JPS6022329Y2 - optical scanning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for scanning a plurality of scanned surfaces with a light beam modulated by substantially the same modulation signal.

As a means of printing information output from a computer, etc.,
Line printers using type have been widely used for a long time, but recently non-impact printers have been used to increase speed to cope with the rapid increase in output information and to reduce noise during machine operation. became.

An example of this type of non-impact printer is one that applies electrophotographic technology and scans a photosensitive drum or the like with a laser beam spot whose intensity is modulated. Some types create an image, develop it with toner, transfer it to recording paper, and then perform a fixing process.

For more detailed examples of this type of printer, see Japanese Patent Application No. 49-79475, which has already been filed by the present applicant.
Details are given in the issue.

As mentioned in this example, it is generally difficult to obtain copies with this type of non-impact printer as with impact printers that use type.

For this reason, if a copy of the output is required, methods such as copying the output recording paper using a copying device, outputting the same information multiple times, or developing and transferring an electrostatic latent image multiple times are required. is used.

Among these methods, to output the same information multiple times, there are two ways to output the same information multiple times:
Similarly, there is a method of repeatedly outputting the same information in the longitudinal direction with respect to the feeding direction, or a method of recording the information on a magnetic tape while outputting a series of outputs, and reading out the same information from the magnetic tape once this is completed. There are ways to print it out.

In this case, whichever method is used, there is a point that it essentially lacks the conditions for copying.

In other words, in this case, the time at which the copy is recorded is different from the time at which the original is recorded, so if the printer malfunctions due to some reason, such as noise entering the electrical circuit, the original and copy will be different. I end up.

If the printer malfunctions while printing the original, information containing exactly the same result of the malfunction must be recorded on both the original and the copy.

In other words, when copies are obtained at such different times, the conditions for copying are essentially not met.

Next, unlike the above-mentioned example, a method in which an electrostatic latent image obtained once is substantially developed and transferred multiple times satisfies the conditions for copying, but requires a significantly complicated apparatus.

Furthermore, in the above example, the original and the copy are often recorded on substantially the same continuous recording paper, and the operation of separating them is extremely troublesome.

The present invention relates to an optical scanning device suitable for, for example, a non-impact printer that uses a means of scanning a recording surface with a light beam, where it is required to obtain a highly reliable copy that is easy to separate from the original. It has the configuration and features described below.

FIG. 1 shows an embodiment of the present invention, in which 1 is a laser oscillator as a light source, 2 is an optical modulator, and an electric signal corresponding to the output from, for example, an electronic computer is input to the driving device 2-1. By being applied to the terminal 2-2, the intensity of the light B1 from the laser oscillator 1 is modulated.

The width of the modulated light B2 is expanded by the beam expander 3 and becomes light B4.

The direction of the expanded beam β is changed by the optical deflection mirror 4 rotating around the point 4-1, and the position of the mirror 4 is 4a,
Corresponding to 4b and 4c, proceed along the routes Ba, Bb, Bc, etc.

In the path of these lights, there is a lens L□? with focal length f□, as shown in the figure. L2 is located.

In the figure, for simplicity, Lt and L2 are shown as so-called thin lenses, so the distance between the center of rotation of the mirror and the point P in the figure is 4f□, but in actual design it is generally longer than this. .

In the case of such an arrangement, Ba, Bb, and Bc are once imaged on S1, and when the mirror 4 rotates from 4a to 4b to 4c, the light spot moves on S0 to Pa+Pb+Pc.

This can be understood from the fact that since the central lights of Ba, Bb, and Bc pass through the focal point of the lens L1, they move parallel to the optical axis after passing through the lens h.

After passing through the S1 surface, these lights are diffused, enter the lens h, and become parallel lights again, and become light that rotates around a position P1 that is a distance f1 away from the crow.

This can be understood from the fact that light traveling parallel to the optical axis travels toward its focal point.

In this case, the lens L,, L,! Since Ba and B are equal,
b, The angle between Bb and F3c (1') is Ba' and Bb',
It is equal to the angle formed by Bb' and BC' (7).

That is, the rotation of the light beam due to the rotation of the mirror at point 4-1 is transmitted to point P1.

L3 is a so-called F/θ lens and is positioned so that point P1 becomes its pupil.

Further, R1 is arranged at the focal plane of the first object to be scanned and the lens L3.

This figure shows an example of a transfer drum in an electrophotographic process.

Regarding the operation of this recording transfer drum, the above-mentioned patent application
Since it is as detailed in No. 9-79475, it is omitted here.

For example, the light incident on the lens L3 is
If the tilt with respect to the optical axis is θ, a light point is connected to a position A separated by F·θ, that is, H in the figure, from the intersection of the optical axis and the recording surface, where F is the focal length of the lens L3.

When the mirror 4 rotates at a constant speed, the light spot on the object to be scanned R0 as a recording medium also scans the object to be scanned R1 at a constant speed.

Next, a semi-transparent mirror M□ is placed between the lens h and Pl to obtain a mirror image P2 of Pl.

Then, at a position far from the mirror image P2, its focal length is f2.
A lens L4 having the same focal length f2 is further placed at a position 2f2 apart from L4.

As a result, light that behaves in the same way as at point P1 is obtained at point P3, which is away from lens L5 by f2.

Note that the ratio of the light intensity at the point P□ and the light intensity at the point P3 is mainly determined by the division ratio of the semitransparent mirror M1.

L6 is an F/θ lens whose pupil is located near the point P3, and the second object to be scanned R2 is placed on its focal plane.

In the case of the above configuration, the scanned object R1,
The position, intensity, etc. of the light incident on R2 are determined by the scanned object R1, until it passes through the semi-transparent mirror M or is reflected by it.
This is completely common to R2, and even after passing through the semi-transparent mirror M1 or being reflected by it, the light only passes through an extremely simple and stable optical path, so both can be treated as substantially equivalent.

Note that E□ is the housing division that includes the first recording system (as shown in the diagram <1. 2. 3. 4. Lit L,!t M□
, L3°R1,k□, L4. R2 is a housing section containing a second recording system that can easily perform copy recording by being connected to the first recording system (as shown in the figure). .R2° Shows the various members and means of R2).

As seen in the figure, the light is in a parallel beam state between the lens L and the F/θ lens h, so even if the F/θ lens h is misaligned with respect to the lens L3, the F/θ lens
If the relative position between the θ lens h6 and the object R2 to be scanned is maintained accurately, there is little deterioration in the imaging performance of the F·θ lens h on the object R2 to be scanned.

Of course, if the F/θ lens h6 has a significant positional shift relative to the lens L5, the F/θ lens h6 may
The light from the lens L will not enter the object R.
However, when actually designing this type of device, for example, the end of F.
If the focal length of the θ lens h6 is approximately 40 cm, it can be designed so that no problem will occur even if the F/θ lens h is displaced in parallel from its normal position by several millimeters with respect to the lens knee. .

Therefore, in the housing R1 containing the first recording system, a lens block, that is, means for generating a light beam that behaves equivalently to the light beam in the vicinity of the scanning reflecting mirror, that is, a light beam corresponding to the point P3 is arranged. By arranging the second recording system built in the housing R2, which is substantially separable from the housing E□, in the housing E1 with a predetermined positional relationship, stable performance and high reliability can be achieved. Thus, an optical scanning device is obtained for a recording system which is capable of being scanned by a plurality of light beams containing the same information at the same time and which is essentially divisible into two housings or functional sections.

FIG. 2 shows another embodiment of the present invention, which uses a different optical system configuration that is convenient for the spatial arrangement of the second recording means.

In this example, the behavior of the luminous flux at point P3 is further controlled by lens LG,
l, is transmitted to point P4.

The light beam centered around P4 is focused by the lens L onto the object R2 to be scanned.

In this case, A and B. C, A'', B'', and C'' are each irradiated with completely equivalent light beams.

Note that M2 is a mirror. In Figure 2, L7 is included in the housing E2.
．． l-89M2. L, l], various members and means of 2°R2 are housed.

In the above diagram, lens L and lens L3. L9 etc. are all drawn to the same size, and the scanned object R, R
2 is said to be the same, but for example, as lens L,
It is also possible to use an F/theta lens with a focal length of 40 cm, an electrophotographic photosensitive drum as the object to be scanned R1, an F/theta lens with a focal length of 10 mm as the lens h, and a microfilm as the object to be scanned R2.

In addition, in the case of the present invention, since the optical deflector for scanning the first object to be scanned and the optical deflector for scanning the second object to be scanned are common, the first object to be scanned is The scanning light spot and the light spot scanning the second scanned object scan the respective scanned objects with the same phase, but for example, in FIG. When E2 is placed in a relatively slightly rotated state, the scanning light spots A', B', C', etc. for the object to be scanned R2 move upward or downward in parallel in the figure.

Therefore, if this amount becomes large, for example, information will be recorded at a specified position on the scanned object R1, whereas information will be recorded at a specified position on the scanned object R2.
There is a possibility that information is recorded in a position shifted from the specified position, and this no longer satisfies the conditions for being a copy.

To avoid this, for example, as shown in Figure 1, it is possible to place light outside the effective recording area near the first scanned object and within the scanning area by the light spot, or at an equivalent position using a reflecting mirror. In addition to arranging the first light-receiving element for beam detection, the second light-receiving element is placed near the second object to be scanned or at an equivalent position, which is equivalent to the arrangement of the first light-receiving element with respect to the first object to be scanned. The device may be operated while confirming or monitoring that the electrical outputs from the two light receiving elements are generated simultaneously within the permissible limits.

To do this concretely, for example, do as shown in FIG.

That is, 1. output from amplifier 2 to amplifier 1
1.1°, and if necessary, the pulse shaper m1. m2, and form them using an AND circuit n
Add to.

1. to the light receiving element. When the time difference between the outputs from 2 and 2 is within the range determined by the output of 1 or 2 to the light receiving element, or the pulse width of the shaped output of these, the output from the AND circuit is constant with the scanning period of the light beam. is obtained.

In other words, while the output is being obtained from the AND circuit with the scanning period, the positional deviation of the scanning light spot with respect to the two objects to be scanned is within the permissible limit.

To detect that the pulses that should be sent regularly from the AND circuit with the scan period have ceased, the output from the AND circuit is changed to a resettable one-shot multivibrator O whose duration is longer than the scan period. Add.

In this way, this one-shot multivibrator will
While the pulses of the AND circuit are constantly being sent in the scanning period, the pulses are always reset without changing from the on state to the off state.

If the output from the AND circuit is interrupted, the one-shot multivibrator is turned off without being reset.

As mentioned above, the duration time of this one-shot multivibrator is longer than the scanning period, but if this value is chosen to be, for example, more than five times the scanning period, four pulses will be missing from the AND circuit. Until then, the multivibrator is in the on state, and only changes to the off state when five vibrators are missing in a row.

This means that the device does not stop operating in response to a single accidental loss of output from the photodetector 1 or 2, but only if there is a continuous loss of AND circuit output. This is a method used when you want to stop it.

It goes without saying that the above-described monitoring means can also be applied to the example shown in FIG.

As shown in the above embodiment, the rotation of the light beam generated by the optical deflector is optically passed through and guided to the vicinity of the pupil of the imaging lens of the first recording system, and a light beam splitter is disposed in the middle. The divided rotating light flux is guided to the vicinity of the pupil of the imaging lens of the second recording system, and the first,
Even when the second recording system is distant, the two recording systems can be scanned with completely equivalent light flux by selecting the focal length of the optical system and the number of optical elements for transmitting the rotation of the light flux. Can be done.

Although each of the above-mentioned embodiments discloses that the luminous flux is divided into two, it goes without saying that the luminous flux may be divided into three or more.

When the number of divisions increases, it is also possible to use a plurality of optical deflectors or the like as appropriate.

As described above, in the present invention, since a common light source, a common optical modulator, and a common optical deflector are used, the information recorded on the first scanned object and the information recorded on the second scanned object are different. This eliminates the problem of different pieces of information having different values, and has an extremely large effect in realizing, for example, a non-impact printer that can record exactly the same information at the same time.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of an embodiment of the optical scanning device of the present invention, FIG. 2 is a diagram of an embodiment of the same gender, and FIG. 3 is a diagram of an example of a monitoring means. 1 is a laser oscillator, 2 is an optical modulator, 4 is an optical deflector, L1
-9 are lenses, M1 is a semi-transparent mirror, R1 and R2 are objects to be scanned, and k1-2 are light receiving elements, respectively.

Claims (1)

[Scope of utility model registration request] a first and a second recording medium, a modulated light flux forming means common to the first and second recording media, a driving means for driving the modulated light flux forming means by a recorded signal, and a modulated light flux. an optical deflector common to the plurality of recording media that rotates and sweeps a beam; a beam splitting means common to the plurality of recording media that divides the beam swept by the optical deflector; a first casing that houses the first recording medium, the modulated light beam forming means, the optical deflector, and the light beam splitting means;
a second casing that is separable from the casing of , and houses the second recording medium; a first light-receiving element configured to divide the beam by a beam splitting means to scan the first and second recording media, respectively, and further receive the swept beam in the first casing; A monitor comprising: a second light-receiving element received in the second casing; and means for detecting whether a time difference between the outputs of the first and second light-receiving elements is within an allowable limit. An optical scanning device comprising a viewing means, with which it is possible to check whether or not a light beam is scanning a prescribed position on the second recording medium.