JPS5915221A - Optical scanner - Google Patents

Abstract

PURPOSE:To eliminate the uneven pitch in scanning lines and to obtain an image having good quality by detecting a moving speed from the code signal provided on the surface of a medium to be scanned or a moving member for the same, and controlling the luminous flux from a deflection member to the auxiliary scanning direction. CONSTITUTION:A speed detector 9 consists of a light source 11 for detection for illuminating the bar code array 8 recorded in the end part of a medium 7 to be scanned with a lens system 10 and a photoelectric transducer 13 for detecting the light reflected from the array 8 with a lens system 12. When a change arises in the peripheral speed of the medium 7, a signal is outputted from the detector 9 at the time intervals corresponding to the change. A control circuit 15 for driving operates to drive a deflection member 3 so as to move the luminous flux L in a D1 direction. Even if the position of the luminous flux A on the surface of the medium 7 displaces according to the plane moving speed of the medium 7, the uneven space between the scanning lines A is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical scanning device for optically scanning a scanned medium, such as a photoreceptor 18 ram, in, for example, a copying machine.

Conventionally, methods are known for optically or electrically removing pitch irregularities in scanning lines caused by tilting of a deflection reflecting surface of a rotating polyhedron or the like due to processing errors or tilting of a rotating shaft. However, in this type of optical scanning device, sub-scanning in the direction perpendicular to the main scanning line direction is usually performed by mechanically moving the scanned medium, so this can be caused by various electrical and mechanical errors. Maintaining the speed of movement of the scanned medium constant is very efficient. Due to such unevenness in the moving speed of the scanned medium and vibration of the apparatus, it is inevitable that pitch unevenness will occur in the scanning lines drawn on the scanned medium. Generally, this kind of pitch unevenness appears as a fairly long-term unevenness with respect to the pitch of the scanning line, and therefore becomes very noticeable when used as an image storage device such as a copying machine.

The causes of this uneven movement speed of the scanned medium include uneven rotation of the drive system's electric motor itself, irregular changes in the frictional force and tension of the transmission system that transmits the rotation of the electric motor to the scanned medium, and other causes. When the scanning medium is drum-shaped, problems include eccentricity of the rotating shaft and non-uniform radius of the drum. In order to keep the moving speed of the scanned medium constant,
It is possible to apply advanced servo technology used in tape recorders, etc., but this would require extremely precise mechanical systems and complex electrical systems.

An object of the present invention is to provide an optical scanning device that can easily eliminate such unevenness in the moving speed of a scanned medium. a scanned medium provided on a surface of a moving member movable in a sub-scanning direction substantially perpendicular to the main-scanning direction;
A code signal consisting of an array that appears periodically in the moving direction of the moving member on the moving member 6 or on the surface of the scanned medium, a detecting means for detecting the amount of movement of the code signal, and the detecting means and a deflection member that is driven by the drive control means and deflects a light beam in the sub-scanning direction, and the deflection member that is driven by the drive control means to deflect a light beam in the sub-scanning direction. The present invention is characterized in that the position of the scanning line is displaced in the moving direction of the moving member to correct uneven spacing between the scanning lines.

The present invention will be explained in detail based on illustrated embodiments.

In FIG. 1, 1 is a directly modulated light source made of a semiconductor laser or an LED, and the light beam emitted from this light source 1 is condensed by a condenser lens 2, and then deflected by a deflection member 3 made of, for example, a galvanometer mirror. The direction of the DI force is controlled in the sub-scanning direction. In the exit direction of the deflection member 3, a main scanning deflector 4 made of, for example, a rotating polygon mirror is arranged, which deflects the light beam in a direction substantially perpendicular to the direction in which the light beam is deflected by the polarization member 3. , a scanning lens 5 such as an fφθ lens is used to scan the surface of a scanned medium 7 placed on a moving member 6 in the so-called D2 direction of the main scanning direction using a beam of light. On the edge of the surface of the scanned medium 7,
Barcode rows 8 arranged at regular intervals in the same direction as the moving direction of the moving member 6 are recorded. Further, a speed detector 9 is arranged near the medium to be scanned, and this speed detector 9
The detection light source 11 illuminates the barcode row 8 via the lens system 12 and the lens system 1
2, and a photoelectric converter 13 for sensing via the photoelectric converter 2.

Furthermore, a drive control circuit 15 is provided for driving the deflection member 3 by the electric motor 4 in accordance with the output signal of the speed detector 9.

In general, the scanned medium 7 is the surface of a photoreceptor drum, which is a cylindrical surface, and if there is no change in peripheral speed due to uneven movement speed of the moving member 6, error in its diameter, eccentricity, etc., the speed detector 9 will detect For a certain period of time.

Electrical signals at intervals are output. In this case, the deflection member 3 is controlled by the drive control circuit 15 so as to deflect the light beam in the predetermined direction D1.

On the other hand, if the circumferential velocity of the surface of the scanned medium 7 changes due to the above-mentioned causes, the speed detector 9 outputs a signal at time intervals corresponding to the change. The drive control circuit 15 operates in response to the time interval of this output signal, and the deflection member 3 is driven so as to move the light beam in the same direction. That is, even if the position of the light beam A on the surface of the scanned medium 7 is displaced in accordance with the surface movement speed of the scanned medium 7, the unevenness in the spacing of the scanning lines A can be corrected.

FIG. 2 is a block circuit diagram of the drive control circuit 15. The drive control circuit 15 consists of a reference signal generator 16 and a phase detector 17.
) is generated and input to the phase detector 17 manually. For this signal S1, FIG.
Electrical No. 43 S2 from the speed detector 9 as shown in b) is also input to the phase detector 17, and depending on the phase difference of the reference signal Sl, an output S3 as shown in FIG. 3(C) is obtained. It will be done.

Therefore, the deflection direction of the deflection member 3 is controlled according to the voltage or current signal S3 output from the drive control circuit 15.

The aforementioned FIGS. 2 and 3 are specific examples of drive control means using analog signals, whereas FIGS. 4 and 5 show drive control means using digital signals. In this case, the reference signal generator 18 generates electrical signals pulses S4 at constant time intervals as shown in FIG. 5(a). t
Manually input the l number circuit 19. On the other hand, the speed detector 9 generates an electric signal pulse S5 as shown in FIG. At this time, in the 51 number circuit 19, as shown in FIG. 5(c), when the signal pulse S5 is inputted, λt Mh
(Clear iUse and count the reference signal pulses S4 until the next signal pulse S5 is finished being input manually. Also, count the reference signal pulses S4 until the next signal pulse S5 is input manually. The output from the flip-flop circuit 2o
As shown in FIG. 5(d), the constant output S7 is maintained until the next signal pulse S5 is input manually. The output S7 from the flip-flop circuit 2o is converted by the DA converter 21 into an analog quantity S8 corresponding to FIG. 3(c), thereby controlling the deflection angle of the deflection member 3.

According to these means, even if the moving speed of the moving member 6 is uneven or the circumferential speed of the scanned medium 7 surface changes, the position of the scanning line A can be made to follow the moving direction of the moving member 6, and the position of the scanning line A can be made to follow the moving direction of the moving member 6. As a result, the unevenness in the interval between one scanning line A can be corrected.

Figure @6 shows another embodiment, in which the luminous flux emitted from the light source l passes through the condensing lens 2 and passes through the cylindrical lens 30.
The light is incident on the light beam, passes through a transmissive deflection member 3' made of, for example, a transmissive plate glass, and forms an image on the main scanning deflector 4. The light beam scanned by the main scanning deflector 4 forms an imaging spot on the surface of the medium 7 to be scanned by a scanning lens system 31 having an anamorphic lens. As disclosed in Japanese Patent Publication No. 5B-366225, this optical system is designed to prevent scanning errors caused by processing errors in the reflecting surface of the main scanning deflector 4, which is a single-axis striped mirror, or by precession of its rotation axis. Line A
This is to correct the unevenness of the spacing. Even in an optical system with such a configuration, the scanned medium 7
Unevenness in the spacing of the scanning lines A due to changes in the peripheral speed of the surface is unavoidable.

Therefore, in the embodiment shown in FIG. 6, the position of the line image near the reflecting surface of the main scanning deflector 4 formed by the cylindrical lens 30 is adjusted approximately in the line direction using the refraction change of the deflection member 3'. This allows movement in the orthogonal sub-scanning direction.

This deflection member 3' made of rotatable transparent plate glass is
As in the previous embodiment, it is driven by the electric motor 14 based on the output from the drive control circuit 15, and moves the scanning position 11A of the scanned medium 7 to follow the change in the circumferential speed of the surface of the scanned medium 7. A constant scan line spacing can be maintained.

The advantage of the embodiment shown in FIG. 6 is that by selecting the thickness of the transparent plate crow, which is the deflecting member 3', the relationship between its rotation angle and the amount of scanning line movement can be set to a desired value. For example, by increasing the thickness of the transmitting plate glass, the ratio of the moving layer of the scanning line position 1〆1 to the rotation angle can be increased, and conversely, by decreasing the thickness of the transmitting plate glass, the ratio can be decreased. Note that the cylindrical lens 3 used in this example
0 may be arranged between the condenser lens 2 and the deflection member 3 shown in FIG.

FIG. 7 shows still another embodiment, in which an optical member 32 consisting of, for example, a mirror for reflecting the optical path is provided between the scanning lens 31 having an anamorphic lens and the scanned medium 7.
33 are arranged so that the light beam emitted from the main scanning deflector 4 is imaged onto the surface of the scanned medium 7 via these optical members 32 and 33. On the other hand, the barcode array 8 is irradiated with light from the detection light source 11, and the diffusely reflected light is condensed by the scanning lens system 31 via the optical members 32 and 33. The reflected light emitted from the scanning lens system 31 enters the photoelectric converter 13 via the lens system 12 at a wavelength of λ.

Here, the modifiable light source 1, the condensing lens 2, the cylindrical lens 30, the deflection member 3', the main scanning deflector 4, and the scanning lens system 31 are installed on the substrate 341-, and the lens system 1
2. The photoelectric converter 13 is also mounted on this substrate 34.

In this case, the vibration of the substrate 34 or the optical members 32, 33
Even if the position of the scanning line A may shift due to the vibration of the optical member 32.
33, a substrate 34 on which the main scanning deflector 4 etc. are mounted.
The light is incident on the photoelectric converter 13 installed at -. Therefore, this reflected light is from the light source J.

By driving the deflecting member 3' in accordance with the detection signal generated by this reflected light, the scanning light beam is The unevenness in the interval is corrected by following the change in the circumferential speed of the medium 7.

In the embodiment of FIG. 7, the cylindrical lens 30 of the substrate 34-1- is not used, and instead of the analogous scanning lens system 31, the scanning lens 5 consisting of the rotationally symmetrical lens shown in FIG. Also, instead of the transmission type deflection member 3', a reflection type deflection member 3 shown in FIG.
A similar effect can be obtained by using .

In the above embodiment, the light source 1 is a semiconductor laser or an LED that can be modulated. The light flux may be modulated using the used light modulation element.

Further, the barcode row 8 may be a periodic shading pattern; for example, as shown in FIG.
) is a plan view, and (b) is a cross-sectional view of the small magneto-optical recording material 1.
1441 may also be used.

This magneto-optical recording material 41 is a pace 42 or a scanned medium 7.
An example of a film with a uniform thickness coated on top is GdTbFe, and the shaded area 43 and non-shaded area 44 in FIG. 9(a) indicate regions with different magnetization directions, and are alternately and periodically arranged! 1
1 has been done.

When using this magneto-optical recording material 41, as shown in FIG. The magnetic recording material 41 may be irradiated. The reflected light includes a polarizing filter 46 that transmits only polarized light in the direction of the magnetizing force, a condensing lens 12, and a photoelectric converter 13.
is used, the scanned medium 7 is moved according to the magnetization direction of -
An electrical output signal proportional to the circumferential speed can be obtained. The magneto-optical recording material 41 has an extremely thin lIQ thickness compared to the silver halide film 40, and can be deposited on the scanned medium 71-1 or the moving member 6 that supports it by 18 depositions. can do. When the surface of the scanned medium 7 is a cylindrical surface, it is possible to accurately detect peripheral velocity irregularities on the surface of the scanned medium 7 caused by errors in diameter or eccentricity. Particularly, in a color printer, for example, in which a plurality of scanned media 7 are used and the respective scanned images are superimposed on one medium, color shift can be reduced and the effect is great.

- In the embodiment described above, the closer the interval between the eight cord rows 8 installed on the surface 1- of the moving member 6 or the scanned medium 7, the higher the frequency at which irregularities in circumferential speed can be detected, and the higher the richness. scan l
It becomes possible to correct the unevenness in the interval of it A. However, if the spacing between the barcode rows 8 is increased, it tends to become difficult to manufacture. In order to improve this, a photoelectric detection section 47 as shown in 1.lA may be used. That is, the 11th
In the figure, barcode rows 8 are light reflecting parts arranged at intervals of pitch d1, and other parts are non-conforming parts.
The barcode array 8 is imaged by the lens 48 onto the slit plate 49J of the photoelectric detection section 47 at an imaging magnification β. This slit plate 49 is provided with N slint openings 50 of d2, and the portion g++ other than the openings 50 serves as a light shielding portion. In this case, (N+1) fist d2−β=
By determining the specifications to satisfy the relationship dl,
Movement of the barcode row 8 can be detected without interruption. By using this flexible barcode string detection system, it is possible to detect the speed of the barcode string 8 at intervals of 1/N.

As explained above, the optical scanning device according to the present invention detects the moving speed of the scanned medium from the code signal provided on the surface of the scanned medium or its moving member, and uses the deflection member to direct the light beam according to this moving speed. By controlling in the sub-scanning direction, it is possible to eliminate pitch irregularities in the scanning lines and obtain a high-quality, well-ordered image.

[Brief explanation of the drawing]

The drawings show an embodiment of the optical scanning device according to the present invention, FIG. 1 is a block diagram of the first embodiment, FIG. 2 is a block circuit diagram of a speed detector, and FIG. 3 is a time chart of its output signal. Figures 1 and 4 are circuit diagrams of a speed detector using digital signals, Figure 5 is a time chart of its output signal, Figure 6 is a configuration diagram of the second embodiment, and Figure 7 is a diagram of the speed detector using digital signals. The figure is a block diagram of the third embodiment, FIG. 8 is a plan view of a barcode array made of silver halide film, FIG. 9(a) is a plan view of a barcode array made of magneto-optical recording material, and (b) 10 is a cross-sectional view thereof, FIG. 1O is a block diagram of a detection system for reading a bar code string of a magneto-optical recording material, and FIG. 11 is a block diagram of a detection system for reading a bar code string with high precision. 1 is a light source, 2 is a condensing lens, 3.3' is a deflection member,
4 is a main scanning optical system, 5 is a scanning lens, 6 is a moving member, 7
is a scanned medium, 8 is a barcode string, 9 is a speed detector, 1
1 is a detection light source, 13 is a photoelectric converter, 15 is a drive control circuit, 30 is a cylindrical lens, 31 is a scanning lens system, 32, 33 is an optical member, 34 is a substrate, 40 is a silver halide film, 41 is a magneto-optical device It is a recording material. Patent applicant Canon Corporation 1151!1 Figure 6 1i8 Figure 11!9 (b) 10rM 1

Claims (1)

[Claims] 1. A deflector for deflecting the light beam emitted from the light source in the main scanning direction and a movable member movable in the sub-scanning direction that is substantially orthogonal to the main scanning direction are provided flush with each other. a scanned medium, a code signal arranged on the moving member or flush with the scanned medium in an array that appears periodically in the moving direction of the moving member, and a detection means for detecting the amount of movement of the code signal. , a drive control means that generates a drive output according to a signal generated from the detection means, and a deflection member that is driven by the drive control means and deflects a light beam in the sub-scanning direction, and the deflection member drives the scanned medium. An optical scanning device characterized in that the position of the scanning line formed above is displaced in the moving direction of the moving member to correct unevenness in the spacing of the scanning line. 2. The movement amount detecting means described in claim 1 irradiates light onto the code signal and receives the reflected light by a photoelectric converter to detect and detect the movement amount of the moving member. Optical scanning device. 3. The photoelectric converter is installed on the same substrate together with a light source, a deflector that deflects the light beam in the main scanning direction, and a deflection member that deflects the light beam in the sub-scanning direction.
The optical scanning device described in Section 1. 4. The optical scanning device according to claim 2, wherein a slit plate having parallel openings is interposed between the code signal and the photoelectric converter to improve accuracy in detecting the amount of movement.