Image recording apparatus

The image recording apparatus of the present invention receives data, such as the recording time interval for recording a predetermined unit of image information, and the speed of transmission of the image information coming from an image information source, and, based on the image information transmission speed and the scanning period of an optical deflector, sets the recording time interval for recording the image to an integer multiple of the scanning speed of the optical deflector, and determines and controls the transport speed of a recording material in accordance with the recording time interval. This image recording apparatus is adaptable to various image information sources (host, interface) with a wide range of transmission speeds without having to use an expensive buffer memory.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an image recording apparatus, specifically 
to an image recording apparatus that does not require the use of an 
expensive memory with a large storage capacity, and one that can be 
connected to various image information sources with different transmission 
speeds. 
2. Description of the Prior Art 
Various types of image recording apparatuses that employ raster scanning 
using a laser beam have been proposed and are being put into practical 
use. 
In this type of image recording apparatus, the image information from an 
image information source like image processing devices, such as an image 
scanner, video machine, television, computer, etc., is received in the 
form of an electrical signal. A laser beam modulated by the image 
information is reflected and deflected along a main scanning direction by 
an optical deflector. An image corresponding to the deflected laser beam 
is formed on a recording material that is transported and scanned along a 
subscanning direction that is generally perpendicular to the 
aforementioned main scanning direction. By this, the recording material is 
exposed to perform image recording by raster scanning method. 
In this type of image recording apparatus, a storage unit such as a buffer 
memory is provided for storing the image information transmitted from the 
aforementioned image information source. One recording block, for example, 
a block containing a number of pages of image or a quantity of image 
information corresponding to one sheet or one page, is stored beforehand 
in this memory, and image recording is performed based on the image 
information stored in the memory. 
In this case, in order to obtain a good image free from uneveness in 
densities and colors the process of image recording is performed as in the 
following: The light beam must be made to scan the recording material 
along the main scanning direction at a constant speed by making the 
optical deflector rotate continuously at an accurately constant speed. The 
optical deflector must be driven by a highly precise driver having small 
fluctuation in the speed of rotation. Also, the aforementioned light beam 
must be made to scan the recording material at a constant speed by making 
the aforementioned recording material move along the subcanning direction 
continuously at a constant speed. By the process described above, the 
recording material is exposed two-dimensionally. 
However, even in this image recording apparatus employing the raster 
scanning method, image recording that produces high-quality pictures with 
high-gradation is still desired. In order to perform the recording of the 
equivalent of only one page of high quality image, the number of rasters 
becomes large and, consequently, the amount of image information required 
to record one page of high-quality image becomes large. Because of this, 
the speed of transmission of the image information from the image 
information source becomes slow relative to the recording speed of the 
image recording apparatus. 
Therefore, in order to obtain a picture of good quality as mentioned above, 
image recording must be performed at a constant main scanning speed and a 
constant subscanning speed, the subscanning operation being performed 
continuously without interruption. To realize this, it is required that at 
least one page of image information transmitted from the image information 
source is first stored in a memory such as a buffer memory. The image 
information is then read from this memory and recording of the image on a 
recording material is performed. 
However, usually for image information, even for monochrome images, one bit 
of information is needed for one pixel and, for one page of image 
information, a memory with a large storage capacity is required. 
Consequently, the image recording apparatus inevitably becomes expensive. 
Further, for full color images, 8 bits of information is needed for one 
color per pixel; for the three colors R, G, and B, 24 bits of information 
is needed. Thus, a very large memory is required. Consequently, the same 
problem arises in that the image recording apparatus becomes very 
expensive. 
Also, as mentioned earlier, this type of image recording apparatus is 
connected to various image information sources and image recording is 
performed based on the image information transmitted from these sources. 
Generally, the speed of transmission of the image information is different 
depending on the image information source. Consequently, because of the 
relation of the storage capacity of the memory and the image recording 
speed, a large number of varied image information sources with widely 
varying image information transmission speeds may not be connected to the 
same image recording apparatus. 
BRIEF SUMMARY OF THE INVENTION 
The object of the present invention is to solve the aforementioned problems 
encountered in the prior art by providing an image recording apparatus 
which can be used even when it is connected to various image information 
generators that transmit the image information at different speeds, and 
which does not require an expensive memory with a large storage capacity. 
In the first aspect of the present invention, the object mentioned above is 
attained by providing an image recording apparatus wherein an image 
information coming from an image information source is received, and a 
light beam is modulated by this image information and deflected in the 
main scanning direction to cause the image to be recorded on a recording 
material being transported in a sub-scanning direction which is generally 
perpendicular to the main scanning direction; said image recording 
apparatus comprising: 
a means for setting the recording time intervals to an integer multiple of 
the scanning period of the aforementioned optical deflector in accordance 
with the speed of transmission of the image information coming from the 
image information source mentioned above; 
a means for receiving a predetermined unit of image information being 
transmitted from the image information source within the aforementioned 
recording time interval; 
a means for recording the image corresponding to the aforementioned image 
information at each recording time interval; and 
a means for changing the speed of scanning the recording material in 
accordance with the recording time interval. 
The second aspect of the present invention provides an image recording 
apparatus for recording image information transmitted from an information 
source on a recording material, wherein the image information transmitted 
from the information source is received by a light beam-source, said image 
information being transmitted such that a predetermined unit of image 
information is transmitted at a predetermined speed within a predetermined 
recording time interval; the image information received by the light-beam 
source is converted to a light beam corresponding to the image 
information; the light beam is deflected by means of an optical deflector 
in a main scanning direction, the optical deflector being moved at a 
predetermined scanning cycle such that the recording time interval 
correspond to at least one scanning periods; and an image is recorded at 
the predetermined recording time interval on the recording material which 
is transported in a direction perpendicular to the main scanning direction 
for a sub-scanning; 
said image recording apparatus being provided with a means for setting the 
recording time interval to an integer multiple of the scanning period of 
the optical deflector, based on the image information-transmission speed 
from the information source; 
a means for receiving the predetermined unit of the image information 
transmitted from the image information source within the recording time 
interval; 
a means for recording the image on the recording material at the 
predetermined time interval within an effective image recording period; 
and 
a means for adjusting the sub-scanning speed of the recording material to 
correspond to the recording time interval. 
In a preferred embodiment of each aspect, said recording time interval 
correspond to at least two scanning periods of the light deflector, and 
the image recording is carried out within one scanning period of the 
recording time interval, and no recording is carried out during other 
scanning periods within the same recording time interval. 
In another preferred embodiment of the present invention, said recording 
time interval correspond to one image recording scanning line and the 
image recording is carried out within one scanning period of the recording 
time interval, and an energy at predetermined level independent of the 
level of the image information is supplied to the light beam-source at 
least for the image recording period included within the period starting 
from the position in non-recording scanning period immediately before the 
image recording scanning period corresponding to the completion position 
of the effective image recording period ending at the position in 
non-recording scanning period immediately after the image recording 
scanning period corresponding to the starting position of the effective 
image recording period. 
BRIEF DESCRIPTION OF THE DRAWINGS 
FIG. 1 is a schematic diagram showing an embodiment of the image recording 
apparatus of the present invention. 
FIG. 2 is a time chart showing the operation of the image recording 
apparatus shown in FIG. 1. 
FIG. 3 is a time chart showing the operation of another embodiment of the 
image recording apparatus of the present invention. 
FIG. 4 is a time chart showing the operation of still another embodiment of 
the image recording apparatus of the present invention. 
FIG. 5 is a time chart showing the energy supplying operation to light 
source of the image recording apparatus shown in FIG. 1. 
FIG. 6 is a schematic diagram of a copying machine equipped with the image 
recording apparatus shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION 
In the image recording apparatus of the present invention, the image 
information transmission speed of an image information source like an 
image processing device such as an image scanner, computer, etc., or the 
transmission time interval of a predetermined unit of image information, 
for example, one line of image, is detected and, based on this image 
information transmission speed and the scanning period of the optical 
deflector, the recording time interval for recording an image is set to an 
integer multiple of the scanning period of the optical deflector and the 
transport speed of a recording material is set and controlled in 
accordance with the aforementioned recording time interval. 
In other words, a predetermined unit, for example, one line of image to be 
recorded, is defined, and the light source is made to illuminate only on 
the predetermined line to be scanned during the aforementioned recording 
time interval. Then, there is a non-recording state, also within this 
recording time interval, wherein the light sources become inactive and the 
next line is not scanned until the transmission of the next line of image 
information from the image information source is completed. 
As a result, the need for a memory with a large storage capacity such as a 
buffer memory is eliminated, instead, it can be substituted with an 
inexpensive memory with small storage capacity, for example, a memory that 
stores one or two lines of image information. Thus, compared to the image 
recording apparatus of the prior art which required a memory with a large 
storage capacity for one page of image information, an inexpensive image 
recording apparatus, particularly a very cheap color image recording 
apparatus, can be realized. 
Also, as mentioned earlier, since the recording time interval is set in 
accordance with the image information transmission speed of the image 
information source despite the fact that a memory with small storage 
capacity is used, various image information sources with different image 
information transmission speeds can be connected to the image recording 
apparatus. 
Further, even if the timing relationship of the transmission of the image 
information and the image recording is adjusted through the setting of the 
recording time interval, a stable image recording performance can be 
maintained always by setting the operating speed of the optical deflector 
at a fixed speed and setting the scanning speed of the recording material 
being recorded with the image at a constant speed. 
The image recording apparatus of the present invention will be described in 
more detail below using a preferred embodiment shown in the attached 
illustrations. 
A schematic diagram of an embodiment of the image recording apparatus of 
the present invention is shown in FIG. 1. 
The image recording apparatus 10 shown in FIG. 1 is connected to various 
types of image information sources 12, such as an image scanner, image 
information processing device, computer, and others, and performs color 
image recording on a recording material A based on the image information 
transmitted from the image information source. Basically, in this image 
recording apparatus used for recording color images, laser beams, each 
corresponding to the exposure of red (R), green (G), or blue (B) light 
depending on the image information transmitted from the image information 
source, are emitted and deflected in the main scanning direction by means 
of an optical deflector, and scans the recording material A being 
transported in the direction shown by the arrow "P" to expose the 
recording material A two-dimensionally. 
This image recording apparatus 10 detects the transmission speed of the 
image information coming from the image information source 12 and sets the 
recording time interval based on this detected speed. The image recording 
apparatus 10 is further provided with: A command discriminating unit 14 
which informs the other parts of the image recording apparatus of the 
recording time interval, thereby controlling them; a memory unit 16 for 
temporarily storing the image information sent from the image information 
source 12; a gradation transforming unit 18 which transforms the image 
information into a gradation signal; a modulating unit 20 which modulates 
the laser beam using the gradation signal as a modulating signal; a motor 
controlling circuit 22 which changes and controls the transport speed of 
the recording material A in accordance with the recording time interval 
that has been set; a recording mechanism 30 which performs the recording 
of the image by exposing the recording material A and comprises the laser 
beam sources 28R, 28G, and 28B, a driving circuit 24 which drives each of 
the laser beam sources based on the image information that has been 
modulated by the modulating unit 20, and a polygonal mirror 26 which 
serves as an optical deflector. 
The command discriminating unit 14 detects the transmission speed of the 
image information coming from the image information source 12 and sets the 
recording time interval for image recording based on the detected speed. 
This time interval is set to a time corresponding to the scanning period 
of the optical deflector, that is, to an integer multiple of the period of 
rotation of the polygonal mirror 26 as shown by the example in the figure. 
The command discriminating unit 14 also sends information on the recording 
time interval to the memory unit 16, gradation transforming unit 18, 
modulating unit 20, and motor controlling circuit 22 thereby controlling 
each of these. 
It is noted here that the image information transmission speed as used in 
the present invention can either be the transmission speed or the time 
required to transmit a predetermined unit of information, for example, one 
line of image information. 
The recording time interval is the time interval between the start of the 
image recording session of a predetermined unit of image information, and 
the start of the image recording session of the following predetermined 
unit of image information. As mentioned earlier, the recording time 
interval is set in accordance with the transmission speed of the image 
information. In other words, in the image recording apparatus 10 of the 
present invention, the recording time interval is set such that, during 
the interval that includes the start of a particular image recording 
session up to the start of the next image recording session, the 
transmission of a predetermined unit of image information from the image 
information source 12 is completely done. 
Therefore, in the image recording apparatus 10 of the present invention, 
after completion of a particular image recording session, during the 
interval starting from the point of completion of a particular image 
recording session up to the start of the next image recording session, the 
laser beam sources 28R, 28G, and 28B are not driven to operate, or are in 
a non-recording state (or in a state wherein the currents flowing through 
the laser sources are just the bias currents). 
For example, in the image recording apparatus 10, it is assumed that the 
scanning period is 2.0 ms/line, the transmission time (image information 
transmission speed) of the image information source 12 is 10.0 ms/line 
maximum, and the amount of image information in a predetermined unit is 
one line of image information. 
The apparatus shown as an example in the figure has a toggle memory (to be 
described in more detail later) in the memory unit 26 which stores the 
equivalent of two lines of image information. In this case, the command 
discriminating unit 14 can set the recording time interval to 10.0 ms as 
the time it takes to record the image information stored in one of the 
memories 16a and the time it takes to complete the transmission of one 
line of image information into the other memory 16b, both recording and 
transmission being done simultaneously within the specified interval. 
In other words, as shown in FIG. 2, in this case, after one line of image 
(one scan, corresponding to one face of the polygonal mirror 26) has been 
recorded, there is a non-recording interval corresponding to 4 lines of 
image (4 scans, corresponding to 4 faces of the polygonal mirror 26). The 
recording operation consists of a repetition of this basic procedure. 
Therefore, the transmission of a predetermined unit of image information 
can be completed while the apparatus is in a non-recording state, and 
image recording can be done at a constant rate without having to change 
the scanning period (speed of rotation of the polygonal mirror 26) or 
having to stop the transport and scanning of the recording material A as 
the transport speed and scanning of the recording material A are adjusted 
in accordance with the recording time interval. 
In the image recording apparatus 10 of the present invention, the 
aforementioned recording time interval is set to an integer multiple of 
the scanning period, that is, to an integer multiple of the period of 
rotation of the polygonal mirror 26 in the embodiment of the apparatus 
shown in the figure. 
By setting the recording time interval in the manner mentioned above, there 
is no possibility of the image recording operation's being performed 
midway through a scanning line even if the image recording and 
non-recording states are alternated. Thus a good image recording 
performance can be realized. 
Also, as shown in FIG. 2, the command discriminating unit 14 generates and 
sends a completion signal to the image information source 12 after each 
recording time interval. In the embodiment shown in the figure, the image 
information source 12 is configured to receive this completion signal and 
then transmit the image information to the memory unit 16. 
The memory unit 16 serves as a temporary storage for the predetermined unit 
of image information that has been transmitted by the image information 
source 12. In the image recording apparatus 10, two memories 16a and 16b, 
each capable of storing one line of image information, are provided. These 
two memories make up a toggle memory that stores two lines of image 
information and is configured to be capable of switching--the memories 16a 
and 16b are configured to alternatively switch to store and read 
operations by means of the toggle switches 32a and 32b. 
The switching of the toggle switches 32a and 32b is such that they operate 
under the control of the command discriminating unit 14, in accordance 
with the recording time interval that has been set. 
In the memory unit 16, while the recording of the image information stored 
in one of the memories, for example, memory 16b in the case wherein the 
toggle switch 32b is connected to the memory 16b as shown in the example 
in the figure (FIG. 2, recording, "P"), the other memory 16a is connected 
to the image information source 12 by means of the toggle switch 32a and 
is configured to store the image information being transmitted to it (FIG. 
2, transmission of information, "b"). 
As mentioned earlier, since the transmission of the image information takes 
longer than image recording, even when the recording of the image 
information from memory 16b has been completed, image information from the 
image information source 12 continues to be transmitted to memory 16a and 
storage of this image information continues to be done. However, the image 
recording apparatus 10 of the present invention is in a non-recording 
state during this period within the recording time interval, and the 
apparatus is configured such that the transmission of the predetermined 
unit of image information is completed before the next image recording 
session. 
When the predetermined recording time interval has passed after the start 
of a particular image recording session, the command discriminating unit 
14 sends a signal to the memory unit 16 and the toggle switches are 
actuated. The toggle switch 32b becomes connected to memory 16a, and, at 
the same time, the toggle switch 32a becomes connected to memory 16b. 
While recording of the image information stored in memory 16a is being 
done (FIG. 2, recording, "b"), memory 16b is receiving and storing the 
image information being sent by the image information source 12 which 
starts transmission after receiving a completion signal from the command 
discriminating unit 14 (FIG. 2, information transmission, "c"). 
Therefore, in the image recording apparatus 10 of the present invention, 
the memory unit 16 is required only to have the capacity to store the 
predetermined unit of image information and the speed of storage to do so 
within the recording time interval. Put in another way, it is necessary to 
set the recording time interval in accordance with the capability of the 
memory unit 16. 
In the example described above, the image information source 12 is 
configured to start transmitting the image information to the memory unit 
16 upon receiving the completion signal from the command discriminating 
unit 12. However, when the image information source 12 and the memory unit 
16 make a handshake every time a unit of image information is transmitted, 
instead of the aforementioned completion signal, the timing for the 
transmission of the image information from the image information source 12 
to the memory unit 16 can be obtained by stopping (standby operation) the 
transmission of the image information from the image information source 12 
during the intervals indicated by the shaded portions shown in FIG. 3. 
This is done by extending the handshake signal after the transmission of 
the last unit up to the point immediately before the start of the next 
recording session (after the recording time interval has passed). 
Also, when the image information source 12 and the memory unit 16 make a 
handshake every time a unit of image information is transmitted, a memory 
that can store only one line of image information can be used as the 
memory unit 16 instead of the toggle memory mentioned earlier. This can be 
achieved by letting the handshake signal, at the start of the unit of 
image information that is transmitted, indicate a standby state until 
after the completion of a recording session (within the recording time 
interval), that is, during the interval shown by the shaded portions in 
FIG. 4. 
Further, the memory unit 16 is not limited to the aforementioned toggle 
memory that can store two lines of image information. A toggle memory that 
can store two or more lines, or one memory that can store one line of 
image information, can be used. In other words, in the present invention, 
one only has to ascertain that the recording time interval is set in 
accordance with the capability of the memory unit 16. 
The image information read from the memory unit 16 is subsequently sent to 
the gradation transforming unit 18 where it is transformed into a 
gradation signal appropriate for image recording on the recording material 
A then sent to the modulating unit 20. 
An actuating signal is sent by the command discriminating unit 14 to the 
gradation transforming unit 18 in accordance with the recording time 
interval. The gradation transforming unit 18 is configured to be actuated 
by the actuating signal in accordance with the recording time interval and 
it transforms the received image information into gradation signals. 
The gradation signal coming from the gradation transforming unit 18 is 
subsequently sent to the modulating unit 20. The modulating unit 20 
modulates the laser beams emitted by the laser beam sources 28R, 28G, and 
28B in the recording mechanism 30 in accordance with the received 
gradation signals, and sends the modulated signal to the driving circuit 
24 of the recording mechanism 30. 
An actuating signal is sent by the command discriminating unit 14 to the 
modulating unit 20 in accordance with the recording time interval, and the 
modulating unit 20 is actuated by this signal in accordance with the 
recording time interval. 
As mentioned earlier, since the image recording apparatus 10 of the present 
invention operates by repetition of a state of recording of a 
predetermined unit of image information such as a line, and a 
non-recording state in accordance with the recording time interval that 
has been set, it is necessary to make each of the laser beam sources emit 
the laser beams in accordance with the recording time interval. To achieve 
this, the modulating unit 20 must detect the signal related to the 
recording time interval, send the modulated signal to the driving circuit 
24 of the recording mechanism 30 in accordance with this recording time 
interval, and control the emission of the laser beams from the laser beam 
sources. 
The recording mechanism 30 performs the image recording operation. It emits 
laser beams in accordance with the modulated signal transmitted by the 
modulating unit 20. These laser beams are reflected and deflected in the 
main scanning direction by the polygonal mirror 26 to two-dimensionally 
scan and expose the recording material A being scanned and transported in 
the direction shown by the arrow "P". 
This type of recording mechanism 30 basically has a driving circuit 24 that 
drives each of the laser beam sources in accordance with the modulated 
signal sent by the modulating unit 20; a laser beam source 28R that emits 
a laser beam having a wavelength corresponding to the exposure of red 
light for producing cyan color, a laser beam source 28G that emits a laser 
beam having a wavelength corresponding to the exposure of green light for 
producing magenta color, and a laser beam source 28B that emits a laser 
beam having a wavelength corresponding to the exposure of blue light for 
producing yellow color; and a polygonal mirror 26 that serves as an 
optical deflector for reflecting and deflecting the laser beams emitted by 
the laser beam sources in the main scanning direction. The deflected beam 
is a composite of the three individual beams with their optical axes 
brought into alignment with one another. 
The driving circuit 24 drives each of the laser beam sources to make them 
emit a laser beam in accordance with the modulated signal transmitted by 
the modulating unit 20. Since the image recording apparatus of the present 
invention performs the image recording operation in accordance with the 
recording time interval that has been set, the modulated signal from the 
modulating unit 20 is sent to the driving circuit 24 in accordance with 
the same recording time interval, and the driving circuit 24 actuates each 
of the laser beam sources in accordance with this recording time interval. 
Each of the laser beams, emitted by the laser beam sources 28R, 28G, and 
28B passes, through and is shaped by respective collimator lenses 34R, 
34G, and 34B. Subsequently, after the beams are aligned by a mirror 36R 
and dichroic mirrors 36G and 36B at their optical axes to form one 
composite beam, this composite beam is reflected by a mirror 38 in a 
predetermined direction and launched onto the polygonal mirror 26. 
The laser beams incident upon the polygonal mirror 26 are reflected and 
deflected in the main scanning direction, pass through an "f-theta" lens 
40, and are bent downward by a rectangular mirror 42 to two-dimensionally 
scan and expose the recording material A that is being transported in the 
subscanning direction indicated by the arrow "P", causing the image to be 
recorded on the recording material A. 
In the image recording apparatus 10 of the illustrated example, the 
recording material A is held and transported by a pair of rollers 44. 
This pair of rollers 44 is connected to a motor 46 that serves as a driving 
source. The speed of rotation of this motor 46 is changeable and is 
controlled by a motor controlling circuit 22. A control signal 
corresponding to the recording time interval set by the command 
discriminating unit 14 is sent to the motor controlling circuit 22, and 
the motor controlling circuit 22 causes the speed of rotation of the motor 
46 to change in accordance with the recording time interval. 
As mentioned earlier, the image recording apparatus 10 of the present 
invention operates by repetitions of a state of recording an image on a 
recording material A being scanned and transported at a constant speed, 
and a non-recording state. Consequently, the interval of the scanning 
lines for image recording must be set appropriately and, to be able to 
perform good image recording, the speed of scanning and transport of the 
recording material A must be adjusted appropriately in accordance with the 
recording time interval that has been set. 
The amount of adjustment of the transport speed of the recording material 
can be suitably determined by setting the interval of the scanning lines 
to be equal to that of normal image recording. In the previous example, 
since there is a non-recording interval corresponding to four lines of 
image information after each recording of one line of image, the transport 
speed of the recording material can be set to 1/5 of the normal speed. 
Therefore, in the image recording apparatus 10 in the illustrated example, 
the motor 46 is not limited to a particular type as long as it is one that 
has a changeable speed of rotation, and various motors such as a pulse 
motor, and others, can be employed. 
In the image recording apparatus that makes use of a laser beam, a bias 
current small enough so as not to let the recording material A be under 
constant exposure (coloring) is allowed to flow through each of the laser 
beam sources in order to obtain a stable laser beam output. 
However, as mentioned earlier, the image recording apparatus 10 of the 
present invention performs image recording at the aforementioned recording 
time interval with a non-recording state within said interval, and the 
transport speed of the recording material A is made slow in accordance 
with the recording time interval. Therefore, when the bias current is 
allowed to flow during the non-recording period, the recording material A 
will become exposed and will color. 
Because of this, in the image recording apparatus 10 of the present 
invention, the bias currents flowing through each of the laser beam 
sources is preferably controlled to flow only at least during the 
effective recording period within an interval starting from a point 
corresponding to the completion point of the effective image recording 
period of the line immediately preceding the line to be recorded, and 
ending at a point corresponding to the starting point of effective image 
recording period of the line immediately following the line to be 
recorded. 
In other words, in the image recording apparatus 10 of the present 
invention, in order to make the laser beams used for image recording 
stable, as shown by the shaded portions in FIG. 5, the bias currents 
allowed to flow through each of the laser beam sources must be controlled 
to flow during the period of emission of the laser beams within the 
recording time interval. Except for these periods, that is, during the 
non-recording periods, the bias current must not be allowed to flow. Now, 
in FIG. 5, the bias current flowing every 2 ms is a bias current flowing 
through the laser beam sources that is used to detect the SOS (start of 
scanning), and is different from the bias current mentioned above. 
Also, as shown by the dashed lines in FIG. 5, the bias current for 
stabilizing the laser beams may be allowed to flow through the laser beam 
sources starting from the point corresponding to the point of completion 
of the effective image recording period in the recording time interval of 
the line immediately preceding the line to be recorded. 
In the image recording apparatus 10 of the present invention, as in the 
conventional image recording apparatus, the bias current may be made to 
flow continuously into the laser beam sources and then employ a 
construction in which the laser beams being emitted through the action of 
the bias current can be blocked by means of a shutter which can come in 
various types. 
By employing the construction described above, the image recording 
apparatus 10 of the present invention is able to produce good images with 
stable concentration. 
In the operation of the image recording apparatus 10 described above, the 
command discriminating unit 14 detects the transmission speed of the image 
information coming from the image information source 12 and sets the 
recording time interval. However, the present invention is by no means 
limited to this type of operation, and the recording time interval may be 
set in relation to the image information source by means of an external 
input. 
FIG. 6 shows a copying machine employing the described image recording 
apparatus 10 of the present invention. For the recording material, this 
machine uses a recording material (light-sensitive material) A which has a 
light-sensitive layer and a transfer forms image on an image-receiving 
material having a receiving layer in an image-forming solvent such as 
water, and requires a thermo-development process. 
The housing 82 of the copying machine 80 is provided with a recording 
material supply unit 84 containing the recording material A; an image 
exposing unit 70 that exposes the recording material A to form a latent 
image after reading and processing the image information from a document; 
and an image forming unit that comprises a water-applying section 86 in 
which water is applied onto the recording material A, an image-receiving 
sheet supply section 88 which contains the image-receiving sheet C, a 
superposing section 90 in which the image-receiving sheet is superposed on 
the recording material A, a thermal development/transfer section 92 in 
which the superposed recording material A and the image-receiving sheet C 
are heated, and a detaching section 94 for separating the image-receiving 
sheet C from the recording material A. 
The document S is placed on a transparent platen 50 provided on top of the 
housing 82. The image exposing unit 70 is positioned below the platen 50. 
The image exposing unit 70 comprises a reading mechanism 72 and the image 
recording apparatus 10 of the present invention described earlier. 
In the copying machine 80 of the illustrated example, the reading mechanism 
72 performs the operation of the image information source 12 shown in FIG. 
1 of the image recording apparatus 10 of the present invention. 
The reading mechanism 72 comprises a light source 74 that is movable in the 
scanning direction beneath the platen 50, a mirror 76a that moves together 
with the light source 74, mirrors 76b and 76c that move in the same 
direction as the light source 74 but at one-half its speed, an imaging 
lens 78, a CCD sensor 79, and a control circuit 81. 
The control circuit 81 is connected to the image recording apparatus 10 of 
the present invention. 
The image recording apparatus 10 is the same as that shown in FIG. 1. 
Therefore, the constituent parts will not be described in detail; suffice 
it to say that the same parts will be indicated by the same numbers. 
In the copying machine of the illustrated example, the light source 74 
illuminates the underside of the original S as the light source scans the 
document in the subscanning direction. The light reflected from the 
document is reflected by the various mirrors, focused by the imaging lens 
78, and launched into the CCD sensor 79 where the light is time-divided 
and subjected to photoelectric conversion. The resulting data is then sent 
to the control circuit 81. The control circuit determines the conditions 
for the emissions from each of the laser beam sources according to the 
received data and sends a signal to the image recording apparatus 10 of 
the present invention. 
The image exposing unit 70 is optically isolated from the other parts of 
the copying machine by means of a partition 98 except for an aperture 96 
through which the light beam for exposing the recording material A will 
pass. 
A detachable magazine 106 containing a roll of the recording material A is 
loaded in the light-sensitive material supply unit 84. The recording 
material supply unit 84 is also provided with pairs of rollers 110a-110d 
for transporting the recording material A up to an exposure position 108. 
Here, a cutter 112 for cutting the recording material A into predetermined 
lengths is provided between the roller pairs 110a and 110b. Also, an 
exposure table 114 provided between the roller pairs 110c and 110d faces 
the exposure aperture 96 formed on the partition 98 enclosing the image 
exposing unit 70. 
Now, as in FIG. 1, a motor controlling circuit 22 is connected to the 
driving source (not shown in the figure) of the pairs of rollers. The 
controlling circuit 22 controls and adjusts the transport speed of the 
recording material A in accordance with the recording time interval that 
has been set. 
A transport path comprising a pair of rollers 110e and a guide plate is 
provided ahead of the exposure position 108 (the term "ahead of" as used 
here means downstream, that is, in the direction of motion of the 
recording material, etc.). 
The recording material A in the exposure position 108 is subjected to 
two-dimensional imagewise exposure to form a latent image. The recording 
material A with the latent image formed on it is transported to the water 
applying section 86 via the aforementioned transport path. 
The water applying section 86 serves to facilitate the transfer of the 
latent image formed on the recording material A. It comprises a water tank 
120 filled with water, a guide plate 118 for guiding the recording 
material A through the water, a pair of roller 110f for transporting the 
recording material A along the guide plate 118, and a pair of squeezing 
rollers 116 that squeezes off the excess water from the recording material 
A which has swelled with the water it has absorbed. 
The recording material A applied with water is transported to the 
superposing section 90 by the pair of squeezing rollers 116. 
The image-receiving sheet supply section 88 that supplies the 
image-receiving sheet C is provided on the right-hand side of the housing 
82. The image-receiving sheet supply section 88 is loaded with a magazine 
122 containing a roll of the image-receiving sheet C. The image-receiving 
sheet C is drawn from the magazine 122 by means of a pair of roller 110g 
and is cut into predetermined lengths by a cutter 124 provided ahead of 
the pair of rollers 110g. 
The cut image-receiving sheet C is transported to the aforementioned 
superposing section 90 by a pair of rollers 110h. 
The thermal development/transfer section 92 is provided ahead of the 
superposing section 90. This thermal development/transfer section 92 heats 
the superposed recording material A and image-receiving sheet C to develop 
the latent image on the recording material A and then transfer the 
developed image onto the image-receiving sheet C. 
The thermal development/transfer 92 is enclosed by a heat-insulating 
partition 126 and includes a hollow cylindrical heating drum 130 
containing a halogen lamp 128 and an endless belt 136 that is wound around 
the heating drum 130 about an angle of about 270 degrees and is supported 
by four belt-supporting rollers 132, 133, 134, and 135. The recording 
material A and the image-receiving sheet C are superposed while they are 
being heated and, by this heating process, the latent image on the 
recording material A is developed and transferred in color onto the 
image-receiving sheet C. 
The detaching section 94 is provided within the space defined by the 
partition 126. This detaching section 94 comprises a first detaching claw 
138 for separating the recording material A from the image-receiving sheet 
C, a second detaching claw 140 for separating the image-receiving sheet C 
from the heating drum 130, and a roller 142 for discharging the 
image-receiving sheet C out of the partition 126. 
A disposal tray 144 for containing the recording material A that has been 
separated by the detaching claw 138 from the image-receiving sheet C and a 
pair of rollers 110i that leads the recording material A into the disposal 
tray 144 are provided on one side ahead of the thermal 
development/transfer section 92. 
Also, on another side ahead of the thermal development/transfer section 92 
are provided a receiving tray 146 for receiving the image-receiving sheet 
C that has undergone heating, and pairs of rollers 110j, 110k, and 110l 
for transporting the image-receiving sheet to the receiving tray 146. The 
image-receiving sheet C with the image transferred onto it is led to and 
contained in the receiving tray 146. 
The image recording apparatus 10 of the present invention has been 
described above using a representative case wherein it was applied to a 
copying machine that uses a type of recording material A which is heated 
to develop and transfer an image onto an image-receiving material having 
an image-receiving layer in the presence of an image-forming solvent such 
as water, and others. It should be understood, however, that the color 
image recording apparatus of the present invention is also applicable to 
other forms of image recording apparatuses like copying machines and 
printers such as image-forming apparatuses that make use of the same type 
of image recording material A, copying machines, and image forming 
apparatuses that make use of electrophotography and silver halide 
photographic materials. 
The image recording apparatus related to the present invention has been 
constructed as described above but the present invention is in no way 
limited to the aforementioned construction. Needles to say, it is possible 
to add various modifications in design and other improvements within a 
scope that does not depart from the spirit of the present invention. 
As described in detail above, the image recording apparatus of the present 
invention detects the recording time interval of a predetermined unit of 
image information and the transmission speed of the image information from 
various types of image information sources and, based on the image 
information transmission speed and the scanning period of the optical 
deflector, sets the recording time interval for image recording to an 
integer multiple of the scanning period of the optical deflector. The 
transport speed of the recording material is likewise determined and 
controlled based on the aforementioned recording time interval. 
Consequently, an inexpensive memory with a small storage capacity, for 
example, one that can store one or two lines of image information, can be 
used. Thus, compared to the prior image recording apparatus which required 
an expensive, large-capacity memory needed to store one page of image 
information, a cheap image recording apparatus can be realized, 
particularly very cheap for color image recording apparatuses which 
process a very large amount of image information. 
Also, since the recording time interval is set according to the speed of 
transmission of the image information coming from the image information 
source as mentioned above, various image information sources with 
different image information transmission speeds can be connected 
regardless of the fact that a memory with small storage capacity is used. 
Further, even when the timing between the transmission of the image 
information and image recording is adjusted through the setting of the 
recording time interval, a stable image recording performance can be 
maintained by keeping the operating speed of the optical deflector 
constant and also by keeping the scanning speed of the recording material 
constant during image recording. 
It is also preferred that the energy, for example, the bias current for 
stabilizing the light beam, be supplied to the light source at least 
during the effective image recording period within the interval starting 
from a point corresponding to the point of completion of the effective 
recording period of the line immediately preceding the line to be recorded 
and ending at a point corresponding to the starting point of the effective 
image recording period of the line following the line to be recorded. By 
keeping the unwanted laser beam from illuminating the recording material 
during the non-recording state, a good and stable image, without 
unevenness and with better color concentration, can be recorded.