JPH09164717A - Head for optical printer - Google Patents

Abstract

(57) Abstract: In a conventional optical printer head, when a plurality of light emitting arrays are combined and complemented in order to increase the density of the dot pitch, independent light emitting arrays must be precisely arranged. Therefore, there is a problem that the assembly work becomes difficult. According to the present invention, n rows of a light emitting array 3 in which a plurality of light emitting portions 3a are formed in rows on a single flat substrate 2 at a predetermined pitch, each row having a pitch of 1 / n. The substrate assembly and the focal point FP on the optical axis Z are arranged on the same straight line, and the object points OP on the optical axis Z are aligned with the light emitting portions 3a of the respective light emitting arrays 3. Then, the optical printer head 1 is composed of a lens assembly composed of n rows of converging rod lens arrays 4 which are radially combined with each other around the straight line. The light emitting array 3 is attached so that the dimensional accuracy between the light emitting arrays 3 can be reliably set, and the problem is solved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a plurality of light sources arranged in a row in the axial direction on the outer periphery of a rotating photosensitive drum, and causes each of the light sources to blink as the photosensitive drum rotates. Thus, the present invention relates to an optical printer head used for forming latent images of characters and figures on the photoconductor drum.

[0002]

2. Description of the Related Art A conventional head 90 for an optical printer of this type.
FIG. 7 shows an example of the configuration of FIG. 7. On the substrate 91 of the optical printer head 90, a plurality of light emitting portions 92a are formed in rows at a predetermined pitch P as shown in FIG. An array, for example, an LED array 92 is mounted with the column direction of the above-mentioned light emitting portions 92a being the direction perpendicular to the paper surface in the state shown in FIG.

Above the LED array 92,
A converging rod lens array 93 formed of an optical fiber having a converging property called a graded index fiber or the like is used to detect the object point OP on the optical axis Z from the LED.
It is located at the light emitting portion 92a of the array 92, and is installed so that the focal point FP on the optical axis Z is located on the photoconductor drum 10.

The reference numeral 94 in the drawing denotes a driving I.
C, each of the light emitting portions 92a is controlled to be turned on or off due to the rotation of the photoconductor drum 10, and a latent image such as a character or a figure is formed on the photoconductor drum 10. Reference numeral 95 is a case for holding the substrate 91 and the converging rod lens array 93 at a predetermined position.

[0005]

In recent years, there has been a strong demand for printers to improve the printing quality, and for example, those having a resolution of about 600 DPI (600 dots per inch) are becoming common. In this case, the LED
The pitch P between the light emitting portions 92a of the array 92 is approximately 0.042.
The size is extremely small as 3 mm, which causes a problem that it is extremely difficult to connect the individual light emitting portions 92a to the driving IC 94, for example.

To solve this problem, for example, 20
0DPI (Pitch P between light emitting parts 92a = 0.127 mm)
Optical printer heads 90 (A,
B, C) are prepared, and each head 90 for optical printer is prepared.
With the light emitting portions 92a of (A, B, C) shifted by 1/3 pitch, the focal points FP of the optical printer heads 90A, 90B, 90C are on the surface of the photosensitive drum 10 as shown in FIG. A configuration that is arranged so as to overlap as a straight line,
Alternatively, as shown in FIG. 10, a configuration has been proposed in which the optical printer heads 90 (A, B, C) are radially arranged with respect to the rotation center RC of the photosensitive drum 10.

However, in the structure shown in FIG. 9, the three optical printer heads 90A, 90B and 90C, which are independent from each other, are accurately displaced by 1/3 pitch, that is, 0.0423 mm when assembled in the printer. Therefore, a high degree of assembling accuracy is required, and three optical printer heads 90A, 90B and 90C are close to each other in order to make the focus straight on the surface of the photosensitive drum 10. This causes a problem that assembly is difficult, for example, interference occurs in 95.

The above is the heads 90A, 9 for the optical printer.
By integrating 0B and 90C, the problem at the time of assembling into the printer can be solved, but at the time of assembling the head part at the time of this integration, the independent boards 91 are still accurately separated by 1/3. Difficult work to shift the pitch is required, and the point is to put the problem ahead of time, and it is not a drastic solution.

Further, in the structure shown in FIG. 10, three independent heads 90A, 90B, 90 for an optical printer are similarly provided.
In order to arrange C by shifting it by 1/3 pitch, there arises a problem that a high degree of assembly precision is required, and the rotating drum 1
The predetermined positions of 0 are the heads 90A and 9A for the respective optical printers.
When the positions of 0B and 90C are reached, each of them has to be exposed, and there arises a problem that the exposure takes time, and the solution of these points becomes a problem. Has become.

[0010]

According to the present invention, as a concrete means for solving the above-mentioned conventional problems, a plurality of light emitting portions are formed in a row on a single flat substrate at a predetermined pitch. N rows of the light emitting array, each row having a pitch of 1 /
The substrate assembly arranged by shifting by n and the focal point on the optical axis are shared on the same straight line, and the object points on the optical axis are aligned with the light emitting portions of the respective light emitting arrays, and the straight line is formed. SUMMARY OF THE INVENTION It is an object of the present invention to solve the problem by providing a head for an optical printer, which is composed of a lens assembly composed of n rows of converging rod lens arrays radially combined with each other.

[0011]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. 1 shows a first embodiment of the present invention, and the reference numeral 1 in the drawing is an optical printer head, and this optical printer head 1 is required to improve print quality. The conventional example is that n rows of the light emitting array having a pitch n times as large as the pitch of the dots to be prepared are prepared and the predetermined dot pitch is obtained by shifting each of the light emitting arrays by 1 / n pitch. Similar to that of.

In the following description, in order to embody numerical values and facilitate understanding, three rows of light emitting arrays having a pitch P between the light emitting portions are prepared. Therefore, each light emitting array has P rows. The following description will be given assuming that P / 3 is obtained in the dot pitch at the time of printing, with the state being shifted by / 3.

First, in the present invention, one flat substrate 2 having high dimensional accuracy such as ceramics is prepared, and three rows of light emitting arrays, for example, LED arrays 3 are provided on the flat substrate 2.
A, 3B and 3C are mounted in parallel. At this time,
As shown in FIG. 2, the LED array 3B is the LED array 3A.
On the other hand, the pitch P between the light emitting portions 3a is displaced by 1/3, and the LED array 3C is similarly displaced by 1/3 with respect to the LED array 3B.

Therefore, in the present invention, since the three rows of LED arrays 3 (A, B, C) are mounted on the flat substrate 2, the light emitting directions of the light emitting portions 3a of the respective LED arrays 3A, 3B, 3C. The central axis X of the light is emitted in a direction perpendicular to the plane substrate 2 (see FIG. 1), but as shown in FIG. That is, light is also emitted in directions other than the right angle direction.

For each of the LED arrays 3A, 3B and 3C mounted on the flat substrate 2 as described above,
Although the converging rod lens arrays 4 (A, B, C) are combined with each other, the focus FP on the optical axis Z of each of the converging rod lens arrays 4A, 4B, 4C is according to the present invention. , And is overlapped on the surface of the photosensitive drum 10 as one straight line parallel to the rotation axis.

On the other hand, the converging rod lens array 4
The object point OP on the optical axis Z of A, 4B, and 4C is, for example, the object point OP of the converging rod lens array 4A.
As for the light emitting section (row) 3a of A, each L has its own L
It is matched with the light emitting portion 3a of the ED array 3 (A, B, C).

Therefore, in the structure of the present invention, the LED array 3 is used.
When the number n of is an odd number, only the central converging rod lens array 4 is orthogonal to the LED array 3, that is,
The optical axis Z coincides with the central axis X of the light emission of the LED array 3, but the other ones are the optical axis Z and the central axis X of the light emission.
And has an inclination angle α, and L
When the number n of the ED arrays 3 is an even number, all the converging rod lens arrays 4 have an inclination angle α with respect to the LED array 3.

Having the inclination angle α firstly means that
An object point O from the focus FP to the converging rod lens array 4.
Second, it is necessary to have different dimension values up to P, and secondly, the optical axis Z of the converging rod lens array 4 and the LED.
Due to the difference in inclination angle α from the central axis X of the light emission of the array 3,
This causes a difference in brightness at the focus FP.

In the first embodiment, a converging rod lens array 4 is prepared which is suitable for the dimensional difference in the distance from the focus FP of the converging rod lens array 4 to the object point OP. The brightness difference at the focus FP is solved by appropriately adjusting the drive current of the LED array 3 (A, B, C).

Incidentally, as shown in FIG. 1, the LED array 3
Is three columns, the inclination angle α of the converging rod lens arrays 4A and 4C is 30 °, and the distance from the focal point FP of the central converging rod lens array 4B to the object point OP is 1, the rod lens The distance from the focal point FP of the arrays 4A and 4C to the object point OP is approximately 1.15.

Further, as shown in the directivity characteristic DF of FIG. 3, the brightness when the inclination angle α is 30 ° is approximately 85.
%, So from this focus FP to the object point OP
The drive current of the LED arrays 3A and 3C may be increased or the drive current of the LED array 3B may be reduced at the same rate in consideration of the loss due to the increased distance.

Further, in the above configuration, since the convergent rod lens arrays 4A and 4C have the inclination angle α, the image of the light emitting portion 3a projected on the photosensitive drum 10 is also inclined. The size of the light emitting portion 3a is as small as 0.005 mm square, and the convergent rod lens arrays 4A and 4C
Since it is within the depth of focus of, there will be no problems such as being out of focus.

It should be noted that the flat substrate 2 and the LED array 3 (A, B, C) constructed as described above are used to assemble the substrate, and three sets of converging rod lens arrays 4 (A, B, C).
The lens assembly according to (1) is integrated with the case 5 having an appropriate shape for fixing each at an appropriate position.

Next, the operation and effect of the optical printer head 1 of the present invention having the above-described structure will be described. It is assumed that the n-row LED array 3 is mounted on one flat substrate 2. , The parallelism between the LED arrays 3 and the amount of pitch to be shifted can be managed on one plane, which simplifies the work and facilitates confirmation of accuracy, which can be expected to improve accuracy. Becomes Further, once the assembly is performed, the error does not occur and the accuracy can be guaranteed.

Further, with the configuration of the present invention, the LED array 3 and the converging rod lens array 4 can all be included in the integrated optical printer head 1, so that they can be assembled in the printer. When attaching the printer, a single mounting operation is sufficient, and the work is simplified even when the printer is assembled. Furthermore, LEs of n columns
Since the image of the D array 3 is linearly combined on the photosensitive drum 10, the exposure for obtaining the latent image can be performed at one place, and the exposure can be performed in the shortest time.

FIG. 4 shows a second embodiment of the present invention. In the configuration of the present invention, the optical axis Z of the converging rod lens array 4 is used.
And the inclination angle α with respect to the central axis X of the light emission of the LED array 3 causes a difference in the distance from the focus FP to the object point OP. In the above-described first embodiment, the required distances converge. This was dealt with by preparing the sex rod lens array 4.

Here, in the second embodiment, the convergent rod lens array 4 having the same distance from the focal point FP to the object point OP corresponds to all the inclination angles α. The array 4 corresponds to the position where the distance from the focus FP to the object point OP is the shortest,
In the state of FIG. 4, a lens having a distance corresponding to the position of the converging rod lens array 4B is prepared.

Then, the converging rod lens array 4
Between the LED array 3 and the LED array 3, a plate-like member 6 formed of a transparent member having a high refractive index such as glass or resin is inserted with its plate surface orthogonal to the optical axis Z, and the converging rod lens array 4 is formed. It extends the focus FP from the object point OP to the required distance. At this time, the plate thickness t of the plate member 6 is adjusted to give the convergent rod lens array 4 a desired distance from the focus FP to the object point OP. The plate member 6 may be provided at the end of the converging rod lens array 4 on the focus FP side.

As described above, in the second embodiment,
As the converging rod lens array 4, it is sufficient to prepare one having a distance from the focal point FP to the object point OP, and it is necessary to prepare the converging rod lens array 4 having different characteristics for each different inclination angle α. Therefore, the parts management aspect is simplified, and the actions and effects other than the above are the same as those in the previous embodiment, and detailed description thereof will be omitted here.

FIG. 5 shows a third embodiment of the present invention. In the converging rod lens array 14 (A, B, C), the end face on the focus FP side and the end face on the object point OP side are parallel to each other. If
Since the lens function is not lost, in this embodiment, both the end surface on the focus FP side and the end surface on the object point OP side are parallel to the surface of the flat substrate 2 on which the LED array 3 is mounted. I am supposed to.

By doing so, the assembly of the converging rod lens array 14 and the flat substrate 2 can be performed with the surface of the flat substrate 2 as a reference, so that the LED array 3 of the converging rod lens array 14 is used. It is possible to simplify the assembly process such as positioning work with respect to, and improve the assembly accuracy.

FIG. 6 shows a fourth embodiment of the present invention, and in each of the previous embodiments, an example in which the LED array 3 is adopted as the light emitting array has been described, but the present invention is not limited to this. As shown in FIG. 6, the light emitting array may be a liquid crystal shutter array 8a configured by a fluorescent lamp 7 that is always turned on and a liquid crystal element 8 that covers the fluorescent lamp 7, and although not shown, fine dot-shaped light emission is also possible. It may be an EL array in which the parts are formed in rows.

[0033]

As described above, according to the present invention, n rows of a light emitting array in which a plurality of light emitting portions are formed in rows on a single flat substrate at a predetermined pitch, each row having the above pitch. And the substrate assembly arranged by shifting them by 1 / n, share the focal point on the optical axis on the same straight line, and make the object points on the optical axis coincide with the light emitting portions of the respective light emitting arrays. , A lens assembly composed of n rows of converging rod lens arrays that are radially combined with each other around the straight line is provided. Firstly, the head is required on one flat substrate. As many light emitting arrays can be attached, the dimensional accuracy between the light emitting arrays can be reliably set,
It is extremely effective in improving print quality.

Secondly, with the above structure, an optical printer head in which all the required numbers of the light emitting array and the converging rod lens array are incorporated is provided, and when the assembly is carried out to the printer, it is the same as the conventional one. In addition, there is no need for precise position adjustment between a plurality of optical printer heads, and the production efficiency of the printer can be improved very effectively.

Further, thirdly, the above-mentioned light emitting array and the converging rod lens array are incorporated into the head for an optical printer, so that the mutual positions of the light emitting arrays are maintained even when maintenance is performed. The relationship between the printer and the like does not change, and the performance at the time of shipment can be stably maintained. Therefore, the performance of the printer of this type can be improved effectively.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of an optical printer head according to the present invention.

FIG. 2 is an explanatory diagram showing a mount state of an LED array in the same embodiment.

FIG. 3 is a graph showing directional characteristics of an LED array in the same embodiment.

FIG. 4 is a sectional view showing a second embodiment of an optical printer head according to the present invention.

FIG. 5 is a sectional view showing a third embodiment of an optical printer head according to the present invention.

FIG. 6 is a sectional view showing an essential part of a fourth embodiment of an optical printer head according to the present invention.

FIG. 7 is a sectional view showing a conventional example.

FIG. 8 is a plan view showing an example of the configuration of an LED array.

FIG. 9 is an explanatory diagram showing an example of an arrangement of heads for an optical printer when the dot pitch is increased in density in a conventional example.

FIG. 10 is an explanatory diagram showing another example of the arrangement of the optical printer heads when the density of the dots is increased in the conventional example.

[Explanation of symbols]

 1 ... Head for optical printer 2 ... Flat substrate 3 (A, B, C) ... LED array 3a ... 4 (A, B, C), 14 ... Convergent rod lens array 5 ... Case 6 ... ... Plate-shaped member 7 ... Fluorescent lamp 8 ... Liquid crystal element 8a ... Liquid crystal shutter array 10 ... Photosensitive drum X ... Central axis of light emission Z ... Optical axis of convergent rod lens array FP ... Focus OP ... Point

Claims (7)

[Claims] 1. A light emitting array in which a plurality of light emitting portions are formed in a row on a single flat substrate at a predetermined pitch, each row being arranged with the pitch shifted by 1 / n. The substrate assembly and the focal point on the optical axis are shared on the same straight line, and the object points on the optical axis are aligned with the light emitting portions of the respective light emitting arrays and are combined radially about the straight line. N
A head for an optical printer, comprising a lens assembly composed of a row-converging rod lens array. 2. A transparent plate-shaped member having a high refractive index is inserted between the light-emitting array and the converging rod lens array, except that the distance between them is shortest. The head for an optical printer according to claim 1, wherein the focus is adjusted by adjusting the thickness of the plate-shaped member. 3. The light emission output of each row of the light emitting array is adjusted according to the tilt angle with respect to the converging rod lens array to which the row corresponds, and all the rows of the light emitting array when imaged on the straight line are formed. The head for an optical printer according to claim 1, wherein the brightness is the same. 4. The finishing of the focal-side end surface and the object-side end surface of each of the converging rod lens arrays is made parallel to the surface of the planar substrate on which the light-emitting array is mounted. The optical printer head according to claim 1, 2, or 3. 5. The head for an optical printer according to claim 1, 2, 3, or 4, wherein the light emitting array is an LED array. 6. The light-emitting array is an EL array, claim 1, claim 2, claim 3, or.
An optical printer head according to claim 4. 7. The light emitting array according to claim 1, 2, 3, or 4, wherein the light emitting array is a light source that is constantly turned on and a liquid crystal shutter array that covers the light source. Optical printer head.