Bar-code printing apparatus

Abstract: A bar code printing apparatus includes a rotary encoder (18) for outputting encoder pulses (EP-A,EP-B) in different two phases. A direction in which said film (15) is transported is discriminated on the encoder pulses and indicated by a forward direction pulse indicating or a reverse direction pulse every predetermined length of transportation of the film. A direction discriminating circuit (82) comprises a clock pulse generator (80) for generating clock pulses on a frequency higher than that on which the encoder pulse is output, a first delay circuit (95) for delaying slightly the clock pulse (CL), a latch circuit for latching one of the encoder pulses in synchronism with the clock pulse to output a transportation signal; a second delay circuit for delaying the transportation signal; and two AND gates, each connected to said first and second delay circuits and said latch circuit, for outputting a forward direction pulse and a reverse direction pulse, respectively.

Description: The present invention relates to a bar code printer as defined in the preamble of claim 1 by which a photosensitive product is provided with latent images of bar codes during the manufacture of the photographic product. In the manufacture of photosensitive products such a photographic films or the like (which is hereinafter referred simply to as a film), it is usual to provide a film with latent images of bar codes indicating necessary information including frame numbers as well as of the frame numbers which are later Photographically developed during the processing of the exposed film. The bar codes are automatically read by an optical reader or other bar code readers to provide information of the film. In particular, when printing extra prints from the film, bar code is automatically read to place a frame of the film of which a print is required in a printing position. The bar code is also printed on a print and used to identify the frame number of the film from which the print was made. If the bar code reader makes an error in reading the bar code of a customer's film, a printer automatically makes a print different from the customer's request. Accordingly, strict quality control should be maintained in printing bar-codes on films. To indicate frame numbers by bar codes printed on a film, a DX bar code system which is heretofore used to indicate a manufacturer or the like, may be available to print a bar code indicating a frame number after a DX code on the film. However, because a frame number bar code after DX code needs a wide space, it often happens that frame number bar codes locate between adjacent frames and are divided separately when the film is cut to several strips. Because actually exposed frames are not always accurately located on the side of frame number bar codes, the wider the space occupied by each frame number bar code is, the higher the chances of cutting frame number bar codes becomes. In the DX bar code system, the film is formed with notches in one margin thereof one for each exposed frame upon being processed. The notch is used to provide a timing signal in order to locate each frame in a proper exposure position of a printer upon making extra prints from the film. If the notch is formed in the film at a location where a frame number bar code is printed, it is hard to read the frame number bar code. Therefore, it is difficult to form notches in a film on which frame number bar codes are previously printed and automatically read upon making prints. In view of the above, a superior printing system is such a system as forming no notches in the film with frame number bar codes. However, the film without notches can not provide timing signals for read the frame number bar codes and accordingly, the frame number bar codes themselves should be positively read. This causes the requirement of printing a higher quality of frame number bar codes than conventional DX bar codes on the film. To print the frame number bar codes with a high quality, not only a printing head should form an optical pattern of bar code which is sharp and uniform in density but also the film to be printed should be placed in a accurate position upon printing the bar codes in order to avoid double exposures. A double exposed bar code is often formed due to the reverse movement of film the which is caused by the fluttering of a moving film, oscilations of a film upon the film stops or a play of gears having backrush included in a film transporting system. US-A-4,548,492 discloses a side printing apparatus in cooperation with a control system comprising a rotary encoder for providing encoder pulse signals in different two phases in synchronism with the transportation of film, a direction discriminator for discriminating a direction in which a film is transported to provide a forward direction signal or a reverse direction signal, an up-down counter for starting to count up the reverse direction signals and count down the forward direction signals and means for stopping a light emitting printing head until the up-down counter counts down to zero (0). Another type of side printing apparatus, known from, for example, Japanese Unexamined Patent Publication No. JP-A-63 106633 (1988), comprises an up-down counter for counting up forward direction pulse signals from a direction discriminator and counting down reverse direction pulse signals from the same. A carry signal of the up-down counter is used as a print timing signal. In such a side printing apparatus, the up-down counter counts down reverse direction pulse signals after the reverse of transportation of a film, so that the amount of movement in the reverse direction can be effectively detected. Because of counting up and down forward direction pulse signals and reverse direction pulse signals in the above noted side printing apparatus, it is essential that forward and reverse direction signals do not overlap upon each other. However, in the case of generating the forward and reverse direction pulse signals from the encoder pulse signals different in phase, if the film violently oscilates in its moving direction, it often happens to provide a reverse direction pulse signal or a forward direction pulse signal immediately after a forward direction pulse signal or a reverse direction pulse signal, respectively, depending upon the amplitude and cycle of oscilation of the film. Because, in such a case, a reverse direction pulse signal or a forward direction pulse signal rises before a forward direction pulse signal or a reverse direction pulse signal falls, respectively, the up-down counter makes an error not to count either one of the forward or the reverse direction pulse signal. That is, because of the direction discriminator consisting of a logic integral circuit to determine an encoder pulse signal signal to be in a high level (H) or in a low level (L) with a threshold level, if the film oscilates at the transition of an encoder pulse signal between the high level (H) and the low level (L), the rotary encoder repeatedly turns in both directions, so as to provide incomplete encoder pulse signals. Accordingly, the conventional direction discriminator is difficult to positively follow the changes of film moving direction so as to make the measurement of film transportation with a high accuracy. This leads to a difficulty of completely preventing a double exposure, thereby printing a sharp pattern of bar code on a film which is automatically readable by means of a bar code reader. It is, therefore, an object of the present invention to provide a bar code printer which can accurently detect the movement of the film. This object is solved by a bar code printer having the features of patent claim 1. Preferred embodiments are subject to the dependent claims. The above and other objects and features of the present invention will be apparent from the following description of preferred embodiments when taken in conjunction with the appended drawings, wherein like parts or elements are designated by like reference characters throughout the views of the drawings and in which: Figure 1 is a schematic illustration showing a side printer in accordance with the present invention; Figure 2 is an illustration showing part of a film on which patterns or bar codes are side printed; Figure 3 is a diagram showing details of a pulse generator and a print timing discriminator incorporated in the side printer of Fig. 1; Figure 4 is a diagram showing an essential part of the circuit diagram of Fig. 3; Figure 5 is a timing chart showing various signals used in the circuit of Fig. 4; Figures 6 and 7 are diagrams showing variations of the circuit of Fig. 4; Figure 8 is a diagram showing a variation of the circuit of Fig. 4 in which monostable multivibrators are used; Figure 9 is a timing chart showing various signals used in the circuit of Fig. 8; Figures 10 and 11 are diagrams showing variations of the circuit of Fig. 8; Figure 12 is a timing chart for explaining the function of correcting reversed film. Referring to the drawings, in particular to Fig. 1, a side printer used in printing bar codes in a side margin of a film in which the present invention is embodied is shown. A film 15 is transported at a constant speed in one direction (which is hereinafter referred to as a forward direction) shown by an arrow by means of a measuring roller 16. The rotation of the measuring roller 16 is monitored by a rotary encoder 18 to to output two phase signals indicating a transported length of film to a pulse generator 20. The pulse generator 20 outputs pulse signals of which number is proportional to the transported length of film to a printing timing discriminator 21. The printing timing discriminator 21 which includes a counter for counting the pulse signals from the pulse generator 20, outputs a timing pulse signal upon counting a predetermined number of pulse signals to CPU 22. Upon receiving the timing signal, CPU 22 outputs an instruction signal for causing an exposure apparatus 24 of the side printer to make an exposure. CPU 22 is connected with a printing data setting unit 25 in which print pattern data and various necessary data are stored in its self-contained memory. Upon causing the exposure apparatus 24, CPU read out the print pattern data from the print pattern data setting unit 25 and sends them to the exposure apparatus 24. The exposure apparatus 24 is provided with an LED driver 27 for selectively lighting LED array 28 to emit light in accordance with print pattern data upon receiving the print instruction signal. The pulse generator 20, as will be described in detail later, is equipped with features of detecting the reverse transportation of film and correcting the reverse transportation of film. Owing to the provision of the features, the transported length of film in the forward direction is accurately detected even if the film is accidentally intermittently transported or reversed, thereby enabling the print timing discriminator 21 to output a print timing signal to CPU 22 at an accurate timing according to the transported length of film. A film type data input unit 29 is used to input data of the type of film including the sensitivity or speed of film and the number of exposures in CPU 22. In accordance with the data, CPU 22 actuates the LED driver 27 to selectively energize LED array 28 so as to form a latent image in the film 15 with a controlled exposure. CPU 22 also controls a cutter 30 so as to cut off the film 15 to rolls of films having a predetermined length or a predetermined number of frames. Light emanating from each LED of the LED array 28 is transmitted by way of a flexible light guide 31 in the form of a fiber bundle comprising a considerably great number of optical fibers and emitted form the end of the light guide 31 toward the film 15. The light in the form of a small dot from the light guide 31 is focused on a margin of the film 15 so as to create a latent image of a small dot. The LED driver 27 selectively lights the LEDs of the LED array 28 to form a light pattern of a numeral or a bar code on the film 15 traveling at a constant speed. Referring to Fig. 2, partly illustrating a film on which frame numbers and bar codes are printed by the side printer constructed as above, the film 15 is formed with perforations 33 at regular spacings in both side margins. Between each row of perforations 33 and a side edge of the film 15, there is printed frame numbers with or without alphabetical characters 34 at regular spacings A. Just after each frame number 34 printed in one side margin, for example in the upper side margin as viewed in Fig. 2, there is printed a bar code 35 indicating the frame number 34. The bar codes 35 are printed at the same spacings A as that for the frame numbers. Further, in the other side margin, for example the lower in this example, there are printed DX codes 36 well known in the photographic art. These bar codes 35 and 36 are capable to be read by an optical reader well known in the art. The exposure apparatus 24 is capable of making a sharp print pattern. For favorable printing, it should be effected to measure the transported length of film with a high accuracy. For accurate measuring, a reverse correction means is provided in association with the pulse generator 20 and the print timing discriminator 21. As shown in Fig. 3, the film 15 is normally transported in the forward direction at a constant speed. The film 15 travels without any slippage between the measuring roller and therefore rotates the measuring roller 16 at a constant speed of rotation. The film possibly moves in the reverse direction shown by a dotted line when a film transporting system (not shown) stops or when the tension on the film 15 changes. The rotary encoder 18 outputs encoder pulse signals EP-A and EP-B (see Fig. 5) in A phase and B phase, respectively, with the rotation of the measuring roller 16. These encoder pulse signals EP-A and EP-B are different in phase by 90′ from each other. These encoder pulse signals EP-A and EP-B are fed to a pulse generator 81 as well as a clock pulse signal CP provided by a clock pulse generator 80. A direction discriminator 82 is comprised from the clock pulse generator 80 and pulse generator 81. The direction discriminator 82 discriminates a direction in which the film 15 is moving based on the encoder pulse signals EP-A and EP-B and the clock pulse signals CP to output forward direction pulse signals FP or reverse direction pulses RP, one for a predetermined length of transportation of the film 15. The reverse direction pulse signals RP are fed to an up-terminal of an up-down counter 85 and up-counted thereby, the forward direction pulse signals FP are fed to a down-terminal of the up-down counter 85 and down-counted thereby. A carry signal CS from the up-down counter 85 and the reverse direction pulse signals RP are fed to a NAND gate 86. The NAND gate 86 outputs a reset signal RS to a flip-flop 87 for resetting it. The flip-flop 87 outputs from its Q terminal a signal FS to a clear terminal CL of the up-down counter 85. When the flip-flop 87 is reset, it changes the signal FS to a high level (H) so as to cause the up-down counter to count pulse signals. Signals S1-S4 from four output terminals of the up-down counter 85 are fed to an AND gate 88. When a binary output is "0", the AND gate 88 changes its output signal SS to a high level (H) so as to set the flip-flop 87. When the flip-flop 87 is set, it changes the signal FS to a high level (H), thereby stopping the up-down counter 85. The forward direction pulse signals FP are also fed to a timer circuit 89. The timer circuit 89 outputs a signal TS to an AND gate 90 as well as the signal FS from the flip-flop 87. The AND gate 90 outputs a signal PS to CPU 22. CPU 22, as long as receiving a signal PS of a high level (H) from the AND gate 90, continuously provides a print signal to the LED driver 27. In the side printing apparatus described above, the up-down counter 85 starts to up-count pulse signals upon the provision of a first reverse direction pulse signal RP from the pulse generator 81 or to down-count pulse signals upon the provision of a first forward direction pulse signal FP from the pulse generator 81. Before the up-down counter has down-counted to zero (0), that is, until the film is transported in the forward direction by a length by which the film has been reversely moved, any exposure is prohibited so as to avoid double exposure. It is possible to actuate the timer circuit 89 timely at the provision of a carry signal CS from the up-down counter 85 so as to output a signal to CPU 22, thereby starting printing. The direction discriminator 82 is shown in detail in Fig. 4. Pulses in one phase, for example in B phase, from the rotary encoder 18 are fed to D-terminal of D-type flip-flop 92. Fed to a clock input terminal or T-terminal of the D-type flip-flop 92 is a clock pulse signal CL from the clock pulse generator 80. The D-type flip-flop 92 latches the encoder pulse signal EP-B at a timing of the rising of a clock pulse signal CL and provides a film transportation condition signal HS from the Q-terminal. The D-type flip-flop 92 also outputs a signal LS, which is reversed in level against to the signal HS from the Q-terminal, from the Q -terminal thereof. Another D-type flip-flop 93, which is connected to the same type flip-flop 92, latches the film transportation condition signal HS from the Q-terminal of the D-type flip-flop 92 at a timing of the rising of a clock pulse signal CL and outputs a latch condition signal MS from the Q-terminal. An AND gate 94 is connected with an output HS from the Q-terminal of the D-type flip-flop 92, encoder pulse signals EP-A in A phase, an output signal NS from the Q -terminal of the D-type flip-flop 93 and delayed clock pulse signal DP from a delay circuit 95. When all of the first three signals or pulse signals HS, EP-A and NS are in a high level (H), the AND gate 94 transmits the delayed clock pulse signals DP as forward direction pulse signal FP. The delay circuit 95 delays the clock pulse signals CL from the clock pulse generator 80 for a predetermined interval and outputs them as the delayed clock pulse signal DP. The delay interval is determined shorter than the period of the clock pulse signal CL for a reason described later. The delay circuit 95 consists, for example, of a plurality of IC gates connected one another. An AND gate 96 is connected with an output LS from the Q -terminal of the D-type flip-flop 92, encoder pulse signals EP-A in A phase, an output signal MS from the Q-terminal of the D-type flip-flop 93 and delayed clock pulse signal DP from a delay circuit 95. When all of the three pulse signals LS, EP-A, MS and DP are in a high level (H), the AND gate 96 transmits the delayed clock pulse signals DP as reverse direction pulse signal RP. Referring to Fig. 5 illustrating a timing chart of various signals in the direction discriminator 82, the film 15 moves in the forward direction before a line T and in the reverse direction after the line T. When the film 15 moves in the forward direction so as to rotate the rotary encoder 18 in the same direction, the rotary encoder 18 outputs encoder pulse signals EP-B in phase B. Upon the rising of the encoder pulse signal EP-B, the leading edge of a first clock pulse signal CL causes the D-type flip-flop 92 to change the output signal HS from its Q-terminal to a high level (H) from a low level (L), the leading edge of a subsequent clock pulse signal CL causes the D-type flip-flop 93 to change the output signal NS from its Q -terminal to a low level (L) from a high level (H). Between the changes of output signals HS and NS of the D-type flip-flops 92 and 93, an encoder pulse signal EP-A in phase A is maintained in a high level and the AND gate 94 receives one delayed clock pulse signal DP from the delay circuit 95. As a result, the AND gate 94 outputs one forward direction pulse signal FP. If the film 15 moves in the reverse direction and thereby rotating the rotary encoder 18 in the same direction, upon the falling of the encoder pulse signal EP-B, the leading edge of a first clock pulse signal CL causes the D-type flip-flop 92 to change its output signal LS from the Q -terminal to a high level (H) from a low level (L), the leading edge of a subsequent clock pulse signal CL causes the D-type flip-flop 93 to change the output signal MS from the Q-terminal to a low level (L) from a high level (H). Between the changes of output signals LS and MS of the D-type flip-flops 92 and 93, an encoder pulse signal EP-A in phase A is maintained in a high level and an AND gate 96 receives one delayed clock pulse signal DP from the delay circuit 95. As a result, the AND gate 96 outputs one reverse direction pulse signal RP. Because a clock pulse signal CL latches an encoder pulse signal, it is essential that the period of clock pulse signal is sufficiently higher than a maximum period of encoder pulse signal. However, because the clock pulse signals are counted by the up-down counter 85, the frequency on which a clock pulse signal is generated is lower than 10MHz the clock pulse signal CL is delayed and transmitted as a forward direction pulse signal or a reverse direction pulse signal through the AND gate 64 or 66, the most desirable frequency is 1MHz. A pulse width of the clock pulse signal CL has a close relationship to the delay time by the delay circuit 95 and the maximum pulse width is expressed by "pulse period" - "delay time" - "operating time of element". The pulse width, which is a duty rate, is most preferable to be 50%. To obtain an output from the AND gate 94 or 96, the delay time of a clock pulse signal CL by the delay circuit 95 is necessary to be shorter than the pulse width of the clock pulse signal CL. For example, when the frequency on which the clock pulse signal CL is generated is 1MHz and the duty rate is 50%, the delay time should be less than 0.5 second. Although, in the direction discriminator 82 shown in Fig. 4, one forward or reverse direction pulse signal FP or RP is provided every encoder pulse signal EP-A, it is required to provide more than one forward or reverse direction pulse signals every encoder pulse signal in order to effect the precise measurement of transported length of the film 15. For this requirement, it is preferred to incorporate another preferred direction discriminator shown Fig. 6 in which AND gates 97 and 98, OR gates 99 and 100 and an inverter 101 are added to the direction discriminator 82 shown in Fig. 4. As shown, the inverter 101 acts to inverse the polarity of encoder pulse signal EP-A in A phase. The inversed polarity of encoder pulse signal IEP-A is fed to the AND gates 97 and 98. The AND gate 97 is further connected with an output signal LS from the Q -terminal of the D-type flip-flop 92, an output signal MS from the Q-terminal of the D-type flip-flop 93 and a delayed clock pulse signal DP from a delay circuit 95 as well as the inversed polarity of encoder pulse signal IEP-A. When at least one of the AND gates 97 and 98 provides an output signal, the OR gate 99 outputs a forward direction pulse signal FP to the up-down counter 85. In a similar manner, the AND gate 98 is connected with the inversed polality of encoder pulse signal IEP-A from the inverter 101, an output signal HS from the Q -terminal of the D-type flip-flop 92, an output signal NS from the Q-terminal of the D-type flip-flop 93 and a delayed clock pulse signal DP from a delay circuit 95. When at least one of the AND gates 97 and 98 provides an output signal, the OR gate 100 outputs a reverse direction pulse signal RP to the up-down counter 85. In this embodiment, the AND gate 94 outputs a pulse signal at a timing of the rising of an encoder pulse signal EP-B and the AND gate 97 outputs a pulse signal at a timing of the falling of an encoder pulse signal EP-B when the film 15 is forwarded, so that two forward direction pulse signals FP are output. Similarly, the AND gate 96 outputs a pulse signal at a timing of the falling of an encoder pulse signal EP-B and the AND gate 98 outputs a pulse signal at a timing of the rising of an encoder pulse signal EP-B when the film is reversed, so that two reverse direction pulse signals RP are output. Fig. 7 shows another embodiment in which four forward or reverse direction pulse signal FP or RP are provided for every encoder pulse signal in order to effect more precise measurement of transported length of the film 15. In this embodiment, D-type flip-flops 102 and 103 and AND gates 104-107 are added to the direction discriminator shown Fig. 6. As shown, the D-type flip-flop 102 receives an encoder pulse signal EP-A at its D-terminal and a clock pulse signal at its clock terminal T. The D-type flip-flop 102 latches the encoder pulse signal EP-A at a timing of a clock pulse signal CL so as to output a condition signal from its Q-terminal. Another D-type flip-flop 103 latches an output from the Q-terminal of the D-type flip-flop 102 at a timing of another clock pulse signal CL. The AND gate 104 is connected to outputs FS, N and P from the Q-terminal of the D-type flip-flop 92, Q -terminal of the D-type flip-flop 102 and the Q-terminal of the D-type flip-flop 103, respectively and receives a delay clock pulse signal DP from the delay circuit 95. Output from the AND gate 104 is sent to the OR gate 99. Similarly, the AND gate 105 is connected to outputs LS, Q and R from the Q -terminal of the D-type flip-flop 92, Q-terminal of the D-type flip-flop 102 and the Q -terminal of the D-type flip-flop 103, respectively, and receives a delay clock pulse signal DP from the delay circuit 95. Output from the AND gate 105 is sent to the OR gate 99. The OR gate 99 transmits as a forward direction pulse signal any one of outputs from the AND gates 94, 97, 104 and 105. The AND gate 106 is connected to outputs LS, N and P from the Q -terminal of the D-type flip-flop 92, Q -terminal of the D-type flip-flop 102 and the Q-terminal of the D-type flip-flop 103, respectively and receives a delay clock pulse signal DP from the delay circuit 95. Output from the AND gate 106 is sent to the OR gate 100. Similarly, the AND gate 107 is connected to outputs HS, Q and R from the Q-terminal of the D-type flip-flop 92, Q -terminal of the D-type flip-flop 102 and the Q-terminal of the D-type flip-flop 103, respectively, and receives a delay clock pulse signal DP from the delay circuit 95. Output from the AND gate 107 is sent to the OR gate 100. The OR gate 100 transmits any one of outputs from the AND gatea 94, 97, 104 and 105 as a reverse direction pulse signal. In this embodiment, because the AND gate 104 outputs a pulse signal at a timing of the falling of an encoder pulse signal EP-A and the the AND gate 105 outputs a pulse signal at a timing of the rising of an encoder pulse signal EP-A in addition to two forward direction pulse signals for one encoder pulse signal EP-B, four forward direction pulse signals are output upon the forward movement of the film 15. Similarly, because the AND gate 106 outputs a pulse signal at a timing of the falling of an encoder pulse signal EP-A and the the AND gate 107 outputs a pulse signal at a timing of the rising of an encoder pulse signal EP-A in addition to two forward direction pulse signals for one encoder pulse signal EP-B, four forward direction pulse signals are output upon the reverse movement of the film 15. It is possible to replace the AND gates with monostable multivibrators 111 and 112. As shown in Fig. 8, a D-type flip-flop 110 receives an encoder pulse signal EP-B at its D-terminal and a clock pulse signal CP from the clock pulse generator 80 at its T-terminal. The D-type flip-flop 110 latches the encoder pulse signal EP-B at a timing of the clock pulse signal CP. A monostable multivibrator 111, which receives a pulse signal SP output from the Q-terminal of the D-type flip-flop 110, outputs a forward direction pulse signal FP at every rising of the input pulse signal SP. The monostable multivibrator 111 also receives an encoder pulse signal EP-A at its reset terminal RP. When the encoder pulse signal EP-A is at a low level (L), the monostable multivibrator 111 is prevented from outputting a forward direction pulse signal FP. Another monostable multivibrator 112, which receives a pulse signal TP output from the Q -terminal of the D-type flip-flop 110, outputs a reverse direction pulse signal RP at every rising of the input pulse signal TP. The monostable multivibrator 112 also receives an encoder pulse signal EP-A at its reset terminal R. When the encoder pulse signal EP-A is at a low level (L), the monostable multivibrator 112 is prevented from outputting a reverse direction pulse signal RP. The pulse widths of the forward direction pulse signal FP and the reverse direction pulse signal RP are determined depending upon capacity and resistance of the monostable multivibrator 111 and the monostable multivibrator 112, respectively. Periods at which the monostable multivibrators 111 and 112 output pulse signals are shorter than that of the clock pulse signal so that the forward direction pulse signal FP and the reverse direction pulse signal RP do not overlap. Referring to Fig. 9 illustrating a timing chart of various signals and pulse signals provided in the direction discriminator 82 shown in Fig. 8, the film 15 moves in the forward direction before a line T and in the reverse direction after the line T. During the forward rotation of the rotary encoder 18, when an encoder pulse signal EP-B rises, the leading edge of a clock pulse signal CL causes the D-type flip-flop 110 to change the output signal SP from its Q-terminal to a high level (H) from a low level (L). Because the encoder pulse signal EP-A, which is fed to the reset terminal R of the monostable multivibrator 111, is at a high level (H), the monostable multivibrator 111 outputs a certain width of forward direction pulse signal FP due to the change of the pulse signal SP output from the Q-terminal of the D-type flip-flop 110 to a high level (H) from a Low level (L). On the other hand, during the reverse rotation of the rotary encoder 18, when an encoder pulse signal EP-B falls, the leading edge of a clock pulse signal CP causes the D-type flip-flop 110 to change the output signal TP from its Q -terminal to a high level (H) from a low level (L). Because the encoder pulse signal EP-A, which is fed to the reset terminal R of the monostable multivibrator 112, is at a high level (H), the monostable multivibrator 112 outputs a certain width of reverse direction pulse signal RP due to the change of the pulse signal TP output from the Q-terminal of the D-type flip-flop 111 to a high level (H) from a Low level (L). Referring to Fig. 10 illustrating a variation of the direction discriminator 82 shown in Fig. 8 in which two pulse signals are provided for a period of encoder pulse signal and monostable multivibrators 124 and 125, an inverter 126 and OR gates 127 and 128 are added to the circuit of a Fig. 8. The inverter 126 acts to inverse the polarity of encoder pulse signal EP-A in A phase. The inversed polarity of encoder pulse signal IEP-A is fed to both of reset terminals R of the monostable multivibrator 124 and 125. The monostable multivibrator 124 receives a pulse signal SP from the Q-terminal of the D-type flip-flop 110 and outputs at its Q-terminal thereof a pulse signal at a timing of falling of the pulse signal SP. The OR gate 127, which receives outputs from the Q-terminals of the monostable multivibrator 111 and 124, transmits one of the outputs as a forward direction pulse signal FP therefrom when it receives either one of the output. The monostable multivibrator 124 outputs a pulse signal at a timing of the falling of encoder pulse signal EP-B when the film moves in the forward direction and the monostable multivibrator 125 outputs a pulse signal at a timing of the rising of encoder pulse signal EP-B when the film moves in the reverse direction. Referring to Fig. 11 illustrating a variation of the direction discriminator 82 shown in Fig. 10 in which a D-type flip-flop 130 and monostable multivibrators 131, 132 and 133 are added to the circuit of a Fig. 9. The D-type flip-flop 130 receives an encoder pulse signal EP-A at its D-terminal and a clock pulse signal CP from the clock pulse generator 80 at its T-terminal. The D-type flip-flop 130 latches the encoder pulse signal EP-A at a timing of the clock pulse signal CP. The monostable multivibrator 131, which receives a pulse signal VP output from the Q-terminal of-the D-type flip-flop 130 as a trigger input, outputs a pulse signal at the falling of the input pulse signal VP. The monostable multivibrator 131, which receives a pulse signal SP output from the Q -terminal of the D-type flip-flop 110 at its reset terminal R, is prevented from outputting a pulse signal at its Q-terminal when the input pulse signal SP is at a low level (L). The monostable multivibrator 132, which receives a pulse signal VP output from the Q -terminal of the D-type flip-flop 130 as a trigger input, outputs a pulse signal at the rising of the input pulse signal VP. The monostable multivibrator 132, which receives a pulse signal TP output from the Q -terminal of the D-type flip-flop 110 at its reset terminal R, is prevented from outputting a pulse signal at its Q-terminal when the input pulse signal TP is at a low level (L). The monostable multivibrator 133, which receives a pulse signal WP output from the Q -terminal of the D-type flip-flop 130 as a trigger input, outputs a pulse signal at the rising of the input pulse signal VP. The monostable multivibrator 133, which receives a pulse signal TP output from the Q-terminal of the D-type flip-flop 110 at its reset terminal R, is prevented from outputting a pulse signal at its Q-terminal when the input pulse signal TP is at a low level (L). The monostable multivibrator 134, which receives a pulse signal WP output from the Q-terminal of the D-type flip-flop 130 as a trigger input, outputs a pulse signal at the falling of the input pulse signal WP. The monostable multivibrator 134, which receives a pulse signal SP output from the Q-terminal of the D-type flip-flop 110 at its reset terminal R, is prevented from outputting a pulse signal at its Q-terminal when the input pulse signal SP is at a low level (L). The OR gate 127, which is connected to output pulse signals from the Q-terminals of the four monostable multivibrator 111, 124, 131 and 132, outputs a forward direction pulse signal FP when it actually receives at least any one of the output pulse signals. Similarly, the OR gate 128, which is connected to output pulse signals from the Q-terminals of the four monostable multivibrator 112, 125, 133 and 134, outputs a reverse direction pulse signal RP when it actually receives at least any one of the output pulse signals. The monostable multivibrator 131 outputs a pulse signal at a timing of the falling of an encoder pulse signal EP-A and the monostable multivibrator 132 outputs a pulse signal at a timing of the rising of the encoder pulse signal EP-A when the film moves in the forward direction. The monostable multivibrator 133 outputs a pulse signal at a timing of the falling of an encoder pulse signal EP-A and the monostable multivibrator 134 outputs a pulse signal at a timing of the rising of the encoder pulse signal EP-A when the film moves in the reverse direction. Thereby, four forward or reverse direction pulse signals are provided for each period of encoder pulse signal. In any embodiment described above, because an encoder pulse signal is latched by a clock pulse signal generated at a high frequency, if the film causes oscilations in the both directions of movement, the direction of movement of the film is restrictively determined to be either forward or reverse between at least two consequtive clock pulse signals. The circuit for discriminating the direction of movement of the film is adapted to provided only one forward or reverse direction pulse signal between the two consecutive clock pulse signals, so as to certainly prevent the overlap of forward and reverse direction pulse signals. The D-type flip-flop used as a latch means in the above embodiments may be replaced with a JK-type flip-flop. Furthermore, the delay circuit in the above embodiments may take the form of a cascaded connection of two monostable multivibrators. As described above, by accurately detecting the reversed movement of the film and effecting a correction of movement of the film, bar-codes are side printed on the film at precise locations and no double exposure is caused.

Claims: A bar code printing apparatus for printing a latent image of a bar code in a lengthwise side margin of a film continuously transported in a lengthwise direction by the use of a light emitting element array, said apparatus comprising: a rotary encoder (18) driven by said moving film to output two encoder pulse signals (EP-A,EP-B) in different two phases every time the film has moved a predetermined length in the forward or reverse direction; a direction discrimination means (82) for detecting the direction in which said film is transported based on said encoder pulse signals to output a forward direction pulse signal (FP) indicating that said film is transported in a forward direction and a reverse direction pulse signal (RP) indicating that said film is transported in a reverse direction; an up-down counter (85) for counting up either one of said forward direction and reverse direction pulse signals and down the other, thereby correctively regulating a transported length of film in said lengthwire direction; characterized in that said direction discrimination means (82) comprises: a clock pulse generating circuit (80) for generating clock pulse signals (CL) having a frequency higher than the frequency of the encoder pulse signals; a latch circuit (92,110) for latching at least one of said encoder pulse signals (EP-B) in different phases in synchronism with said clock pulse signal (CL) means (94,95,96,111,112) for combining the at least one of the latched encoder pulse signals (EP-B), the other encoder pulse signal (EP-A) having a different phase and the clock pulse signal (CL) in order to provide said direction pulse signals at a frequency lower than the frequency of the clock pulse signal in a manner such that at any one time either only the forward (FP) or only the reverse direction pulse signal (RP) is outputted from the direction discrimination means. The bar code printing apparatus according to claim 1, wherein said means for combining comprise: at least two monostable multivibrators (111,112,124,125, 131,132,133,134) each triggered by the at least one of the latched encoder pulse signals (EP-A,EP-B). The bar code printing apparatus according to claim 1, wherein said means for combining comprise: a first delay circuit (95) for delaying said clock pulse signal to output it as a delayed clock pulse signal (DP), a second delay circuit (93) for delaying the latched encoder pulse signal, and at least two logic gates (94,96,97,98) each connected to said first and second delay circuits and said latch circuit (92).

Inventors: AKIYOSHI NOBUYASU C O FUJI PHO, SHIMIZU SHIGEHISA C O FUJI PHO, SHIMODA TOMOYUKI C O FUJI PHOT, AKIYOSHI, NOBUYASU C/O FUJI PHOTO FILM CO., LTD, SHIMIZU, SHIGEHISA C/O FUJI PHOTO FILM CO., LTD, SHIMODA, TOMOYUKI C/O FUJI PHOTO FILM CO., LTD
Applicants: FUJI PHOTO FILM CO LTD, FUJI PHOTO FILM CO., LTD.
Application year: 1989
Main classification: G06K1
IPC codes: G06K1, G03B27, G03C1