JPH0786645B2 - Image reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to an image reading apparatus that uses a pulse motor as a drive source and runs an optical system to read an original image. The present invention relates to a fixing means for a motor unit, which is composed of

"Prior Art" Conventionally, the construction of a motor unit for driving a traveling optical system in an image reading apparatus and its attachment to the apparatus are configured as shown in FIG. That is, the pulse motor 1 is the motor mounting plate 2
The motor mounting plate 2 is supported by the motor support plate (1) 4 by the elastic body fastening member 3 (trade name: QUITITE). The motor support plate (1) 4 is further coupled to the motor support plate (2) 5 and the motor support plate (3) 6 by the elastic body fastening member 3. Gear shafts 7, 8 and 9 are swaged to the motor support plate (2) 5, and gears 10 and 11 and a two-stage gear 12 are rotatably held in mesh with each other. Pulse motor 1
A timing pulley 13 is fixed to the motor shaft 1a, and a timing belt 14 is hung between the timing pulley 13 and the timing pulley 10a provided integrally with the gear 10. The motor unit M having the above-described structure is a gear gap ensuring member 16 fitted to the optical drive shaft 15 and the gear shaft 9 which are rotatably fixed to the apparatus.
And holes formed in the bosses 17, 18, 19 formed on the motor unit mounting surface of the machine frame 40 (see FIG. 3) and the motor support plate (2) 5 and the motor support plate (3) 6. The motor support plate (2) 5 and the motor support plate (3) are positioned by fitting.
6 is mounted on the motor unit mounting surface by directly tightening the screw 20.

"Problems to be Solved by the Invention" The reason why a pulse motor is used as a drive source of an image reading device which is an image input terminal of an image processing system is that
The storage capacity of the computer is not large enough to accommodate the image information of one document at a time, the reading is paused in the middle of the document, the image information stored in the memory is processed, and then the reading is restarted from the stop position. This is because a drive source having excellent rising and falling characteristics is required to realize this function.

The problems of the conventional image reading apparatus to which the above-mentioned method of fixing the motor unit to the apparatus is applied will be described below while explaining the configuration of the image reading apparatus.

FIG. 3 is a plan view of the image reading apparatus, and FIG. 3 (a) is a side view showing only the optical path of FIG. The manuscript is the lighting member 21
The reflected light image is deflected by the first mirror 22, the second mirror 23, and the third mirror 24, is guided to the imaging lens 25, and is imaged on the photoelectric conversion element 26. The illumination member 21 and the first mirror 22 are integrated to form a first traveling body 27, and the second mirror 23 and the third mirror 24 are integrated to form a second traveling body 28.

The drive wire 30 wound around the drive pulley 29 fixed to the optical drive shaft 15 is a shaft fixed to the second traveling body 28 by being locked to the first traveling body 27 as shown in FIG. 3 (b). It is wound so as to be wound in the circumferential direction on the same side of a pulley 32 which is rotatable around and its end is fixed to the device. In the above structure, when the pulse motor 1 rotates, the rotation is transmitted to the drive gear 31 fixed to the drive pulley 29, and the drive shaft 15 and the drive pulley
29 rotates, winds up the drive wire 30, and the first traveling body 27
And the second traveling body 28 is caused to travel at a speed ratio of 1: 1/2.

In this way, image information is obtained by scanning the entire screen of the document, but in the conventional motor unit mounting method,
The rapid rise of the pulse motor may cause the following problems.

The rapid rise of the pulse motor at the start of scanning is due to the drive wire.
A shock is applied to the first traveling body 27 that locks 30 to vibrate the first traveling body 27 in the traveling direction. This vibration is usually damped early, but in some cases, the first traveling body 27 may be resonated and maintained for a long period of time. The deterioration of the image quality of the read image will be described with reference to FIGS. 4 to 6 by taking as an example the case where the time of one cycle of this vibration is about four times the accumulation time of the photoelectric conversion element 26. FIG. 4 is a diagram showing a time-distance relationship of the first traveling body 27. The solid line indicates that the vehicle travels at a constant speed, and the dotted line indicates that the vehicle travels at a non-constant speed with vibration. is there.
The horizontal axis represents time, and one scale corresponds to the storage time of the photoelectric conversion element. The vertical axis represents the traveling distance of the traveling body 27. First traveling body 27
Is accompanied by vibration, the movement amount of each accumulation time unit is a
Although it changes as 1, a2, a3, a4, the y coordinate value of the chart represented by the xy coordinate of the waveform shown in FIG. 5 is subdivided by the above movement amount, and the density information of each subdivided portion is 1 (white), When the image is taken out as 0 (black) and the image is reproduced at the same coordinates as in FIG. 5 based on this information, lines having a uniform width become nonuniform as shown in FIG. 6 and the image is changed to lack smoothness.

According to the present invention, by flexibly holding the motor unit in the image reading apparatus, the impulse effect is exerted on the rapid rising at the time of starting the pulse motor to soften the impact given to the first traveling body and suppress the resonance thereof. This is intended to solve the above-mentioned deterioration in image quality of the read image.

[Structure of Invention]

"Means for Solving Problems" The present invention relates to an image reading apparatus for reading an image by rotating a drive shaft around which a wire is wound by a pulse motor to run an optical system in which the wire is locked. The image capturing device is characterized in that a motor unit composed of a pulse motor and a power transmission device arranged between drive shafts is mounted on a motor unit mounting surface via a sheet-like elastic body.

[Examples] Examples of the present invention will be described below with reference to the drawings.

The schematic configuration of the image reading apparatus and the configuration excluding the motor unit mounting portion are the same as those described above, and thus description thereof will be omitted. FIG. 1 is a plan view showing a first embodiment of a motor unit mounting method of the present invention, and FIGS. 7 and 8 are partial sectional views of FIG.
In FIGS. 1, 7 and 8, reference numeral 41 denotes a sheet-like elastic body such as rubber placed on the machine frame 40. A tubular portion 45 corresponding to the bosses 42, 43, 44 formed on the mounting surface of the motor unit (the details of the boss 43 are not shown but similar to the bosses 42, 44) and fittingly enclosing it. , 46, 47 are formed and are positioned by fitting them. The motor unit M is supported by the elastic fastening member 3 to support the other one of the motor support plates (1) 4, and the gear shafts 7, 8 and 9 are fixed similarly to the motor support plate (2) 5 of the conventional example described above. 1
The motor support plate (2) 48 supporting 0, 11, 12 and the motor support plate (3) 49 supporting one of the motor support plates (1) 4 with the elastic body fastening member 3 are provided. The tubular part
The sheet-like elastic body 41 is formed by the elongated holes 50, 51, 52 fitted with 45, 46, 47 and the gear gap ensuring member 16 fitted with the optical drive shaft 15.
Sheet-like elastic body while ensuring the relationship between the optical drive shaft 15 and
It is placed on 41. Reference numeral 54 is a motor retainer (1) for pressing the motor support plate (2) 48 against the motor unit mounting surface of the machine frame 40 as shown in FIG. 7, one end of which is fixed on the machine frame 40 and the other end of which is a motor support plate (2). ) Leaf spring that presses the machine frame 40 via the base of 48
55 and the root of the leaf spring 55 are pressed against the machine frame 40, and the leaf spring 55
And a sheet metal member 56 that covers up to the vicinity of the tip side. 57 designates the motor support plate (3) 49 as shown in FIG.
Motor retainer that presses against the motor unit mounting surface of (2)
Then, like the motor presser (1) 54, the leaf spring 58 and the sheet metal member 59 are
It consists of and.

Next, the operation of the present embodiment having the above structure will be described.

When a drive pulse is input to the pulse motor 1, the motor shaft 1a instantly rotates by a specified angle.

At the same time, the timing pulley 13 rotates, and its rotational movement is the timing belt 14, the timing pulley 10a, the gears 10,11,1.
2 is transmitted to the drive gear 31. The drive gear 31 is connected to the first and second traveling bodies 2 via the drive pulley 29 and the drive wire 30.
Since it is connected to 7,28, it has a rotational load to start traveling. When the gear 12 which is the final stage of drive transmission of the motor unit M tries to rotate the drive gear 31,
Due to the rotational load of the drive gear 31, the gear 12 receives a reaction force on its surface. Due to the reaction force applied to the tooth surface of the gear 12, the motor unit M flexibly held by the sheet-like elastic body 41 and the leaf springs 55 and 58 is slightly displaced. Once the traveling bodies 27 and 28 start scanning, the motor unit M does not receive a new impact and drives the traveling bodies while recovering the minute displacement at the time of starting.

As described above, when the pulse motor 1 is started and the gear 12 at the final stage of the motor unit M starts the drive gear 31 having a rotational load, the reaction force thereof causes the motor unit M to move.
Due to the slight displacement, the rotation of the drive gear 31 that receives the rotational force by the gear 12 is gently raised.
Therefore, when the drive wire 30 starts the traveling of the first traveling body 27, the impulse given to the first traveling body 27 becomes small, and the resonance of the first traveling body 27 can be suppressed. Fig. 9, Fig.
FIG. 10 is a graph showing vibration in the traveling direction when the first traveling body 27 starts traveling, the horizontal axis represents time, and the vertical axis represents the magnitude of vibration acceleration. As described above, FIG. 10 shows the vibration of the first traveling body when the motor unit is held, and FIG. 10 shows the vibration of the first traveling body when the conventional motor unit holding method is used.

According to this, in the conventional method of holding the motor unit M, the first traveling body 27 resonates due to the impact that the first traveling body 27 receives by the wire 30 at the start of traveling. It is understood that no resonance occurs in the method of holding the motor unit M shown in FIG.

The cylindrical portions 45, 46, 47 provided on the sheet-like elastic body 41 are fitted into the motor unit mounting portion of the machine frame 40 on the inner surface and the motor unit M on the outer surface. The sheet-like elastic body 41 and the leaf springs 55 and 58 hold the sheet elastically to prevent the misalignment along the mounting surface of the motor unit M which may be a concern.

In particular, the motor unit M will not be displaced even if strong vibration or shock is applied during transportation. Motor presser (1) 54, motor presser (2) 57 sheet metal members 56, 5
9 is a leaf spring 55, 5 when the motor unit M floats up due to strong vibration or shock during transportation.
It has a stopper function for accommodating the deformation of 8 within the elastic deformation and for preventing the motor unit M from coming off from the cylindrical portions 45, 46, 47 of the sheet-like elastic body 41. Further, the sheet-like elastic body 4 completely separates the motor unit M and the motor unit mounting surface by the tubular portions 45, 46, 47 even in the positioning portion of the motor unit M, so that the motor unit M is The generated vibration is greatly attenuated from being transmitted to the machine casing 40, which has the effect of suppressing the noise of the device to a low level.

FIG. 11 shows another embodiment of the motor retainer 54, in which rubber 61 is used in place of the leaf spring 55. Since the rubber 61 has a high spring constant, the pressing force greatly changes due to variations in the amount of deformation, so that it is necessary to manage the amount of deformation, but the same effect can be obtained.

FIG. 12 also shows another embodiment of the motor retainer 57, in which a sheet-like elastic body 62 is bent instead of the leaf spring 58.

In the present embodiment, the optical system has been described as a 1: 1/2 traveling system, but the present invention is not limited to this, and an optical system in which an illuminating unit and a photoelectric conversion element are integrated and scanning is performed. However, the present invention is effective.

〔The invention's effect〕

As described above, in an image reading apparatus that scans an original by moving an optical system from a pulse motor through a wire, a motor unit including a pulse motor and a power transmission device is sandwiched between elastic bodies. When the optical system is started to travel, the impact exerted on the traveling body by the rapid rising of the pulse motor is softened and the resonance of the traveling body is suppressed. As a result, the traveling speed of the traveling body is ensured, and the read image quality can be improved.

Further, since the motor unit is completely isolated from the machine frame by the elastic body, the vibration generated by the motor unit is significantly dampened by the time the vibration generated by the motor unit is transmitted to the machine frame. It also has the effect of suppressing the noise of the car.

Further, since the sheet-like elastic body is provided with the means for restricting the displacement of the motor unit, it is possible to hold the motor unit at a fixed position of the apparatus despite the flexible holding.

[Brief description of drawings]

FIG. 1 is a plan view of a motor unit mounting method embodying the present invention, FIG. 2 is a plan view showing details of a motor unit and a conventional mounting method, and FIG. 3 is a plan view showing an outline of an image reading apparatus. FIG. 3 (a) is a side view showing the optical system of FIG.
FIG. 3 (b) is a side view showing the traveling body drive wire of FIG. 3, and FIGS. 4, 5, and 6 are lines for explaining image deterioration caused by disturbance of traveling of the traveling body at a constant speed. Figures and 7 are the first
FIG. 8 is a sectional view taken along the line AA, FIG. 8 is a sectional view taken along the line BB in FIG. 1, and FIGS. 9 and 10 are diagrams showing the vibration of the running body, FIG. 11, FIG.
FIG. 12 is a perspective view showing another embodiment of the motor pressing method. 1 ... Pulse motor, 41 ... Sheet elastic body, 42,43,44
...... Boss, 45,46,47 …… Cylindrical part, 50,51,52 …… Oval hole, 5
4,57 …… Motor retainer, 55,58 …… Leaf spring, M …… Motor unit.

Claims (2)

[Claims] 1. An image reading device for rotating a drive shaft around which a wire is wound by a pulse motor to drive an optical system in which the wire is locked to read an image, and is arranged between the pulse motor and the drive shaft. An image reading apparatus characterized in that a motor unit composed of an installed power transmission device is placed on a motor unit mounting surface via a sheet-like elastic body. 2. A motor unit mounting surface is provided with at least two boss portions, a sheet-like elastic body is provided with a tubular portion for fittingly including the boss portion, and the motor unit is fitted with the tubular portion. The image reading apparatus according to claim 1, further comprising a matching hole.