Solving the Problems] The present invention has been made in view of the following points. In the case of simple binary image reading that does not emphasize gradation reproducibility, the preliminary lighting time of the light source is short, and in the case of multi-value image reading that emphasizes gradation reproducibility, the light intensity of the light source is stabilized. It is possible to give instructions from an external device, such as starting reading after a sufficient pre-light source lighting time has elapsed.

[Embodiment] FIG. 1 shows a configuration example of an image reading device to which the present invention is applied.

In FIG. 1, 1 is the main body of the image reading device.

The original 18 is placed face down on the platen glass 17J, illuminated by the fluorescent lamp 15a in the original illumination unit 15, and illuminated by the lens 14 via the reflective mirror 16.
It is configured to form an image of a document on a CCD (charge coupled device) 12 and read it. 13 is a CC-D driver, and 11 is a control unit which will be described later. 19 is
This is a platen cover for bringing the document 18 into close contact with the platen glass 17. The original illumination unit 15 and the mirror 16 are reciprocated at a speed of 2:1 by a pulse motor (not shown).

The original 18 is placed on the platen glass 17 in FIG. 1 so that the right end is the leading edge of the original. Further, the original illumination unit 15 is configured such that the right end in FIG. 1 is the initial position, and the position can be confirmed by a sensor (not shown). FIG. 2 shows a block diagram of the image reading device. To explain according to this diagram, 12 is a CCD that reads images.
21 is an amplifier for amplifying the CCD image analog signal; 22 is an A/D converter that digitizes the analog signal from the CCD; 24 is shading of the image signal digitized by the A/D converter; A shape ink correction circuit performs correction; 27 is a CPU that controls the device; 28 is a timing generation circuit for the CCD and other circuits; 25 is a binarization circuit for binarizing the image signal; The configuration allows for binarization, etc.

Reference numeral 30 is a signal line for giving instructions to the image reading device from the outside, and information from the image reading device to the outside is also transmitted through this signal line.

That is, this signal line is bidirectional, and its direction is determined according to instructions from an external device.

Further, a command for setting the preliminary lighting time of the fluorescent lamp is transmitted from an external device to the main image reading device through the signal line, and the main image reading device transmits the command to the CPU 27 via the interface circuit 26. The fluorescent lamp preliminary lighting time is controlled by the CPU 27 controlling the fluorescent lamp lighting circuit 31 (shown in the third diagram) using a lamp control signal.

The image reading device of this embodiment is used by being connected to an external device (for example, a personal computer) not shown, and commands from these external devices and image data from the image reading device are transmitted and received through an interface circuit. 2
It is configured to be carried out through 6.

FIG. 5 is a flowchart showing the control procedure of the CPU 27, and FIG. 4 is a timing chart regarding lighting of the fluorescent lamp. Note that the signal PH is a fluorescent lamp preheating signal,
The signal ON is a fluorescent lamp lighting signal.

The operation will be explained according to the operation flowchart shown in FIG.

After the initialization operation after turning on the power (Sl), the image reading device l
Prior to the operation, various commands are input from an external device (S2). For example, set the pixel density to 300.150°7
Which of the 50 DPI is selected is a setting command for transmitting the image data format, ie, binary or multi-value mode, and a setting command for the preliminary lighting time of the light source prior to the start of document reading.

Upon receiving these commands, the CPU 27 makes the necessary settings in advance to the tanning signal generation circuit 28, the binarization circuit 25, etc., and also updates the set values such as the preliminary lighting time t of the fluorescent lamp (SIO ).

When a reading start command is input from an external device (S
3) The fluorescent lamp preheating signal PH is set to L level, and it is checked whether the lighting unit 15 is at the home position (S4), and if it is not at the home position, the pulse motor is controlled to move it to the home position. .

The home position referred to here means that the lighting unit 1 is moved all at once in the opposite direction to the direction of arrow A in Figure 1.
5, and whether or not the lighting unit 15 is at the home position is detected by a sensor (not shown).

Next, set the fluorescent lamp lighting signal ON to L level, and set the fluorescent lamp 15
a is turned on (S5), and the lamp waits for the fluorescent lamp pre-lighting time t set at this point to stabilize the light amount (S6).
).

After a period of time has elapsed, reading operation begins (S7) and scanning begins in the direction of arrow A shown in FIG. The distance from the initial position of the original illumination unit 15 to the leading edge of the original on the platen glass 17'' is about 2+++n+ to 3+nm, and during this time the scanning speed of the mirror is controlled to be stable by a pulse motor (not shown). Then, when the original illumination unit 15 reaches the leading edge of the original, the CPU 27 issues permission to output image signals to the interface circuit 26, and the read image signals are sequentially sent to an external device.

The scanning length of the optical system is determined by the CPU 27 or the number of pulses driving the pulse motor.
7 determines that the document reading is finished when the necessary number of pulses are output to the motor (S8), and turns off the fluorescent lamp 15a.
outputting an image output disable signal to the interface circuit 26;
Controls such as motor reversal are performed, and the end of image reading is sent to the external device (S9).

As a result, the document illumination unit 15 is controlled in the direction opposite to the arrow A in FIG.
When it is confirmed that the motor has returned to the home position, the motor stops. If the next reading command is not received from the external device while the optical system returns, the optical system stops at the initial position and the operation ends.

[Effects of the Invention] As explained above, according to the present invention, when reading is desired in a short time, the preliminary lighting time of the light source is shortened, and when reading with good gradation reproducibility is desired, the preliminary lighting time is shortened. You can easily set the settings according to the desired image quality level of the output image you are trying to obtain from an external device, such as a long time, and by eliminating unnecessary pre-lighting time, you can easily set the setting according to the image quality level desired for the output image you are trying to obtain from an external device. This has the effect of being able to perform reading.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of an image reading device to which the present invention is applied. FIG. 2 is a block diagram of an image reading device according to the present invention. FIG. 3 is a block diagram of a fluorescent lamp lighting circuit. Figure 5 shows the operating timing chart of fluorescent lamps.
PU control flowchart, l... Original reading device 11... Control unit 12... CCD 15... Original illumination unit 15a... Fluorescent lamp 26... Interface circuit 27... CPU I 1≦↓ 1 to 1≦

Claims (1)

[Scope of Claims] A bar-shaped light source that illuminates a document to be read; a photoelectric conversion element array arranged in a line; and a light output from the light source reflected from the surface of the document onto the photoelectric conversion element array. What is claimed is: 1. An image reading device comprising: a lens system for forming an image; the light source is preliminarily lit prior to the start of reading the document; and the preliminary lighting time can be set in two or more ways.