JPH01152995A - Image reader - Google Patents

Abstract

PURPOSE:To suppress vibration of a motor and to prevent noise or vibration of carrier, by exciting an electromagnetic clutch in the vicinity of a resonance frequency and connecting a suppressing means. CONSTITUTION:An instruction for connecting an electromagnetic clutch 19 is fed to the electromagnetic clutch 19 only when sub-scanning is performed in the vicinity of driving frequency with which a step motor 12 resonates. Upon connection of the electromagnetic clutch 19, vibration of the step motor 12 is converted through a damper 17A into thermal energy so as to suppress vibration. Consequently, resonance of the step motor 12 does not cause increase of vibration of carrier and the like even at resonant driving frequency.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to image entertainment fEiK, and more specifically, the present invention relates to an image entertainment system fEiK, and more specifically, a document or a photoelectric conversion element, an optical system for forming an image, a light source, etc. The present invention relates to an image reading device including a stepping motor for movement in a sub-scanning direction.

[Conventional technology]

7 and 8, a light source (2) consisting of, for example, a Japanese Patent Laid-Open No. 60-260915 light lamp is provided, and a rod lens array (1) is provided.
) is provided with a photoelectric conversion element (3).

These rod lens array (1), light source (2), and photoelectric conversion element (3) are loaded on a carrier (4)K. The document surface glass (5) is attached to the main body (6) of the apparatus at a constant distance from the rod lens array (1). A sliding bearing (7) provided at one end of the carrier (4) is slidably attached to a shaft (8) fixed to the reader main body (6) parallel to the document surface glass (5). As a result, the carrier (4) is positioned in the main scanning direction and supported so as to be movable in the sub-scanning direction. A wheel (9) is rotatably attached to the other end of the carrier (4), and the wheel (9) rests on a rail (10) fixed to the reader body (6) in parallel with the document surface glass (5). In particular, the carrier (4) is positioned in the vertical direction. The electric circuit section (11) includes a light source (2), a circuit for driving the photoelectric conversion element (3), etc., and is fixed to the carrier (4). The stepping motor (12) is attached to the mounting stay (13)
is fixed to the reading device main body (6). motor(
The pulley (14a) and pulley (12) attached to the shaft of
4b) A belt (15) is stretched between them.

A part of the belt (15) is connected to the carrier (4). The original (16) is placed on the original glass (5) when reading the image.
) with the reading side facing the glass.

With the above configuration, when reading an image, the light source drive circuit (not particularly shown) in the electric circuit (11) is activated by an instruction from the outside.
The light source (2) is turned on to illuminate the original (16) on the original glass (5). The reflected light from the original (16) is
The rod lens array (1) illuminates the photoelectric conversion element (3) at the same magnification. The photoelectric conversion element (3) is connected to the electric circuit (1
1) is driven by a drive circuit (not particularly shown) in the main scanning direction, and sequentially converts reflected light into electrical signals in the main scanning direction. By simultaneously rotating the stepping motor (12), the power is applied to the pulley (14a).

(14b), is transmitted to the carrier (4) via the belt (15), and the sliding bearing provided in the carrier (4) is connected to the part (14b).
5) and the shaft (8) fixed to the apparatus main body (6) slide, and the carrier (4) moves in the sub-scanning direction. Moreover, one end of the carrier (4) has wheels (9) and rails (
Since the shaft (8) and rail (10) are fixed parallel to the original glass (5), the carrier (4) is supported by the original (1o) on the original glass (5).
16) Always move at a constant distance. In this way, by moving the carrier (4) in the sub-scanning direction and sequentially reading the document (1
6) The image (not shown) is converted into an electrical signal and sent to the outside as a read image signal.

[Problem that the invention seeks to solve]

The vibration characteristics of the stepping motor (12) in the conventional image reading device as described above and the associated carrier (4)
) will be explained with reference to FIGS. 9 and 10. FIG. 9 shows the vibration characteristics of the stepping motor (12), where the horizontal axis is the drive frequency and the vertical axis is the vibration component voltage representing the magnitude of motor vibration. Figure 10 shows the carrier (
4) shows the vibration state in the sub-scanning direction, the horizontal axis is the driving frequency of the stepping motor (12), and the vertical axis is the carrier (4).
is the absolute value of the imaging acceleration.

Because the stepping motor (12) has a natural frequency in its rotating system due to its structure, a resonance phenomenon occurs at a specific drive frequency, as shown in FIG. As a result,
The motor is photographed by the reader body (6), shaft (8),
Since the vibration is transmitted through the belt (15) and the like and excites the carrier (4), the carrier (4) vibrates greatly at a specific driving frequency, as shown in Fig. 1θ.

From the above, when performing sub-scanning at a driving frequency that causes resonance in the stepping motor (12), K, the motor (12)
) and the carrier (4), which causes noise and deteriorates the quality of the read image. In order to obtain a signal, there are problems such as the fact that sub-scanning driving cannot be performed at the driving frequency at which the stepping motor (12) causes resonance.

This invention was made to solve the above-mentioned problems, and provides an image reading device that can suppress the resonance of the stepping motor when sub-scanning is performed near the drive frequency where the stepping motor causes resonance. The purpose is to obtain.

[Means for solving problems]

The image reading device according to the present invention quickly connects a shaft equipped with a damping means to the shaft of a stepping motor via an electromagnetic clutch, and performs sub-scanning near the same driving wave number where the stepping motor causes resonance. Only a control circuit is provided to connect the electromagnetic clutch.

[For production]

In this invention, when the stepping motor is installed at a drive frequency that causes random vibration, the electromagnetic clutch is connected by the control circuit and the shaft of the stepping motor is directly connected to the vibration damping means, so the vibration generated by the stepping motor is damped. be done.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In Figures 1 and 2, carrier (4)
A pair of sliding bearings provided at both ends of the slider (7) are slidably mounted on a shaft (8) fixed to the reader body (6) in parallel with the document surface glass (5). The carrier (4) is positioned in the main scanning direction and in the vertical direction, and is supported so as to be movable in the sub-scanning direction. The double-shaft type stepping motor (12) is attached to the mounting stay (13).
) is fixed to the reader main body (6). A pulley (14a) attached to the shaft (12b) of the motor (12)
) and the pulley (14b), a belt (15) is stretched between the belt (15) and the pulley (14b).

Damper (17) that converts vibration energy into thermal energy
A) constitutes a damping means, and is a shirt) (1B)
A damper (17A) is attached to the.

The ti clutch (19) connects and disconnects between the motor shaft (12b) and the shaft (18) based on a command from a control circuit (not shown).

In addition, the same reference numerals as in FIG. 7 indicate the same parts.

With the above configuration, the image of the document (16) is converted into an electrical signal and the read image signal is sent to the outside by performing thread removal by repeatedly moving the carrier (4) in the sub-scanning direction and repeating the process in the main scanning direction K11l. However, in this embodiment, a control circuit (not shown) activates the electromagnetic clutch only when sub-scanning is performed near the driving frequency at which the stepping motor (12) causes resonance. (19) is sent to the electromagnetic clutch (19). When the electromagnetic clutch (19) is connected, the vibration of the stepping motor (12) is converted into thermal energy by the damper (17A) and damped.

Therefore, even at the driving frequency W, the vibration of the carrier (4) etc. does not increase due to the resonance of the stepping motor (12). Also, at frequencies other than around the driving frequency where the stepping motor (12) causes resonance, the control circuit The electromagnetic clutch (19) is disconnected, and the motor shaft (xzb) and damper (1
7A)) (18) is disconnected, so there is no increase in the inertial load on the stepping motor (12).

FIG. 3 shows carrier vibration characteristics in the above example.

In Figure 3, as in Figure 10, the horizontal axis is the stepping motor (
12), the driving frequency, the vertical axis is the absolute value of the vibration acceleration of the carrier (4), and it can be seen that the vibration of the carrier (4) is significantly reduced compared to the conventional one.

FIG. 4 shows another embodiment, in which a flywheel (17B) is provided as a vibration damping means.

The other configurations are the same as shown in FIGS. 1 and 2.

With the above configuration, the control circuit (not shown) issues a command to connect the electromagnetic clutch (19) only when sub-scanning is performed near the drive frequency where the stepping motor (12) causes resonance. Send. When the electromagnetic clutch (19) is connected, the stepping motor (
The flywheel (17B) is directly connected to 12).

FIG. 5 shows the vibration characteristics of the stepping motor when the flywheel (17B) is coupled to the stepping motor (12). Due to the increase in rotor inertia of the stepping motor (12) due to the addition of the flywheel (17B), the resonant frequency is lowered overall. As a result, when sub-scanning feed of the carrier (4) is performed near the driving frequency at which the stepping motor (12) causes resonance, the resonant frequency decreases due to an increase in the rotor inertia of the stepping motor (12). ) does not cause resonance.

In addition, the electromagnetic clutch (19) is released by the control circuit at frequencies other than the drive frequency at which the stepping motor (12) causes resonance, and the resonant frequency range of the motor @ (12b) and the shaft to which the flywheel (17B) is attached is There is no change in , and no resonance occurs as before.

As shown in FIG. 6, the vibration of the electromagnetic clutch stepping motor (12) is significantly reduced by the above control circuit compared to the conventional one.

In the above embodiment, the carrier (4) is provided with slide bearing portions (7) at both ends, and is slidably supported by two shafts (8). , a wheel and rail support is used, with a pulley (14a) on one shaft and a tire on the other shaft.
Although the clutch (19) is shown attached, the pulley and clutch may be attached to only one shaft and connected to the shaft (18) to which the damping means is attached.

Furthermore, in the above embodiment, the pulley (14a), (t4b
) Bell) (15"l is shown installed at one end of the carrier (4), but it can be installed on both sides of the carrier (4) and both ends of the carrier (4) are connected to the belt. Good too.

Further, in the above embodiment, two fluorescent lamps are used as the light source, but a light source such as an LED array may be used, and the number is not particularly limited to two.

Furthermore, in the above embodiment, the case of an image reading device that uses a contact type image sensor, which is a 1-magnification optical system, for a stationary document is explained. A shape image reading device may also be used, and the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, a shaft equipped with a damping means such as a damper or a flywheel is connected to the shaft of a stepping motor via an electromagnetic clutch, and the shaft is connected to the shaft of a stepping motor at a frequency near the driving frequency at which the stepping motor resonates. A control circuit is provided that connects the electromagnetic clutch only when performing sub-scanning, so when sub-scanning feed is performed near the drive frequency where the stepping motor resonates, motor vibration is suppressed by the damping means. , the generation of noise,
The quality of the read image signal does not deteriorate due to carrier vibration. In addition, at drive frequencies other than those listed above, the connection between the damping means and the motor shaft is disconnected, and there is no increase in the inertial load on the stepping motor, so the motor drive current does not need to be increased. There is.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a main part of an embodiment of the present invention, Fig. 2 is a partial plan view of the one shown in Fig. 1, Fig. 3 is a carrier vibration characteristic diagram of the one shown in Fig. 1, and Fig. 4 is another diagram. A partial plan view of an embodiment of
5 and 6 are motor vibration characteristic diagrams of the one shown in FIG. 4, FIG. 7 is a perspective view of main parts of a conventional image reading device, and FIG. 8 is a partial side sectional view of the one shown in FIG. 7, 9 is a motor vibration characteristic diagram of the one shown in FIG. 7, and FIG. 10 is a carrier vibration characteristic diagram of the one shown in FIG. 7. (1)...Rod V array (optical system), (2) -
-Light source, (3)...Photoelectric conversion element, (12)...Stepping motor, (12b) motor shaft, (17A)...
・Damper, (17B)・Flywheel, (19)・
・Electromagnetic clutch. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Teru Wa Do -1-(N
('l N(■ 一ト一飄y r−1n -１１１１１〉 Ki↑97 width giant Lu force (IGI
) Root i”l Ashin Electric Works (V) Top!fl Bottom Voltage (V) □ Tatami Gravity Minute 1i 10,000'F- (V) □ Kiyari 7 Handling 1 Power (IGI ”)

Claims (3)

[Claims] (1) A light source that illuminates the original, a photoelectric conversion element that converts light into an electrical signal, an optical system that forms an image of light from the original surface onto the photoelectric conversion element, and a light source that illuminates the original and the photoelectric conversion element. an image reading device including one of the optical system and a stepping motor for moving the light source in the sub-scanning direction; An image reading device comprising: a control circuit that connects the electromagnetic clutch only when sub-scanning is performed near a drive frequency at which the stepping motor causes resonance. (2) The image reading device according to claim 1, wherein the vibration damping means is a damper that converts vibration energy into thermal energy. (3) The image reading device according to claim 1, wherein the vibration damping means is a flywheel that lowers the resonance frequency of the stepping motor.