JPS62257267A - Image recorder - Google Patents

Abstract

PURPOSE:To reduce cost and to simplify the constitution of the titled recorder by specifying the scanning pitch of the same laser beam to obtain a high scanning density without inclining a semiconductor laser array. CONSTITUTION:Laser beams R1 and R2 emitted from the semiconductor laser array 1 transmit through a collimator lens 2 and a cylindrical lens 3, an form images and is reflected on a rotary polygon mirror 4, and transmit a spherical lens 5 and a toric lens 6, and form images on a photosensitive drum 7. The distance Ps between the laser beams R1 and R2 on the drum 7 is scanned plural times with the same laser beam in a manner that the scanning pitch Pp of the same laser beam is determined so that any one part is not scanned double by the beam. In such a way, the distance between the leaser beams emitted by neighboring emitting parts of the semiconductor laser array on the photosensitive body is scanned by means of many pieces of laser beams to make the scanning density higher.

Description

Detailed Description of the Invention (Industrial Application!?) The present invention relates to an image recording device such as a laser beam printer or a laser facsimile.

(Prior Art) Conventionally, as an image recording apparatus of this type, there is one that records an image by scanning a light beam onto a rotary multi-sided stirrup galver 2 lar t. In this device,
In order to obtain high-speed and high-quality printing, one rotation multifaceted Tj,
': It is necessary to significantly increase the operating speed of jv.
.

However, there is a limit to the operating speed of the above-mentioned rotating polygon mirrors, etc., and a so-called multi-beam scanning method, in which multiple light beams are focused in one main scan, is known as a way to speed up printing. ing.

As such a multi-beam scanning type light source, there is an element having an array of conductor lasers, that is, a ≠conductor laser array. The semiconductor laser has many advantages in that it cannot be directly modulated and is small and inexpensive, and it is easy to form an array of semiconductor lasers using semiconductor manufacturing technology. However, the pitch between each laser emitting element is 50g.
This is considered to be the limit, and if the north pitch is made smaller beyond this limit.

Stable operation cannot be expected due to the heat generated by each light emitting part.

By the way, since the beam emitted from the semiconductor laser array is irradiated onto the photoreceptor through the lens system, it is magnified 20 to 30 times by the lens system. Therefore, the pitch of the semiconductor laser array is 5 as described above.
Since the pitch of the imaged spot on the photoreceptor by a lens system with a magnification of 30 times is about 1.5
More than Rinho.

What is the scanning density required for normal printers?

Since the scanning density is about 10 lines/layer, when a semiconductor laser array is used as a light source, the scanning density is 0.67 lines/II.
■It is not suitable for practical use.

Therefore, when using an L semiconductor laser array as a light source for an image recording device, the following methods have been proposed as methods for increasing the scanning density.
In No. 0-33019, as shown in FIG. 7, the conductor laser array lO is tilted with respect to the optical axis direction It is made smaller to increase scanning density. In this case, as shown in FIG. 8, in order to align the occupancy positions jrL of each beam R in the main scanning direction, each light emitting section is provided with a delay u.
F = stages are provided. In addition, Tokukai (Ts) (60-31
417t;-, the b-conductor laser array is tilted by a minute rotation angle adjustment mechanism to set a delay time corresponding to one rotation angle.

(Problems to be Solved by the Invention) However, in the case of such conventional techniques, the start timing of modulation of each light emitting section 11 of the semiconductor laser array 10 is sequentially delayed with respect to the main synchronization signal of beam scanning. The latter requires a special mechanism and highly accurate adjustment to tilt the semiconductor laser array, which increases cost, complicates the structure, and makes adjustment difficult. The problem is that it is troublesome.

In addition, since the semiconductor laser array is tilted with respect to the optical axis direction, as the tilt angle increases, the effective light beam emitted in the optical axis direction decreases, and compared to the case where the semiconductor laser array is not tilted, high output There is a problem in that a semiconductor laser is required.

Therefore, the present invention has been made to solve the problems of the prior art described above, and its purpose is to: I!
- High scanning density can be obtained without tilting the conductor laser array, reducing costs and simplifying the configuration.
The purpose of the present invention is to provide an fI image recording device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an image recording apparatus that records one image by scanning a photoreceptor with an f-conductor laser array having a plurality of light emitting parts. , the distance on the photoreceptor between the laser beams emitted from adjacent light emitting parts of the conductor laser array is determined by the distance on the photoreceptor between the laser beams emitted from adjacent light emitting parts of the conductor laser array, when the same laser beam moves over multiple scans, and the laser beam covers the same part of the photoreceptor. The scanning pitch of the same laser beam is determined so as not to scan twice.

(Function) In the present invention, the distance on the photoreceptor E of the laser beams emitted from adjacent light emitting parts of the conductor laser array is scanned by a large number of laser beams to increase the scanning density.

(Example) The present invention will be described above based on the illustrated embodiments.

FIG. 2 is a schematic diagram showing an embodiment of the image recording device according to the present invention. In FIG. 0, l is a semiconductor laser array that integrates two semiconductor lasers la and lb as shown in FIG. The laser beams R1 and R2 emitted from the semiconductor laser array 1 are converted into parallel beams by a collimator lens 2, and then imaged by a cylindrical lens 3 onto a rotating polygon #i14 rotating at high speed.

The laser beam reflected by this rotating polygon mirror 4 is 1
An image is formed on a photosensitive drum 7 via a spherical lens 5 and a toric lens 6. In addition, if the conductor is
The laser beam emitted from the photosensitive drum 71 is expanded by the optical system and focused on the photosensitive drum 71.

The rotating mirror 4 has a rotation axis parallel to the y-axis, rotates in the direction of arrow W1, and scans the photosensitive drum 7 with a laser beam in the direction of arrow A. The photoreceptor drum 7 has a rotation axis along the X axis that is parallel to the y axis, rotates in the direction of arrow W2, and performs optical scanning +q over the entire surface of the photoreceptor drum 7.
tE.

When optically scanned, the semiconductor laser array 1 is optically modulated by a signal generated by a control circuit 9, and an arbitrary pattern is recorded on the photosensitive drum 7. A beam detector 8 detects the position of the laser beam, and its detection signal serves as a synchronization signal for pattern generation by the control circuit 9.

In this embodiment, the interval on the photoreceptor drum of the laser beams emitted from adjacent light emitting parts of the semiconductor laser array is changed so that the same laser beam moves over a plurality of scans, and the laser beam moves on the photoreceptor drum. The scanning pitch of the same laser beam is determined so as not to double scan the same part of the image.

Next, a method for determining the scanning pitch of the laser beam in this embodiment will be explained using FIGS. 1 and 4.

Adjacent light emitting sections 1a of the semiconductor laser array 1.

1b is the pitch interval PG (m+m), the interval on the photoreceptor drum 7 of the laser beams R1°R2 emitted from the adjacent light emitting parts la and lb is PS (+m layer), and the sub-scanning direction of the photoreceptor drum 7 The scanning pitch of Psd (mm
), and the imaging magnification of the optical system is m.

The relationship Ps = mPo - (1) holds true, and the interval Ps between the beam spots is generally larger than the scanning pitch Psd in the sub-scanning direction.

Incidentally, the modulation of the laser beam is performed as follows. That is, the laser beam R1 emitted from the first light emitting section 1a of the semiconductor laser array l is modulated by the first line image signal stored in the bitmap memory of the control circuit 9.

At the same time, the laser beam R2 emitted from the second light emitting section lb is modulated by the image signal of the second line.

By the way, in this embodiment, two laser beams are used for scanning as shown in FIG. 1, and this is called interlaced scanning. Figure 4 (A) shows the bare beam R of two trees.
1, R2 is the reflecting surface of the rotating polygon mirror 4 (6),
FIG. 4B shows the recording position when the photosensitive drum 7 is scanned and the ON-OFF state of the beam. FIG. 4B shows the recorded image on the photosensitive drum 7 formed by the paired beams.

The recording starts with a rotating multi-face! The recording is performed from the reflective surface D@) of
state.

Here, the t4 pitch of the same laser beam is 4PSd
and the photosensitive drum 7J:.

The pitch P of the beam spot is set to Ps=29Psa. By doing this, the same laser beam can cover the distance of pitch Ps multiple times (7 times in the illustrated example).
, and the same laser beam does not double scan the same part on the photoreceptor drum 7. Therefore, the value of Psd on the photoreceptor drum 7 is 77-
scanned at the pitch provided.

By the way, between the pitch Psd in the sub-scanning direction and the pitch Ps of the beam spot, Ps = n Psdn: natural number (II) CI)
, from equation (n), the light emitting part 1a of the semiconductor laser array l,
Calculating the pitch Po of lb, Po=-XP d
...(III).

The scanning density on the photosensitive drum 7 is set to 16 lines/track layer, that is, P
When Sd = 0.0825, the pitch Pa of the light emitting sections 1a and lb of the semiconductor laser array l has the following value. Note that the imaging magnification m of the optical system is 30 times. (m)
From the formula.

So, the thermal shape between the light emitting parts! Condition Po to avoid )
50 em...(17) is satisfied.

Therefore, by scanning the laser beam as described in J.
The photosensitive drum can be scanned to Psd=82.5 gm and ' without increasing the distance between the light emitting parts so much that the thermal influence becomes noticeable.

5 and 6 schematically show the positional relationship between the recording position on the photosensitive drum 7L and the reflecting surface of the rotating polygon mirror when the number of light emitting parts of the semiconductor laser array is three and four, respectively. It is.

Generally, in the case of multi-beam scanning with one beam, if the scanning pitch of the same laser beam is Pp, then P p = J X Psd = ('/) P5 = kX
Pp + Psd k: natural number - (Vl) these (V)
By performing interlaced scanning so as to satisfy the formula (VI), the interval Ps between the laser beams emitted from adjacent light emitting sections of the dielectric conductor laser array on the photosensitive drum can be closely scanned.

(Effect of the invention) Honsei 1 consists of the following structure and function.

Even when using a four-body laser array with multiple light emitting parts as a light source, it is possible to densely scan the photoreceptor without tilting the sample laser array. This eliminates the need for a delay circuit or a mechanism for tilting, reducing costs and making the configuration more cylindrical.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a diagram 1jII showing the main parts of an embodiment of the image recording device according to the present invention, Fig. 2 is a schematic configuration diagram showing the image recording device, and Fig. m3 is a semiconductor laser array. 4(A) and 4(B) are explanatory diagrams showing a scanning pattern 78, FIGS. 5 and 6 are explanatory diagrams showing other embodiments, and FIG. 7 is a conventional semiconductor laser. A schematic diagram showing an array, and FIG. 8 is an explanatory diagram showing the scanning timing of a conventional laser beam. Explanation of symbols■...Semiconductor laser array la, lb...Light emitting section 4...Rotating polygon mirror 7...
・Photoconductor drum PS... Distance fraud on the photoconductor tram of adjacent laser group 1 person Canon Co., Ltd. Agent Patent Attorney IT Yoshikazu Shinsuke ＼
-G? (Fig. 5, Fig. 6)

Claims (1)

[Claims] In an image recording device that records an image by scanning a photoreceptor with a semiconductor laser array having a plurality of light emitting parts, the distance on the photoreceptor between laser beams emitted from adjacent light emitting parts of the semiconductor laser array is , an image recording characterized in that the same laser beam moves over multiple scans and the scanning pitch of the same laser beam is determined so that the laser beam does not scan the same part on the photoreceptor twice. Device.